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Fouling remains a widespread challenge as its nonspecific and uncontrollable character limits the performance of materials and devices in numerous applications. Although many promising antifouling coatings have been developed to reduce or even prevent this undesirable adhesion process, most of them suffer from serious limitations, specifically in scalability. Whereas scalability can be particularly problematic for covalently bound antifouling polymer coatings, replacement by physisorbed systems remains complicated as it often results in less effective, low-density films. In this work, we introduce a two-step adsorption strategy to fabricate high-density block copolymer-based antifouling coatings on hydrophobic surfaces, which exhibit superior properties compared to one-step adsorbed coatings. The obtained hybrid coating manages to effectively suppress the attachment of both lysozyme and bovine serum albumin, which can be explained by its dense and homogeneous surface structure as well as the desired polymer conformation. In addition, the intrinsic reversibility of the adhered complex coacervate core micelles allows for the successful triggered release and regeneration of the hybrid coating, resulting in full recovery of its antifouling properties. The simplicity and reversibility make this a unique and promising antifouling strategy for large-scale underwater applications.

Polymer brushes are thin polymer films that consist of densely grafted, chain-end tethered polymers. These thin polymer films can be produced either by anchoring presynthesized chain-end functional polymers to the surface of interest ("grafting to"), or by using appropriately modified surfaces to facilitate growth of polymer chains from the substrate ("grafting from"). The vast majority of polymer brushes that have been prepared and studied so far involved chain-end tethered polymer assemblies that are anchored to the surface via covalent bonds. In contrast, the use of noncovalent interactions to prepare chain-end tethered polymer thin films is much less explored. Anchoring or growing polymer chains using noncovalent interactions results in supramolecular polymer brushes. Supramolecular polymer brushes may possess unique chain dynamics as opposed to their covalently tethered counterparts, which could provide avenues to, for example, renewable or (self-)healable surface coatings. This Perspective article provides an overview of the various approaches that have been used so far to prepare supramolecular polymer brushes. After presenting an overview of the various approaches that have been used to prepare supramolecular brushes via the "grafting to" strategy, examples will be presented of strategies that have been successfully applied to produce supramolecular polymer brushes via "grafting from" methods.

In this work, we design a multi-category inverse design neural network to map ordered periodic structures to physical parameters. The neural network model consists of two parts, a classifier and Structure-Parameter-Mapping (SPM) subnets. The classifier is used to identify structures, and the SPM subnets are used to predict physical parameters for desired structures. We also present an extensible reciprocal-space data augmentation method to guarantee the rotation and translation invariant of periodic structures. We apply the proposed network model and data augmentation method to two-dimensional diblock copolymers based on the Landau–Brazovskii model. Results show that the multi-category inverse design neural network has high accuracy in predicting physical parameters for desired structures. Moreover, the idea of multi-categorization can also be extended to other inverse design problems.

This work deals with molecular mobility in renewable block copolymers based on polylactide (PLA) and poly(propylene adipate) (PPAd). In particular, we assess non-trivial effects on the mobility arising from the implementation of crystallization. Differential scanning calorimetry, polarized light microscopy and broadband dielectric spectroscopy were employed in combination for this study. The materials were subjected to various thermal treatments aiming at the manipulation of crystallization, namely, fast and slow cooling, isothermal melt- and cold-crystallization. Subsequently, we evaluated the changes recorded in the overall thermal behavior, semicrystalline morphology and molecular mobility (segmental and local). The molecular dynamics map for neat PPAd is presented here for the first time. Unexpectedly, the glass transition temperature, Tg, in the amorphous state drops upon crystallization by 8–50 K. The drop becomes stronger with the increase in the PPAd fraction. Compared to the amorphous state, crystallization leads to significantly faster segmental dynamics with severely suppressed cooperativity. For the PLA/PPAd copolymers, the effects are systematically stronger in the cold- as compared to the melt-crystallization, whereas the opposite happens for neat PLA. The local βPLA relaxation of PLA was, interestingly, recorded to almost vanish upon crystallization. This suggests that the corresponding molecular groups (carbonyl) are strongly involved and immobilized within the semicrystalline regions. The overall results suggest the involvement of either spatial nanoconfinement imposed on the mobile chains within the inter-crystal amorphous areas and/or a crystallization-driven effect of nanophase separation. The latter phase separation seems to be at the origins of the significant discrepancy recorded between the calorimetric and dielectric recordings on Tg in the copolymers. Once again, compared to more conventional techniques such as calorimetry, dielectric spectroscopy was proved a powerful and quite sensitive tool in recording such effects as well as in providing indirect indications for the polymer chains’ topology.

Fouling on filtration membranes is induced by the nonspecific interactions between the membrane surface and the foulants, and effectively hinders their efficient use in various applications. Here, we established a facile method for the coating of membrane surface with a dual stimuli-responsive antifouling microgel system enriched with a high polyzwitterion content. Different poly(sulfobetaine) (PSB) zwitterionic polymers with defined molecular weights and narrow dispersities were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization and integrated onto poly(N-vinylcaprolactam) (PVCL) microgels via a controlled dosage of a cross-linker, adapting a precipitation polymerization technique to obtain a core-shell microstructure. Increasing the PSB macro-RAFT concentration resulted in a shift of both upper critical solution temperature and lower critical solution temperature toward higher temperatures. Cryogenic transmission electron microscopy at different temperatures suggested the formation of a core-shell morphology with a PVCL-rich core and a PSB-rich shell. On the other hand, the significant variations of different characteristic proton signals and reversible phase transitions of the microgel constituents were confirmed by temperature-dependent 1H NMR studies. Utilizing a quartz crystal microbalance with dissipation monitoring, we have been able to observe and quantitatively describe the antipolyelectrolyte behavior of the zwitterionic microgels. The oscillation frequency of the sensor proved to change reversibly according to the variations of the NaCl concentration, showing, in fact, the effect of the interaction between the salt and the opposite charges present in the microgel deposited on the sensor. Poly(ethersulfone) membranes, chosen as the model surface, when functionalized with zwitterionic microgel coatings, displayed protein-repelling property, stimulated by different transition temperatures, and showed even better performances at increasing NaCl concentration. These kinds of stimuli-responsive zwitterionic microgel can act as temperature-triggered drug delivery systems and as potential coating materials to prevent bioadhesion and biofouling as well.

Poly(diisopropylaminoethyl methacrylate) (PDPA) is a pH- and thermally responsive water-soluble polymer. This study deepens the understanding of its phase separation behavior upon heating. Phase separation upon heating was investigated in salt solutions of varying pH and ionic strength. The effect of the counterion on the phase transition upon heating is clearly demonstrated for chloride-, phosphate-, and citrate-anions. Phase separation did not occur in pure water. The buffer solutions exhibited similar cloud points, but phase separation occurred in different pH ranges and with different mechanisms. The solution behavior of a block copolymer comprising poly(dimethylaminoethyl methacrylate) (PDMAEMA) and PDPA was investigated. Since the PDMAEMA and PDPA blocks phase separate within different pH- and temperature ranges, the block copolymer forms micelle-like structures at high temperature or pH. Poly(diisopropylaminoethyl methacrylate) (PDPA) is a pH-and thermally responsive water-soluble polymer. This study deepens theunderstanding of its phase separation behavior upon heating. Phase separationupon heating was investigated in salt solutions of varying pH and ionicstrength. The effect of the counterion on the phase transition upon heating isclearly demonstrated for chloride-, phosphate-, and citrate-anions. Phaseseparation did not occur in pure water. The buffer solutions exhibited similarcloud points, but phase separation occurred in different pH ranges and withdifferent mechanisms. The solution behavior of a block copolymer comprisingpoly(dimethylaminoethyl methacrylate) (PDMAEMA) and PDPA wasinvestigated. Since the PDMAEMA and PDPA blocks phase separate withindifferent pH- and temperature ranges, the block copolymer forms micelle-likestructures at high temperature or pH

International audience; Functional nanoporous polymeric materials have been prepared from novel polystyrene-block-poly(ethylene oxide) (PS-b-PEO) diblock copolymer precursors containing a reversible boronate ester junction between both blocks. To this purpose, homopolymers presenting either a boronic acid or a (nitro)catechol end functionality were synthesized. The coupling of each homopolymer presenting complementary chemical functions was successfully achieved under mild conditions and allowed for the generation of the corresponding boronate ester-containing diblock copolymers. Upon orientation of these precursors on silicon wafers via solvent vapor annealing, the resulting films were submitted to PEO etching through selective cleavage of the boronate ester junction under mild acidic conditions. SEM micrographs of the as-obtained thin films revealed the generation of 12 nm-diameter oriented cylindrical nanopores perpendicular to the silicon support surface.

