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Polyhydroxyethyl methacrylate

A route of synthesizing molecular bottlebrush polymers in a one-pot, one-step polymerization approach is presented. Through the combination of two orthogonal polymerization techniques, the backbone...

With a bifunctional symmetric RAFT agent well-defined polymer structures can be achieved. This paper shows the possibility to synthesize block copolymer systems consisting out of different activated monomers. With the novel bifunctional symmetric RAFT agent water-born polymer systems with a block structure (B-b-A-b-B) can be polymerized. The symmetric RAFT agent is designed to polymerize both more activated monomers (A) and less activated monomers (B). Due to the ability of a controlled radical polymerization of different activated monomers the dispersity of the resulting polymers is broader compared to common RAFT polymerizations. In regard to industrial applications like emulsifiers, stabilizers or viscosity modifiers the broader molecular weight distribution has no impact. Overall, this paper shows the possibility towards new functional polymers with unique properties.

A procedure to obtain very uniform polyolefin copolymers by supported metallocenes is presented. Conventional metallocene or Ziegler–Natta catalysts, both immobilized on inorganic supports, yield only copolymers with inhomogeneous comonomer incorporation and broad short-chain branching distribution. The main reasons are diffusional limitations of the monomers or the multisite character of the catalysts. By comparing inorganic and organic supports, we demonstrate that metallocenes immobilized on organic supports solve these problems. In this regard, organic and soft nanosized polystyrene particles (nPS) versus industrially used, hard, and inorganic SiO₂ were used to support [Me₂Si(Ind)₂ZrCl₂/MAO (I) and Me₂Si(Benz[e]-Ind)₂ZrCl₂/MAO (BI)] catalysts for ethylene/1-hexene copolymerization. In the inorganic case, the catalyst systems show a substantial inconsistency in the copolymers’ branching distribution, resulting in phase separation. One phase is hexene-poor with high melting temperature (Tₘ) and high molecular weight (MW). The second, hexene-rich phase, however, shows lower Tₘ and MW. By using organic supports, comonomers are uniformly inserted into the polymer chain and homogeneous microstructured copolymers are obtained. These findings are mainly attributed to diffusion processes of the monomers into the soft organic material. To prove this conclusion and to elucidate the structure of the catalyst system, various characterization techniques such as time-of-flight secondary ion mass spectrometry and scanning electron microscopy–energy-dispersive X-ray were performed.

In polymer based ionic conductors, the conductivity is suppressed by a low degree of chain mobility, therefore it is imperative to design a molecular system in which ionic groups can be mobilized and immobilized as a function of temperature to allow ions to move freely as well as in a controlled manner with a low energy barrier. Herein, we report an innovative approach to combine both the concepts of self-assembly and disassembly of the functionalized molecules to investigate anhydrous ionic (proton) conduction and related activation energy (Ea). For this purpose, organic proton conductors are designed in such a way that self-assembly of the molecules can occur via non-covalent interactions giving rise to an organized solid state in which ionic groups are held together via a network of hydrogen bonds. A new class of anhydrous ionic conductors with hydrophobic and hydrophilic counterparts namely alkyl chains and a phosphonic acid group, respectively, are investigated for fuel cell applications. The highest anhydrous proton conductivity of up to 10−2 S cm−1 at 140 °C is recorded for these ionic molecules. Thermal gravimetric analysis of these materials demonstrates their stability up to 190 °C and thereby their ability to perform at high temperature.

Discotic liquid crystals based on hexa-peri-hexabenzocoronenes (HBCs) symmetrically substituted with six poly(ethylene glycol) (PEG) chains and further doped with LiCF3SO3 (LiTf) salt at different [EG]:[Li+] ratios nanophase-separate in domains composed from HBC columns and PEG chains. These model amphiphiles behave as viscoelastic solids with a shear modulus of 5 × 106 Pa and an ionic conductivity of 10–5 S/cm at 373 K. At temperatures below 333 K an ionic superstructure is formed of higher shear modulus (108 Pa) that surrounds the HBC columns and follows the disks in their rotational motion. However, the ionic superstructure impedes ion transport. Substituting the HBC core with two PEG chains breaks the symmetry of the ionic superstructure and increases ionic conductivity by an order of magnitude while retaining a high shear modulus and a viscoelastic response. These findings demonstrate that PEG-functionalized HBCs have great potential as new electrolytes because they combine ionic conductivity with me...

Given their increasing importance in a variety of applications, the preparation of carbon fibers with well-defined chemical structures and innocuous byproducts has garnered a growing interest over the past decade. We report the preparation of medium molecular weight poly(methyl vinyl ketone) (PMVK) as a potential carbon fiber precursor material which can easily undergo carbonization via the well-known, acid-catalyzed aldol condensation with water as a sole byproduct. Rheological studies further show that PMVK (MW ∼ 50 kg/mol) exhibits excellent physical and thermal properties for the spinning of single and multifilament fibers and easily produces carbon yields of 25% at temperatures as low as 250 °C. Analysis of the carbonized product also suggests a more defect-free structure than commercially available carbon fibers.

