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We disclose an efficient synthesis to prepare polymeric membranes containing cyclodextrins (CDs). Bulk polymerization of ethyl acrylate containing peracetylated γ-CD (PAcγCD) yields a porous polymeric membrane containing CDs [CD membrane (BP)]. Krypton adsorption measurements reveal that the CD membrane (BP) has a porous structure. The specific surface area of the CD membrane (BP) is 10 times higher than that of a CD-based polymeric membrane prepared via solution casting using a solution containing poly(ethyl acrylate) and PAcγCD. Due to the large specific surface area of the CD membrane (BP) and the molecular recognition of CD, the capabilities and selectivity of CD membrane (BP) to separate bisphenol A as an environmental pollutant from water are demonstrated.

Additive manufacturing (AM) affords the opportunity to print tailored pharmaceuticals to customize the quantity of medicine, number of medicines, and time and rate of release to be adapted for an individual's needs. A series of sulfonated poly(ethylene glycol) (SPEG) polymers for fused filament fabrication (FFF) that (i) dissolves quickly (

For polymer-based (nano)composites, the strain/stress induced by reinforcing agents within the polymer may be identified and quantified at molecular level by Raman spectroscopy. The manuscript focuses on correlations between mechanical properties of composites and their Raman spectra, with emphasis on the displacements of the position(s) of Raman lines due to local strains/stress. Investigations on polystyrene-(ethylene-co-butylene)-styrene block copolymers filled with various amounts of graphite are reported. The modifications of Raman's parameters (line intensity, position, and width) upon the loading with graphite are analyzed. Raman revealed a strong dampening of molecular vibrations within the polymer, upon the loading with graphite, indicating a good mechanical coupling between the polymer and the reinforcing agent. Significant differences between Raman spectra obtained with green and red lasers, were reported; Raman spectra obtained with red laser are more sensitive to motions occurring within the polymer while the spectra obtained using green laser are more sensitive to graphite.

The effects of hydrogen bonding, existing between hydroxyls of TSOS (trisilanolheptaphenyl POSS) molecules and carbonyls of PLLA chains, on the crystallization behaviors of PLLA have been detailedly investigated by DSC and temperature-programmed FTIR. The results of DSC scanning demonstrate that the recrystallization capability of quenched PLLA melts is remarkably enhanced in cold crystallization after introducing TSOS molecules due to the nucleating of TSOS molecules and hydrogen bonding interactins. In isothermal melt crystallization, TSOS molecules play a dual role of both inhibitors of crystallization because of hydrogen bonding interactions and nucleating agents resulting from aggregated TSOS molecules. Hydrogen bonding interaction between carbonyls of PLLA and hydroxyls of TSOS is determined by FTIR. Owing to the hydrogen bonding interaction in PLLA/TSOS nanocomposite, mobility and folding of PLLA chains are highly impeded, resulting in decrease of the overall crystallization rate in melt crystallization. The melt crystallization kinetics show that hydrogen bonding interaction plays a predominant role in determining the overall crystallization of PLLA. Besides, hydrogen bonding interactions in PLLA/TSOS blending system are further substantiated by a control experiment of PLLA/OVS blending system, where there is no existence of hydrogen bonding interaction. Because of high specific area of TSOS nano-filler, TSOS readily aggregates into POSS grains, which is detected by SEM and wide angle XRD.

Recent progress on polymerization of diazoacetates is described. Polymerization of diazoacetates has attracted much attention as an efficient method for C1 polymerization, which constructs C-C main chains from one carbon units. A variety of initiating systems consisting of Cu, Pd, B, and microwave activation have been revealed to afford polymers from diazoacetates with relatively low molecular weight. Rh-initiated polymerization of diazoacetates is remarkable for its ability of affording high molecular weight polymers in a stereospecific manner. The essence of the active species and mechanistic details for the Rh-initiated polymerization have been clarified by a combination of experimental and theoretical investigations. Copolymerization of diazoacetate with (CH2)n-affording monomers yielded unique polymer structures comparable to those of ethylene-acrylate copolymers. A series of postpolymerization modification approaches have been examined for the polymers obtained by the Rh-initiated polymerization. Some Pd-based initiating systems have been revealed to be effective for the polymerization of diazoacetates. A variety of substituents were introduced as ester substituents of diazoacetates, and they were polymerized by the Pd-based initiating systems. The effect of dense packing of the substituents on properties of the resulting polymers were examined in comparison to their vinyl polymer counterparts, and the enhanced properties in poly(substituted methylene)s were indeed observed in a number of examples.

Supramolecular polymerization is influenced by many factors, especially the stiffness of the polymers, which is directly related to cyclization of the polymers. We have proposed a supramolecular “ring opening” polymerization system with DNA molecules to study the ring-chain equilibrium of supramolecular polymerization. The molecular weight of the supramolecular polymers was characterized by Asymmetric Flow Field Flow Fractionation, and the diffusion coefficient of the supramolecular polymers was characterized by Fluorescent Correlation Spectra. Tuning the ratio of the “ring opening” strand, the length of the DNA monomers and temperature could change the ring-chain equilibrium, thus influence the molecular weight and diffusion coefficient. This strategy has offered us a useful platform to dig into the kinetic mechanism of supramolecular polymerization.

A series of starch-graft-poly (methyl methacrylate) (S-g-PMMA) copolymers were prepared by single electron transfer living radical polymerization (SET-LRP) at molecular level under mild conditions. The successful grafting polymerization was confirmed by FT-IR and 1H NMR spectroscopies. The hydrolysate of S-g-PMMA via acid-catalyzed hydrolysis proved to be a mixture of 1-arm, 2-arm and 3-arm polymers by MALDI-TOF measurements. Furthermore, the micelles formed by S-g-PMMA copolymers in water were studied at various conditions by SEM, TEM and DLS measurements. The results indicate that the sizes of micelles decreased following the order of the common solvents of 1,4-dioxane, tetrahydrofuran, acetone and acetonitrile, and also increased with the increase of initial copolymer concentrations, addition rate of water and length of grafted chains.

To optimize a dynamic network structure is a key feature for a supramolecular self-healing material capable of perfectly and repeatedly restoring its morphology and performance following a mechanically damaging event. Despite significant progress in self-healing supramolecular networks over the past few decades, many questions surrounding the dynamic responses of these networks during healing still remain. Herein, we present the self-healing behavior of a dual dynamic supramolecular network (DDN) consisting of a weak clustery supramolecular network and a strong dendritic supramolecular network simultaneously. The DDN is easily prepared by the complexation of linear and non-linear poly(e-caprolactone)s end functionalized with 2-ureido-4[1H]-pyrimidinone, which exhibits 100%-optical and 95%-mechanical healing efficiencies within 2 and 5 min, respectively, at 90 °C. In addition, the DDN film is shown to repeatedly self-heal ten times, even when damaged at the same position. DDN healing depends significantly on the density of the supramolecular network, and is specifically accomplished by the reassociation of hydrogen bonds between UPy moieties at the thermally swollen status of the dendritic network following the thermal disassembly of the clustery network. The DDN-coated nylon fabric exhibits excellent self-healing characteristics, which opens opportunities for creating scratch-protective materials.

