Poly(hydroxyether of bisphenol A)-block-polydimethylsiloxane alternating block copolymer and its nanostructured blends with epoxy resin

Mannich condensation was utilized to synthesize poly(hydroxyether of bisphenol A)-block-polydimethylsiloxane alternating block copolymer (PH-alt-PDMS). The polymerization between the phenolic hydroxyl-terminated oligo(hydroxyether of bisphenol A) and amino-terminated oligodimethylsiloxane with the defined lengths was carried out via the formation of benzoxazine ring linkages, which was mediated with paraformaldehyde. The alternating block copolymer was characterized by means of Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR) and gel permeation chromatography (GPC). The block copolymer was incorporated to prepare nanostructured thermosetting blends. The nanostructures of the thermosetting blends were investigated by means of atomic force microscopy (AFM) and small angle X-ray scattering (SAXS). The formation of the nanostructures in the thermosetting composites was judged to follow the self-assembly mechanism in terms of the difference in miscibility of PDMS and PH subchains with epoxy resin after and before curing reaction. The fracture toughness of the nanostructured blends was evaluated in terms of the measurement of stress field intensity factor (K_IC). It is noted that the epoxy resin was significantly toughened.     

Influence of semi‐crystalline poly(ε‐caprolactone) and non‐crystalline polylactide blocks on the thermal properties of polydimethylsiloxane‐based block copolymers

Poly(A)‐block‐poly(B), poly(A)‐block‐poly(B)‐block‐poly(A) and B(A)₂ block copolymers were prepared through coordinated anionic ring‐opening polymerization of ε‐caprolactone (CL) and lactic acid (LA) using hydroxy‐terminated polydimethylsiloxane (PDMS) as initiator. A wide range of well‐defined combinations of PDMS‐block‐PCL and PDMS‐block‐PLA diblock copolymers, PCL‐block‐PDMS‐block‐PCL and PLA‐block‐PDMS‐block‐PLA triblock copolymers and star‐PDMS(PCL)₂ copolymers were thus obtained. The number‐average molar masses and the structure of the synthesized block copolymers were identified using various analytical techniques. The thermal properties of these copolymers were established using differential scanning calorimetry. Considering PDMS‐block‐PCL copolymers, the results demonstrate the complex effect of polymer architecture and PCL block length on the ability of the PDMS block to crystallize or not. In the case of diblock copolymers, crystallization of PCL blocks originated from stacking of adjacent chains inducing the extension of the PDMS block that can easily crystallize. In the case of star copolymers, the same tendency as in triblock copolymers is observed, showing a limited crystallization of PDMS when the length of the PCL block increases. In the case of PDMS‐block‐PLA copolymers, melting and crystallization transitions of the PLA block are never observed. Considering the diblock copolymers, PDMS sequences have the ability to crystallize. © 2019 Society of Chemical Industry     

Synthesis and surface properties of polydimethylsiloxane‐based block copolymers: poly[dimethylsiloxane‐block‐ (ethyl methacrylate)] and poly[dimethylsiloxane‐block‐(hydroxyethyl methacrylate)]

A polydimethylsiloxane (PDMS) macroazoinitiator was synthesized from bis(hydroxyalkyl)‐terminated PDMS and 4,4′‐azobis‐4‐cyanopentanoic acid by a condensation reaction. The bifunctional macroinitiator was used for the block copolymerization of ethyl methacrylate (EMA) and 2‐(trimethylsilyloxy)ethyl methacrylate (TMSHEMA) monomers. The poly(DMS‐block‐EMA) and poly(DMS‐block‐TMSHEMA) copolymers thus obtained were characterized using Fourier transform infrared and ¹H NMR spectroscopy and differential scanning calorimetry. After the deprotection of trimethylsilyl groups, poly(DMS‐block‐HEMA) and poly(DMS‐block‐EMA) copolymer film surfaces were analysed using scanning electron microscopy and X‐ray photoelectron spectroscopy. The effects of the PDMS concentration in the copolymers on both air and glass sides of films were examined. The PDMS segments oriented and moved to the glass side in poly(DMS‐block‐EMA) copolymer film while orientation to the air side became evident with increasing DMS content in poly(DMS‐block‐HEMA) copolymer film. The block copolymerization technique described here is a versatile and economic method and is also applicable to a wide range of monomers. The copolymers obtained have phase‐separated morphologies and the effects of DMS segments on copolymer film surfaces are different at the glass and air sides. Copyright © 2010 Society of Chemical Industry     