Immunotherapy is deemed one of the most powerful therapeutic approaches to treat cancer. However, limited response and tumor specificity are still major challenges to address. Herein, mannosylated polycations targeting mannose receptor are developed as vectors for plasmid DNA (pDNA)-based vaccines to improve selective delivery of genetic material to antigen presenting cells and enhance immune cell activation. Three diblock glycopolycations (M15A12, M29A25, and M58A45) and two triblock copolymers (M29A29B9 and M62A52B32) are generated by using mannose (M), agmatine (A), and butyl (B) derivatives to target CD206, complex nucleic acids, and favor the endosomal escape, respectively. All glycopolycations efficiently complex pDNA at N/P ratios

This article belongs to the Special Issue Block Copolymers with Crystallizable Blocks: Synthesis, Self-Assembly and Applications., The crystallization and morphology of two linear diblock copolymers based on polymethylene (PM) and poly(vinylidene fluoride) (PVDF) with compositions PM23-b-PVDF77 and PM38-b-PVDF62 (where the subscripts indicate the relative compositions in wt%) were compared with blends of neat components with identical compositions. The samples were studied by SAXS (Small Angle X-ray Scattering), WAXS (Wide Angle X-ray Scattering), PLOM (Polarized Light Optical Microscopy), TEM (Transmission Electron Microscopy), DSC (Differential Scanning Calorimetry), BDS (broadband dielectric spectroscopy), and FTIR (Fourier Transform Infrared Spectroscopy). The results showed that the blends are immiscible, while the diblock copolymers are miscible in the melt state (or very weakly segregated). The PVDF component crystallization was studied in detail. It was found that the polymorphic structure of PVDF was a strong function of its environment. The number of polymorphs and their amount depended on whether it was on its own as a homopolymer, as a block component in the diblock copolymers or as an immiscible phase in the blends. The cooling rate in non-isothermal crystallization or the crystallization temperature in isothermal tests also induced different polymorphic compositions in the PVDF crystals. As a result, we were able to produce samples with exclusive ferroelectric phases at specific preparation conditions, while others with mixtures of paraelectric and ferroelectric phases., Technical and human support by SGIker (UPV/EHU) is gratefully acknowledged for the TEM images acquired. We would also like to acknowledge funding from MINECO through grant MAT2017-83014-C2-1-P and from the Basque Government through grant IT1309-19. This research was funded by ALBA synchrotron facility through granted proposal 2020084441.

A growing body of work shows that the phase behavior of supramolecular polymers assembled from telechelic building blocks featuring binding motifs at the two termini is quite similar to that of conventional block copolymers. However, it remains unclear how crystallization of the phase formed by the binding motifs, which occurs in many supramolecular polymers, affects the phase morphology of such materials. Here we report a systematic investigation of a series of supramolecular polymers based on poly(ethylene-co-butylene) (PEB) telechelics and the complementary H-bonding pair isophthalic acid-pyridine (IPA-Py). These polymers were designed to feature two blocks that assemble into an amorphous low-glass-transition phase formed by the PEB segments and crystalline domains consisting of the binding motifs. The nature of the latter was systematically varied via the choice of the pyridine employed. The influence of the binding motif on the phase morphology and thereby properties of these supramolecular polymers was investigated by means of thermal analysis, polarized optical microscopy, (dynamic) mechanical analyses, small-angle X-ray scattering, and transmission electron microscopy. In the melted state, all materials assembled into hexagonal phases. However, when cooled below the crystallization temperature of the IPA-Py domains, three different scenarios were observed: breakout crystallization resulting in complex morphologies, retention of the melt morphology, and the formation of a lamellar phase.

A versatile approach towards porous polystyrene-based frameworks functionalized with triazolyl moieties is reported. These porous materials were prepared from poly( D , L -lactic acid)-block-poly(styrene-stat-4-azidomethylstyrene) (PLA-b-P(S-stat-4-AMS)) diblock copolymer precursors. Upon macroscopic orientation and subsequent alkaline hydrolysis of the PLA block, such triazolyl-containing porous polystyrenes were produced. Experimentally, a PLA macroinitiator was synthesized by ring-opening polymerization (ROP) of D , l -lactide using a heterobifunctional initiator. The prepared macroinitiator containing a terminal tertiary α-bromo ester group allowed for further ATRP statistical copolymerization of styrene and 4-azidomethylstyrene, affording the second block, i.e. the P(S-stat-4-AMS) block. The styrene to 4-azidomethylstyrene molar ratio was tuned to obtain various compositions of the hydrophobic block. PLA macroinitiators and corresponding PLA-b-P(S-stat-4-AMS) diblock copolymers were fully characterized by size exclusion chromatography (SEC), 1H and 13C nuclear magnetic resonance (NMR), Fourier Transform Infrared (FT-IR) spectroscopy, and differential scanning calorimetry (DSC). Functionalization of PLA-b-P(S-stat-4-AMS) diblock copolymers with p-tolylacetylene or 2-methyl-3-butyn-2-ol was carried out via copper-catalyzed azide-alkyne cycloaddition (CuAAC), yielding triazole ring in high yields (>90%). Finally, the porous structure of such functional polystyrene frameworks was examined by scanning electron microscopy (SEM).

Native plant cellulose has an intrinsic supramolecular structure. Consequently, it can be isolated as nanocellulose species, which can be utilized as building blocks for renewable nanomaterials. The structure of cellulose also permits its end-wise modification, i.e., chemical reactions exclusively on one end of a cellulose chain or a nanocellulose particle. The premises for end-wise modification have been known for decades. Nevertheless, different approaches for the reactions have emerged only recently, because of formidable synthetic and analytical challenges associated with the issue, including the adverse reactivity of the cellulose reducing end and the low abundance of newly introduced functionalities. This Review gives a full account of the scientific underpinnings and challenges related to end-wise modification of cellulose nanocrystals. Furthermore, we present how the chemical modification of cellulose nanocrystal ends may be applied to directed assembly, resulting in numerous possibilities for the construction of new materials, such as responsive liquid crystal templates and composites with tailored interactions.

Polymers 13(18), 3131 (2021). doi:10.3390/polym13183131, Polypeptoids, a class of synthetic peptidomimetic polymers, have attracted increasing attention due to their potential for biotechnological applications, such as drug/gene delivery, sensing and molecular recognition. Recent investigations on the solution self-assembly of amphiphilic block copolypeptoids highlighted their capability to form a variety of nanostructures with tailorable morphologies and functionalities. Here, we review our recent findings on the solutions self-assembly of coil-crystalline diblock copolypeptoids bearing alkyl side chains. We highlight the solution self-assembly pathways of these polypeptoid block copolymers and show how molecular packing and crystallization of these building blocks affect the self-assembly behavior, resulting in one-dimensional (1D), two-dimensional (2D) and multidimensional hierarchical polymeric nanostructures in solution., Published by MDPI, Basel

In this work we constructed a detailed phase diagram for the solutions of ideal diblock-copolymers and compared such diagram with that obtained during polymerization-induced self-assembly (PISA), a wide range of polymer concentrations as well as chain compositions was studied. As the length of the solvophobic block nB increases (the length of the solvophilic block nA was fixed), the transition from spherical micelles to cylinders and further to vesicles (lamellae) occurs. We observed a rather wide transition region between the spherical and cylindrical morphology in which the system contains a mixture of spheres and short cylinders, which appear to be in dynamic equilibrium, the transition between the cylinders and vesicles was found to be rather sharp. Next, upon increasing the polymer concentration in the system, the transition region between the spheres and cylinders shifts towards lower nB/nA values, a similar shift but with less magnitude was observed for the transition between the cylinders and vesicles. Such behavior was attributed to the increased number of contacts between the micelles at higher polymer volume concentrations. We also found that the width of the stability region of the cylindrical micelles for small polymer volume concentrations is in good quantitative agreement with the predictions of analytical theory. The obtained phase diagram for PISA was similar to the case of presynthesized diblock copolymer, however, the positions of the transition lines for PISA are slightly shifted towards higher nB/nA values in comparison to the presynthesized diblock copolymers, which is more pronounced for the case of the cylinders-to-vesicles transition. We believe that the reason for such behavior is the polydispersity of the core-forming blocks: The presence of the short and long blocks being located at the micelle interface and in its center, respectively, helps to reduce the entropy losses due to the insoluble block stretching, which leads to the increased stability of more curved micelles.