Mullins effect of carbon black filled nitrile butadiene rubber compounds and vulcanizates during cyclic tensile deformation is investigated and the influences of thermal annealing of the stretched samples, the deformation velocity and history and the solvent swelling are discussed. The energy losses associated with recovery hysteresis and softening accompanying the Mullins effect at a given crosshead velocity are quantitatively analyzed. The results show that the recovery hysteresis involves in microscopic deformation of the rubber phase in the nanocomposites but it disappears in the swollen samples. On the other hand, the softening is associated with both the rubber and filler phases; its energy loss increases with increasing filler content and decreases significantly by swelling. Furthermore, the softening of samples stretched at room temperatures is recoverable after conditioning at 80 °C but the recovery is retarded significantly by filler. The investigation allows gaining recognition of the important role played by the viscoelastic rubber matrix and the influence of the filler.

In this work we successfully synthesized degradable microgels based on poly(N-vinylcaprolactam) (PVCL) with hydrophobic pockets for the uptake/release of poorly water-soluble molecules. The degradability as well as the presence of hydrophobic pockets in the microgel structure are ensured by incorporation of a star-shaped acrylate-functionalised poly(e-caprolactone) (starPCL) crosslinkers. Microgels with variable amount of star PCL crosslinker, narrow size distribution and a hydrodynamic radius of 200–400 nm were obtained by miniemulsion polymerisation. The microgel size and size distribution was characterised by means of dynamic light scattering (DLS), field emission scanning electron microscopy (FESEM) and sedimentation analysis. The obtained microgels undergo enzymatic degradation in aqueous medium as evidenced by DLS, nuclear magnetic resonance (NMR) and FESEM. Additionally, the uptake of hydrophobic molecules like the dye Nile-Red (model system) and the drug Ibuprofen into the starPCL-based microgels was proven by ultraviolet–visible spectroscopy (UV/Vis). The experimental data indicate that the solubilisation ability of microgels can be regulated by the amount of crosslinker in the microgel structure.

This work reports the rubber electrostatic potential due to repeated strain as a function of time for periods as long as the lifetime of the sample. Rubber potential depends on two main contributions: hygroelectricity added to the mechanochemical reactions evidenced by spectroscopy and microscopy/microanalytical experiments. Hygroelectricity produces fast periodic charging in phase with rubber strain, while a slower charging process is assigned to the mechanochemical reaction products, in conjunction with residual hygroelectricity. This result explains the significant negative potential displayed by rubber over long periods in the absence of any external applied voltage. These findings may contribute to improving dielectric elastomer performance in many applications that are currently of great interest in robotics and energy harvesting. Additionally, electric potential real-time measurements show desirable features as a tool for real-time, non-contact detection of rubber structural change and fatigue.

Redox-responsive ferrocene (Fc)-containing hydrogels have attracted increasing interest for their potential applications in materials science, biomedicine and catalysis. Herein, we report the synthesis of a novel polynorbornene-based tetrablock terpolymer containing consecutively aldehyde, Fc, and dentritic triethylene glycol and aldehyde groups in the side chain by the ring-opening metathesis polymerization with the aid of the 3rd generation Grubbs catalyst. Owing to the presence of Fc and triazole groups, this copolymer could be used as both reducing and stabilizing agents for the formation of silver nanoparticles (AgNPs). Also, this copolymer could be used as a crosslinking agent to fabricate gelatin hydrogels based on the Schiff's base reaction between the aldehyde groups and the side-chain amino groups of gelatin. Based on the above properties, the AgNPs composites of gelatin hydrogels were further successfully fabricated by blending this copolymer, gelatin and AgNO3 together or soaking this Fc-containing gelatin hydrogels into the AgNO3 solution, in which the AgI was in situ reduced into Ag0 by the Fc groups. Results of inhibition zone experiments confirmed the antibacterial activities of the obtained composites against both Escherichia coli and Staphylococcal aureus.

Degumming of Bombyx mori silk cocoons by a novel and mild process using aqueous ammonia and fabrication of electrospun polycaprolactone/silk fibroin (PCL/SF) nanofibrous scaffolds is reported. Cocoons were degummed in 0.3% w/w solutions of boiling ammonia (28–30%) for 45 min. Degummed SF fibers were dissolved in phosphoric and formic acid (7/3 v/v) mixture, coagulated in methanol, filtered and dried. PCL solutions containing different amounts of SF were electrospun in formic acid, a green solvent. Scaffolds were characterized to confirm the successful incorporation of SF and to demonstrate formation of nanofibrous webs with good biomechanical properties. Cell viability assay was performed by seeding Human BJ fibroblast cells on scaffolds. In vitro analysis showed that the scaffolds produced were non-toxic and incorporation of SF resulted in enhanced cell proliferation. Nanofibrous PCL/SF scaffolds with good biomechanical properties developed through dialysis free processing of silk fibroin can be promising substrates for tissue engineering applications.

Microscopic details of the tensile behavior of disulfide crosslinked cis-1,4-polybutadiene are unveiled using atomistic molecular dynamics (MD) simulations. Stepwise deformation and relaxation method was employed to determine the tensile behavior and underlying molecular mechanism was clarified by analyzing the MD trajectory. Calculated stress-strain curve well reproduces the experimental observation. We found that tensile behavior of rubber is predominantly correlated to its microscopic structural transformation, which is primarily governed by the crosslinking topology. Strain dependence of the structural transformation due to crosslinking of polymer chains results in hyperelastic tensile behavior of rubber. Rapid increase in the stress for initial strain arises due to the realignment of randomly oriented polybutadiene chains along the pulling direction. For the intermediate strain, polybutadiene chains elongate upon the application of deforming force, giving rise to a gentle increase in the stress. However, elongation of polybutadiene chains is non-uniform due to system topology. This gives rise to the heterogeneity in the system, resulting in formation and of the void. Sharp increase in the stress at large strain can be attributed to extensibility of the polybutadiene chains. Finally, material failure transpires by dissociation of crosslinking chemical bonds.