Porous hollow silica particles (HSPs) are presented as new templates to control the product morphology in metallocene-catalyzed olefin polymerization. By selectively immobilizing catalysts inside the micrometer-sized porous hollow silica particles, the high hydraulic forces resulting from polymer growth within the confined geometries of the HSPs cause its supporting shell to break up from the inside. As the shape of the support is replicated during olefin polymerization, perfectly spherical product particles with very narrow size distribution can be achieved by using HSPs exhibiting a monomodal size distribution. Furthermore, the size of the obtained product particles can be controlled not only by the polymerization time but also by the size of the support material.

While substantial progress has been achieved in the design of more biocompatible nanoparticles (NP), detailed data are required on the precise interactions of NPs and their environment for more reliable interpretation of toxicity results. Therefore, this study aims to investigate the interaction of two quantum dots (QDs) of the same core material CdSe/ZnS coated with two different amphiphilic polymers, with two well-established mammalian cell lines representing possible sites of QD accumulation. Results are linked to either extracellular QD concentrations (given dose) or cellular QD levels (number of internalized particles). In this study, QD internalization, effects on cellular homeostasis, and consequent inflammatory and cytoskeletal alterations caused by these QDs were explored. Fluorescence imaging techniques, including; image-based flow cytometry, confocal microscopy and high-content imaging with the InCell analyzer were used in a multiparametric methodology to evaluate cell viability, induction of oxidative stress, mitochondrial health, cell cytoskeletal functionality and changes in cellular morphology. Gene expression arrays were also carried out on 168 key genes involved in the cytoskeletal architecture and inflammatory pathway accompanied with the analysis of focal adhesions as key markers for actin-mediated signaling. Our results show distinct differences between the PMA and PTMAEMA-stat-PLMA coated QDs, which could mainly be attributed to differences in their cellular uptake levels. The toxicity profiles of both QD types changed drastically depending on whether effects were expressed in terms of given dose or internalized particles. Both QDs triggered alterations to important but different genes, most remarkably the up-regulation of tumor suppression and necrosis genes and the down regulation of angiogenesis and metastasis genes at sub-cytotoxic concentrations of these QDs. peerreview_statement: The publishing and review policy for this title is described in its Aims & Scope. aims_and_scope_url: http://www.tandfonline.com/action/journalInformation?show=aimsScope&journalCode=inan20 ispartof: Nanotoxicology vol:10 issue:9 pages:1318-1328 ispartof: location:England status: published

Water pollution with large-scale and small-scale plastic litter is an area of growing concern. Macro-plastic litter is a well-known threat to aquatic wildlife; however, the effects of micro-sized and nano-sized plastic particles on the health of organisms are not well understood. Small-scale plastic particles can easily be ingested by various aquatic organisms and potentially interfere with their immune system; therefore, the authors used a freshwater fish species as a model organism for nanoplastic exposure. Characterization of polystyrene (41.0 nm) and polycarbonate (158.7 nm) nanoplastic particles (PSNPs and PCNPs, respectively) in plasma was performed, and the effects of PSNPs and PCNPs on the innate immune system of fathead minnow were investigated. In vitro effects of PSNPs and PCNPs on neutrophil function were determined using a battery of neutrophil function assays. Exposure of neutrophils to PSNPs or PCNPs caused significant increases in degranulation of primary granules and neutrophil extracellular trap release compared to a nontreated control, whereas oxidative burst was less affected. The present study outlines the stress response of the cellular component of fish innate immune system to polystyrene and polycarbonate nanoparticles/aggregates and indicates their potential to interfere with disease resistance in fish populations. Environ Toxicol Chem 2016;35:3093–3100. © 2016 SETAC