We investigate the electrical response of the insulating diblock copolymer system (DBC) filled with conductive spherical fillers depending on the affinities of these fillers for copolymer blocks and the interaction between fillers. We demonstrate that the contrast (difference) between the affinities of the fillers for dissimilar copolymer blocks is a decisive factor that determines the distribution of these fillers in the DBC system. The distribution of filler particles, in turn, is found to be directly related to the electrical response of the DBC-particle composite. In particular, increasing the affinity contrast above a certain threshold value results in the insulator-conductor transition. This transition is found to be caused by the preferential localization of the fillers in the microphases of the DBC system having larger affinity for these fillers. The effect of the interaction between fillers is found to be secondary to the described effect of the affinity contrast that dominates in determining the distribution of fillers in the composite. This effect of the inter-particle interactions is shown to be significant only when the affinity contrast and filler volume fraction are sufficiently large., Finanziert durch den Open-Access-Publikationsfonds der Westfälischen Wilhelms-Universität Münster (WWU Münster).

Topology and defects are of fundamental importance for ordered structures on all length scales. Despite extensive research on block copolymer self-assembly in solution, knowledge about topological defects and their effect on nanostructure formation has remained limited. Here, we report on the self-assembly of block copolymer discs and polymersomes with a cylinder line pattern on the surface that develops specific combinations of topological defects to satisfy the Euler characteristics for closed spheres as described by Gauss-Bonnet theorem. The dimension of the line pattern allows the direct visualization of defect emergence, evolution, and annihilation. On discs, cylinders either form end-caps that coincide with λ+1/2 disclinations or they bend around τ+1/2 disclinations in 180° turns (hairpin loops). On polymersomes, two λ+1/2 defects connect into three-dimensional (3D) Archimedean spirals, while two τ+1/2 defects form 3D Fermat spirals. Electron tomography reveals two complementary line patterns on the inside and outside of the polymersome membrane, where λ+1/2 and τ+1/2 disclinations always eclipse on opposing sides ("defect communication"). Attractive defects are able to annihilate with each other into +1 disclinations and stabilize anisotropic polymersomes with sharp tips through screening of high-energy curvature. This study fosters our understanding of the behavior of topological defects in self-assembled polymer materials and aids in the design of polymersomes with preprogrammed shapes governed by synthetic block length and topological rules.

Block copolymers (BCPs), through their self-assembly, provide an excellent guiding platform for precise controlled localization of maghemite nanoparticles (MNPs). Diblock copolymers (di/BCP) represent the most applied matrix to host filler components due to their morphological simplicity. A series of nanocomposites based on diblock copolymer or triblock terpolymer matrices and magnetic nanoparticles were prepared to study and compare the influence of an additional block into the BCP matrix. MNPs were grafted with low molecular weight polystyrene (PS) chains in order to be segregated in a specific phase of the matrix to induce selective localization. After the mixing of the BCPs with 10% w/v PS-g-MNPs, nanocomposite thin films were formed by spin coating. Solvent vapor annealing (SVA) enabled the PS-g-MNPs selective placement within the PS domains of the BCPs, as revealed by atomic force microscopy (AFM). The recorded images have proven that high amounts of functionalized MNPs can be controllably localized within the same block (PS), despite the architecture of the BCPs (AB vs. ABC). The adopted lamellar structure of the &ldquo, neat&rdquo, BCP thin films was maintained for MNPs loading approximately up to 10% w/v, while, for higher content, the BCP adopted lamellar morphology is partially disrupted, or even disappears for both AB and ABC architectures.

A block copolymer poly(ethylene glycol)-b-poly(vinylbenzyltrimethylammonium triflate), PEG-PVBTMA-OTf, and a homopolymer PVBTMA-OTf were synthesized through RAFT reactions. The polymers were studied in aqueous triflate solutions with varying temperatures, changing also the polymer and salt concentrations. The hydrophobic triflate anion turns polycations thermoresponsive, and they show an UCST. In the block copolymer, the interaction between the PEG and the cationic block makes the phase separation occur in distinct steps. Upon cooling, transparent solutions first turn turbid and then partially clear at T cL. The T cL is not observed in a mixed solution of PVBTMA-OTf and PEG macro-CTA. By considering the interplay between ionic, hydrogen bonding, and hydrophobic interactions, an overall picture of the complex phase separation processes is suggested.

Amphiphilic diblock copolymers consisting of a hydrophobic core containing a polymerized ionic liquid and an outer shell composed of poly(N-isoprolylacrylamide) were investigated by capillary electrophoresis and asymmetrical flow-field flow fractionation. The polymerized ionic liquid comprised poly(2-(1-butylimidazolium-3-yl)ethyl methacrylate tetrafluoroborate) with a constant block length (n = 24), while the length of the poly(N-isoprolylacrylamide) block varied (n = 14; 26; 59; 88). Possible adsorption of the block copolymer on the fused silica capillary, due to alterations in the polymeric conformation upon a change in the temperature (25 and 45 degrees C), was initially studied. For comparison, the effect of temperature on the copolymer conformation/hydrodynamic size was determined with the aid of asymmetrical flow-field flow fractionation and light scattering. To get more information about the hydrophilic/hydrophobic properties of the synthesized block copolymers, they were used as a pseudostationary phase in electrokinetic chromatography for the separation of some model compounds, that is, benzoates and steroids. Of particular interest was to find out whether a change in the length or concentration of the poly(N-isoprolylacrylamide) block would affect the separation of the model compounds. Overall, our results show that capillary electrophoresis and asymmetrical flow-field flow fractionation are suitable methods for characterizing conformational changes of such diblock copolymers.

Block copolymer melts self-assemble in the bulk into a variety of nanostructures, making them perfect candidates to template the position of nanoparticles. The morphological changes of block copolymers are studied in the presence of a considerable filling fraction of colloids. Furthermore, colloids can be found to assemble into ordered hexagonally close-packed structures in a defined number of layers when softly confined within the phase-separated block copolymer. A high concentration of interface-compatible nanoparticles leads to complex long-lived block copolymer morphologies depending on the polymeric composition. Macrophase separation between the colloids and the block copolymer can be induced if colloids are unsolvable within the matrix. This leads to the formation of ellipsoid-shaped polymer-rich domains elongated along the direction perpendicular to the interface between block copolymer domains.

This work focuses on the synthesis and self-assembly of triphilic poly(2-oxazoline) triblock copolymers with high fluorine content toward our future aim of developing poly(2-oxazoline) magnetic resonance imaging (MRI) contrast agents. A highly fluorinated 2-substituted-2-oxazoline monomer, namely 2-(1H,1H,2H,2H-perfluorooctyl)-2-oxazoline, was synthesized using the Grignard reaction. The polymerization kinetics of the synthesized monomer was studied, and it was used for the preparation of triblock copolymers with hydrophilic 2-methyl-2-oxazoline, hydrophobic 2-octyl-2-oxazoline, and fluorophilic blocks by cationic ring-opening polymerization yielding polymers with low relatively dispersity (1.21.4). The presence of the blocks with the different nature in one copolymer structure facilitated self-assembly of the copolymers in water and dimethyl sulfoxide as observed by dynamic light scattering, cryo-transmission electron microscopy, and small-angle neutron scattering. The nanoparticle morphology is strongly influenced by the order and length of each block and the nature of solvent, leading to nanoparticles with coreshell structure as confirmed by small-angle neutron scattering. The reported poly(2-oxazoline) block copolymers with high fluorine content have high potential for future development of MRI contrast agents.