Polyurethane elastomers have been widely used in the industry and daily life due to their versatile physical and chemical properties. Therefore, a fundamental understanding of the structures and dynamics at a molecular level will provide piercing insights into the precise design and application of new polyurethane materials. In this study, we mainly focused on investigating the strain-induced structural and dynamic changes in a typical polyurethane elastomer composed of poly(e-caprolactone) (PCL) and 4,4′-diphenylmethylene diisocyanate (MDI) as the soft and hard segments, respectively. Obvious strain-hardening phenomenon was observed during the mechanical tensile test, and a systematic comparison was performed on the fractured and pristine samples. DSC results revealed that the crystallization of PCL chains was still going on after the sample was fractured, and the crystallite structures became stable after physical aging at 25 °C for two days. 1H solid-state nuclear magnetic resonance (NMR) experiment was further employed to determine the fraction of mobile PCL chains that were converted to crystallites during stretching. Besides, the microphase separation was also significantly enhanced in the fractured sample. The mobility of amorphous PCL chains was largely reduced due to the strain-induced crystallization of nearby PCL segments, as revealed by the 1H magic-sandwich echo (MSE) NMR experiments. 1H multiple quantum (MQ) NMR experiments also quantitatively revealed the strain-induced orientation of amorphous PCL chains in the fractured sample, indicating that the PCL crystallites were acting as the physical cross-linkages to prevent the contraction of the elongated PCL chains when the sample is fractured.

Observations of large property changes in the presence of nanoparticles have motivated an increasing interest towards the interfacial effect in polymer nanocomposites. In this work, the interface between poly(ethylene oxide) (PEO) and silica (SiO2) was modulated by the inclusion of SiO2 with three different surface functionalities, namely unfunctionalized SiO2 (SiO2-OH, grafting density = 0 chains/nm2), PEO-grafted SiO2, SiO2-g-PEO-1.1 (grafting density = 1.1 chains/nm2) and SiO2-g-PEO-2.2 (grafting density = 2.2 chains/nm2), and the interfacial effect on crystallization behavior of PEO/SiO2 nanocomposites was studied by the combination of differential scanning calorimetry (DSC) and polarized light optical microscopy (PLOM) analysis. In contrast to the unfunctionalized SiO2, PEO grafting imparts SiO2 with a high nucleation ability, even though SiO2-OH demonstrates more homogenous dispersion in PEO matrix than PEO-grafted SiO2. The overall crystallization rate of PEO/SiO2 nanocomposites follows the order PEO/SiO2-g-PEO-2.2 > PEO/SiO2-g-PEO-1.1 > PEO/SiO2-OH. These results highlight the role of grafted chains on crystallization. It is speculated that the interfacial structure, as a function of grafting density, plays a critical role in the formation of nuclei, which ultimately determines the crystallization behavior. This work can contribute to understanding the interfacial effect in polymer nanocomposites and is believed to provide theoretical guidance for manipulating the properties of materials.

Polymers with dynamically exchanging crosslinks possess the ability to be repurposed, in whole or part, following a stimulus. The ability of imines to undergo dynamic exchange reactions under mild conditions was utilized to chain extend or crosslink silicone polymers. Schiff-base crosslinked polysiloxanes were prepared by reacting aminopropyl-functionalized polydimethylsiloxane with aromatic aldehydes. The reactions occur efficiently and the water byproduct spontaneously separates from the silicone if the weight fraction of silicone is sufficiently high. The physical properties of the products were readily tunable by crosslink density; the most practical reaction partners were commercial pendant aminopropylsilicones with terephthaldehyde, although telechelic silicones and triformylbenzene were also utilized. Complete breakdown of the polymers occurred with addition of excess amine. Silicone imine cleavage with excess aldehyde also occurred, but the two processes followed different pathways. The rate of the dynamic processes was increased with good solvents, or acid or amine catalysts. However, even in the absence of catalysts the dynamic transimination was efficient. Simply placing two strips of the elastomer in contact led to an adhesive bond that, depending on contact surface area, was stronger than the cohesive strength of the rubber. The process of self-healing was followed using rheology and was shown to be complete within an hour. Surface modification of elastomers with amines occurred in water, or at aminated solid surfaces.

Mold filling plays a crucial role in determining the cells' structural morphology and uniformity in high-pressure foam injection molding. This process affects the formation, deformation, and dissolution of premature cells, which nucleate in the melt/gas mixture during the mold filling. We investigated the mold-filling phenomena and the cell structure development in the high-pressure foam injection molding process with mold opening. Polystyrene was used as the matrix, and carbon dioxide and nitrogen were used as physical blowing agents. We adopted an in-situ visualization technique, which enabled us to monitor and study the formation and evolution of the cells during the mold-filling and melt-packing phases. It was found that both the shape and the size of cells, which had nucleated during the mold filling process inside the melt, were changed by the packing condition selected. Statistical analyses have shown that the packing pressure and its duration were the most influential parameters affecting the size and the shape of cells that had nucleated in the melt before the mold opening. A greater packing pressure and a longer packing time resulted in a smaller cell size with a larger deformation in the melt during mold filling. A proper packing condition eventually removed all of the cells and re-dissolved them back into the melt before mold opening. The effect of the mold-filling parameters on the final cellular structure was also investigated, using carbon dioxide and nitrogen as physical blowing agents. A complete dissolution of the premature cells during the mold-filling and packing phases resulted in a more uniform and finer cellular structure after mold opening. The obtained results and the developed knowledge provide a deeper insight into the fundamental aspects of cellular structure development in foam injection molding process, which can be used to produce highly expanded, ultra-light foams with uniform cell structure.

Silica nanomaterials modified with monomolecular C18-alkyl silane or oligomeric dimethylsiloxane units were loaded in-situ during the formation of PDMS membrane. The small-angle neutron scattering (SANS) study was performed to probe structural compatibility between the modified silica and PDMS. The Ornstein-Zernike (OZ) and Debye-Anderson-Brumberger (DAB) models were excellently fit to the SANS data describing nanoscale structure morphology in terms of correlation length scales of the soft and hard segmental units. The polymeric chain was stretched or contracted depending upon the type and amount of silica incorporation. This indicated limiting amount of silica incorporation in the PDMS membrane structure depending upon structural compatibility between the silica and PDMS. The C18-alkyl silylated silica was found to be the best compatible with the membrane structure. The membrane with 30% (w/w) C18-alkyl silylated -silica loading exhibited the best performance in pervaporation separation of alcohol/water.