Synthesis of polydimethylsiloxane‐block‐polystyrene‐block‐polydimethylsiloxane via polysiloxane‐based macroinitiator in supercritical CO2

Polydimethylsiloxane‐block‐polystyrene‐block‐polydimethylsiloxane (PDMS‐b‐PS‐b‐PDMS) was synthesized by the radical polymerization of styrene using a polydimethylsiloxane‐based macroazoinitiator (PDMS MAI) in supercritical CO₂. PDMS MAI was synthesized by reacting hydroxy‐terminated PDMS and 4,4′‐azobis(4‐cyanopentanoyl chloride) (ACPC) having a thermodegradable azo‐linkage at room temperature. The polymerization of styrene initiated by PDMS MAI was investigated in a batch system using supercritical CO₂ as the reaction medium. PDMS MAI was found to behave as a polyazoinitiator for radical block copolymerization of styrene, but not as a surfactant. The response surface methodology was used to design the experiments. The parameters used were pressure, temperature, PDMS MAI concentration and reaction time. These parameters were investigated at three levels (?1, 0 and 1). The dependent variable was taken as the polymerization yield of styrene. PDMS MAI and PDMS‐b‐PS‐b‐PDMS copolymers obtained were characterized by proton nuclear magnetic resonance and infrared spectroscopy. The number‐ and weight‐average molecular weights of block copolymers were determined by gel permeation chromatography. Copyright © 2004 Society of Chemical Industry     

Synthesis and characterization of advance PA6‐b‐PDMS multiblock copolymers

Advance polyamide‐6‐b‐polydimethylsiloxane (PA6‐b‐PDMS) multiblock copolymers were first synthesized via the polymerization in bulk. Binary carboxyl terminated PA6 was served as the hard segment and PDMS modified with hexamethylene diisocyanate (PDMS‐NCO) was the soft segment. A series of PA6‐b‐PDMS copolymers based on different content and length of soft segments were obtained. Interestingly, Differential scanning calorimetry (DSC) studies revealed no obvious change in melting temperature after introducing PDMS segments to copolymers. The high melting temperatures indicated these copolymers possess potential applications in automotive industry that require high continuous use temperatures. DSC and transmission electron microscopy studies both demonstrated increasing the length and the content of the soft segment contributed to increasing of the degree of microphase separation. However, the improvement of thermal stability resulting from PDMS segments was also observed by thermo gravimetric analysis. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41114.     

Surface microphase separation in PDMS‐b‐PMMA‐b‐PHFBMA triblock copolymer films

Well‐defined poly(dimethylsiloxane)‐block‐poly(methyl methacrylate)‐block‐poly(2,2,3,3,4,4,4‐heptafluorobutyl methacrylate) (PDMS‐b‐PMMA‐b‐PHFBMA) triblock copolymers were synthesized via atom transfer radical polymerization (ATRP). Surface microphase separation in the PDMS‐b‐PMMA‐b‐PHFBMA triblock copolymer films was investigated. The microstructure of the block copolymers was investigated by transmission electron microscopy (TEM) and atomic force microscopy (AFM). Surface composition was studied by X‐ray photoelectron spectroscopy (XPS). The chemical composition at the surface was determined by the surface microphase separation in the PDMS‐b‐PMMA‐b‐PHFBMA triblock copolymer films. The increase of the PHFBMA content could strengthen the microphase separation behavior in the PDMS‐b‐PMMA‐b‐PHFBMA triblock copolymer films and reduce their surface tension. Comparison between the PDMS‐b‐PMMA‐b‐PHFBMA triblock copolymers and the PDMS‐b‐PHFBMA diblock copolymers showed that the introduction of the PMMA segments promote the fluorine segregation onto the surface and decrease the fluorine content in the copolymers with low surface energy. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

AB‐ and ABC‐type di‐ and triblock copolymers of poly[styrene‐block‐(ε‐caprolactone)] and poly[styrene‐block‐(ε‐caprolactone)‐block‐lactide]: synthesis,characterization and thermal studies