Extending earlier studies where phosphocholinated brushes and phosphocholine-exposing phosphatidylcholine lipid bilayer vesicles (PC-liposomes) were shown to be very efficient boundary lubricants in aqueous media by virtue of the highly-hydrated phophocholine groups, we examined interactions between surfaces bearing phosphocholinated polystyrene nanoparticles (pc-PS-NPs). We synthesized such particles by incorporation of alkyl chains terminated with phosphocholine groups in the PS-NP, with the hydrophilic phosphocholines exposed at the NP surface. These were then allowed to adsorb onto mica surfaces, and the normal and shear interactions between them were examined in a surface force balance. On moderate compressions (contact pressures > 9 atm) the pc-PS-NPs were squeezed out, leaving a single layer between the surfaces. Shear of the surfaces revealed a large frictional dissipation, with a friction coefficient μ ≈ 0.2, in contrast to our expectations that such phosphocholinated NPs would provide highly lubricating analogues of PC-liposomes (for which μ ≈ 10−3 – 10−4). This is attributed to a number of factors, including the inherent roughness of the NP multilayers at low compressions and the relatively low areal density of the phosphocholine groups on the PS-NP surfaces. In particular, at higher compressions, sliding results in energy-dissipating breaking and reforming of phosphocholine/mica (dipole/charge) bonds at the mica surfaces (and thus high friction), because of bridging of the surfaces by a single layer of pc-PS-NPs. Copyright © 2016 John Wiley & Sons, Ltd.

Gel formation without chemical cross-links requires strong physical bonds, as observed in diverse molecular and macromolecular systems or supramolecular assemblies above a critical concentration. Here, we present a new molecular amphiphile of propeller-like hexaphenylbenzene derivative bearing two short poly(ethylene glycol) (PEG) chains which forms reversible physical gels comprising long (∼2.2 μm) bundles of hydrogel fibrils in coexistence with spherical micelles. Combination of topological (entanglement-like) interactions between the fibers and specific hydrophobic interactions due to the helicity of the PEG chains is proposed to account for the hydrogelation in the semidilute regime. The present supramolecular hydrogels, which are based on small molecules, exhibit extraordinary properties with an exceptionally strong dependence of the shear modulus on concentration, akin to the behavior of ultrahigh molecular weight cellulose-based fibers.

Oilfield iron sulfide (FeS) control and prevention have been mostly proprietary with several disparate solutions. Frequently FeS control involves milling, jetting, acid soaking, pulling and replacing tubing and manually cleaning tanks, vessels, separators and pumps. These methods are costly, wasteful and strenuous. This paper reviews the latest developments in oilfield FeS researches with an attempt to integrate viable solutions and expose unworkable practices.In this work, we review and evaluate the most common FeS prevention and control solutions in an attempt to summarize the state-of-art FeS mitigation technologies. We have a closer look on FeS formation and control as well as potential integrated solutions. The paper reviews and differentiates treatment solutions between corrosion byproduct and FeS scale deposition from formation.Most FeS scales have generally been treated as the same, using various treatment methods. Complex FeS polymorphs have resulted in different outcomes. This work focuses on different treatment options that assert to work for all FeS scale not differentiating between corrosion-byproduct and reservoir formed scale.Successful case histories and suspected FeS polymorph are presented in this paper next to discussion of the model used to predict severity of the deposition and analyze the treatment design. FeS formation and deposition is evaluated, especially crystallography and fundamental studies into mechanistic aspects of FeS precipitation and how it relates to oilfield FeS precipitation.In this paper state-of-art FeS scale research is summarized and differences to normal scale types are presented. Mineral scale in the true sense of going through the stages of nucleation, pre-crystallization, crystal growth, agglomeration and deposition. This is an important step change in consolidating all the disparate areas of FeS studies into an advanced solution focused approach. If FeS scale is considered a mineral scale then solutions such as scale inhibitor applications (continuous injection and squeeze) that work for common mineral scales should work for FeS deposition as well. Thereby moving FeS research from a relatively empirical level with vastly different approaches that are mostly unrealistic into solutions that will be viable in the oilfield.

A new method is described for fabricating autonomic, self-healing, deformable organogels. We combined imidazolium-based poly(ionic liquid) (PIL) and azobenzene-grafted poly(carboxylic acid) (PAA-Azo) in N,N-dimethyl formamide. Further, complexing PIL with unirradiated (trans) or irradiated (cis) PAA-Azo tuned the elastic modulus of the organogel.

A route of synthesizing triblock terpolymers in a one-pot, "one-step" polymerization approach is presented. The combination of two distinct polymerization techniques through orthogonal catalyst/initiator functionalities attached to a polymeric linker furnishes novel pathways to ABC-terpolymers. Both polymerizations have to be compatible regarding mechanisms, chosen monomers, and solvents. Here, an α,ω-heterobifunctional poly(ethylene glycol) serves as poly-meric catalyst/initiator to obtain triblock terpolymers of poly(norbornene)-b-poly(ethylene glycol)-b-poly(L-lactic acid) PNB-PEG-PLLA via simultaneous ring opening metathesis poly-merization and ring opening polymerization in a fast one-pot polymerization. Structural characterization of the polymers is provided via (1)H-, DOSY-, and (1)H,(1)H-COSY-NMR, while solution and thin film self-assembly are investigated by dynamic light scattering and atomic force microscopy.