We propose a solution strategy for a multimaterial minimum compliance topology optimization problem, which consists in finding the optimal allocation of a finite number of candidate (possibly anisotropic) materials inside a reference domain, with the aim of maximizing the stiffness of the body. As a relevant and novel application we consider the optimization of self-assembled structures obtained by means of diblock copolymers. Such polymers are a class of self-assembling materials which spontaneously synthesize periodic microstructures at the nanoscale , whose anisotropic features can be exploited to build structures with optimal elastic response , resembling biological tissues exhibiting microstructures, such as bones and wood. For this purpose we present a new generalization of the classical Optimality Criteria algorithm to encompass a wider class of problems, where multiple candidate materials are considered, the orientation of the anisotropic materials is optimized, and the elastic properties of the materials are assumed to depend on a scalar parameter , which is optimized simultaneously to the material allocation and orientation. Well-posedness of the optimization problem and well-definition of the presented algorithm are narrowly treated and proved. The capabilities of the proposed method are assessed through several numerical tests.

The synthesis of vinyl-based oligocelluloses using cellodextrin phosphorylase as biocatalyst in buffer solution is presented. Various types of vinyl glucosides bearing (meth)acrylates/(meth)acrylamides functionalities served as the glucosyl acceptor in the enzyme catalyzed reverse phosphorolysis reaction and α-glucose 1-phosphate as the glucosyl donor. The enzymatic reaction was followed by thin layer chromatography and the isolated product yields were about 65%. The synthesized vinyl-based oligocelluloses had an average number of repeating glucosyl units and a number average molecular weight up to 8.9 and 1553 g mol−1, respectively. The majority of the bonds at the alpha position of acrylate units in oligocellulosyl-ethyl acrylate was fragmented as characterized by 1H NMR spectroscopy and MALDI-ToF spectrometry. Nevertheless, a minor amount of fragmentation was observed in oligocellulosyl-ethyl methacrylate and oligocellulosyl-butyl acrylate but no fragmentation was detected in the (meth)acrylamide-based oligocelluloses. Crystal lattice of the prepared vinyl-based oligocelluloses was investigated via wide-angle X-ray diffraction experiments.

Jiao Liu,1,* Jie Cao,1,* Jianhua Cao,2 Shangcong Han,1 Yan Liang,1 Mingfeng Bai,3 Yong Sun1 1Department of Pharmaceutics, School of Pharmacy, Qingdao University, Qingdao, China; 2Department of Pharmacy, Qingdao No 3 Hospital, Qingdao, China; 3Department of Radiology and Radiological Sciences, Institute of Imaging Sciences, Vanderbilt University Medical Center, Nashville, TN, USA *These authors contributed equally to this work Introduction: Nanoparticles are increasingly used as drug carriers for oral administration. The delivery of drug molecules is largely dependent on the interaction of nanocarriers and gastrointestinal (GI) mucus, a critical barrier that regulates drug absorption. It is therefore important to understand the effects of physical and chemical properties of nanocarriers on the interaction with GI mucus. Unfortunately, most of the nanoparticles are unable to be prepared with satisfactory structural monodispersity to comprehensively investigate the interaction. With controlled size, shape, and surface chemistry, copolymers are ideal candidates for such purpose. Materials and methods: We synthesized a series of diblock copolymers via the atom transfer radical polymerization method and investigated the GI mucus permeability in vitro and in vivo. Results: Our results indicated that uncharged and hydrophobic copolymers exhibited enhanced GI absorption. Conclusion: These results provide insights into developing optimal nanocarriers for oral administration. Keywords: absorption barriers, oral drug delivery system, ATRP, nanoparticles

Controlled self-assembly of diblock copolymers offers the possibility of fabricating multilength scale, three-dimensional (3D) porous/fibrous structures (or scaffolds) with defined internal nano- or microstructure, with opportunities for application in a variety of fields, ranging from energy storage to bioengineering. Traditional methods by which such 3D constructs are produced are time-consuming and tedious, hindering their broader exploitation within larger scale industrial processes. We report the development of a one-step process to fabricate "as-electrospun" self-assembled diblock copolymer micro- to nanometer-sized fibers incorporating core shell or lamellar, closely packed spheres or bicontinuous gyroid nanosized structures. Isotropic and anisotropic (aligned) porous mats presenting spatially controlled chemistries, including bioactive (peptide-based) motifs, were successfully made from these hierarchical fibers. When functionalized with peptide sequences derived from a cell adhesion molecule (E-cadherin) and an extracellular matrix glycoprotein (laminin), these novel materials provided new insight into the impacts of such exquisitely tailored contact -guidance cues on the haptokinesis of human mesenchymal stem cells.

By combining poly(1,4-isoprene) (PI) with poly(ferrocenylmethyl methacrylate) (PFMMA) in a diblock copolymer structure by means of anionic polymerization we obtained narrowly dispersed PI-b-PFMMA copolymers with molecular weight ranging from 13000 to 62000 g/mol. The products were stable up to 228 °C, according to thermal gravimetry, which allowed us to further investigate their viscoelastic and X-ray scattering properties at elevated temperature by rheology and SAXS, respectively. For PI-b-PFMMA with total molecular weight 13400 g/mol a phase transition at 105 °C was identified leading to the segmental mixing at T > 105 °C and microphase separation at T

The bond fluctuation model was employed to characterize the approach to the mesophase separation transition of pure linear AB copolymers and symmetric miktoarms, also called Janus, star polymers, Af/2Bf/2 , where f = 6 or 12 is the total number of arms, in a common good solvent. We consider a concentration sufficiently high to mimic the melting behavior and also a lower concentration. The segregation between A and B units is represented by a repulsive interaction parameter, . Different total numbers of units are also considered. Results for different properties, such as the molecular size, the asphericity and orientational correlation of blocks, or arms, of different compositions are obtained as a function of the segregation parameter. We also calculate scattering structure factors. The initial effect of segregation on the scattering with opposite contrast factors between the A and B blocks can be explained with a common description based on the random phase approximation for both the linear copolymers and the f = 6 miktoarms, once the numerical form factors of the different molecules in their particular systems are considered. However, the results for f = 12 clearly deviate from this description probably due to some degree of ordering in the position of highly armed molecules.

The formation of ordered morphologies in thin films of symmetric diblock copolymer melts is considered theoretically. Somewhat surprisingly, under proper boundary conditions the presence of a lamellar chemical pattern on the substrate, being sufficiently pronounced and with the right period, is found to induce the formation of diamond-like morphologies. The phase diagram of the most stable phases on the plane (the substrate period Lx the film width H) is built within the self-consistent field theory numerical procedure. We also discuss the behavior of the order parameter Fourier spectrum at the transitions between the various morphologies.

