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Altering the surface wettability by external stimulation has received great attention recently. While different stimuli, such as temperature, pH, etc. can be applied for this purpose, light combines several advantages. It is a contact-free stimulation, which can be applied locally, thereby allowing a versatile patterning. This review article summarizes recent developments in the area of polymers that allow a light-induced change in surface wettability. For this purpose, different photochromic dyes have been incorporated into polymers, which enable a photo-isomerization upon light irradiation resulting in a change in polarity. Several examples based on azobenzene or spiropyran will be discussed, but also some more exotic examples, such as those based on salicylideneaniline, will be highlighted. The different approaches how to apply these photochromic dyes to various surfaces are presented and discussed. Additionally, the combination with other stimuli-responsive moieties will be explored and the paper will be concluded by mentioning the remaining challenges and by providing a future perspective. [ABSTRACT FROM AUTHOR]

Highlights: [•] Functionalization approaches of collagen. [•] Collagen mimetic peptides as building blocks. [•] Conjugates with collagen mimetic peptides. [•] Stimuli responsive or spontaneously assembly behavior. [ABSTRACT FROM AUTHOR]

Abstract: Highly porous polymers (polyHIPEs) incorporating activated esters have been prepared by photopolymerisation of high internal phase emulsions (HIPEs) containing pentafluorophenyl acrylate (PFPA) in the monomer phase. The resulting materials have nominal porosity of 80% and a well-defined, interconnected pore morphology with average pore diameters ranging from 30 to 50 μm. PFPA could be added at up to 50 wt% of the monomer phase without destabilising the HIPE noticeably, however analysis of the polyHIPE materials revealed that only around half of this was incorporated into the final porous materials. The pentafluorophenyl groups were shown to be reactive towards a range of amines (tris-(2-aminoethyl)amine, benzylamine and Rhodamine 123), giving near complete loss of fluorine over the period of the reaction. The extent of functionalisation was however determined to be around 50% by elemental analysis, suggesting some loss of fluorine by hydrolysis of activated esters. We believe that this represents a facile method for the preparation of a variety of well-defined functional porous polymers by a post-polymerisation functionalisation route. [Copyright &y& Elsevier]

Abstract: Four different series of polyacrylamides containing different amounts of azobenzene moieties have been synthesized via a polymer analogous reaction of poly(pentafluorophenylacrylate) (PPFPA). All copolymers were designed to exhibit a lower critical solution temperature (LCST) in aqueous solution, which was dependent on (i) the amount of incorporated chromophoric azobenzene groups and (ii) the isomerization state of the respective azobenzene group. Higher LCST values were measured for UV-irradiated solutions of the copolymers in comparison to the non-irradiated copolymer solutions. A maximum difference in the LCST of up to 7°C was found for the copolymer poly(N,N-dimethylacrylamide) containing 8.5mol% of azobenzene groups. Within this temperature range, a reversible solubility change of the copolymer could be induced by irradiation with light. [Copyright &y& Elsevier]

Proton transfer in polymer electrolyte membrane is an essential mechanism in polymer electrolyte membrane fuel cell (PEMFC). The development of PEM mostly relies on polymer modification with proton conductive species followed by membrane casting. This brings in the random existence of conductive species in the membrane to result in a limit of conductivity. The present work proposes an alignment of conductive species, i.e., proton donor and acceptor polymer chains, on the membrane through the surface-initiated polymerization so that the proton transfer proceeds effectively and continuously. The grafting of poly(acrylic acid) (Poly(AA) and/or poly(benzimidazole acrylamide) (Poly(BImAm)) onto sulfonated poly(ether ether ketone) membrane (SPEEK) enables the polymer brush decoration on the SPEEK surface. Among various types of copolymer architecture, the statistical copolymer, i.e. SPEEK-Poly(AA 63 - stat -BImAm 26), shows the most significant proton conductivity. The present work demonstrates a simple approach to modify the surface of PEMFC membrane with proton donor/acceptor for proton conductivity enhancement. [Display omitted] • SPEEK membrane with proton donor and acceptor as polymer brushes on surface. • Membrane grafted with proton donor and acceptor by surface-initiated polymerization. • Comparative study of membrane with homopolymer and copolymer brushes. • Increment of proton conductivity by surface grafted membrane for 48 times. [ABSTRACT FROM AUTHOR]