Polyhydroxyethyl methacrylate-linked by-polysulfone amphiphilic polymer conetworks of two types of segments with Tg above room temperature are presented. The conetworks are prepared by free radical copolymerization of methacryloyl-terminated PSU macromers with 2-ethyl methacrylate, followed by removal of the TMS protecting groups by acidic hydrolysis. Phase separation in the nanometer range due to the immiscibility of the two covalently linked segments is observed using transmission electron and scanning force microscopy. The swelling of the conetworks in water and methanol as polar solvents and chloroform as nonpolar solvent are studied gravimetrically and then in a more detailed fashion by solid-state NMR spectroscopy. Selective swelling and also targeted loading of a small organic model compound specifically to one of the two phases are demonstrated.

Smart scale management techniques are of great demand in nowadays oil and gas industry. The formation of zinc, iron and lead sulphide scales can cause severe damages of production equipment which ultimately results in loss of productivity.1-4 Currently used materials act inefficient, as high amounts of materials are needed, which makes research in this field demanding.5 However, to develop anti-scaling agents, a deeper understanding of the molecular interactions of the typically used polymers is required. To understand the occurring interactions, isothermal titration calorimetry (ITC) is introduced as a new method, which allows for a more rational design of a new material and makes screenings, as the have been done in the past, unnecessary. With the use of ITC it was proven, that several sulfonic acid, phosphonic acid and carboxylic acid carrying monomers are suitable candidates showing strong interaction with the zinc sulfide surface, which is one of the exotic problems in scale formation.6 Furthermore, the influence of the molecular weight and the composition was identified during the investigations of the different homopolymers and copolymers of the previously tested monomers.

Numerous catechol-containing polymers, including biodegradable polymers, are currently heavily discussed for modern biomaterials. However, there is no report combining poly(phosphoester)s (PPEs) with catechols. Adhesive PPEs have been prepared via acyclic diene metathesis polymerization. A novel acetal-protected catechol phosphate monomer was homo- and copolymerized with phosphoester comonomers with molecular weights up to 42000 g/mol. Quantitative release of the catechols was achieved by careful hydrolysis of the acetal groups without backbone degradation. Degradation of the PPEs under basic conditions revealed complete and statistical degradation of the phosphotri- to phosphodiesters. In addition, a phosphodiester monomer with an adhesive P-OH group and no protective group chemistry was used to compare the binding to metal oxides with the multicatechol-PPEs. All PPEs can stabilize magnetite particles (NPs) in polar solvents, for example, methanol, due to the binding of the phosphoester groups in the backbone to the particles. ITC measurements reveal that multicatechol PPEs exhibit a higher binding affinity to magnetite NPs compared to PPEs bearing phosphodi- or phosphotriesters as repeating units. In addition, the catechol-containing PPEs were used to generate organo- and hydrogels by oxidative cross-linking, due to cohesive properties of catechol groups. This unique combination of two natural adhesive motives, catechols and phosphates, will allow the design of novel future gels for tissue engineering applications or novel degradable adhesives.

The synthesis of a series of propeller-shaped hexaphenylbenzenes (HPB) substituted with one (3), two (1) and four (2) poly(ethylene glycol) (PEG) chains as well as of an ortho-connected trimer of H...

A series of novel polyfluorenes, soluble exclusively in perfluorinated solvents, were prepared. The new materials were studied with regard to orthogonal processing of organic electronic materials. The desired solubility was achieved by introducing semifluorinated side chains to the fluorene monomers. Since the use of long perfluoroalkyl chains (RF) is restricted due to public health concerns, a synthetic route for polyfluorenes with short RF chains branched by aromatic units has been developed. The photophysical behavior of the resulting polymers was investigated in solution and thin films by UV/Vis absorption and photoluminescence spectroscopy. The photoluminescence quantum yields were found to be in the range of those of alkylated polyfluorenes. The electroluminescent properties were studied in single-layer polymer light-emitting diodes, with the new polymers as active materials, which exhibited similar characteristics to previously published single-layer devices with polyfluorenes containing long RF. The wetting properties of different polyfluorene films containing fluorinated, polar, polyethylene glycol, or nonpolar alkyl groups were investigated by contact angle measurements.

The formation of polyethylene fibers via metallocene-catalyzed polymerization using anisotropic organic supports as templates is presented. The supports are obtained by electrospinning a mixture of polyvinyl alcohol and functionalized polystyrene nanoparticles. After loading the MAO-activated metallocene on the support and olefin polymerization, the obtained catalyst system yields polyethylene fibers displaying a core-sheath structure with a controlled diameter in the range of 0.3–2 μm. This strategy represents a direct method to fabricate well-defined polyolefin fibers and mats during the polymerization without any further processing.

