Preparation of multi‐level honeycomb‐structured porous films by control of spraying atomized water droplets

Honeycomb‐structured porous films have been widely applied in various industrial areas such as chemical sensors, tissue engineering, and micro reactors. In this article, one novel self‐assembly approach is proposed to fabricate well‐ordered polyphenylene oxide honeycomb films by a facile control of spraying ultrasonic humidifier atomized water droplets. Proper spraying retention time is necessary for porous films formation with highly uniform pore size. The effect of atomized water droplets flux on the pore size and the regularity of the hexagonal arrays were experimentally investigated. The pore size became larger with increasing the solution concentration. Especially, honeycomb films with two‐level pores were fabricated by spraying atomized water droplets two times and the influence of interval time on the two‐level honeycomb films formation was investigated. Apart from analysis of structural characteristics, self‐assembly mechanism was also discussed. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41163.     

Water‐assisted formation of honeycomb films of poly(L‐lactic‐co‐glycolic acid)

The ordered honeycomb structures of poly(L ‐lactic‐co‐glycolic acid) and poly(D ,L ‐lactic‐co‐glycolic acid) fabricated in a humid atmosphere were reported in this paper. It was found that surfactants were important in the formation of honeycomb films of hydrophobic polymer. The affecting factors, such as the environment temperature, the atmosphere humidity, and the concentration of the polymer solution of the honeycomb porous structure, were also tested. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1013–1018, 2006     

Hydrophilic and hydrophobic poly(l‐lactic acid) films by building porous topological surfaces

Surface wettability of thin films is significant for their functional properties. Poly(l ‐lactic acid) (PLLA) is proposed as film matrix for building porous topological surfaces. By controlling the dope composition and ambient conditions, the films with ordered pores at micrometer scale are obtained. The results demonstrate that the hydrophilic or hydrophobic surface can be realized by building the porous topological surfaces. Increasing polymer concentration can lead to decreased pore size. The transition behavior of surface pores from discrete bowl‐like to interconnected honeycomb‐like structure with the increasing humidity is observed. The contact angle of top surface of film is higher than that of bottom surface, which verified the different roughness performance. The morphology and scale of topological structure are markedly related with the template effect of water droplets. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44572.     

Synthesis of amine‐functionalized block copolymers for nanopollutant removal from water

Polyamines are rare in literature owing to increased reactivity, sensitivity to air and moisture, low stability, and processing difficulties. Here, we report the synthesis and characterization of highly processable polyamines and use them for the removal of dissolved metallic nanoparticles from water. Three amphiphilic block polyamines such as poly(N‐aminoethyl acrylamide‐b‐styrene), poly(N‐aminopropyl acrylamide‐b‐styrene), and poly(N‐aminoxylyl acrylamide‐b‐styrene) have been synthesized using atom transfer radical polymerization of ethyl acrylate and styrene followed by aminolysis of the acrylic block. The polymerization and properties of the polymers are studied using different physicochemical techniques. Surface morphology of films prepared from these block copolymers by dissolving in different solvents such as chloroform, tetrahydrofuran and N,N‐dimethylformamide, and drop‐casting polymers on a glass substrate show interesting porous films and spherical nanostructures. In addition, the amine‐functionalized block copolymers have been used for the removal of nanoparticles from water and show high extraction efficiency toward silver (Ag) and gold (Au) nanoparticles. All three amine‐functionalized block copolymers show higher extraction capacities (Q_e) toward Au NPs (50–109 mg g^?1) and Ag NPs (99–117 mg g^?1). Our approach allows us to make amine‐functionalized block copolymers which are stable in air and can be easily processed in nonpolar solvents. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40943.     