Reactive compatibilization is an effective strategy to improve compatibility of incompatible polymer blends. However, the strategy is usually limited to the polymer blends that one of the components contains reactive groups. In this work, we have succeeded in the reactive compatibilization of the immiscible poly(vinylidene fluoride)/low density polyethylene (PVDF/LDPE) blends of which both components do not contain the reactive groups. We simultaneously incorporated the carboxylic acid terminated poly(methyl methacrylate) (PMMA) oligomer (PMMA−COOH) and ethylene-glycidyl methacrylate copolymer (EGMA) into the PVDF/LDPE blend. The ring-opening reactions of the carboxylic acid groups of PMMA oligomer and epoxide groups on the EGMA main chains happen during the melt blending and the in-situ formed EGMA-g-PMMA graft copolymers enhance the compatibility of PVDF/LDPE blend s significantly. The reactive compatibilized PVDF/LDPE blends have the elongation at break and fracture strength of 507% and 40.2 MPa, respectively, as compared with the 11% and 25.6 MPa of the uncompatibilization blends. Moreover, the architecture effects of the in-situ formed EGMA-g-PMMA by varying PMMA-COOH oligomer loadings, PMMA-COOH molecular weight and the processing time on the compatibilization efficiency have been investigated. It was found that compatibilizing efficiency increases with increasing the grafted density, the length of the side chain and the degree of reaction. This one-pot strategy with the in-situ formed graft compatibilizers in incompatible blends paves new possibility for unreactive blends by reactive compatibilization.

Thermo-responsive hydrogels consist of natural and synthetic macromolecules were presented based on dynamic acylhydrazone formation, which is self-healable and pH-sensitive. Hydrazone groups modified poly(N-isopropylacrylamide) (PNIPAM) copolymers and aldehyde groups exposed oxidized sodium alginate (OSA) were adopted to prepare the functional hydrogels without any catalyst. Specifically, acylhydrazone bonds, which were served as cross-linking points, endowed the hydrogels with self-healing property confirmed by rheological recovery test. Meanwhile, the hydrogels displayed obvious reversible sol-gel transition under different conditions, leading to that the hydrogels were able to be reshaped repeatedly exposed to pH trigger. Besides, due to the PNIPAM segments were served as the frameworks, the hydrogels were testified to exhibit tunable phase transition temperature between 30 °C and 40 °C around body temperature, which was regulated by variation in aldehyde and hydrazone ratio. The as-prepared hydrogels with self-healing and dual stimuli-responsive properties are beneficial to their bioapplications as drug delivery system, biosensors and soft tissue filling agents, etc.

We developed a network polymer with solvent-assisted self-healing ability based on vicinal tricarbonyl chemistry. A copolymer bearing vicinal tricarbonyl pendant groups was crosslinked with α,ω-alkanediol through the addition reaction between diol and vicinal tricarbonyl. The resulting hemiketal acted as a dynamic crosslink because it could undergo reversible alcohol-alcohol or water-alcohol exchange reaction in an ambient condition. Thermal and mechanical analyses showed that the polymer networks were in the rubbery state at room temperature while they became a viscoelastic liquid at elevated temperature. The mechanical property and the qualitative self-healing ability were found to depend on the crosslinker concentration. The network polymer with lower crosslinker concentration was less stiff and could be autonomously healed at room temperature. Those with higher crosslinker concentration were stiffer and could not be autonomously healed at room temperature. However, addition of the simplest monool, methanol, to the cut surfaces drastically improved the self-healing ability of the latter samples. The self-healing mechanism and the role of added methanol were discussed in terms of both the chemical and physical aspects.

In this study, we grafted brush-like CBMA copolymer brushes onto the surface of PVA hydrogel membrane through photo-induced electron transfer–reversible addition fragmentation chain transfer (PET-RAFT) polymerization. ATR-FTIR, XPS, AFM, UV–Vis absorption spectra and elemental analysis were adopted to characterize the hydrogels, and equilibrium swelling, water contact angle, vitro cytotoxicity assay, protein adsorption and cells adhesion experiments were used to evaluate the related property of hydrogels. The results of ATR-FTIR and XPS showed that pCBMA was successfully grafted onto the surface of PVA hydrogel membrane. The Ra roughness of hydrogel surface in AFM increased slightly from 5.44 nm to 6.12 nm. Transmittance of the PVA-g-pCBMA hydrogel in the visible range (380 nm-780 nm) was remaining at 91.2%–97.0%. The optimal reaction conditions (CPADB: 1.20 mmol/L, Eosin Y: 0.03 mmol/L and CBMA: 358 mmol/L) were confirmed through control experiments. The equilibrium swelling and water contact angle showed that the swelling ratio increased from 2.06 cm3 g−1 to 3.65 cm3 g−1, while the water contact angle decreased from 45.94° to 18.06° with the increase of grafting ratio (23.92%–55.18%). In vitro cytotoxicity assay by CCK-8 showed that the cells relative viability remained at least 90.55%. Anti-protein adsorption experiment illustrated approximately 57.2% improvement of anti-protein capacity at 37 °C, while cells adhesion experiment also showed about 64.57% improvement of anti-cells capacity. These results revealed the applicability of the oxygen tolerant PET-RAFT mechanism on the PVA modification and it was effective, feasible and non-cytotoxic method to prepare the other functional PVA hydrogel membrane.

Fabrication of self-supported 2D organic materials with controllable surface properties is a challenge due to their thermodynamic instability. Herein, a series of crystalline-coil block copolymers poly(e-caprolactone)-b-poly(acrylic acid) (PCL-b-PAA) with different compositions were synthesized for this purpose by the ring opening polymerization (ROP) of e-caprolactone (e-CL) and the subsequent atom transfer radical polymerization (ATRP) of tert-butyl acrylate, followed by treatment of trifluoroacetic acid (TFA). Two 2D polymer platelets with the spindle shape and the elongated truncated lozenge-like shape, respectively, were successfully fabricated via crystallization-driven self-assembly of the as-synthesized PCL-b-PAA. Effect of the properties of solvents and block copolymer compositions on the morphologies of 2D polymer platelets were carefully studied. The resultant 2D polymer platelets can quickly respond to environmental pH values due to the PAA chains tethered on surface of PCL crystals can undergo a different degree of ionization as pH changes. Moreover, Ag nanoparticles were also successfully loaded on the 2D polymer platelets by in situ reduction of AgNO3.

Frontal polymerization was successfully used to prepare two series of copolymers from a tetraphenylporphyrin-containing monomer (TPP-TEG-MA) and poly(ethylene glycol) methyl ether acrylate (PEGMA) or di(ethylene glycol) methyl ether methacrylate (DEGMA). Tricaprylmethylammonium (Aliquat) persulfate (APSO) was used as radical initiator to obtain highly fluorescent hydrogels with different chromophore contents. The obtained hydrogels, PEGTPP and DEGTPP series, were characterized by FT-IR spectroscopy, and the successful incorporation of TPP-TEG-MA monomer into the polymer backbone was observed. Their thermal properties were determined by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The swelling behavior of the obtained hydrogels was measured at 25 °C and pH = 7. The swelling ratio increased until equilibrium was reached after 24 h. Furthermore, the pH and temperature responses of the obtained hydrogels were measured. The optical properties of these materials were studied by absorption and fluorescence spectroscopies. They exhibited an absorption band at 418 nm (Soret band) and an emission band at 653 nm, which are typical of the porphyrin moiety.