Abstract: Nine active ester monomers based on 4-vinylbenzoic acid have been synthesized. Under free radical polymerization conditions these monomers could successfully be polymerized yielding reactive polymers with molecular weights of around M n =20.000–50.000g/mol and molecular weight distributions M w/M n of around or below 2 in good yields. Polymer analogous reactions with amines have been investigated by time-resolved FT-IR spectroscopy and it was found that especially poly(pentafluorophenyl 4-vinylbenzoate) featured a significant reactivity, such that polymer analogous reactions proceeded quantitatively with amines within less than 5min at 0°C. [Copyright &y& Elsevier]

Abstract: Acetone oxime acrylate has been synthesized as a new active ester monomer. Free radical polymerization yielded a reactive polymer soluble in various organic solvents, such as chloroform, dioxane, DMSO, acetone, methanol, dichloromethane, DMF, and ethanol. Controlled radical polymerization of acetone oxime acrylate was successfully conducted using the RAFT, NMP and Iniferter method. Partly polymer analogous reaction with N-isopropylamine resulted in the reactive copolymer poly(N-isopropylacrylamide-co-acetone oxime acrylate), which featured a lower critical solution temperature (LCST) of 61°C in water. Further, the reactivity of the copolymer was exemplary proven by complete reaction with ammonia yielding poly(N-isopropylacrylamide-co-acrylamide), which does not possess a LCST. [Copyright &y& Elsevier]

A major challenge in tissue engineering is the lack of proper vascularization. Although various approaches have been used to build vascular network in a tissue engineering construct, there remain some drawbacks. Herein, a glucose-sensitive self-healing hydrogel are employed as sacrificial materials to fabricate branched tubular channels within a construct. The hydrogel composes of mainly reversibly crosslinked poly(ethylene glycol) diacrylate and dithiothreitol with borax as the glucose-sensitive motif. The hydrogel is injectable and mechanically strong after injection. Moreover, it can be rapidly removed by immersion in the cell culture medium. To show the feasibility in building a vascularized tissue construct, the designed branching vascular patterns of the glucose-sensitive hydrogel are extruded and embedded in a non glucose-sensitive hydrogel containing neural stem cells. Vascular endothelial cells seeded in the lumen of the channels by perfusion can line the channel wall and migrate into the non-sacrificial hydrogel after 3 days. In long-term (∼14 days), the endothelial cells form capillary-like structure (vascular network) while neural stem cells form neurosphere-like structure (neural development) in the construct, revealing the morphology of “a vascularized neural tissue”. The novel sacrificial materials can create complicated but easily removable structure for building a vascularized tissue construct particularly a neurovascular unit. [ABSTRACT FROM AUTHOR]

In the present study, we described a facile method for introducing functional moieties into block copolymer structures by sequential aminolysis of pentafluorophenyl acrylate (PFPA) ester and methyl salicylate acrylate (MSA) ester. For the first time, reversible addition-fragmentation transfer (RAFT) polymerization of MSA yielding block copolymers poly(MSA)- b -poly(PFPA) was reported. The yielded block copolymers were subsequently modified step-by-step using amino moieties, affording polymers with bespoke functionality. By exploring the reactivity difference of two activated esters (PFPA and MSA) toward amines, the installation of amine functionalities on polymer backbones while maintaining a block copolymer architecture was realized in a controlled manner. The selective reactivity of these two esters (PFPA and MSA) toward aliphatic amines, such as isopropylamine, cyclopropylamine and N , N -diethylethylenediamine, provided a novel synthetic approach in making temperature and pH dual responsive polymers. Finally, the self-assembly behavior of the obtained block copolymers was investigated. [ABSTRACT FROM AUTHOR]

A series of azobenzene containing copolymers were synthesized by post-modification of poly(methyl methacrylate- co -pentafluorophenyl methacrylate) with an amine-functionalized azobenzene. Light- and thermo-responsive behavior of these copolymers was investigated in ethanol–water solvent mixtures with various amounts of ethanol. The upper critical solution temperature (UCST) of the polymer solutions, resulting from the poly(methyl methacrylate), was found to be highly tunable by the substitution degree of the copolymers as well as the ethanol content of the solvent mixture. In addition, the copolymers are light responsive based on the cis – trans isomerization of the azobenzene group under UV irradiation. The cloud point temperatures ( T CP ) of the polymer solutions decreased after UV-irradiation due to the higher dipole moment of the cis -isomer of the azobenzene moiety leading to better solubility in ethanol–water solvent mixtures. Furthermore, the UV responsiveness was found to strongly depend on the solvent composition, revealing a higher decrease in cloud point after UV-irradiation in ethanol–water solvent mixture with higher water content. To the best of our knowledge, this is the first reported dual responsive polymer that combines light responsiveness with UCST behavior in aqueous solvent mixtures. [ABSTRACT FROM AUTHOR]