A versatile nanoparticle system is presented in which drug release is triggered by enzymatic polymer cleavage, resulting in a physicochemical change of the carrier. The polylactide-block-peptide-block-polylactide triblock copolymer is generated by initiation of the ring-opening polymerization of L-lactide with a complex bifunctional peptide having an enzymatic recognition and cleavage site (Pro-Leu-Gly-Leu-Ala-Gly). This triblock copolymer is specifically bisected by matrix metalloproteinase-2 (MMP-2), an enzyme overexpressed in tumor tissues. Triblock copolymer nanoparticles formed by nonaqueous emulsion polymerization are readily transferred into aqueous media without aggregation, even in the presence of blood serum. Cleavage of the triblock copolymer leads to a significant decrease of the glass transition temperature (Tg) from 39 °C to 31 °C, likely mediating cargo release under physiological conditions. Selective drug targeting is demonstrated by hampered mitosis and increased cell death resulting from drug release via MMP-2 specific cleavage of triblock copolymer carrier. On the contrary, nanocarriers having a scrambled (non-recognizable) peptide sequence do not cause enhanced cytotoxicity, demonstrating the enzyme-specific cleavage and subsequent drug release. The unique physicochemical properties, cleavage-dependent cargo release, and tunability of carrier bioactivity by simple peptide exchange highlight the potential of this polymer-nanoparticle concept as platform for custom-designed carrier systems.

In the ideal case, a precise synthesis yields molecules with a constitutional as well as a conformational perfectness. Such a case of precision is demonstrated by the synthesis of semi-rigid amphiphilic polyphenylene dendrimers (PPDs). Polar sulfonate groups are precisely placed on their periphery in such a manner that patches of polar and non-polar regions are created. Key structural features are the semi-rigid framework and shape-persistent nature of PPDs since the limited flexibility introduces a nano-phase-separated amphiphilic rim of the dendrimer. This results in both attractive and repulsive interactions with a given solvent. Frustrated solvent structures then lead to a remarkable solubility in solvents of different polarity such as toluene, methanol, and water or their mixtures. Water solubility combined with defined surface structuring and variable hydrophobicity of PPDs that resemble the delicate surface textures of proteins are important prerequisites for their biological and medical applications based upon cellular internalization.

Branched fluorinated amphiphiles containing carbohydrate-based hydrophilic groups are presented and compared with traditional poly(ethylene glycol)-based amphiphiles. The carbohydrate and poly(ethylene glycol) groups are grafted onto a hydrophobic block having two or three short, non-bioaccumulative perfluoroalkyl chains by Click Chemistry. The presented amphiphiles containing two perfluoroalkyl chains and 1-desoxy-lactose moiety decrease the static surface tension to below 20 mN/m in water, which is significantly lower than other reported carbohydrate derivatives. Static surface tension is measured by Wilhelmy plate method in aqueous solutions and used to calculate the interfacial packing density. The use of multiple shorter fluorophilic chains into the same surfactant molecule provides comparable surface activity to and circumvents the need for longer fluorinated chains which are banned in several industrial countries for environmental reasons by the year 2015. Hence, the presented amphiphiles are potential alternatives for utilization in e.g. wetting or coating applications.

Summary Nanoscience often focuses on the formation of nanoparticles without paying enough attention to their further manipulation. One of the fundamental issues concerning nanoparticles upon processing and utilization is overcoming the problem of aggregation. Special methods are therefore required to keep them as individual, isolated objects. Especially for inorganic particles, we demonstrate practical methods herein for nanoparticle functionalization, stabilization, and transfer between media of different polarities. The homogeneous incorporation of inorganic nanoparticles into matrix polymers to yield nanocomposites is a primary concern. In all cases, amphiphiles appear to play a decisive role in avoiding aggregation. We therefore compare block copolymers, statistical copolymers and low molecular weight surfactants to derive practical guidelines regarding the efficient stabilization of nanoparticles. Inorganic nanoparticles stand in the foreground but many comparisons to their organic analogues can be applied.

Free-standing nanomembranes with molecular or atomic thickness are currently explored for separation technologies, electronics, and sensing. Their engineering with well-defined structural and functional properties is a challenge for materials research. Here we present a broadly applicable scheme to create mechanically stable carbon nanomembranes (CNMs) with a thickness of similar to 0.5 to similar to 3 nm. Monolayers of polyaromatic molecules (oligophenyls, hexaphenylbenzene, and polycyclic aromatic hydrocarbons) were assembled and exposed to electrons that cross-link them into CNMs; subsequent pyrolysis converts the CNMs into graphene sheets. In this transformation the thickness, porosity, and surface functionality of the nanomembranes are determined by the monolayers, and structural and functional features are passed on from the molecules through their monolayers to the CNMs and finally on to the graphene. Our procedure is scalable to large areas and allows the engineering of ultrathin nanomembranes by controlling the composition and structure of precursor molecules and their monolayers.