Fused deposition modeled parts of polymeric origin exhibit inferior interlayer mechanical properties. To enhance interfacial weld stiffness, poly(lactide) blends containing low molecular weight polymers of chemically identical but enantiomerically different nature are explored. The enantiomeric composition of the low molecular weight fraction is either random or opposite, promoting molecular diffusion or nucleation respectively. The structure-relationship of the interfaces is studied using torsional stiffness, calorimetry, and rheology. Fully miscible, non-crystallizable low molecular weight additives of random L and D enantiomeric composition reduce melt viscosity and crystallization rate, promoting molecular diffusion. Nevertheless, incomplete entangling and crystallization upon interfacial mixing induce poor interfacial stiffening. Poly(lactide) stereocomplex enriched interfaces promote crystallization. Chains across weld interfaces may be mechanically anchored in crystals, but hindered diffusion limits molecular mixing and thus the extent of mechanical stiffening. Ultimately, combining melt plasticization and increased crystallization rates distinctly increases weld stiffness and thermodynamic/geometrical stability of fused deposition modeled poly(lactides).

Starting from hexachlorocyclotriphosphazene (HCCTP), hexamethylenediamine (HMDA) and 2-dimethylaminoethylamine (DMEN) novel amino-functional cyclomatrix-type poly(organophosphazene) microgels with tunable amount of cross-links were synthesized via precipitation polycondensation in acetonitrile. The synthesis is carried out as a facile one-pot approach in which the microgels' cross-linking density is directly adjusted through the concentration of DMEN acting as reactive diluent. In addition, the influence of different concentrations of DMEN on the cross-linking density of poly(HCCTP-HMDA-DMEN) microgels is investigated through corresponding changes of the microgels' size, degree of swelling, form factor and deformability. To this end, microgels prepared with different ratios of DMEN are thoroughly characterized by means of FTIR spectroscopy, dynamic light scattering (DLS), static light scattering (SLS) and microscopy (FESEM and AFM). The obtained microgels are uniform in size and exhibit high degrees of swelling in water. Our study clearly shows that the microgels' cross-linking density gradually decreases with an increasing concentration of the reactive diluent DMEN. This direct correlation is particularly verified via side-view FESEM micrographs and AFM cross-section profiles, which both reveal an increasing deformability of the microgels with the concentration of DMEN. Results from DLS and SLS measurements support these findings as they reveal an increase of the microgels’ size and degree of swelling, while the form factor (ρ = Rg/Rh) shows a gradual decrease with increasing DMEN concentration. To our knowledge, this study demonstrates for the first time a facile one pot approach for the synthesis of a new class of cyclomatrix-type poly(organophosphazene) microgels with tunable crosslink density providing a functional colloidal toolbox for different applications. © 2001 Elsevier Science. All rights reserved.

To strengthen the interfacial adhesion between aramid fiber and rubber, inspired by mussel adhesion protein and mimicking adhesive molecule, a new environmentally friendly dipping system was developed. Specifically, water-soluble pyrogallic acid and polyethyleneimine are reacted to form a network structure, which is then mixed with rubber latex to prepare the dipping solution. We use blocked isocyanate and epoxy aqueous solution to activate the fiber, and then conduct the dipping treatment. The H pull-out force between modified aramid fiber and rubber reached 147 N, achieving the level of traditional resorcinol-formaldehyde-latex dipping system (154N), while avoiding the utilization of harmful resorcinol and formaldehyde. In addition, we employed atomic force microscope for the first time to quantitatively characterize the modulus of the transition layer between the fiber and rubber. Results from this research provide new insights into the interfacial design of aramid fiber/rubber composites and will facilitate the development of aramid fiber/rubber composites.

This study reported the control of molecular weights of functional polymer chains attached to the surfaces of the narrowly distributed environmentally responsive particles obtained from a single step process. As a proof-of-concept, a pH-responsive poly( l -glutamic acid) (PLGA) macromonomer with a degree of polymerization (n) of 50 or 260 was prepared by the ring-opening polymerization of γ-benzyl- l -glutamate N-carboxy anhydride; this was performed using 4-vinylbenzylamine and was followed by hydrolysis. The pH-responsive PLGA macromonomer was further used as a stabilizer for the dispersion polymerization of styrene. Each macromonomer stabilized the dispersion polymerization, affording narrowly distributed polystyrene particles exhibiting pH-responsive aggregation or dispersion behavior, thereby indicating the graft of PLGA chains on the particle surface. Large particles with a low surface density were obtained using PLGA260. The particle sizes and surface glutamic acid densities were tunable over 0.8–2.0 μm and 0.4–1.8 unit/nm2, respectively, while maintaining narrow size distributions.

A novel block copolymer is fabricated by orthogonally coupling two end-functionalized polymers, glucose-capped methoxypoly(ethylene glycol) (mPEG2k-diol) and phenylboronic acid-capped poly(e-caprolactone) (PBA-PCL), with dual boronate ester and B N/B O dynamic covalent interactions. Due to their synergetic effect, this block copolymer can self-assemble into micelles in aqueous solution with high stability. More importantly, micellar disassembly can be only triggered in the presence of both signal inputs, acid and salt, displaying an “AND” logic-gate responsive behavior.

This study aims at the effect of electro-osmotic flow on a fibrous membrane comprised of assembled oppositely-charged polyelectrolytes and submerged in aqueous ionic solution. As electric field is applied across an edge-clamped circular membrane, it deforms under the action of a transverse force, the origin of which is in focus. Fibers were electrospun from a blend of poly(allylamine hydrochloride)/poly(acrylic acid) (PAH/PAA). A model is presented, which explains and describes the membrane deformation in terms of the ionic strength and pH level of the solution, the membrane geometry and porosity, the ζ-potential and elastic modulus of the membrane, as well as the applied cross-membrane electric potential difference. The model is corroborated by a set of experiments. The dependence of the membrane deformation on the electric potential was found to be rather weak, while the elastic modulus was found to be strongly dependent on the solution pH.