Bibliographical references at the end of each chapter. Number of sources in the bibliography: 113 Thesis (Ph. D.) -- University of Cyprus, Faculty of Pure and Applied Sciences, Department of Chemistry, 2019. The University of Cyprus Library holds the printed form of the thesis. Η παρούσα Διδακτορική Διατριβή πραγματεύεται τη διερεύνηση τριών στρατηγικών για την ενίσχυση των μηχανικών ιδιοτήτων πολυμερικών υδροπλεγμάτων. Αυτές οι στρατηγικές ήταν η πολλαπλότητα, η αμφιφιλικότητα, και η αντιστρεπτότητα των δικτύων. Οι πρώτες δύο στρατηγικές αποδείχθηκαν επιτυχείς, με το πλέγμα με τη μεγαλύτερη πολλαπλότητα, ίση με 5, και τη μεγαλύτερη συγκέντρωση μονομερούς, ίση με 5 Μ, να παρουσιάζει την πολύ υψηλή τάση θραύσης συμπίεσης των 51 MPa, και το καλύτερο αμφιφιλικό πολυμερικό δίκτυο, με ενδιάμεση περιεκτικότητα σε υδρόφοβο μονομερές, να παρουσιάζει επίσης την υψηλή τάση θραύσης συμπίεσης των 11 MPa. Στην περίπτωση των πολλαπλών υδροπλεγμάτων, η τάση θραύσης αυξήθηκε με αύξηση και της πολλαπλότητας του δικτύου και της συγκέντρωσης του μονομερούς, ως συνέπεια της προστασίας των προηγούμενων δικτύων από τα επόμενα δίκτυα ως προς τη δημιουργία και διάδοση ρωγμών. Στην περίπτωση των αμφιφιλικών πολυμερικών δικτύων, η τάση θραύσης τους αυξήθηκε με το ποσοστό του υδρόφοβου μονομερούς ως αποτέλεσμα της μειωμένης πρόσληψης νερού, αλλά, κυρίως, λόγω των ελκτικών αλληλεπιδράσεων μεταξύ των επαναλαμβανόμενων μονάδων του υδρόφοβου μονομερούς. Τα πιο αραιά διασταυρωμένα αμφιφιλικά πολυμερικά δίκτυα παρουσίασαν την ιδιότητα «μνήμης σχήματος» (“shape memory”), μία πολύ σημαντική ιδιότητα που μπορεί να αξιοποιηθεί σε πολλές εφαρμογές στην τεχνολογία και στην ιατρική. Σχετικά με την αντιστρεπτότητα του δικτύου, ο συγκεκριμένος δυναμικός ομοιοπολικός δεσμός που χρησιμοποιήθηκε για τις αντιστρεπτές διασταυρώσεις ήταν πολύ σταθερός και δύσκολο να επιτευχθεί η ανταλλαγή του.Η προαναφερθείσα στρατηγική για τα πολλαπλά πλέγματα είναι αρκετά καινοτόμα, καθώς αποτελεί την επέκταση της κλασικής προσέγγισης των διπλών πλεγμάτων σε πενταπλά πλέγματα. Το μονομερές που χρησιμοποιήθηκε για τα πολλαπλά πλέγματα ήταν το ουδέτερο υδρόφιλο μονομερές Ν,Ν-διμεθυλακρυλαμίδιο (DMAAm). Το ίδιο μονομερές χρησιμοποιήθηκε επίσης στην παρασκευή των αμφιφιλικών πολυμερικών δικτύων, σε συνδυασμό με το σπανίως χρησιμοποιούμενο υδρόφοβο και κρυσταλλικό μονομερές Ν-δωδεκυλακρυλαμίδιο (DDAAm). Μέχρι πολύ πρόσφατα, το τελευταίο μονομερές δεν ήταν εμπορικά διαθέσιμο και έπρεπε να συντεθεί στο εργαστήριο. Παρόλο που κάποιες από τις συνθέσεις των πολυμερών περιλάμβαναν πολυμερισμό ελευθέρων ριζών, αρκετές από τις συνθέσεις πραγματοποιήθηκαν με χρήση μίας ελεγχόμενης μεθόδου πολυμερισμού ριζών, και, συγκεκριμένα, τον πολυμερισμό μεταφοράς αλυσίδας μέσω αντιστρεπτής προσθήκης και απόσπασης. This PhD Thesis involves the exploration of three strategies for the improvement of the mechanical properties of polymer network hydrogels. These strategies were network multiplicity, network amphiphilicity, and network reversibility. The first two strategies were proven successful, with the multiple network possessing the highest multiplicity, equal to 5, and prepared at the highest monomer concentration, 5 M, presenting a very high compressive fracture stress of 51 MPa, and the strongest amphiphilic polymer conetwork, bearing an intermediate content of the hydrophobic monomer, also exhibiting a high compressive fracture stress of 11 MPa. In the case of the multiple network hydrogels, fracture stress increased both with network multiplicity and monomer concentration, a result of the protection of the earlier networks from the later networks with regard to crack formation and crack propagation. In the case of the amphiphilic polymer networks, their strength increased with the content in the hydrophobic monomer, a consequence of the reduced water uptake, but, more importantly, the associations among the hydrophobic monomer repeating units. Interestingly, the more loosely cross-linked amphiphilic polymer networks displayed shape memory, a very useful property which can be exploited in many applications in technology and medicine. Regarding network reversibility, the particular dynamic covalent bond employed for the reversible cross-links in this investigation was too stable and, consequently, difficult to exchange. Our above-mentioned multiple network strategy was highly innovative, in that it greatly extended the classical approach of double network hydrogels to quintuple (5-fold) network hydrogels. The monomer employed for these multiple networks was the nonionic hydrophilic N,N-dimethylacrylamide (DMAAm). The same monomer was also employed for the preparation of the amphiphilic polymer networks, in combination with the rarely used hydrophobic and crystalline N-dodecylacrylamide (DDAAm) monomer. Until very recently, this latter monomer was not commercially available and had to be prepared in the laboratory. Although several of our polymer syntheses employed free radical photopolymerization, many of the synthesis used a controlled radical polymerization method, and, in particular, reversible addition-fragmentation chain transfer (RAFT) polymerization.

CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior Este trabalho aborda o estudo da síntese, organização e caracterização de nanopartículas de prata (AgNPs) empregando o copolímero poliestireno- b--poli(2-vinilpiridina) (PS- b--P2VP) em substratos de vidro modificados por litografia de nanoimpressão (μCP). Investigamos ainda a deposição de nanopartículas de ouro (AuNPs) sobre filmes de PS- b--P2VP. Estes sistemas foram utilizados como substrato SERRS empregando o Azul do Nilo e o IR-820 como moléculas prova. Como ferramentas para a caracterização dos filmes finos foram empregadas as técnicas: espectroscopia eletrônica no UV-VIS, microscopia de força atômica (AFM), microscopia eletrônica de transmissão (TEM) e microscopia eletrônica de varredura (SEM). Os substratos de vidro quimicamente modificados foram preparados por μCP. Uma solução de octadeciltriclorosilano (OTS) foi depositada seletivamente sobre um substrato de vidro utilizando um carimbo de PDMS preparado a partir das ranhuras de um CD, criando regiões de hidrofilicidade diferentes com a finalidade de orientar a organização das cadeias do PS- b--P2VP. A microscopia AFM foi empregada na caracterização destes substratos. Foram utilizados PS- b--P2VP de diferentes composições na síntese in situ de AgNPs sobre substratos modificados por μCP. As imagens AFM dos filmes de AgNP/PS- b--P2VP produzidos em substratos não modificados e modificados por μCP demonstraram a importância da modificação, da massa molecular dos copolímeros e do aquecimento na organização, morfologia e propriedades ópticas dos filmes. Foi observado que os filmes produzidos sobre substratos modificados por μCP apresentaram nanopartículas multifacetadas e bem dispersas quando comparados a filmes produzidos em substratos não modificados. Os espectros de absorção no UV-VIS mostraram que apenas os filmes produzidos sobre substratos modificados por μCP apresentaram uma banda característica de cristal fotônico devido à organização em microfases do PS- b--P2VP. AuNPs foram sintetizadas e posteriormente depositadas sobre filmes de PS- b--P2VP com diferentes tratamentos. Os tratamentos empregados foram: imersão do filme de PS- b--P2VP em etanol ou água e tratamento térmico. No intuito de verificar a importância dos tratamentos na deposição e propriedades ópticas das AuNPs também foram sintetizados filmes em que o copolímero não passou por nenhum tratamento. Ao compararmos os filmes produzidos notouse que o tratamento com etanol induziu uma deposição mais homogênea de AuNPs sobre a superfície do vidro e que o tratamento térmico gerou um filme de PS- b--P2VP com morfologia giróide, onde as AuNPs se depositaram preferencialmente nos microdomínios referente ao bloco P2VP. This work presents the study of synthesis, organization, and characterization of silver nanoparticles (AgNPs) in modified substrates by microcontact-printing (μCP) using the copolymer polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP). The deposition of gold nanoparticles (AuNPs) over PS-b-P2VP films was also investigated. The SERRS activity of these systems were tested with two dye molecules, IR-820 and Blue of Nile. The nanocomposite thin films were characterized by electronic UV-VIS spectroscopy, atomic force microscopy (AFM), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Prepatterned chemically heterogeneous glass substrates were prepared by μCP, to which octadecyltrichlorosilane (OTS) solution was selectively transferred using a PDMS stamp with periodic microscale stripes that were obtained from a CD, creating regions with different hydrophilicity. These OTS-patterned substrates have the purpose of directing the assembly of the domains of the PS-b-P2VP. AFM was used for the characterization of these substrates. PS-b-P2VP, with different compositional ratios of PS to P2VP, was used for the in situ synthesis of AgNPs on prepatterned substrates (which were prepared using μCP). The AFM images of the AgNP/PS-b-P2VP films reveal the importance of the modification of the substrate, the molecular weight of the copolymer, and heating, in the assembly, morphology and optical properties of the films. It was observed that multifaceted nanoparticles dispersed well in the films spin-coated onto the prepatterned substrates when compared with the films spin-coated in bare glass substrates. The UV-VIS absorption spectra show that the stop band is only detected in the films spin-coated onto the prepatterned substrates, because of the microphases organization of the PS-b-P2VP. AuNPs were synthetized and then deposited onto the PS-b-P2VP films with different treatments. The following treatments were applied: immersion of the film in ethanol or water for 10 min, and thermal treatment. To verify the importance of the treatment in the adsorption and optical properties of the AuNPs, synthetized films without any prior treatment were also used. When comparing the prepared films, it was noticed that the ethanol treatment induced a more homogeneous adsorption of the AuNPs onto the glass substrate and that the thermal treatment created a PS-b-P2VP film with gyroid morphology, where the AuNPs were deposited preferentially in the P2VP microdomains.