Synthesis and photoluminescent properties of poly(aryl ether)s containing alternate emitting and electron‐transporting moieties

A new diphenylbutadiene‐containing bisphenol was successfully synthesized from benzylideneaniline and 4‐propenylanisole via an anil synthetic method. A series of copoly(arylene ether)s consisting of an alternate isolated blue chromophore (diphenylbutadiene) and an electron‐transporting moiety (1,3,4‐oxadiazole) was synthesized and characterized. High molecular weight copoly(arylene ether)s with an inherent viscosity of >0.5 dL/g were prepared by the nucleophilic displacement reaction of oxadiazole‐activated bis‐fluorocompounds with bisphenols. Introduction of ether linkages into the copolymers led to an enhanced solubility in organic solvents such as N,N‐dimethylacetamide (DMAc) and N‐methyl‐2‐pyrrolidinone (NMP). The resulting copolymers can be cast into tough and transparent films. The copolymers were amorphous in structure with high glass transition temperatures ranging from 182.29 to 194.50°C. They also exhibited good thermal stability with the maximum decomposition temperatures higher than 500°C in nitrogen. The absorption peaks of these copolymers in thin films varied from 375 to 391 nm, while the photoluminescent peaks varied from 410 to 433 nm. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1645–1651, 2003     

Porous honeycomb films prepared from poly (phthalazionone ether sulfone ketone) (PPESK) by self‐organization method

Preparation of honeycomb‐patterned films from Poly (phthalazionone ether sulfone ketone) (PPESK), one of the thermally stable polymers, in a humid atmosphere was reported in this article. The mechanism of forming honeycomb structure was discussed. Some influences, such as the effect of PPESK concentration and the atmosphere humidity were tested. Furthermore, the thermal stability of honeycomb‐patterned films was also investigated, and it was shown that the honeycomb structures could be stable existed at 300°C. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and properties of polystyrene‐b‐poly(ethylene oxide)‐b‐polystyrene triblock copolymers

A series of well‐defined and property‐controlled polystyrene (PS)‐b‐poly(ethylene oxide) (PEO)‐b‐polystyrene (PS) triblock copolymers were synthesized by atom‐transfer radical polymerization, using 2‐bromo‐propionate‐end‐group PEO 2000 as macroinitiatators. The structure of triblock copolymers was confirmed by ¹H‐NMR and GPC. The relationship between some properties and molecular weight of copolymers was studied. It was found that glass‐transition temperature (T_g) of copolymers gradually rose and crystallinity of copolymers regularly dropped when molecular weight of copolymers increased. The copolymers showed to be amphiphilic. Stable emulsions could form in water layer of copolymer–toluene–water system and the emulsifying abilities of copolymers slightly decreased when molecular weight of copolymers increased. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 727–730, 2006     

Formation of honeycomb films from poly(L‐lactide)‐block‐poly(ethylene glycol) via water‐droplet templating

The fabrication of honeycomb‐patterned films from amphiphilic poly(L ‐lactide)‐block‐poly(ethylene glycol) (PLEG) in a high‐humidity atmosphere is reported. The influence of the solution concentration on pattern formation was investigated. Moreover, by comparing the different conditions of fabricating regular structures between PLEG and poly(phenylene oxide), the mechanism of the regular pattern formation was studied. Finally, by adding sodium dodecylsulfate to a concentrated solution of 1 g L^?1 PLEG? CHCl₃ which otherwise could not form regular pores, we found that regular pores could be obtained. The PLEG honeycomb films are expected to be of use in cell culture, tissue engineering and many other areas. Copyright © 2007 Society of Chemical Industry     

Crystallization kinetics of poly(1,4‐butylene‐co‐ethylene terephthalate)

The crystallization kinetics of poly(butylene terephthalate) (PBT), poly(ethylene terephthalate) (PET), and their copolymers poly(1,4‐butylene‐co‐ethylene terephthalate) (PBET) containing 70/30, 65/35 and 60/40 molar ratios of 1,4‐butanediol/ethylene glycol were investigated using differential scanning calorimetry (DSC) at crystallization temperatures (T_c) which were 35–90 °C below equilibrium melting temperature . Although these copolymers contain both monomers in high proportion, DSC data revealed for copolymer crystallization behaviour. The reason for such copolymers being able to crystallize could be due to the similar chemical structures of 1,4‐butanediol and ethylene glycol. DSC results for isothermal crystallization revealed that random copolymers had a lower degree of crystallinity and lower crystallite growth rate than those of homopolymers. DSC heating scans, after completion of isothermal crystallization, showed triple melting endotherms for all these polyesters, similar to those of other polymers as reported in the literature. The crystallization isotherms followed the Avrami equation with an exponent n of 2–2.5 for PET and 2.5–3.0 for PBT and PBETs. Analyses of the Lauritzen–Hoffman equation for DSC isothermal crystallization data revealed that PBT and PET had higher growth rate constant G_o, and nucleation constant K_g than those of PBET copolymers. © 2001 Society of Chemical Industry     