Polystyrene terminated with benzyl alcohol units was employed as a macroinitiator for ring‐opening polymerization of ε‐caprolactone and L ‐lactide to yield AB‐ and ABC‐type block copolymers. Even though there are many reports on the diblock copolymers of poly(styrene‐block‐lactide) and poly(styrene‐block‐lactone), this is the first report on the poly(styrene‐block‐lactone‐block‐lactide) triblock copolymer consisting of two semicrystalline and degradable segments. The triblock copolymers exhibited twin melting behavior in differential scanning calorimetry (DSC) analysis with thermal transitions corresponding to each of the lactone and lactide blocks. The block derived from ε‐caprolactone also showed crystallization transitions upon cooling from the melt. In the DSC analysis, one of the triblock copolymers showed an exothermic transition well above the melting temperature upon cooling. Thermogravimetric analysis of these block copolymers showed a two‐step degradation curve for the diblock copolymer and a three‐step degradation for the triblock copolymer with each of the degradation steps associated with each segment of the block copolymers. The present study shows that it is possible to make pure triblock copolymers with two semicrystalline segments which also consist of degradable blocks. Copyright © 2009 Society of Chemical Industry     

Polyvinylpyrrolidone–polydimethylsiloxane amphiphilic co‐networks: Synthesis,characterization, and perm‐selective behavior

An amphiphilic co‐network (APCN) membrane has been synthesized through end‐crosslinking of amphiphilic grafts of polyvinylpyrrolidone (PVP) backbone carrying polydimethylsiloxane (PDMS) branches fitted with terminal vinylsilyl groups via free radical polymerization. The synthesis strategy has been carried out by the free radical polymerization of N‐vinylpyrrolidone (VP) with methacrylate allyl terminated polydimethylsiloxane (MA‐PDMS‐V) and dimethacrylate terminated polydimethylsiloxane (MA‐PDMS‐MA) to form a soluble graft consisting of PVP main chains carrying vinyl terminated PDMS branches, which is crosslinked with polymethylhydrosiloxane through hydrosilylation. The resulting APCN membrane exhibited a combination of unique properties, that is, high transparency, high mechanical properties, and high permeation rate to inulin. Notably, the mechanical properties and inulin permeability of fabric‐support APCN membrane were higher than that of pure APCN membrane. As a result of their unique performance, the resulting APCN membranes showed a wide range of potential applications in drug release vectors, soft contact lenses, and biomedical separation materials. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42985.     

Copolymers based on poly(butylene terephthalate) and polycaprolactone‐block‐polydimethylsiloxane‐block‐polycaprolactone

A series of novel thermoplastic elastomers, based on poly(butylene terephthalate) (PBT) and polycaprolactone‐block‐polydimethylsiloxane‐block‐polycaprolactone (PCL‐PDMS‐PCL), with various mass fractions, were synthesized through melt polycondensation. In the synthesis of the poly(ester‐siloxane)s, the PCL blocks served as a compatibilizer for the non‐polar PDMS blocks and the polar comonomers dimethyl terephthalate and 1,4‐butanediol. The introduction of PCL‐PDMS‐PCL soft segments resulted in an improvement of the miscibility of the reaction mixture and therefore in higher molecular weight polymers. The content of hard PBT segments in the polymer chains was varied from 10 to 80 mass%. The degree of crystallinity of the poly(ester‐siloxane)s was determined using differential scanning calorimetry and wide‐angle X‐ray scattering. The introduction of PCL‐PDMS‐PCL soft segments into the polymer main chains reduced the crystallinity of the hard segments and altered related properties such as melting temperature and storage modulus, and also modified the surface properties. The thermal stability of the poly(ester‐siloxane)s was higher than that of the PBT homopolymer. The inclusion of the siloxane prepolymer with terminal PCL into the macromolecular chains increased the molecular weight of the copolymers, the homogeneity of the samples in terms of composition and structure and the thermal stability. It also resulted in mechanical properties which could be tailored. Copyright © 2010 Society of Chemical Industry     

Versatile synthesis of self‐assembling ABA triblock copolymers with polymethyloxazoline A‐blocks and a polysiloxane B‐block decorated with supramolecular receptors