The existence of a dendritic box in polyphenylene dendrimers is demonstrated by isothermal titration calorimetry (ITC). The thermodynamic parameters of the uptake process of a variety of small guest molecules into the dendrimers are measured. ITC revealed that for dendrimers with an unpolar interior this process is mainly entropically driven. Two processes have been elucidated for the entropy gain: (i) the release of solvent molecules which solvate the guests and (ii) solvent molecules in the voids of the dendrimers which are replaced by the guests. For dendrimers which are substituted with polar functionalities in the core, enthalpic effects become more dominant as some hydrogen bonds and π–π-interaction come into play. Because of the rigidity of the dendrimer host, these less specific interactions can only occur in the core of the differently functionalized interior of the dendrimers since the surface is the same all over. Thereby, it is evidenced that guest molecules can be selectively trapped inside t...

Polypeptides are successfully incorporated into poly(l-lactide) (PLLA) chains in a ring-opening polymerization (ROP) of l-lactide by using them as initiators. The resulting ABA triblock copolymers possess molecular weights up to 11000 g·mol(-1) and polydispersities as low as 1.13, indicating the living character of the polymerization process. In a nonaqueous emulsion, peptide-initiated polymerization of l-lactide leads to well-defined nanoparticles, consisting of PLLA-block-peptide-block-PLLA copolymer. These nanoparticles are easily loaded by dye-encapsulation and transferred into aqueous media without aggregation (average diameter of 100 nm) or significant dye leakage. Finally, internalization of PLLA-block-peptide-block-PLLA nanoparticles by HeLa cells is demonstrated by a combination of coherent anti-Stokes Raman spectroscopy (CARS) and fluorescence microscopy. This demonstrates the promise of their utilization as cargo delivery vehicles.

Water ecosystems represent main targets of unintentional contamination of nanomaterials, due to industrial waste or other anthropogenic activities. Nanoparticle insult to living organisms may occur in a sequential way, first by chemical interactions of the material with the target membrane, then by progressive internalisation and interaction with cellular structures and organelles. These events trigger a signal transduction, through which cells modulate molecular pathway in order to respond and survive to the external elicitation. Therefore, the analysis of the global changes of the molecular machinery, possibly induced in an organism upon exposure to a given nanomaterial, may provide unique clues for proper and exhaustive risk assessment. Here, we tested the impact of core/shell CdSe/ZnS QDs coated by a positively charged polymer on two aquatic species, the polyp Hydra vulgaris and the coral S. pistillata, representative of freshwater and sea habitats, respectively. By using reliable approaches based on animal behaviour and physiology together with a whole transcriptomic profiling, we determined several toxicity endpoints. Despite the difference in the efficiency of uptake, both species were severely affected by QD treatment, resulting in dramatic morphological damages and tissue bleaching. Global transcriptional changes were also detected in both organisms, but presenting different temporal dynamics, suggesting both common and divergent functional responses in the two sentinel organisms. Due to the striking conservation of structure and genomic organisation among animals throughout evolution, our expression profiling offers new clues to identify novel molecular markers and pathways for comparative transcriptomics of nanotoxicity., This project was supported by Italy-Israel Joint Innovation Program for Scientific and Technological Cooperation in R&D to CT and by the European Commission (project FutureNanoNeeds to WJP).

Well-defined copolymers of various compositions possessing polar polyphosphonate brushes precisely placed on an unsaturated polyethylene backbone were obtained by a combination of ADMET and ATRP. Both a macromonomer and macroinitiator approach were explored along with conversion to requisite poly(vinylbenzyl phosphonic acid) (PVBPA)/polyolefin graft copolymers. All polymers were quantitatively deprotected to the corresponding free phosphonic acid-containing PVBPA/polyolefin graft copolymer electrolytes. The thermal behavior and the phase transitions of these materials showed amorphous behavior that was exploited in subsequent proton conductivity experiments. Proton conductivity properties of the PVBPA/polyolefin graft copolymers in anhydrous as well as in humidified conditions reached magnitudes of 10−2 S cm−1 with particular architectures.

The preparation of poly(L-lactide) nanoparticles via ring-opening polymerization (ROP) of L-lactide is conducted in non-aqueous emulsion. In this process, acetonitrile is dispersed in either cyclohexane or n-hexane as the continuous phase and stabilized by a PI-b-PEO, respectively, a PI-b-PS copolymer as emulsifier. The air and moisture sensitive N-heterocyclic carbene 1,3-bis(2,4,6-trimethylphenyl)-2-ididazolidinylidene (SIMes) catalyzes the polymerization of L-lactide at ambient temperatures. Spherical poly(L-lactide) nanoparticles with an average diameter of 70 nm and a tunable molecular weight are generated. Hence, the non-aqueous emulsion technique demonstrates its good applicability toward the generation of well-defined poly(L-lactide) nanoparticles under very mild conditions.