Porous biodegradable microspheres were fabricated by successful RAFT polymerization of methyl vinyl ketone onto polycaprolactone followed by an oil/water emulsion-evaporation method, then finally photodegradation of PMVK blocks by UV irradiation. Macro-CTA (chain transfer agent) was synthesized by reacting carboxylic acid-terminated CTA, S-1-dodecyl-S’-(α,α′-dimethyl-α’‘-acetic acid) trithiocarbonate (DDMAT) with hydroxyl terminated polycaprolactone, which was then used for the synthesis of triblock copolymer with methyl vinyl ketone (MVK). The synthesized triblock copolymers were characterized by FT-IR, 1H NMR spectroscopies. Gel permeation chromatography (GPC) was used to evaluate the molecular weight and molecular weight distribution and monitored the photodegradability of the block copolymers. The morphology of microspheres was spherical with smooth surfaces before UV irradiation. However, those from PCL-PMVK triblock copolymers had rough surfaces and porous structures after UV irradiation due to the photodegradation of PMVK blocks as a porous template. The porosity and shape of the microspheres and shape of microspheres were dependent on the PMVK contents and size of microspheres.

In this work, electrospun membranes of biodegradable polylactic acid and hydrosoluble collagen with multilevel architectures were fabricated by pattern template electrospunning method. The performances influenced by constituent of electrospun matrix and multilevel structures of electrospinning membranes were discussed. The mechanical properties and hydrophilicity were improved both by blending nature collagen and inducing the multilevel structures. The multilevel-architecture membranes were seeded by L929 fibroblast cells with phenotypic shape and guided growth according to pattern orientation. Cells infiltration through the fibers, cell attachment, and proliferation with fiber membranes were observed during the process. More interestingly, for further investigation of promotion the cell infiltration by multilevel structures, the electrospinning membranes were processed into tubular scaffold with 3D print scaffold. The in vivo result confirmed the scaffold favourable biocompatibility and improved tissue regeneration behaviors in vivo. The novel biodegradable membranes and scaffolds will be applicable for tissue engineering based upon their particularly multilevel architectures, which acts to support and guide cell growth in regular way.

The prominent success of polycaprolactone (PCL) bioengineered fibrous scaffolds has expanded the use of PCL over other polymers in the wide electrospinning literature. Several highly toxic solvent systems providing a good PCL solubility-spinability are recurrently applied in the overwhelming majority of studies. One of the current major focuses revolves around the challenging generation of aligned fibers that are very desirable in numerous tissue engineering applications. Moreover, the critical influence of fiber size on cellular performance has led to the use of different solvent systems for the production of specific nano- or micro-sized PCL fibers while neglecting the solvents toxicity. Therefore, our goal is to use the unconventional solvent system acetic acid/formic acid of very low toxicity, recently defined as the system producing ultra-thin PCL fibers, in a trial to outspread the size range and to tackle fiber alignment. After profound analysis of the effect of varying collector motion and collector design on fiber alignment, a novel collector producing highly aligned PCL fibers based on synchronic mechanical and electrical effects is designed. In a subsequent step, the fiber diameter is manipulated by analyzing 3 influential parameters: polymer concentration, tip-to-collector distance and the frequently overlooked parameter humidity. The parameters fine-tuning study has resulted in very broad PCL fiber diameter ranges of 94–1548 nm and 114–1408 nm for random and aligned fibers respectively. PCL fibers properties are also characterized in this study by means of water contact angle (WCA), X-ray photoelectron spectroscopy (XPS) and tensile measurements. Despite the detection of the same surface chemical composition on all fiber conditions, the WCA values tend to decrease with increased fiber diameters, especially for aligned fibers. Moreover, aligning the fibers and decreasing their size is found to lead to considerably enhanced mechanical properties. Overall, it can be concluded that this work represents a picture-perfect reference for the electrospinning of PCL fibers having different orientations, diameters and physico-chemical properties from a benign solvent system.

In this research we report a complex material formed between poly (methyl methacrylate) (PMMA) and urea. The disassociation temperatures of the PMMA/U complexes are higher than the glass transition temperature of neat PMMA and lower than the melting temperature of neat urea. As we reported previously, the as received-PMMA (asr-PMMA) contained a small amount of residual alkane-like surfactant. When forming the PMMA/U complexes with saturated urea-methanol solution, the originally contained contaminant can be encapsulated by urea in the form of a crystalline inclusion compound (IC) and dispersed within the PMMA/U complex. Since urea has been reported to form ICs with various small molecules, this phenomenon provides a potential way for small molecule encapsulation by using PMMA as the substrate and urea as the encapsulant.

Sintering process at temperature intervals close to the melting point of polymers is greatly important due to its role in synthesizing porous materials. During sintering, particles of polymeric materials coalesce throughout a process called interdiffusion. On the contrary, crystallization strongly affects the interdiffusion process at temperature intervals below and close to the melting point. Apparently, the outcome of the contention between these two factors would determine the interfacial width. Therefore, the current study presents a model, which takes both crystallization and interdiffusion into account, to predict sintering kinetic. Consequently, interfacial strength was assessed with respect to the following influencing mechanisms, “reentanglement” relying on mutual interpenetration distance and “cocrystallization” determined by interfacial lamellar thicknesses. Based on the results of the present study, by changing sintering temperature of high molecular weight high density polyethylene nascent powder from 125 to 129 °C, the mutual interpenetration distance changes from 4.8 to 52.9 nm and interfacial lamellae thicknesses also vary from L ≈ 0–35.4 nm. On the other hand, porosity measurements revealed the reverse dependency to the sintering temperature. Interfacial lamellae thicknesses were calculated by means of differential scanning calorimetry (DSC) and also scanning electron microscope (SEM) micrographs. Eventually, the results of the shear punch test clearly demonstrated the role of sintering temperature in interfacial strength. Accordingly, the maximum bearable load in the samples sintered at 125 and 129 °C, increases from 25 to 315 N, respectively, which was attributed to change in interfacial volume of two sintered particles in a simplified model. Resultantly, the present study indicates that even a degree centigrade temperature variation would significantly affect the interfacial strength and porosity of the samples due to its effect on crystallization; which in consequence might transform a porous material into a dense one.

In situ radical polymerization method, which is a method for toughening thermosetting resins by modifier polymers radically generated in the curing system of the resins, was applied to epoxy resin for the matrix of carbon fiber reinforced plastic (CFRP) to achieve both high fracture toughness of the cured resin and low viscosity of the resin composition. Benzyl methacrylate (BzMA) and poly(ethylene glycol) methyl ether methacrylate (PEGMEMA) were selected as the modifier monomers, and the resulting cured epoxy resin having co-continuous phase separation with the polymerized modifier at a nanometer level showed 2.1 times higher fracture toughness (KIC) than the unmodified cured resin. The modified epoxy resin system was then successfully applied to the fabrication of CFRP by resin transfer molding (RTM) due to its low viscosity in the uncured state. The resultant CFRP system showed 30% increase of the interlaminar fracture toughness (GIC) from the unmodified system.

