Surface modification of ultra‐high molecular weight polyethylene fibers by chromic acid

Ultra‐high molecular weight polyethylene (UHMWPE) fibers were modified by chromic acid. The effects of surface modification were evaluated with Fourier transform infrared spectroscopy (FTIR), X‐ray photoelectron spectroscopy (XPS), contact angle measurement, and scanning electron microscope (SEM). The results showed that both the content of O‐containing functional groups and surface roughness of modified fibers increased. The polar groups on the modified fiber surface decreased the contact angles with water and ethylene glycol, as evidenced by contact angle measurement. The tensile test results showed the strength and the elongation at break of UHMWPE fibers decreased but the modulus increased after chromic acid modification. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthesis and micellization of PSt‐PNIPAM‐PDMAEMA hetero‐arm star polymer with double thermo‐responsibility

A hetero‐arm star polymer, polystyrene‐poly(N‐isopropylacrylamide)‐ poly(2‐(dimethylamino)ethylmethacrylate) (PSt‐PNIPAM‐PDMAEMA), was synthesized by “clicking” the alkyne group at the junction of PSt‐b‐PNIPAM diblock copolymer onto the azide end‐group of PDMAEMA homopolymer via 1,3‐dipolar cycloaddition. The resultant polymer was characterized by gel permeation chromatography, proton nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy. PSt‐PNIPAM‐PDMAEMA micelles with PSt block as core and PNIPAM and PDMAEMA blocks as shell were formed when adding the copolymer solution in THF into 10 folds of water. Lower critical solution temperature (LCST) of PNIPAM and PDMAEMA homopolymer is 32 °C for PNIPAM and 40 to 50 °C for PDMAEMA, respectively. Upon continuous heating through their LCSTs, PSt‐PNIPAM‐PDMAEMA core‐shell micelles exhibited two‐stage thermally induced collapse. The first‐stage collapse, from 20 to 34 °C, is ascribed to the shrinkage of PNIPAM chains; and the second‐stage collapse, from 38 to 50 °C, is due to the shrinkage of PDMAEMA chains. Dynamic light scattering was used to confirm the double phase transitions. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 786–796, 2009     

Hemocompatibility and ultrafiltration performance of PAN membranes surface‐modified by hyperbranched polyesters

Maleic anhydride was grafted onto a polyacrylonitrile (PAN) membrane surface via ultraviolet irradiation. Then, hyperbranched polyester, with varying numbers of hydroxyl end‐groups (H20, H30, and H40), was grafted onto the PAN membrane surface by the reaction of hydroxyl groups with anhydride groups of maleic anhydride. The modified membranes were characterized by scanning electron microscopy, static water contact angle, and attenuated total reflectance‐Fourier transform infrared spectroscopy measurements. The modified membranes showed a higher water flux and better antifouling properties than pristine PAN membranes, and their hydrophilicity was significantly improved. Membrane biocompatibility was characterized by platelet adhesion, and the results indicate that the modified membranes exhibited good biocompatibility. Copyright © 2016 John Wiley & Sons, Ltd.     

Preparation and characterization of temperature‐ and pH‐responsive diblock copolymers and their silica‐coated nanoparticles

Multiresponsive amphiphilic poly(N,N‐dimethylaminoethyl methacrylate)‐b‐poly(N‐isopropylacrylamide) (PDMAEMA‐b‐PNIPAM) was successfully synthesized by reversible addition‐fragmentation chain transfer polymerization. Poly(N,N‐dimethylaminoethyl methacrylate)‐b‐poly(N‐isopropylacrylamide) has thermal and pH stimuli responsiveness. Their lower critical solution temperature and hydrodynamic radius can be adjusted by varying the copolymer composition, block length, solution pH, and temperature. In addition, a convenient method has been established to prepare cross‐linked silica‐coated nanoparticles with PDMAEMA‐b‐PNIPAM micelles as a template, resulting in good organic/inorganic hybrid nanoparticles defined as 175 to 220 nm. The structure and morphology were characterized by proton nuclear magnetic resonance (₁HNMR), Fourier‐transform infrared spectroscopy (FT‐IR), transmission electron microscopy (TEM), and transmission electron microscopy‐energy dispersive X‐ray spectroscopy (TEM‐EDS).     