BACKGROUND: Self‐assembling amphiphilic block copolymers with incorporated, biologically relevant functionalities have received limited attention, partly due to the fact that biomolecules are not robust enough to synthetic manipulation, do not lend themselves readily to systematic studies due to their complexity and leach rather quickly from a vesicle or membrane when physically incorporated. Synthetic supramolecules are used as biomolecule mimics in functional membranes. RESULTS: Reaction conditions were established for the synthesis of a tosyl‐terminated siloxane end‐blocker, which serves as molecular weight control in the synthesis of polydimethylsiloxane (PDMS) and poly(dimethylsiloxane‐co‐methylhydrosiloxane) [P(DMS‐co‐MHS)] copolymers. Hydrosilylation reactions were investigated for the covalent coupling of synthetic supramolecules (18‐crown‐6 ether, hydroxybenzoate) to the polymer backbone using the methylhydrosiloxane repeat units as the anchor moiety. Using P(DMS‐co‐MHS) or derivatized P(DMS‐co‐MHS) copolymers as macroinitiator for the ring‐opening polymerization of 2‐methyl‐4‐hydroxy‐oxazoline led to the formation of poly[(dimethylsiloxane‐co‐methylhydrosiloxane)‐block‐oxazoline] [P(DMS‐co‐MHS‐b‐Ox)] ABA triblock copolymers with defined PDMS to PMHS ratios and controlled molecular weights. CONCLUSION: Derivatized P(DMS‐co‐MHS‐b‐Ox) ABA triblock copolymers synthesized using a novel versatile procedure undergo vesicle formation upon electroformation with vesicle diameters ranging from 2 to 10 µm. The size of the vesicle depends on the overall polarity of the macromolecule. Copyright © 2008 Society of Chemical Industry     

Nanophase morphology and crystallization in poly(vinylidene fluoride)/polydimethylsiloxane‐block‐poly(methyl methacrylate) blends

A polydimethylsiloxane‐block‐poly(methyl methacrylate) (PDMS‐b‐PMMA) diblock copolymer was synthesized by the atom transfer radical polymerization method and blended with a high‐molecular‐weight poly(vinylidene fluoride) (PVDF). In this A‐b‐B/C type of diblock copolymer/homopolymer system, semi‐crystallizable PVDF (C) and PMMA (B) block are miscible due to favorable intermolecular interactions. However, the A block (PDMS) is immiscible with PVDF and therefore generates nanostructured morphology via self‐assembly. Crystallization study reveals that both α and γ crystalline phases of PVDF are present in the blends with up to 30 wt% of PDMS‐b‐PMMA block copolymer. Adding 10 wt% of PVDF to PDMS‐b‐PMMA diblock copolymer leads to worm‐like micelle morphology of PDMS of 10 nm in diameter and tens of nanometers in length. Moreover, morphological results show that PDMS nanostructures are localized in the inter‐fibrillar region of PVDF with the addition of up to 20 wt% of the block copolymer. Increase of PVDF long period by 45% and decrease of degree of crystallization by 34% confirm the localization of PDMS in the PVDF inter‐fibrillar region. © 2018 Society of Chemical Industry     

Nanophase morphology and crystallization in poly(vinylidene fluoride)/polydimethylsiloxane‐block‐poly(methyl methacrylate)‐block‐polystyrene blends

An approach to achieve confined crystallization of ferroelectric semicrystalline poly(vinylidene fluoride) (PVDF) was investigated. A novel polydimethylsiloxane‐block‐poly(methyl methacrylate)‐block‐polystyrene (PDMS‐b‐PMMA‐b‐PS) triblock copolymer was synthesized by the atom‐transfer radical polymerization method and blended with PVDF. Miscibility, crystallization and morphology of the PVDF/PDMS‐b‐PMMA‐b‐PS blends were studied within the whole range of concentration. In this A‐b‐B‐b‐C/D type of triblock copolymer/homopolymer system, crystallizable PVDF (D) and PMMA (B) middle block are miscible because of specific intermolecular interactions while A block (PDMS) and C block (PS) are immiscible with PVDF. Nanostructured morphology is formed via self‐assembly, displaying a variety of phase structures and semicrystalline morphologies. Crystallization at 145 °C reveals that both α and β crystalline phases of PVDF are present in PVDF/PDMS‐b‐PMMA‐b‐PS blends. Incorporation of the triblock copolymer decreases the degree of crystallization and enhances the proportion of β to α phase of semicrystalline PVDF. Introduction of PDMS‐b‐PMMA‐b‐PS triblock copolymer to PVDF makes the crystalline structures compact and confines the crystal size. Moreover, small‐angle X‐ray scattering results indicate that the immiscible PDMS as a soft block and PS as a hard block are localized in PVDF crystalline structures. © 2019 Society of Chemical Industry     