Surfaktanter og kopolymerer er molekyler som kan selvassosiere på nanonivå til en rekke forskjellige strukturer. Dette kan være alt fra sfærer og sylindre, til bi-lag tilsvarende de som finnes i cellemembraner. Disse strukturene har mange viktige anvendelser som for eksempel surfaktanter i såpe og kosmetikk, til mer avanserte anvendelser som medisinbærere i nanomedisinsystemer. På bakgrunn av dette kan forskning på disse molekylene og strukturene være meget nyttig, og det er spesielt viktig å forstå hvordan de avhenger av forskjellige molekylære egenskaper og hvordan de påvirkes av endringer i eksterne parametere som temperatur, pH og salt. Ny forskning på dette feltet kan dermed brukes til å bedre forståelsen av den fundamentale termodynamikken til selvassosierende systemer og for å skreddersy disse til spesifikke anvendelser. Et av de mest viktige og velstuderte amfifile molekylene er den anioniske surfaktanten natriumdodecylsulfat (SDS). Denne surfaktanten danner globulære miceller i vandige lønsinger som er høyst sensitive til små endringer i eksterne parametere som temperatur, pH og ionestyrke. En interresant egenskap ved disse er at de i tilstedeværelse av salt forlenges og danner sylindriske miceller som kan nå nesten makroskopiske lengder. Selv om denne prosessen er velstudert, har ikke mekanismene bak denne overgangen blitt fullstendig beskrevet kvantitativt. Eksperimentelle resultater kan i kombinasjon med datasimuleringer bli brukt til å utvikle mer nøyaktige modeller for å beskrive detaljene rundt denne overgangen. Ved å bruke lav-vinkel røntgenspredning (SAXS) fra en synkrotronkilde i kombinasjon med analytiske modeller, ble globulær-til-sylinderovergangen i dette arbeidet karakterisert som en funksjon av ionestyrke med forskjellige salter (NaCl, MgCl2, KCl and CaCl2). Både NaCl og MgCl2 forårsaket en eksponentiell økning i konturlengden til micellenene som en funksjon av ionestyrke, mens KCl og CaCl2 forårsaket faseseparasjon. Fasediagrammer basert på disse resultatene viser overlapp mellom overgangsområdene ved bruk av ionestyrke for NaCl og MgCl2. Ved den høyeste konsentrasjonen av MgCl2 ble det i tillegg påvist lange, fleksible sylindre med mulig krysslinking og/eller forgrening av micellene. Det andre hovedemnet i dette arbeidet er diblokk-kopolypeptidene PBLG-PLL bestående av en hydrofobisk del av poly-γ-benzyl-L-glutamat (PBLG) og en hydrofil del av poly-L-lysin (PLL). Disse kopolypeptidene er forventet å produsere store vesikler i vandig løsning og er frem til nå ubeskrevet i litteraturen. Vesiklene ble studert ved å forsøke å tilpasse en analytisk modell for en vesikkelstruktur til SAXS-data basert på resultater fra dynamisk lysspredning (DLS) og transmisjonselektronmikroskopi (TEM). Selv om tegn til vesikler ble funnet med TEM, indikerte spredningseksperimentene tilstedeværelse av andre morfologier. Den strukturelle karakteriseringen av systemene ved bruk av en vesikkelmodell ble derfor mislykket. På tross av dette, ble spredningskurvene fra partiklene analysert kvalitativt, og partiklene ble funnet til å være eksepsjonelt stabile ved endringer av parametere som temperatur og ionestyrke, noe som er ønsket i mange anvendelser. Vanntransporten gjennom vesiklene ble også studert ved bruk av tidsoppløst lav-vinkelnøytronspredning (TR-SANS) for å måle permeabiliteten til membranene. En komplett utveksling av vann gjennom bi-laget skjedde her raskere enn tidsskalen som var tilgjengelig med det eksperimentelle oppsettet, noe som er bemerkelsesverdig og en utypisk egenskap ved kopolymermembraner.

Narrowly dispersed diblock copolymers containing poly(methyl methacrylate) [PMMA] or poly(nonafluorohexyl methacrylate) [PF9MA] as the first block and poly(ferrocenylmethyl methacrylate) [PFMMA] as the second block, were prepared by anionic polymerization for the first time. Disordered bulk morphologies in the case of PMMA-b-PFMMA were observed and explained in terms of low Flory–Huggins interaction parameter (χ ≤ 0.04). In the case of PF9MA-b-PFMMA hexagonally packed cylinder morphology (HEX) was substantiated from TEM and SAXS observations. Furthermore, high incompatibility between PF9MA and PFMMA blocks allowed for the formation of well-ordered ferrocene containing cylinders on silica substrate upon exposure of the thin films to a saturated solvent vapor. It was shown that the cylinder orientation, parallel or perpendicular to the surface, could easily be controlled by appropriate choice of the solvent and without the need for preliminary surface modification, for example by means of grafted brush layer. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016

Chemical enhanced oil recovery (EOR) is surely a topic of interest, as conventional oil resources become more scarce and the necessity of exploiting heavy and unconventional oils increases. EOR methods based on polymer flooding, surfactant-polymer flooding and alkali-surfactant-polymer flooding are well established, but new challenges always emerge, which give impulse to the search for new solutions. Polymeric surfactants represent a very attractive alternative to these techniques, because they can provide simultaneously increase in water viscosity and decrease in interfacial tension, both beneficial for the efficiency of the process. The analysis of the literature shows that the use of polymeric surfactants as displacing fluid has the potential to improve the performances of EOR in some cases. However, the synthesis are often challenging and costly and the available data about the real performances of such systems in oil recovery are still sparse. This holds back the possibility of a significant use of polymeric surfactants for EOR This review collects the relevant work done in the last decades in developing and testing polymeric surfactants for EOR, with a particular emphasis on the chemical aspects, the patent literature and bio-based systems. (c) 2016 The Authors. Published by Elsevier B.V.

Chemical enhanced oil recovery (EOR) is surely a topic of interest, as conventional oil resources become more scarce and the necessity of exploiting heavy and unconventional oils increases. EOR methods based on polymer flooding, surfactant-polymer flooding and alkali-surfactant-polymer flooding are well established, but new challenges always emerge, which give impulse to the search for new solutions. Polymeric surfactants represent a very attractive alternative to these techniques, because they can provide simultaneously increase in water viscosity and decrease in interfacial tension, both beneficial for the efficiency of the process. The analysis of the literature shows that the use of polymeric surfactants as displacing fluid has the potential to improve the performances of EOR in some cases. However, the synthesis are often challenging and costly and the available data about the real performances of such systems in oil recovery are still sparse. This holds back the possibility of a significant use of polymeric surfactants for EOR This review collects the relevant work done in the last decades in developing and testing polymeric surfactants for EOR, with a particular emphasis on the chemical aspects, the patent literature and bio-based systems. (c) 2016 The Authors. Published by Elsevier B.V.