Hydrophilic Modification of Microporous Polysulfone Membrane via Surface‐Initiated Atom Transfer Radical Polymerization and Hydrolysis of Poly(glycidylmethacrylate)

Poly(glycidylmethacrylate) (PGMA) brushes were grafted from chloromethylated polysulfone (CMPSF) membrane surface by surface‐initiated atom transfer radical polymerization (SI‐ATRP), and the grafting was followed by hydrolysis of epoxy groups in the grafting chains to improve the membrane's hydrophilic property. Fourier transform infrared spectroscopy (FT‐IR) and X‐ray photoelectron spectroscopy (XPS) measurements confirmed the successful grafting and hydrolysis of PGMA. The grafting degree of the monomer, measured by periodic acid titration and gravimetric analysis, increased linearly with the polymerization time, while the static water contact angle of the membrane grafted with PGMA or hydrolyzed PGMA linearly decreased. In comparison with the PGMA‐grafted membranes, the hydrolyzed PGMA‐grafted membranes possess stronger hydrophilicity as indicated by their contact angle and hydration capacity, and as a result they have an improved antifouling property. Therefore, the control of the hydrophilicity of PSF membrane could be realized through adjusting the polymerization time and transforming the functional groups in the grafting chain.     

Porous poly(vinylidene fluoride) membrane modified with hyperbranched poly(amine‐ester)

Poly(vinylidene fluoride) (PVDF) membranes were hydrophilic modified with hydroxyl group terminated hyperbranched poly(amine‐ester) (HPAE). Fourier transform infrared spectroscopy (FT‐IR) was used to study the chemical change of PVDF membranes. X‐ray photoelectron spectroscopy (XPS) indicated that some HPAE molecules were retained in PVDF membrane through polymer chain coiling. The presence of HPAE would improve the hydrophilicity of PVDF membrane. Scanning electron microscopy (SEM) was employed to characterize the morphology of different membranes. The thermodynamic stability for PVDF/DMAc/HPAE/Water system was characterized by the determination of the gelation values. Precipitation kinetics for PVDF/DMAc/HPAE/Water system was studied by precipitation time measurement. The water contact angle indicated that the hydrophilicity and the biocompatibility corresponding to protein adsorption of PVDF membrane were improved significantly after blending with hydrophilic HPAE molecules. Copyright © 2011 John Wiley & Sons, Ltd.     

Novel superhydrophobic silica/poly(siloxane‐fluoroacrylate) hybrid nanoparticles prepared via two‐step surface‐initiated ATRP: Synthesis,characterization, and wettability

Poly(siloxane‐fluoroacrylate)‐grafted silica hybrid nanoparticles were prepared by surface‐initiated atom transfer radical polymerization (SI‐ATRP). The silica nanoparticles with α‐bromo‐ester initiator group for copper‐mediated ATRP were prepared by the self‐assembled monolayers of (3‐aminopropyl)triethoxysilane and 2‐bromoisobutyrate bromide. Well‐defined diblock copolymer brushes consisting of poly(methacryloxypropyltrimethoxysilane) and poly(2,2,3,3,4,4,4‐heptafluorobutyl methacrylate) blocks were obtained by using initial homopolymer brushes as the macroinitiators for the SI‐ATRP of the second monomer. Chemical compositions and structures of the nanoparticles were characterized by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, and gel permeation chromatography. Surface properties and morphology of the nanoparticles were investigated with X‐ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscopy, and water contact angle measurement. It is revealed that the surfaces of the nanocomposites are rough at the microscale and nanoscale. The formation reason of the superhydrophobic surfaces was also discussed in this work. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Comparison of copolymer emulsions of fluorine and siloxane‐containing acrylates with core–shell structure for water‐repellent cotton fabrics coatings

This paper described the synthesis of copolymer emulsions of fluorine and siloxane‐containing acrylates for water‐repellent cotton fabrics coatings. Chemical composition, morphology structure, and properties of the latex copolymers were investigated by Fourier transform infrared (FTIR), dynamic light scattering (DLS), gel permeation chromatography (GPC), and transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). Effects of water‐repellent functional monomers (R_f) on surface morphology, water contact angle, and water‐repellent properties of the coated fabric surface were also studied. The results indicated that R_f greatly influenced molecular mass distribution of the latex copolymers, the molecular aggregation states and orientation of R_f on the coated fabric surface, and water‐repellency of coated cotton fabrics. Copyright © 2014 John Wiley & Sons, Ltd.     