Long‐range‐ordered,hexagonally packed nanoporous membranes from degradable‐block‐containing diblock copolymer film templates

Polystyrene (PS)‐b‐polylactide (PLA) diblock copolymers with different molecular weights and fractions were synthesized through a combination of living anionic polymerization and controlled ring‐opening polymerization. Then, the PS–PLA films were guided to phase‐separate by self‐assembly into different morphologies through casting solvent selection, solvent evaporation, and thermal and solvent‐field regulation. Finally, perpendicularly oriented PS–PLA films were used as precursors for PS membranes with an ordered periodic nanoporous structure; this was achieved by the selective etching of the segregated PLA domains dispersed in a continuous matrix of PS. Testing techniques, including IR, ¹H‐NMR, gel permeation chromatography, scanning electron microscopy (SEM), and atomic force microscopy (AFM), were used to determine the chemical structure of the PS–PLA copolymer and its film morphology. AFM images of the self‐assembled PS‐PLA films indicate that vertical tapers of the PLA domains were generated among PS continuum when either toluene or tetrahydrofuran was used as the annealing solvent. The SEM images certified that the chemical etching of the PLA component from the self‐assembled PS–PLA films led to a long‐range‐ordered array of hexagonally packed nanoporous membranes with a diameter about 500 nm and a center‐to‐center distance of 1700 nm. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39638.     

All‐polymer electromechanical systems consisting of electrostrictive poly(vinylidene fluoride‐trifluoroethylene) and conductive polyaniline

The low elastic modulus and the ability to withstand high strain without failure make the conducting polymer attractive for a wide range of acoustic applications based on high‐strain electroactive polymers. In this article, we examine the electric and electromechanical performance of all‐polymer electromechanical systems, fabricated by painting conductive polyaniline (PANI) doped with camphor sulfonic acid (HCSA) on both sides of electrostrictive Poly(vinylidene fluoride‐trifluoroethylene) (P(VDF‐TrFE)) copolymer films, and compare them with those from the same copolymers with gold electrodes. The all‐polymer composite films are flexible, with strong coherent interfaces between the electrostrictive polymer layer and the conductive polymer layer. The electric performance such as dielectric properties and polarization hysteresis loops from P(VDF‐TrFE)/PANI film is nearly identical to those of P(VDF‐TrFE)/gold films in a wide temperature (from −50 to 120°C), and frequency range (from 1 Hz to 1 MHz). The all‐polymer systems also show a similar or even larger electric field induced strain response than that of films with electrodes under identical measurement conditions. The results demonstrate that the polyaniline/HCSA is good candidate material as the electrodes for electroactive polymers. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 945–951, 2000     

Substituent effect on the optoelectronic properties of poly(p‐phenylenevinylene) based conjugated‐nonconjugated copolymers

Two classes of light emitting Poly(p‐phenylenevinylene) (PPV) based conjugated‐nonconjugated copolymers (CNCPs) have been synthesized. The conjugated chromophores containing 2‐methoxy‐5‐(2′‐ethylhexyloxy)‐1,4‐phenylenevinylene (MEHPV) and 2,5‐dimethyl‐1,4‐phenylenevinylene (DMPV) moieties are rigid segments and nonconjugated portion containing hexyl units are flexible in nature. All copolymers were synthesized by well‐known Wittig reaction between the appropriate bisphosphonium salts and the dialdehyde monomers. The resulting polymers were found to be readily soluble in common organic solvents like chloroform, THF and chlorobenzene. The effect of chromophore substituents on the optical and redox properties of the copolymers has been investigated. Color tuning was carried out by varying the molar percentage of the comonomers. The UV‐Vis absorption and PL emission of the copolymers were in the range 314–395 nm and 494–536 nm respectively. All the polymers show good thermal stability. Polymer light‐emitting diodes (PLEDs) were fabricated in ITO/PEDOT:PSS/emitting polymer/cathode configurations of selected polymers using double‐layer, LiF/Al cathode structure. The emission maxima of the polymers were around 499–536 nm, which is a blue‐green part of the color spectrum. The threshold voltages of the EL polymers were in the range of 5.4–6.2 V. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation of 2‐(dimethylamino) ethyl methacrylate copolymer micelles for shape memory materials