[Display omitted] • Polyimide-poly(ethylene oxide) copolymers were synthesized using an eco-friendly method. • Ionic conductivity increases with the rise in salt concentration. • Solid polymer electrolytes based on polyimides demonstrate non-flammable properties. The rapid pace of technological advancement in field of electric vehicles and need in sustainable energy sources calls for new, high-performance energy storage technologies. Lithium metal batteries (LMBs) based on solid polymer electrolyte represent a promising battery technology to increase energy density of conventional batteries while enhancing safety, eliminating dendrite formation, and providing mechanical flexibility. In this study, we developed novel polyimide-poly(ethylene oxide) (PI-PEO) copolymers and employed them as solid polymer electrolytes for LMBs. Copolymers with 5, 15, and 30 mol% of PEO-containing diamine were synthesized by reacting with aromatic dianhydride and diamine, using a facile and eco-friendly method in a benzoic acid melt. Chemical structures were confirmed using NMR and IR spectroscopy. Glass transition temperatures varied from 24 °C to 195 °C, increasing with a decrease in the PEO/PI moiety ratio. All copolymers demonstrated good thermal stability up to T 5% > 345 °C with a two-step degradation and favorable mechanical properties below the glass transition temperature, as observed by DMA measurements. Solid polymer electrolytes with 70 wt% of LiTFSI exhibited an ionic conductivity of 1.4 × 10−4 S cm−1 at 70 °C, with a transference number of 0.7. The polymer electrolyte exhibited non-flammable properties and the potential for utilization in lithium metal batteries, indicating the promising application of these new polymers for high-safety battery systems. [ABSTRACT FROM AUTHOR]

Abstract: Contact angle measurement is conducted to determine surface hydrophilicity of RO membrane with the intention of predicting membrane performance or fouling potential. Most researchers of membrane technology have used contact angles without considering effective factors for contact angle measurement such as measurement time, drop volume and membrane sample preparation. In fact, significantly different contact angles are reported even on the same RO membrane. In this study, contact angles were measured by the sessile drop method and captive bubble method and were compared with various conditions such as measurement time, drop volume, membrane sample preparation and liquid type in the commercialized RO membranes. As a result, sessile drop method showed unreliable contact angles, which varied dramatically with the preparation conditions. On the other hand, the captive bubble method, which represents conditions closer to the real RO membrane process, showed reproducible contact angles. For the different commercially available RO membranes, similar hydrophilicity was observed. Overall, the captive bubble method appears to be a more adequate method for measuring contact angle of RO membranes. [Copyright &y& Elsevier]

C1 polymerization, poly(propargyl 2-ylidene-acetate) (PPA), post-polymerization modification. [Display omitted] • C1 polymerization of propargyl 2-diazoacetate in the presence of low valence Rh-catalysts. • Well-defined polymethylenes and their subsequent post-modification were achieved. • Polymers were efficiently post-modified via CuAAC. Rhodium(I)-catalyzed C1 polymerization of propargyl 2-diazoacetate was conducted for the first time resulting in a novel functional polymethylene derivative, poly(propargyl 2-ylidene-acetate), which is suitable for a subsequent post-polymerization modification under mild reaction conditions via copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction. The post-modification reaction results in quantitative conversions, and provides an efficient and general route for the selective post-modification of C1 polymers with a variety of azide compounds. The structure of the poly(propargyl 2-ylidene-acetate) was confirmed and characterized by NMR, FT-IR, and GPC techniques. Upon comparison with results on post-polymerization modification of the corresponding C2 polymer, poly(propargyl acrylate), no obvious influence on the reactivity towards the post-modification of acetylene group on the C1 polymer precursor was observed. Noteworthy, the introduction of pentafluorophenyl azide facilitated a subsequent second modification via the Para-Fluoro-Thiol reaction (PFTR). Accordingly, cascade post-modifications of C1 polymers yielded novel polymethylenes that are not accessible by direct C1 polymerization. [ABSTRACT FROM AUTHOR]