Nanoparticles significantly reinforce rubber and enhance nonlinear mechanical behavior while the underlining mechanisms are not clear. Herein the effects of crosslinking, filler content and filler surface chemistry on the linear and nonlinear rheological responses of silica filled nitrile butadiene rubber are investigated. A time-concentration superposition principle is employed for constructing rheological master curves. While the strain amplification and dynamics retardation contribute to the high-frequency linear rheology of the compounds, the former is crucial for the vulcanizates with matrix of similar crosslinking degree. In both the compounds and vulcanizates, the Payne effect is initiated at a similar microscopic strain of the rubber phase. A weak overshoot of loss modulus appears in compounds containing hydrophilic silica and vulcanizates containing hydrophobic silica. It is suggested that the viscoelastic matrix is highly important for the rheological responses of the filled compounds and vulcanizates.

Living poly[(2-dimethylamino)ethyl methacrylate] (PDMAEMA) has been synthesized by Atom Transfer Radical Polymerization (ATRP) of (2-dimethylamino)ethyl methacrylate in bulk at 30 °C using CuCl/N,N,N′,N″,N″-pentamethyldiethylenetriamine catalyst. Addition of catalytic amount of tricaprylylmethylammonium chloride (AQCl) keeps the deactivator cupric complex soluble throughout the polymerization resulting in controlled polymerization. The solubility of the charged copper complexes in bulk monomer is proposed through their entrapment within the ionic core of the reverse micelle like aggregates formed by AQCl, as observed from Cryo-TEM and dynamic light scattering analysis. An adventitious role of water molecules in respect of control over polymerization is noted when moist monomer or AQCl is used. Synthesized PDMAEMA molecules work efficiently as macroinitiators for the synthesis of different stimuli responsive, multifunctional di- or triblock copolymers through sequential polymerization. The diblock copolymer PDMAEMA-b-poly[di(ethyleneglycol) methyl ether methacrylate] stabilizes CdS quantum dots in aqueous medium which show stimuli dependent reversible switch between micelle ‘core-confined’ and ‘corona-embedded’ morphologies.

Poly(dimethyl siloxane)-containing (PDMS), segmented polyureas represent an important class of high-performance elastomers that leverage the low glass transition temperature (Tg) of PDMS and superior mechanical reinforcement from bidentate hydrogen bonding. Current synthetic methods exclusively employ highly reactive/toxic isocyanate reagents and volatile organic solvents; the latter must be quantitatively removed prior to use. This report details an isocyanate-, solvent-, and catalyst-free synthetic method towards PDMS polyureas using urea and a disiloxane diamine chain extender in the melt phase. Melt polymerization afforded segmented PDMS polyureas, which formed optically clear, mechanically ductile, freestanding films. Observation of distinct thermal transitions with differential scanning calorimetry and dynamic mechanical analysis, corresponding to the respective segments, suggested microphase separation. Tensile and hysteresis measurements corroborated similarities between these PDMS polyureas and their isocyanate-containing analogues with strain at break ranging from 495 to 1180%. This facile, isocyanate-free approach provides a commercially viable alternative to the current industrial process for high performance elastomers.

Electrospun nanofiber is regarded as a promising candidate for many high-end applications due to its advantageous unique structure. Ultrafine fiber and good mechanical property are essential to ensure its performance. In this work, tunable ultrafine diameter and significantly enhanced mechanical strength of electrospun Styrene-butadiene-styrene tri-block copolymer (SBS) membrane are attained by means of the addition of LiBr into SBS solution dissolved in tetrahydrofuran/dimethylformamide (THF/DMF). Solution conductivity is found to grow in two steps with the increasing lithium bromide (LiBr) concentration and a critical point is observed at the ultralow concentration of 0.005 wt%, sharp increase below it but modest increase above it. Interestingly, the diameter of electrospun fiber shows a significant reduction with increase of LiBr concentration below this critical point but minor fluctuation above this. Welded structure is observed between adjacent fibers and the degree of welding goes deeper with increase of salt concentration. Accordingly, the mechanical strength of electrospun membrane is gradually enhanced and reaches to the highest value of 5.7 MPa at the critical concentration, with enhancement of 134% in comparison with pure electrospun SBS membrane, and then declines when further adding LiBr. TEM observation confirms more oriented and distinct self-assembly domains in the finer fibers, which contribute greatly to the property enhancement for electrospun SBS membrane obtained below critical concentration. The finding of critical concentration is important for the preparation of high performance electrospun membrane by adding salt in the spinning solution.

This paper reports the effects of hydrogen bonding on the starch granule dissolution, spinnability of the starch solution, and the properties of the electrospun starch fibers. Dissolution behaviors of the starch granules in dimethyl sulfoxide (DMSO) and water mixed solvents are characterized by confocal laser microscope, differential scanning calorimetry (DSC), and rheologic measurement. The starch granules are dissolved in the 100%DMSO or 6%H2O/94%DMSO solvent, resulting in good electrospinnability. On the other hand, the gelatinization behavior is observed for the starch granules in the 22%H2O/78%DMSO solvent, resulting in poor fiber formation during electrospinning. Infrared spectroscopy, DSC, x-ray diffraction, and mechanical property characterizations of the electrospun starch nanofibers suggest that the water content in the solvent plays an important role in the properties of the nanofibers. The dissolution behavior, electrospinnability, and the properties of the electrospun nanofibers are explained by the effects of the DMSO and H2O molecules on the ubiquitous hydrogen bonds in starch.

A novel, poly(dimethyl siloxane)-based photopolymer that exhibits simultaneous linear chain extension and crosslinking was suitable for vat photopolymerization additive manufacturing. Photopolymer compositions consisted of dithiol and diacrylate functional poly(dimethyl siloxane) oligomers, where simultaneous thiol-ene coupling and free radical polymerization provided for linear chain extension and crosslinking, respectively. Compositions possessed low viscosity before printing and the modulus and tensile strain at break of a photocured, higher molecular weight precursor after printing. Photorheology and soxhlet extraction demonstrated highly efficient photocuring, revealing a calculated molecular weight between crosslinks of 12,600 g/mol and gel fractions in excess of 90% while employing significantly lower molecular weight precursors (i.e.