An inverse emulsion technique which allows the anisotropic growth of a broad variety of inorganic nanoparticles, together with an efficient hydrophobization, is described. This method is based upon the combined use of amphiphilic copolymers, which act as emulsifiers as well as compatibilizers, and structure-directing agents that control the crystallization of the inorganic nanoparticles. As a consequence, water-soluble, structure-directing agents can now be applied for the synthesis of hydrophobic, shape-anisotropic nanocrystals. More precisely, spherical, rod-like, and branched CdS as well as Au nanoparticles were prepared. Due to their excellent hydrophobization, these particles were homogeneously incorporated into a poly(2-ethylhexyl methacrylate) matrix. Their shape-dependent properties were transferred to nanocomposites as demonstrated for branched CdS nanocrystals. In comparison to more traditional materials composed of branched CdS nanoparticles, which are stabilized by low molecular weight amphiphiles, our composites show much less scattering. This is due to the homogenous distribution of the nanoparticles in the matrix.

A synthetic strategy to prepare various amphiphilic, conjugated graft copolymers by means of the grafting onto technique via click coupling reaction is described. In particular, amphiphilic, conjugated polyelectrolyte brush copolymers based on 2,7-linked carbazole–fluorene copolymers as main chains and pH-sensitive, highly charged poly(acrylic acid) side chains (PAA) are presented. The main chain is obtained by a Suzuki polycondensation of dibromo- and diboronic ester of fluorene and carbazole monomers, resulting in conjugated polyphenylene-type copolymers with both alternating and statistical carbazole–fluorene structures. In order to vary the amphiphilicity of the graft copolymers, 9,9-disubstituted fluorene derivatives with different polarities, induced by branched alkyl as well as by methoxytetra(ethylene glycol) (TEG) groups, were used. To graft the side chains on the conjugated backbone, the carbazole units are, first, N-functionalized by pentynyl groups. These units are reacted in a click reaction ...

Block copolymers containing poly(phenylene oxide) (PPO) and poly(vinyl benzyl phosphonic acid) segments are synthesized via atom transfer radical polymerization (ATRP). Monofunctional PPO blocks are converted into ATRP active macroinitiators, which are then used to polymerize a diethyl p-vinylbenzyl phosphonate monomer in order to obtain phosphonated block copolymers bearing pendent phosphonic ester groups. Poly(phenylene oxide-b-vinyl benzyl phosphonic ester) block copolymers are hydrolyzed to corresponding acid derivatives to investigate their proton conductivity. The effect of the relative humidity (RH) is investigated. The proton conductivity at 50% RH and one bar of vapor pressure approaches 0.01 S cm−1.

A series of amphiphilic copolymers with variable charge densities on their backbone is synthesized. Positively charged N,N,N-trimethylammonium-2-ethyl methacrylate iodide or negatively charged 2-(methacryloyloxy)ethylphosphonic acid and lauryl methacrylate are used as building blocks. When wrapped around hydrophobically capped inorganic nanoparticles (NPs), the latter are able to disperse in aqueous solutions. Using this method, positively as well as negatively charged colloidal NPs can be synthesized in a reliable way. The method presented herein allows the charge on the NPs to be adjusted to different negative and positive values by using polymers with a variable ratio of charged monomers and lauryl methacrylate. Virtually all kinds of hydrophobic inorganic NPs could be coated with these amphiphilic polymers. The coating procedure is demonstrated for Au particles as well as for CdSe/ZnS quantum dots. To date, wrapping amphiphilic polymers around NPs has led only to anionic NPs. The polymers synthesized in this work allow for positively charged NPs with a high colloidal stability.

The production of silver and copper particles by laser ablation in an organic solvent and their in situ functionalization with amphiphilic copolymers bearing fluorinated side chains is presented. Aside the stabilization of the particles, the fluorinated side chains render the modified particles compatible with a perfluorinated matrix, which results in a homogeneous distribution of the particles in the matrix. The incorporation of silver particles in perfluorinated matrices is of special interest for the preparation of antibacterial composites, e.g. PTFE, which might be applied in antibacterial implants, e.g. antibacterial vascular prostheses. Laser ablation in liquids as a general method to produce charged nanoparticles of any metal is hence combined with sophisticated surface active compounds.