Synthesis and surface characterization of poly(methyl methacrylate)‐block‐polydimethylsiloxane copolymers from macroazoinitiator

Poly(methyl methyacrylate)‐block‐polydimethylsiloxane (PMMA‐b‐PDMS) copolymers with various compositions were synthesized with PDMS‐containing macroazoinitiator (MAI), which was first prepared by a facile one‐step method in our lab. Results from the characterizations of X‐ray photoelectron spectroscopy (XPS), contact angle measurements, and atomic force microscopy (AFM) showed that the copolymer films took on a gradient of composition and more PDMS segments enriched at the film surfaces, which then resulted in the low surface free energy and little microphase separation at the film surfaces. By contrast, transmission electron microscopy (TEM) analysis demonstrated that distinct microphase separation occurred in bulk. Slight crosslinking of the block copolymers led to much steady morphology and more distinct microphase separation, in particularly for copolymers with low content of PDMS. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Photophysical properties of fluorene‐based copolymers synthesized by connecting twisted biphenyl units with fluorene via para‐ and meta‐linkages

BACKGROUND: Wide bandgap semiconducting polymers are of great interest in the development of organic and polymeric emissive materials for display purposes since they can be used to generate light of all colors either by irradiation of luminescent dyes or by energy transfer to emissive dopants. The aim of the present work is to construct new fluorene‐based semiconducting polymers with a wide bandgap. RESULTS: A novel polyfluorene derivative, poly[(9,9‐dihexyl‐2,7‐fluorene)‐alt‐(5,7‐dihydrodibenz[c,e]oxepin)], with a wide bandgap, was synthesized by connecting rigidly twisted biphenyl monomers with dihexylfluorene via para‐linkages and it was compared with poly[(9,9‐dihexyl‐2,7‐fluorene)‐alt‐(spirocyclohexane‐1,6′‐dibenzo[d,f][1,3]dioxepin)], which has meta‐linkages. Both polymers emit in the ultraviolet and blue regions. Electronic spectral absorption data and electrochemical measurements demonstrate that ca 40° torsion angle of the biphenyl units induces an increase in the HOMO–LUMO gap of 0.18 eV, and that meta‐linkage of the twisted segment in the polymer induces another increase of 0.24 eV compared to polydihexylfluorene. CONCLUSION: The new twisted biphenyl compounds are efficient segments to tune the bandgaps of conjugated polymers. The two fluorene‐based copolymers have wide bandgaps and exhibit potential as host materials. Copyright © 2008 Society of Chemical Industry     

Synthesis and antitumor activity of poly(3,4‐dihydro‐2H‐pyran‐co‐maleic anhydride‐co‐vinyl acetate)

The radical‐initiated terpolymerization of 3,4‐dihydro‐2H‐pyran (DHP), maleic anhydride (MA), and vinyl acetate (VA), which were used as a donor–acceptor–donor system, was carried out in methyl ethyl ketone in the presence of 2,2′‐azobisisobutyronitrile as an initiator at 65°C in a nitrogen atmosphere. The synthesis and characterization of binary and ternary copolymers, some kinetic parameters of terpolymerization, the terpolymer‐composition/thermal‐behavior relationship, and the antitumor activity of the synthesized polymers were examined. The polymerization of the DHP–MA–VA monomer system predominantly proceeded by the alternating terpolymerization mechanism. The in vitro cytotoxicities of poly(3,4‐dihydro‐2H‐pyran‐alt‐maleic anhydride) [poly(DHP‐alt‐MA)] and poly(3,4‐dihydro‐2H‐pyran‐co‐maleic anhydride‐co‐vinyl acetate) [poly(DHP‐co‐MA‐co‐VA)] were evaluated with Raji cells (human Burkitt lymphoma cell line). The antitumor activity of the prepared anion‐active poly(DHP‐alt‐MA) and poly(DHP‐co‐MA‐co‐VA) polymers were studied with methyl–thiazol–tetrazolium testing, and the 50% cytotoxic dose was calculated. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2352–2359, 2005     