Block copolymers are known to spontaneously form ordered structures at the nano-to mesoscale. Although the number of different morphologies is rather limited in diblock copolymer systems, their phase behavior becomes increasingly more complex with each additional building block. Synthesis of such all-covalent materials is, however, a very challenging task. By moving to supramolecular chemistry these preparation methods can be avoided while maintaining the same kind of macromolecular complexity. After a brief introduction, this feature article will provide a selection of the most recent work performed in the field of self-assembling supramolecular block copolymer-containing materials. By careful choice of both the copolymer and, in many cases, the small organic surface active compound, fascinating morphologies can appear in supramolecular comb-shaped block copolymers. Several examples will be discussed, while a number of functional materials (e.g. thermal, optical, electronic) originating from these type of complexes will be addressed as well.

The self-assembly of the hydrogen-bonded complexes between poly(p-hydroxystyrene) (PpHS) and 4-alkylpyridine amphiphiles is studied using infrared spectroscopy, differential scanning calorimetry, polarized optical microscopy, transmission electron microscopy and small-and wide-angle X-ray scattering. Interesting differences are observed with the well-studied inverted system of poly(4-vinylpyridine) and alkylphenol amphiphiles. When the alkyl tails of the 4-alkylpyridine amphiphiles are long enough, 19 and 21 respectively, an ordered lamellar structure is formed on cooling where the ordering and crystallization of the alkyl tails occur quasi simultaneously. For a shorter alkyl tail of length 17 no ordered structure is formed. This is quite different from the inverted P4VP/alkylphenol systems, where already for an alkyl tail of length 15, i.e., pentadecylphenol, an ordered structure is formed below ca. 55 degrees C, followed by crystallization of the alkyl tails at ca. 20 degrees C. This can be attributed to the possibility of (intramolecular) hydrogen bond formation of PpHS. (C) 2016 Elsevier Ltd. All rights reserved.

We present a combined theoretical/experimental study to investigate the effect of selective solvent vapor annealing treatment on the obtainment of highly ordered morphologies of symmetric poly(styrene-b-methyl methacrylate) diblock copolymer (PS-b-PMMA DBC) films loaded with compatibilized magnetic (Fe3O4) nanoparticles (NPs). Different amounts of NPs were considered (1, 2, and 5 wt %) to study the effect of the inorganic content on the final properties of Fe3O4/PS-b-PMMA films. A precise control of the DBC nanostructure could be obtained by very simple and cost-effective fabrication steps, compatible with current industrial processes. Moreover, the modified NPs could be selectively placed into the PMMA domains of the DBC up to NP concentration of 5 wt % while preserving the corresponding DBC lamellar morphology.

International audience; Polyhydroxyalkanoates (PHAs) are biocompatible and biodegradable polyesters widely used for biomedical applications. Amphiphilic triblock copolymers with a PHB hydrophobic segment recently demonstrated attractive advantages such as high colloidal stability and low critical micellar concentration (CMC) values for the elaboration of drug delivery systems. Our approach aims at associating PHB with a fully biodegradable hydrophilic block to access new self-assembled systems with unique potential. Well-defined alpha,omega-dihydroxy telechelic PHA-based hydrophobic triblock copolymers with tunable segments length were synthesized by the controlled ring-opening polymerization (ROP) of benzyl beta-malolactonate, using polyhydroxybutyrate (PHB) diol/Nd(OTf)(3) as the catalytic system. Remarkably, the reaction proceeds with the selective oxygen-acyl bond cleavage of the beta-lactone. The corresponding amphiphilic copolymers were then obtained by hydrogenolysis. These copolymers are the only examples of fully biodegradable PHA-PHB-PHA triblock copolymers. The hydrophilic weight fraction of the copolymers was tuned from 7 to 83% upon modulating the monomer loading thus affording the ability to next access different self-assembling architectures.

Due to their ability to self-assemble into a variety of periodic nanostructures, block copolymers already play an important role in designing diverse functional materials. A refined way to rationally tailor the morphology of a block copolymer system is the incorporation of varying amounts of an amphiphile e.g. 3-pentadecylphenol (PDP). In order to identify self-assembled structures suitable for the design of various functional materials, different supramolecular complexes of polystyrene-block-poly(4-vinylpyridine)(PDP)(x) (PS-b-P4VP(PDP)(x)) were prepared and mophologically characterized by small-angle X-ray scattering and scanning electron microscopy techniques. Thereby, the focus was set on the cylindrical-to-lamellar region with a minor P4VP(PDP)(x) block. For the first time, the lamellar-in-gyroid morphology was obtained directly by an annealing process. After amphiphile removal, apart from the nanoporous gyroid polymer foam, exceptionally long-range ordered polymer networks with cylindrical pores were obtained. The manifold possible applications of the self-assembled polymer morphologies were exemplarily validated by a template-directed formation of a bicontinuous nickel network via electroless plating.

Peptoids are a family of sequence-defined, non-natural biomimetic polymers which show excellent properties including good chemical and enzymatic stability and high structural tunability. The solid-phase submonomer synthesis method allows precise control over the identity and sequence of chemically diverse side chains, enabling the atomic engineering of their chemical structures for a variety of applications. This unprecedented level of structural control enables access to atomically defined three-dimensional chain conformations and assemblies, facilitating the design and optimization of a variety of nanoscale architectures that can function in biology and materials science. In order to approach the rational design of peptoid materials in a more predictive and precise manner, it is crucial to fully understand how chemical information, in the form of the monomer sequence, encodes their folding and assembly into structurally defined, functional 3D shapes. This perspective focuses on recent studies into the atomic engineering of peptoid nanostructures by examining the impact of sequence variations on their secondary and three-dimensional structures, as well as their functional properties.

The incorporation of double dynamic bonds into hydrogels provides an effective strategy to engineer their performance on demand. Herein, novel hydrogels were PREPARED by combining two kinetically distinct dynamic covalent bonds, boronate ester and acylhydrazone bonds, and the synergistic properties of the hydrogels were studied comprehensively. The functional diblock copolymers P(N-isopropyl acrylamide-co-N-acryloyl-3-aminophenylboronic acid)-b-(N-isopropyl acrylamide-co-diacetone acrylamide) (PAD) were prepared via reversible addition&minus, fragmentation chain transfer (RAFT) polymerization. The hydrogel was constructed by exploiting dynamic reaction of phenyboronic acid moieties with polyvinyl alcohol (PVA) and ketone moieties with adipic dihydrazide (ADH) without any catalyst. The active boronate ester linkage endows the hydrogel with fast gelation kinetics and self-healing ability, and the stable acylhydrazone linkage can enhance the mechanical property of the hydrogel. The difference in kinetics endows that the contribution of each linkage to mechanical strength of the hydrogel can be accurately estimated. Moreover, the mechanical property of the hydrogel can be readily engineered by changing the composition and solid content, as well as by controlling the formation or dissociation of the dynamic linkages. Thus, we provide a promising strategy to design and prepare multi-responsive hydrogels with tunable properties.

This article demonstrates that ionizing radiation induces simultaneous crosslinking and scission in poly(trimethylene carbonate-co-d-lactide) diblock and random copolymers. Copolymer films were electron-beam (EB) irradiated up to 300 kGy under anaerobic conditions and subsequently examined by evaluation of their structure (FT-IR, NMR), molecular weight, intrinsic viscosities, and thermal properties. Radiation chemistry of the copolymers is strongly influenced by the content of ester linkages of the lactide component. At low lactide content, crosslinking reaction is the dominant one, however, as the lactide ratio increases, the ester linkages scission becomes more competent and exceeds the crosslinking. Electron paramagnetic resonance (EPR) measurements indicate that higher content of amorphous carbonate units in copolymers leads to a reduction in free radical yield and faster radical decay as compared to lactide-rich compositions. The domination of scission of ester bonds was confirmed by identifying the radiolytically produced alkoxyl and acetyl radicals, the latter being more stable due to its conjugated structure.