Traditional hydrophobic association (HA) hydrogels can obtain excellent mechanical properties in the presence of anionic surfactants. However, such surfactants are sensitive to salt solutions, resulting in large fluctuation of mechanical properties for hydrogels. Here, a combined surfactant consisting of anionic surfactants (sodium dodecyl sulfate, SDS) and amphoteric surfactants (dodecyl dimethyl betaine, BS-12) was successfully introduced into HA hydrogels as stable physical crosslinking points. The resulting SDS/BS-12-HA hydrogels exhibited high tensile stress up to about 700 kPa. Moreover, the hydrogels demonstrated salt-inactive, self-healing and fatigue resistance properties owing to their unique dynamic and reversible physical crosslinking structure. Therefore, it's envisioned that this work may open a new method to develop a soft salt-inactive material with stable and excellent mechanical properties for extending the application range of hydrogels.

This work establishes the fact that Polyaniline (PANI) contributes to cationic scavenging on the polymerization of a cross linking polymer, i.e. Divinylbenzene (DVB), resulting in a significant change in the properties of the PANI-based DVB resin system. Furthermore, it is also shown that the cationic scavenging is directly related to the degree of doping of PANI and its dispersion state. Various intermediate doped PANI was added with a fixed amount of DVB to prepare thermosetting matrices. The degree of doping of PANI was assessed with the DSC, FT-IR, and UV-VIS-NIR analyses before mixing with DVB matrix. It has been shown that the Polyaniline (PANI) agglomerates broke and a uniform dispersion was obtained with an increased degree of doping, which led to more exposed amines groups of PANI. These groups acted as scavengers to the cationic polymerization of the DVB monomer. DSC and viscosity measurement of the uncured PANI-DBSA/DVB resin system confirmed the scavenging effect of PANI on the curing profile and subsequently to the electrical and mechanical properties of the cured composites. This paper presents a detailed analysis of the advantages and disadvantages of the scavenging behavior of PANI in the context of preparing PANI-based polymer composites.

The current investigation was to present composite membranes with strong interfacial adhesion between top polymeric selective layer and the bottom micro-porous support layer with appropriate gas permeation behavior and practically suitable processing characteristics. To this end, a series of acrylate-terminated polyurethanes (APUs) based on poly (ethylene glycol) (PEG) with different molecular weights (Mn) of 600, 1000, 1500, 2000 and 4000 g/mol, toluene diisocyanate (TDI), and 2-hydroxyethyl methacrylate (HEMA) were synthesized. Composite membranes were prepared with UV-curable acrylate-terminated polyurethane/acrylate diluent (APUAs) as selective layer and polyester/polysulfone (PS/PSF) as support layer. FTIR-ATR and DSC analyses indicated that the micro-phase separation of soft and hard segments increased by increasing the molecular weight of PEG. The experimental results revealed that the gas permeation behavior of APUA was mostly similar with rubbery materials; however, its morphological characteristics such as degree of micro-phase separation and crosslinking density are influential for the overall gas permeation behavior. It was revealed that the adhesion of APUA membranes to support layer was found to be strong and did not deteriorate after swelling in water. APUA composite membranes also exhibited very good long term gas permeation stability due to its stable structure originated from the cross-linked network.

Hyperbranched aliphatic polyethers containing hydroxyl and amine end groups were produced from glycerol carbonate (4-hydroxymethyl-1,3-dioxolan-2-one) and cyclic carbonate bearing phthalimide moieties. The new monomer N-[(2-oxo-1,3-dioxolan-4-yl)methyl]phthalimide was synthesized in a simple two-step, one-pot process. The structure of the monomer was proved by means of NMR, FTIR and X-ray techniques. Anionic polymerization of cyclic carbonate monomers, which proceeds with simultaneous decarboxylation, was performed using a simple catalyst - potassium carbonate and trimethylolpropane (TMP) or glycerol carbonate as an initiator. The polymerization conditions were investigated and optimized. The polymers were characterized by means of nuclear magnetic resonance, FTIR, MALDI-TOF, GPC and elemental analysis. It was shown that during the process of polymerization an intermediate - glycidol is formed and acts as initiator or monomer.

To develop tissue engineering scaffolds that possess similar morphological structures to natural extracellular matrices (ECMs) is a major technological challenge. Herein, the feasibility of utilizing polycaprolactone (PCL) as biocompatible and biodegradable binding agent to fabricate electrospun three-dimensional (3D) scaffolds has been demonstrated. The obtained 3D scaffolds are soft while elastic, and they possess interconnected and hierarchically structured pores with sizes in the range from sub-microns to hundreds of microns; hence, they are morphologically similar to natural ECMs thus well suited for cell functions and tissue formation. It is envisioned that various thermoplastic polymers could be fabricated into 3D nanofibrous scaffolds/structures by first making blend nanofibers with PCL followed by processing via the thermally induced (nanofiber) self-agglomeration (TISA) method and finally being thermally stabilized, and the resulting electrospun 3D nanofibrous scaffolds/structures might to be useful for a variety of applications (particularly those related to tissue engineering).

RAFT dispersion polymerization following the formulation of polymerization induced self-assembly (PISA) and micellization of pre-prepared amphiphilic block copolymers in block-selective solvents are generally used to prepare block copolymer nano-assemblies. Herein, we make a comparison between these two methods by employing two typical block copolymers of poly(acrylic acid)-block-polystyrene (PAA-b-PS) and poly(ethylene glycol)-block-polystyrene (PEG-b-PS). It is found that the block copolymer nano-assemblies prepared by these two methods are similar with each other when the solvophilic block is relatively long and the solvophobic block is relatively short. Otherwise, the block copolymer nano-assemblies by these two methods are different. The possible reasons leading to the difference between PISA and micellization are discussed, and the kinetic factors including temperature, polymer concentration and solvent are ascribed. It is thought that the present study is helpful to clarify how the kinetic factors beyond the block copolymer itself affecting block copolymer morphology.

A more efficient route for the synthesis of phosphonated dimethyl isophthalate, disodium salt is shown to provide a significantly higher yield (42%), in contrast to a previously reported yield (15%). This higher yield enabled the synthesis of phosphonated poly(ethylene terephthalate) (PPET) ionomers using conventional melt polycondensation with ethylene glycol and dimethyl terephthalate. The physical properties of these phosphonated PET ionomers (Na+-PPET) were characterized using differential scanning calorimetry (DSC), melt rheology, and tensile testing. DSC analysis showed that the crystalline melting temperatures, crystallization temperatures, degrees of crystallinity, and crystallization rates decreased with increasing ionic content. Melt rheology confirmed the existence of physical crosslinks in Na+-PPET ionomers, as indicated by a crossover of the storage and loss moduli, attributed to strong electrostatic associations between phosphonated units on the polymer chains. Tensile tests of the Na+-PPET samples showed enhanced Young's modulus and yield stress compared to pure PET.