Researchers are actively developing shape memory polymers (SMPs) for smart biomaterials. This paper reports a new SMP system synthesized from biocompatible 2‐(dimethylamino) ethyl methacrylate (DMAEMA), butyl acrylate (BA) and tri(ethylene glycol) divinyl ether (TDE). Preliminary results show that the DMAEMA‐co‐BA‐co‐TDE copolymers form micelles in aqueous solution due to chemical crosslinking and hydrophobicity. The micelle size decreased with the increase in the BA content since the hydrophobicity of copolymers increases with the increase of BA content. The resulting polymer films contain–N(CH₃)₂ functional groups for further biomaterial applications. The thermal stability of DMAEMA‐co‐BA‐co‐TDE copolymers is determined by the DMAEMA structure and content. Moreover, the copolymers form micro‐phase‐separated structures containing a reversible amorphous soft phase, and the storage moduli decreases significantly around T_g. Therefore, good thermal‐induced shape memory effects are achieved in the DMAEMA‐co‐BA‐co‐TDE copolymers by adjusting the BA content. This work proposes a new strategy for designing smart biomaterials using a biocompatible monomer. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42312.     

Viscosity behavior and surface and interfacial activities of hydrophobically modified water‐soluble acrylamide/N‐phenyl acrylamide block copolymers

In this study, the viscosity behavior and surface and interfacial activities of associative water‐soluble polymers, which were prepared by an aqueous micellar copolymerization technique from acrylamide and small amounts of N‐phenyl acrylamide (1.5 and 5 mol %), were investigated under various conditions, including the polymer concentration, shear rate, temperature, and salinity. The copolymer solutions exhibited increased viscosity due to intermolecular hydrophobic associations, as the solution viscosity of the copolymers increased sharply with increasing polymer concentration, especially above a critical overlap concentration. An almost shear‐rate‐independent viscosity (Newtonian plateau) was also displayed at high shear rates, and typical non‐Newtonian shear‐thinning behavior was exhibited at low shear rates and high temperatures. Furthermore, the copolymers exhibited high air–water and oil–water interfacial activities, as the surface and interfacial tensions decreased with increasing polymer concentration and salinity. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2290–2300, 2003     

Synthesis and properties of side chain cholesteric liquid‐crystalline polyacrylates containing two mesogenic groups

The synthesis of side chain cholesteric liquid‐crystalline polymers containing both 4‐cholesteryl‐4'‐acryloyloxybenzoate (M_I) and 4‐methoxyphenyl‐4'‐acryloyloxybenzoate (M_II) mesogenic side groups is described. The chemical structures of the obtained monomers and polymers are confirmed by Fourier transform infrared (FTIR) spectroscopy. The phase behavior and optical properties of the synthesized monomers and polymers were investigated by polarizing optical microscopy (POM), differential scanning calorimetry (DSC), and thermogravimetric analyses (TGA). The homopolymer IP reveals a cholesteric phase and VIIP displays a nematic phase. The copolymers IIP–VIP exhibit, respectively, cholesteric oily‐streak texture and focal‐conic texture. The fixation of the helical pitch and oily‐streak texture of the cholesteric phase is achieved by quenching, and polymer films with different reflection colors are obtained. The experimental results demonstrate that the glass transition temperature (T_g) and the melting temperature (T_m) of the copolymers IIP–VIP decrease, whereas the isotropization temperature (T_i) and the mesomorphic temperature range (ΔT) increase with increasing content of mesogenic M_II units. TGA results indicate that the temperatures at which 5% mass loss occurred (T_5wt%) of all copolymers are >245°C. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1936–1941, 2003     

Polymers of norbornenyl‐4‐phenol: Dissolution rate characteristics,positive tone photo‐patterning,and polymer properties

Vinyl addition norbornene polymers with phenol pendent groups are obtained by methanolysis of the 4‐acetoxyphenyl norbornene polymer. Thin films of this polymer blended with additives such as norbornene polymers with hexafluoroalcohol pendent groups and diazonaphthoquinone compounds result in linear dissolution in tetramethylammonium hydroxide developer. Good resolution, positive tone patterns are obtained from image‐wise exposure of thin films of blends of the diazonaphthoquinone additives with both phenol pendent norbornene homopolymer and with norbornene copolymers with both phenol and hexafluoroalcohol pendent groups. Properties such as transparency, dielectric constant, chemical, and thermal resistance were determined for cured copolymer compositions containing an epoxy crosslinker. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44952.     