Polymeric micelles are potentially efficient in encapsulating and performing the controlled release of various hydrophobic drug molecules. Understanding the fundamental physicochemical properties behind drug–polymer systems in terms of interaction strength and compatibility, drug partition coefficient (preferential solubilization), micelle size, morphology, etc., encourages the formulation of polymeric nanocarriers with enhanced drug encapsulating capacity, prolonged circulation time, and stability in the human body. In this review, we systematically address some open issues which are considered to be obstacles inhibiting the commercial availability of polymer-based therapeutics, such as the enhancement of encapsulation capacity by finding better drug–polymer compatibility, the drug-release kinetics and mechanisms under chemical and mechanical conditions simulating to physiological conditions, and the role of preparation methods and solvents on the overall performance of micelles.

Block copolymers consisting of a polyethylene block and a polar polymer block are interesting structures for the compatibilization of polyethylene/polar polymer blends or polyethylene-based composites. Since the synthesis of polyethylene-based block copolymers is an elaborate process, diblock copolymers consisting of "polyethylene-like" poly-(pentadecalactone) (PPDL) and poly(L-lactide) (PLLA) were synthesized using a one-pot, sequential-feed ring-opening polymerization of pentadecalactone (PDL) and L-lactide (LLA). The peculiar activity of the used aluminum salen catalysts yielded a block copolymer consisting of two blocks with both a high dispersity, as a result of intra block transesterification. Interestingly, interblock transesterification was effectively suppressed. The obtained poly(PDL-block-LLA) of various block lengths showed coincidental crystallization of the two blocks with an associated microphase-separated morphology, in which PLLA. spheres with a high dispersity are distributed within the PPDL matrix. The complex morphologies is believed to arise from the presence of a whole range of block sizes as a consequence of the large dispersity of both blocks. The application of these block copolymers as compatibilizers for high density polyethylene (HDPE)/PLLA blends led to a clear change in blend morphology and a steep decrease in particle size of the dispersed phase. Furthermore, addition of the block copolymers to blends of linear low density polyethylene (LLDPE) and PLLA led to a significant increase in adhesion between the two phases. For both HDPE/PLLA and LLDPE/PLLA blends, the compatibilization efficiency of the poly(PDL-block-LLA) increased when the length of the PPDL block was increased. The presented results clearly show that PPDL can function as a substituent for various types of polyethylene, which opens up a new method for compatibilizing polyethylene with polar polymers using easy attainable "PE-like" block copolymers.

cited By 15; International audience; A series of novel block copolymers, processable from single organic solvents and subsequently rendered amphiphilic by thermolysis, have been synthesized using Grignard metathesis (GRIM) and reversible addition-fragmentation chain transfer (RAFT) polymerizations and azide-alkyne click chemistry. This chemistry is simple and allows the fabrication of well-defined block copolymers with controllable block lengths. The block copolymers, designed for use as interfacial adhesive layers in organic photovoltaics to enhance contact between the photoactive and hole transport layers, comprise printable poly(3-hexylthiophene)-block-poly(neopentyl p-styrenesulfonate), P3HT-b-PNSS. Subsequently, they are converted to P3HT-b-poly(p-styrenesulfonate), P3HT-b-PSS, following deposition and thermal treatment at 150 °C. Grazing incidence small- and wide-angle X-ray scattering (GISAXS/GIWAXS) revealed that thin films of the amphiphilic block copolymers comprise lamellar nanodomains of P3HT crystallites that can be pushed further apart by increasing the PSS block lengths. The approach of using a thermally modifiable block allows deposition of this copolymer from a single organic solvent and subsequent conversion to an amphiphilic layer by nonchemical means, particularly attractive to large scale roll-to-roll industrial printing processes. © 2015 American Chemical Society.

Well-defined amphiphilic triblock poly(sodium methacrylate)-polystyrene-poly(sodium methacrylate) (PMAA-b-PS-b-PMAA) copolymers characterized by a different length of either the hydrophilic or the hydrophobic block have been synthesized by ATRP. In solution the micelle-like aggregates consist of a collapsed PS core surrounded by stretched charged PMAA chains. The micelles are kinetically ‘frozen’ and as a consequence the triblock copolymers do not show a significant surface activity. The hydrophilic block length has a major influence on the rheology, the shortest PMAA blocks yielding the strongest gels (at the same total weight concentration). The hydrophobic block length has only a minor influence until a certain threshold, below which the hydrophobic interactions are too weak resulting in weak gels. A mathematical model is used to describe the micelle radius and the results were in good agreement with the experimentally found radius in transmission electron microscopy. The influences of the ionic strength, pH and temperature on the rheology has also been investigated, showing the potential of these polymers as smart hydrogels. The change in conformation of the hydrophilic corona from the collapsed state to the stretched state by changing the pH was quantified with zeta-potential measurements. To the best of our knowledge, this is the first systematic investigation of this kind of triblock copolymers in terms of their rheological behavior in water.

Mixed micelle formation between two oppositely charged diblock copolymers that have a common thermosensitive nonionic block of poly(N-isopropylacrylamide) (PNIPAAM) has been studied. The block copolymer mixed solutions were investigated under equimolar charge conditions as a function of both temperature and total polymer concentrations by turbidimetry, differential scanning calorimetry, two-dimensional proton nuclear magnetic nuclear Overhauser effect spectroscopy (2D H-1 NMR NOESY), dynamic light scattering, and small angle X-ray scattering measurements. Well-defined and electroneutral cylindrical micelles were formed with a radius and a length of about 3 nm and 35 nm, respectively. In the micelles, the charged blocks built up a core, which was surrounded by a corona of PNIPAAM chains. The 2D H-1 NMR NOESY experiments showed that a minor block mixing occurred between the core blocks and the PNIPAAM blocks. By approaching the lower critical solution temperature of PNIPAAM, the PNIPAAM chains collapsed, which induced aggregation of the micelles. (c) 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017, 55, 1457-1469

This thesis describes the characterization of polymer tailored surfaces by means of quartz crystal microbalance with dissipation monitoring and contact angle measurement. There are three projects described in this thesis: a) investigation of adsorption of different homopolymers to silica surfaces; b) investigation of adsorption of different diblock copolymers to silica surfaces; c) investigation of sequential adsorption of diblock copolymers to silica surfaces and demonstration of the responsiveness of mixed-polymer layers. In the adsorption studies, quartz crystal microbalance with dissipation played an important role in characterization of tailored surfaces. Two methods, Sauerbrey equation and Voigt model, were used for analysis of tailored surfaces. In the surface responsiveness studies, contact angle measurement played a key role in characterization of the conformational changes of different surface.

A simple fiber optic based scheme for the selective detection of proteins, based on surface electrostatic interactions, is presented. The implementation of this method is conducted using a modified polymer optical fiber's surface and thin overlayers of properly designed sensitive copolymer materials with predesigned molecular characteristics. Block poly(styrene-b-2vinylpyridine) (PS-b-P2VP) and random PS-r-P2VP copolymers of the same monomers and similar molecular weights, were modified and used as sensing materials. This configuration proved to be efficient concerning the fast detection of charged proteins, and also the efficient discrimination of differently charged proteins such as lysozyme and bovine serum albumin. Results on the sensing performance of block and random copolymers are also discussed drawing conclusion on their efficiency given their considerable different fabrication cost., This work was funded by the R&D Project WelCOM 09SYN-71–856 funded by National Strategic Reference Framework NSRF 2007-2013/Hellenic General Secretariat of Research and Technology GSRT and supported also by the NANOMACRO project which is implemented in the framework of the Operational Program “Education and Life-long Learning” (Action “ARISTEIA I”) and it is co-funded by the European Union (European Social Fund) and by national funds.

The synthesis and characterization of diblock copolymers formed by poly(styrene) and poly(γ-benzyl-L-glutamate) (PBLG) were studied. The PS and PBLG blocks were obtained by anionic and open ring polymerization, respectively. The homopolymers and copolymers were characterized by classical techniques such as nuclear magnetic resonance of proton and carbon (1H and 13C NMR), gel permeation chromatography (GPC) and thermal analysis (differential scanning calorimetry (DSC) and thermogravimetry (TGA)). The characterization in solution was performed using static light scattering (SLS). In the analysis by SLS, parameters such as average molar mass (Mwm), second virial coefficient (A2) and critical concentration (C*) for the pure homopolymers and the copolymer PS100-b-PBLG330 were determined.