Synthesis and self‐assembly of amphiphilic star‐block copolymers consisting of polyethylene and poly(ethylene glycol) segments

We report on the synthesis and self‐assembly in water of well‐defined amphiphilic star‐block copolymers with a linear crystalline polyethylene (PE) segment and two or three poly(ethylene glycol) (PEG) segments as the building blocks. Initially, alkynyl‐terminated PE (PE‐?) is synthesized via esterification of pentynoic acid with hydroxyl‐terminated PE, which is prepared using chain shuttling ethylene polymerization with 2,6‐bis[1‐(2,6‐dimethylphenyl) imino ethyl] pyridine iron (II) dichloride/methylaluminoxane/diethyl zinc and subsequent in situ oxidation with oxygen. Then diazido‐ and triazido‐terminated PE (PE‐(N₃)₂ and PE‐(N₃)₃) are obtained by the click reactions between PE‐? and coupling agents containing triazido or tetraazido, respectively. Finally, the three‐arm and four‐arm star‐block copolymers, PE‐b‐(PEG)₂ and PE‐b‐(PEG)₃, are prepared by click reactions between PE‐(N₃)₂ or PE‐(N₃)₃ and alkynyl‐terminated PEG. The self‐assembly of the resultant amphiphilic star‐block copolymers in water was investigated by dynamic light scattering, transmission electron microscopy, and atomic force microscopy. It is found that, in water, a solvent selectively good for PEG blocks; these star‐block copolymer chains could self‐assemble to form platelet‐like micelles with insoluble PE blocks as crystalline core and soluble PEG blocks as shell. The confined crystallization of PE blocks in self‐assembled structure formed in aqueous solution is investigated by differential scanning calorimetry. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Novel 2,4‐divinyl‐3‐alkylthiophene/1,3,4‐oxadiazole alternating conjugated copolymer synthesized by the Heck coupling method: Synthesis,characterization, and electronic and optical properties

A novel alternating copolymer with 3‐alkylthiophene and oxadiazole (or pyridine) units in ordered arrangement was synthesized with vinyl as a bridge for the first time. The synthesis process included four steps: bromomethylation, preparation of the ylide monomer, the formation of 2,4‐divinyl‐3‐alkylthiophene, and Heck alternating copolymerization. The Fourier transform infrared spectroscopy, ¹H‐NMR, and gel permeation chromatography measurements showed that all of the copolymers had the required structures. The weight‐average molecular weights of the copolymers were in the range 5500–15,000 with a relatively low polydispersity index of 1.4–1.7. The solubility of the copolymers in common solvents (e.g., methylene chloride, chloroform, tetrahydrofuran) was excellent. The optical properties and bandgap of the copolymers was compared with corresponding poly(3‐alkylthiophene) homopolymers. The photoluminescence quantum efficiency (QE) of the copolymers improved markedly in chloroform. The QEs of poly(2,4‐divinyl‐3‐hexylthiophene‐alt‐2,5‐diphenyl‐1,3,4‐ oxadiazole) and poly(2,4‐divinyl‐3‐octythiophene‐alt‐2,5‐diphenyl‐1,3,4‐oxadiazole) were 43.2 and 34.2%, respectively, which were about 20 and 21 times higher than those of the homopolymers, respectively. The ionization potential of the copolymers between 5.53 and 6.13 eV was appropriated to poly(3‐alkylthiophene)s. The high electron affinity of the copolymers (2.71–2.95 eV) made the electrons inject from the cathode more easily. With excellent solubility, low bandgap energy, high QE, and both electron‐transporting and hole‐transporting abilities, the proposed copolymers might be excellent polymeric materials for applications in polymer light‐emitting diodes, light‐emitting electrochemical cells, and polymer solar cells. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and properties of poly(siloxane‐ether‐urethane)‐acrylic hybrid emulsions