Physical properties of poly(vinyl chloride)–grafted N‐isopropylacrylamide graft copolymers and corresponding polyblends

The physical properties of poly(vinyl chloride) (PVC) and poly(N‐isopropylacrylamide) [poly(NIPAAm)] blend systems, and their corresponding graft copolymers such as PVC‐g‐NIPAAm, were investigated in this work. The compatible range for PVC–poly(NIPAAm) blend systems is less than 15 wt % poly(NIPAAm). The water absorbencies for the grafted films increase with increase in graft percentage. The water absorbencies for the blend systems increase with increase in poly(NIPAAm) content within the compatible range for the blends, but the absorbencies decrease when the amount of poly(NIPAAm) is more than the compatible range in the blend system. The tensile strengths for the graft copolymers are larger than the corresponding blends. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 170–178, 2000     

Regulating the physical and biological performances of poly(p‐dioxanone) by copolymerization with L‐phenylalanine

The high crystallinity, low solubility in normal solvents, and low hydrophilicity of poly(p‐dioxanone) (PPDO) are unsuitable for the expansion of its biomedical applications. In order to circumvent these problems and induce biological properties, a series of poly(ester amide)s based on p‐(dioxanone) and l ‐phenylalanine were synthesized by copolymerization of p‐dioxanone with l ‐phenylalanine N‐carboxyanhydride monomers. The structures of the copolymers were confirmed by ¹H NMR. The crystallinity of the copolymers was investigated by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). Increasing contents of phenylalanine resulted in decreased crystallinity owing to the rigid phenyl groups of phenylalanine, which disrupted the regularities of the chains, thus confining their movement. The synthesized copolymers were more soluble in chloroform than PPDO. Moreover, the copolymers were more hydrophilic and hydrolyzed more slowly than PPDO, as indicated by water angle contact measurements and in vitro hydrolysis studies. Especially, the copolymers showed inhibition on cell proliferation of L929 mouse fibroblasts by MTT assay, suggesting that the polymers might be useful in the areas where cell proliferation need to be inhabited such as adhesion prevention. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2311–2319, 2013     

Controllable self‐assembly of polystyrene‐block‐poly(2‐vinylpyridine)

Block copolymers can form various ordered structures by self‐assembly, and their composites with inorganic materials may give surprising properties. This review summarizes recent developments in the preparation, mechanism and application of various types of self‐assembly of polystyrene‐block‐poly(2‐vinylpyridine) (PS‐b‐P2VP). The focus of the review is on how to control the self‐assembly of the dynamic and ordered structure of PS‐b‐P2VP based materials by applying effective factors such as thermal annealing, solvent annealing, block composition and blending. Moreover, the combination of the self‐assembly of PS‐b‐P2VP and various nanoparticles, with potentials in drug delivery, sensors and catalysis, is highlighted. © 2018 Society of Chemical Industry     

Study of high thermal conductive epoxy resins containing controlled high‐order structures

Heat is transported by phonons through dielectric solids such as ceramics and organic insulating resins. Especially in organic insulating resins, phonons scatter intensely mainly by their amorphous structure, which affects their thermal conductivities, usually 1 to 3 orders lower than those of ceramics and metals. Here, we show that by the thermosetting resin system with a crystal‐like structure that is microscopic anisotropy, the thermal conductivities of the resin themselves can be improved while keeping their macroscopic isotropy. We studied four kinds of diepoxy monomers with a biphenyl group or two phenyl benzoate groups as mesogens, and cured them thermally with an aromatic diamine curing agent. These thermal conductivities were maximally 5 times higher than that of conventional epoxy resins because mesogens were highly ordered to form crystal‐like structures to suppress phonon scattering. We also succeeded in the direct confirmation of the existence of crystal‐like structures in the epoxy resins by TEM observation. These results suggest a novel strategy to improve thermal conductivities of insulating resins themselves by controlling the high‐order structures. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2464–2467, 2003