A one-step inverse emulsion process using amphiphilic surface-active copolymers for the synthesis of hydrophobized, shape-anisotropic inorganic nanoparticles is presented. While such structures are normally prepared sequentially by particle formation and hydrophobization, we have combined both reactions. This approach is demonstrated exemplarily with zinc oxide (ZnO) nanoparticles. A key issue is the design of amphiphilic copolymers that act as emulsifiers to enable an aggregate-free redispersion of the particles and to stabilize the inverse emulsion for the precipitation in the droplets. In a first approach, the stabilizing as well as the hydrophobizing property of the copolymers are combined with the ability to control the crystallization in one polymer (structure-directing emulsifier—SDE). In a second approach, a mixture of two polymers is applied: an amphiphilic copolymer for hydrophobizing/stabilizing the inorganic nanoparticles and a polar or double hydrophilic polymer that induces the anisotropic growth of the ZnO nanocrystals (structure-directing agents—SDA). Homopolymers and block copolymers, consisting of phosphonic acid groups or propylene oxide groups, were used as SDAs. Typically, hydrophobized shape-anisotropic particles of up to 600 nm in length and with an aspect ratio of 1:4 were obtained.

The use of nonaqueous emulsions to synthesize particles by ROMP is described. The applied emulsions - consisting of two immiscible, organic, aprotic solvents - are versatile reaction systems for the preparation of polymer particles from moisture sensitive monomers and catalysts. Whereas up to now only polycondensations or polyadditions have been utilized in nonaqueous emulsions, catalytic polymerizations are now presented. Four different functionalized norbornene derivatives were applied for ROMP by a second-generation Grubbs catalyst to form polymer nanoparticles. Furthermore, core/shell and surface functionalized nanoparticles applicable to "click" reactions were prepared to demonstrate the use of different polymerization procedures in one pot.

The preparation of nanosized, molecularly imprinted polymer particles by nonaqueous emulsion polymerization is presented. Monodisperse cross-linked polymer nanospheres with a diameter of around 100 nm were synthesized using a standard monomer mixture of methacrylic acid and ethylene dimethacrylate, containing (±)-propranolol as a template. The rebinding efficiency of the resulting particles was determined by batch rebinding tests and isothermal titration calorimetry (ITC). The results indicate that the proposed imprinting process under nonaqueous conditions lead to particles with an enhanced capacity of template rebinding compared to both nonimprinted ones and to particles obtained by more conventional emulsion polymerization in water.

Two synthetic approaches to modify the surface of inorganic particles are presented. In the first approach the inorganic particles are prepared in-situ in a confined space in inverse emulsions. The used amphiphilic statistical copolymers act not only as emulsifiers, but they also hydrophobize the remaining inorganic particles after the precipitation. This approach represents a versatile method to obtain various inorganic nanoparticles as well as more complex inorganic materials like core-multiple shell and perovskite-based nanoparticles. The second procedure uses preformed inorganic particles, as an aqueous dispersion, to modify them with surface active amphiphilic copolymers in a multicomponent solvent system. This method turns out to be a simple but highly efficient method to modify preformed inorganic nanoparticles. The particles are characterized by SEM, TEM and dynamic light scattering. The modified inorganic nanoparticles are suitable to be homogenously incorporated into a polymer matrix to form transparent nanocomposite materials.

We studied the fluorescence enhancement of a dye-loaded polyphenylene dendrimer in a gap of 2-3 nm between a silver film and single silver particles with an average diameter of 80 nm. This sphere-on-plane geometry provides a controllable plasmonic resonator with a defined dye position. A strong fluorescence signal was seen from all particles, which was at least 1000 times stronger than the signal from the plane dye-coated metal surface. The fluorescence emission profile varied between the particles and showed light emission at higher energies than the free dye, which we assigned to hot luminescence. The maximum fluorescence emission peak shifted along with the scattering maximum of the plasmonic resonance. Two classes of scattering resonators could be distinguished. Up to a significant line-broadening, the response of the "sphere-on-plane"-like cases resembled the theoretical prediction for a perfect sphere-on-plane geometry. Resonators which deviate strongly from this ideal scenario were also found. Electron microscopy did not show significant differences between these two classes, suggesting that the variations in the optical response are due to nanoscale variations of shape and roughness in the gap region. The strong modifications of the dye emission spectrum suggested the presence of physical mechanisms at very small metal/dye separations, which are beyond a simple wavelength-dependent enhancement factor.

Polyethylene structures containing precisely placed phosphonic acids were synthesized varying both the frequency of acid appearance along the backbone and the architecture associated with each position. Single, geminal, and benzyl attachment schemes are described with symmetry of placement being an important feature. Altering these precision primary structures has a direct effect on secondary structure where changes in thermal behavior become obvious, particularly in terms of crystallization behavior. It is evident that strong interactions between polymer chains exist, effecting polymer crystallization and solubility depending upon both the length of methylene run-lengths between symmetrically placed acids and whether or not the acid group is protected as the ester or free to participate in hydrogen bonding, which directly influences interchain interaction.