• For the first time, a systematic study was performed on the post-polymerization modification of polymeric active esters towards distinct TEMPO containing polymers with varying backbone composition. • The influence of side reactions (such as hydrolysis) on the redox reaction of TEMPO containing polymers was explored. • The battery performance of polymer with the highest TEMPO content was investigated exhibits a 12–22 mAh/g higher specific capacity compared to PTMA synthesized by conventional oxidation method when running at 5 C for 500 cycles. Organic radical batteries (ORB) are a novel promising class for energy storage, particularly featuring a fast charging capability and extraordinary cycle life. The representative polymer, i.e. poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl methacrylate) (PTMA), is usually synthesized by a post-polymerization oxidation method. As an alternate strategy for developing TEMPO-containing polymers, we focused on the post-polymerization modification of poly(pentafluorophenyl acrylate) and poly(pentafluorophenyl methacrylate) with three different TEMPO nucleophiles by transesterification or amidation reactions. Optimizing the conditions of the post-polymerization functionalization reaction by varying different parameters, such as the type of nucleophile, catalyst and solvent, the feeding ratios of catalysts and nucleophiles, along with reaction time and temperatures, resulted in structurally distinct TEMPO containing polymers with varying backbone composition. Intriguingly, poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl acrylamide) revealed the highest degree functionalization with TEMPO (96.2%) within 3 hrs. under considerably mild conditions, while poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl methylmethacrylamide) exhibited the lowest TEMPO content owing to the steric hindrance from methyl group on both the methacrylate chain and the TEMPO derivative. All other four TEMPO containing polymers had a radical content similar to PTMA (66.6%) synthesized by the post-oxidation methodology. Noteworthy, compared to TEA (trimethylamine), DMAP (4-dimethylaminopyridine) facilitated an efficient ester bond cleavage independent of the polymer precursor, thus, side reactions such as hydrolysis were increased. Though hydrolysis side reaction occurred, the resulting carboxylic acid group was proven to accelerate ion transfer in a certain way during the redox process. Furthermore, due to the higher TEMPO content, poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl acrylamide) exhibited a 12–22 mAh/g higher specific capacity compared to the PTMA-oxidation when running at 5C for 500 cycles. [ABSTRACT FROM AUTHOR]

• Polymers precisely modified with multi functionalities within same polymer repeating unit. • Thiol-ene addition reaction yielded substantially low conversions. • Epoxidation resulted in conversions significantly higher than 90%. • Epoxidized and brominated polymers were subsequently modified with nucleophiles. Poly(1,1-disubstituted-2-vinylcyclopropanes) were submitted to various substitution and addition reactions in order to modify the side chain and ethylenic moiety within the polymer backbone. Explicitly, bromination, epoxidation and thiol-ene addition reactions were performed on the ethylenic bond that is present in the main chain of poly(vinycyclopropanes) with varying ester and amide side chains. Bromination and epoxidation reactions proceeded with up to 90% conversion, while thiol-ene additions resulted in substantially lower conversions, i.e. <50%. The scope of this study is to reveal the potential of 1,1-disubstituted-2-vinylcyclopropanes as appealing monomers for the efficient synthesis of periodic copolymers with precise positioning of substituents within the constitutional repeating units. [ABSTRACT FROM AUTHOR]

Novel thermosensitive nanocomposite (NC) hydrogels have been synthesized by copolymerization of 2-(2-methoxyethoxy) ethyl methacrylate (MEO 2 MA), oligo(ethylene glycol) methacrylate (OEGMA), and using inorganic clay as cross-linker via in-situ free radical polymerization. The structure and morphology of clay/P(MEO 2 MA -co- OEGMA) NC hydrogels were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM), and the results indicated that the inorganic clay was uniformly dispersed in the NC hydrogels and obviously affected the network structure. Furthermore, physical properties such as equilibrium swelling/deswelling ratio, water retention, reversible thermosensitivity, and temperature dependence behaviors of NC hydrogels with different chemical compositions (molar ratio of comonomer, clay, and mass fraction of polymer) were investigated carefully. Moreover, the deswelling kinetics at specific temperature was studied, and the deswelling rates were well described with a first-order kinetics equation. The results indicated that the obtained NC hydrogels showed a controllable equilibrium swelling/deswelling behavior and possessed remarkable thermosensitivity. In addition, when the molar ratio of MEO 2 MA and OEGMA was 80 mol%: 20 mol%, the equilibrium swelling ratio of NC hydrogels with 5 wt% clay reached 1640%, which is four times higher than that of N,N ′ - methylenebisacrylamide cross-linked hydrogels (410%). Consequently, this novel clay/P(MEO 2 MA -co- OEGMA) NC hydrogel with interesting thermosensitive properties would be promising for potential applications, such as stimuli-responsive valve, drug delivery system, artificial muscle, and biosensor. [ABSTRACT FROM AUTHOR]