Poly(siloxane‐ether‐urethane)‐acrylic (PU‐AC) hybrid emulsions were prepared by introducing different hydroxyethoxypropyl‐terminated polydimethylsiloxane (PDMS) content into the acrylic‐terminated poly(ether‐urethane) backbone and then in situ copolymerizing with methyl methacrylate and butyl acrylate via emulsion process. The effects of PDMS on the particle size and viscoelastic behavior of the hybrid emulsions were investigated. Meanwhile, the hydrogen bonding, mechanical and thermal mechanical properties, water resistance, the surface gloss, and wettability of the resultant hybrid films were also studied. The results showed that all the hybrid emulsions showed shear‐thinning behaviors, and the introduction of PDMS resulted in the formation of the hybrid emulsions with increased average particle size and decreased viscosity. The chemical bonds built between PU and AC yielded higher than 73% crosslinking fraction in all the hybrid materials, but this value decreased with increasing PDMS content because PDMS reduced the hydrogen bonding interactions and enhanced the phase separation. As a result, an increase in the PDMS content led to an increase in the elongation, water resistance, surface roughness, and water hydrophobic of the films, but the tensile strength, hardness, storage modulus, and glass transitions temperature decreased. It is suggested that introduction of PDMS can provide the hybrid materials with the improved flexibility, water resistance, and surface hydrophobicity, which has potential application value in the fouling‐release coatings, biomaterials, and surface fishing. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44927.     

Microphase separation behavior on the surfaces of poly(dimethylsiloxane)‐block‐poly(2,2,3,3,4,4,4‐heptafluorobutyl methacrylate) diblock copolymer coatings

Microphase separation behavior on the surfaces of poly(dimethylsiloxane)‐block‐poly(2,2,3,3,4,4,4‐heptafluorobutyl methacrylate) (PDMS‐b‐PHFBMA) diblock copolymer coatings was investigated. The PDMS‐b‐PHFBMA diblock copolymers were successfully synthesized via atom transfer radical polymerization (ATRP). The chemical structure of the copolymers was characterized by nuclear magnetic resonance and Fourier transform infrared spectroscopy. Surface composition was studied by X‐ray photoelectron spectroscopy. Copolymer microstructure was investigated by atomic force microscopy. The microstructure observations show that well‐organized phase‐separated surfaces consist of hydrophobic domain from PDMS segments and more hydrophobic domain from PHFBMA segments in the copolymers. The increase in the PHFBMA content can strengthen the microphase separation behavior in the PDMS‐b‐PHFBMA diblock copolymers. And the increase in the annealing temperature can also strengthen the microphase separation behavior in the PDMS‐b‐PHFBMA diblock copolymers. Moreover, Flory‐Huggins thermodynamic theory was preliminarily used to explain the microphase separation behavior in the PDMS‐b‐PHFBMA diblock copolymers.© 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Morphology and thermomechanical properties of epoxy thermosets modified with polysulfone‐block‐polydimethylsiloxane multiblock copolymer

Polysulfone‐block‐polydimethylsiloxane (PSF‐b‐PDMS) multiblock copolymer was synthesized via the Mannich polycondensation between phenolic hydroxyl‐terminated polysulfone and aminopropyl‐terminated polydimethylsiloxane in the presence of formaldehyde. The multiblock copolymer was characterized by means of nuclear magnetic resonance spectroscopy (NMR) and gel permeation chromatography (GPC) and used as a modifier to improve the thermomechanical properties of epoxy thermosets. Transmission electron microscopy (TEM) showed that the epoxy thermosets containing PSF‐b‐PDMS multiblock copolymer possesses the microphase‐separated morphological structures. Depending on the content of the PSF‐b‐PDMS multiblock copolymer, the spherical particles with the size of 50–200 nm in diameter were dispersed into the continuous epoxy matrices. The measurement of static contact angles showed that with the inclusion of PSF‐b‐PDMS multiblock copolymer, the epoxy thermosets displayed the improved surface hydrophobicity. It is noted that the epoxy resin was significantly toughened in terms of the measurement of critical stress field intensity factor (K_1C). © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011