In this work we demonstrate the remarkable phase control on the crystallization of calcium carbonate by the stereochemistry of carbohydrate-based polymers. The polymers (poly(2-(2,3,4,6-tetra-O-acetyl-β- d -glucosyloxy)ethyl methacrylate) and poly(2-(2,3,4,6-tetra-O-acetyl-β- d -galactosyloxy)ethyl methacrylate)) have been synthesized from the respective glucose or galactose containing monomers (3 step synthesis) by RAFT polymerization leading to well-defined carbohydrate-based polymers with number averages of the molecular weights ( M w ) of 10,000–18,000 g/mol and a dispersities (Đ) from 1.1 to 1.2. For the deprotected polymers we found differences in the phase selection of calcium carbonate. We found that this effect is based on the chelating character of the hydroxyl groups of the pyranoses and their individual orientation, as demonstrated by comparison of the protected and unprotected polymers in crystallization experiments as well as computer assisted simulations. [ABSTRACT FROM AUTHOR]

Two 1,1-disubstituted-2-vinylcyclopropane monomers, namely 1-aceto-1-pentafluorophenoxycarbonyl-2-vinylcyclopropane and 1-dodecanoxycarbonyl-1-pentafluorophenoxycarbonyl-2-vinylcyclopropane containing activated pentafluorophenyl esters, were polymerized by free radical ring opening polymerization. The obtained reactive polymers were then employed for the synthesis of non-ionic and zwitterionic polymeric surfactants via sequential post-polymerization modifications. [ABSTRACT FROM AUTHOR]

Electrospun polybutadiene (BR) was crosslinked in situ during the spinning process to obtain stable fibers. Crosslinking was induced by addition of photoinitiator to the electrospun BR solution. Due to the very low glass transition temperature ( T g ) of BR (below −80 °C) it is necessary to crosslink the fibers thereby improving the mechanical properties and creating stable fibers by preventing fibers from melting together. In order to prevent the polymer fibers from melting onto the grounded collector, a solution of sodium chloride in methanol was used to collect the fibers thereby letting the fibers float and increase the irradiation time of the UV curing during the electrospinning process. Subsequent surface modification via thiol-ene click chemistry on remaining C C bonds was successfully employed with mercaptoethanol or thioglycolic acid, leading to superhydrophilic fiber mats. [ABSTRACT FROM AUTHOR]

Abstract: The precursor [FeIII(L)Cl (L= N,N′-bis(2′-hydroxy-3′-methyl-benzyliden)-1,7-diamino-4-azaheptane) is combined with [Mo(CN)8]4− yields a star shaped nona-nuclear cluster, [MoIV{(CN)FeIII(L)}8]Cl4. This Fe8Mo molecule is a high-spin system at room temperature. On cooling to 20K some of the iron(III) centres in the molybdenum(IV)-star switch to the low-spin state as proven by Mössbauer spectroscopy. This molecule was deposited on TiO2 nanowires by electrostatic interactions between the cluster cations and the surface functionalized titanium oxide nanowire. The synthesis and surface binding of the multistable molecular switch was demonstrated using IR and UV–Vis spectroscopy (high-resolution) transmission electron microscopy ((HR)TEM) and Mössbauer spectroscopy. High- and low-temperature Mössbauer spectra indicate that the spin state transition of the free cluster molecules is preserved after surface binding. The above results emphasize the possibility of fabricating molecule-based low-dimensional structures by using traditional bottom-up approaches based on the electrostatic interaction between the cluster cations and polymer functionalized nanowires. These results can be generalized for the application to both charged and non-charged molecules. [Copyright &y& Elsevier]

• We prepared polysulfobetaine copolymers containing O 2 -switchable perfluoroalkyl amide pendants. • We investigated the O 2 -switchable thermo-responsiveness of the copolymers in water. • We explored the release property of encapsulated dye with the UCST copolymers. Polysulfobetaine copolymers, poly[(ethylene glycol)- block -(3-((3-aminopropyl)dimethylammonio)propane-1-sulfonateacrylamide- co -benzylacrylamide- co -2,2,2-trifluoroethylacrylamide)], p(PEG- b -ADPS x -Bz y -Tf z), comprising hydrophobic components by varying their chemical compositions, are successfully synthesized by reversible addition–fragmentation chain-transfer polymerization (RAFT) and subsequent post-polymerization modification of an activated polymer scaffold. Owing to its amphiphilic nature p(PEG- b -ADPS 0.58 -Bz 0.31 -Tf 0.11) copolymer can self-assemble into vesicles in aqueous solution and exhibits a dual-responsive behavior toward O 2 and temperature stimuli. The O 2 switchable temperature-dependent aqueous solution behavior of the derived species was assessed through turbidity measurements, NMR spectroscopy, transmission electron microscopy (TEM) and dynamic light scattering, revealing that such vesicles can exhibit size change behavior via external stimuli due to their suitable chemical structure and stimuli responsiveness. [ABSTRACT FROM AUTHOR]