Nanostructured polybenzoxazine thermosets via reaction‐induced microphase separation

A multiblock copolymer consisting of main‐chain polybenzoxazine and poly(propylene oxide) blocks was synthesized via Mannich polycondensation among 4,4′‐dihydroxyldiphenylisopropane, 4,4′‐diaminodiphenylmethane, amino‐terminated poly(propylene oxide), and paraformaldehyde, which was evidenced by Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, and gel permeation chromatography. The multiblock copolymer was incorporated into polybenzoxazine to access the nanostructured polybenzoxazine thermosets. The morphology of the thermosets was investigated by means of atomic force microscopy and small angle X‐ray scattering. It was judged that the formation of the nanostructures in the thermosetting composites follows the mechanism of reaction‐induced microphase separation. Owing to the big difference in thermal stability between polybenzoxazine thermosets and poly(propylene oxide), the nanostructured thermosets were subjected to the pyrolysis at moderate elevated temperatures to remove poly(propylene oxide) microdomains, to access the nanoporous polybenzoxazine thermosets. The nanoporosity of the resulting polybenzoxazine thermosets was investigated by means of Fourier transform infrared spectroscopy and field‐emission scanning electronic microscopy. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1148–1159, 2010     

Dual‐responsive copolymer poly(2,2,3,4,4,4‐hexafluorobutyl methacrylate)‐block‐poly[2‐(dimethylamino)ethyl methacrylate] synthesized via photoATRP for surface with tunable wettability

In this work, a series of block copolymers of poly(2,2,3,4,4,4‐hexafluorobutyl methacrylate)‐block‐poly[2‐(dimethylamino)ethyl methacrylate] (PHFBMA‐b‐PDMAEMA) were synthesized via photo‐induced atom transfer radical polymerization (photoATRP) at room temperature. By the introduction of PDMAEMA segment, the hydrophilicity of the silicon wafer surface spin‐coated with PHFBMA homopolymer was improved. Furthermore, the study of tunable surface wettability showed that the surface wettability was pH‐dependent and thermal‐independent at pH 2 and 10. The as‐fabricated surface coated with PHFBMA₁₁₀‐b‐PDMAEMA₁₈₇ showed switchable water contact angle from 85.4° at pH > 4 to 55.0° at pH 2 due to the protonation and deprotonation of tertiary amine groups of PDMAEMA. However, because of the ascendancy of protonated PDMAEMA at pH 2 and the decreased LCST at pH 10, the wettability of the as‐prepared surfaces was thermal‐insensitive. Finally, surface morphology and composition investigation showed that the property of wettability‐controllable surface was not only influenced by surface composition, but also affected by chain conformation. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3868–3877     

Preparation of bow tie–type methacrylated poly(caprolactone‐co‐lactic acid) scaffolds: effect of collagen modification on cell growth

A branched methacrylated poly(caprolactone‐co‐lactic acid) and methacrylated poly(tetramethylene ether glycol) (PTMG‐IEM) resins were synthesized. ¹H‐NMR spectroscopy, attenuated total reflectance Fourier transform infrared spectroscopy (ATR‐FTIR) spectroscopy, and gel permeation chromatography confirmed the chemical structures of copolymers. The photoinitiated polymerization of formulation composed of various amounts of methacrylated poly(caprolactone‐co‐lactic acid), PTMG‐IEM, poly(ethylene glycol) diacrylate, water, and photoinitiator were performed. The curing reactions were followed by photo‐DSC (Differential scanning calorimetry). Gel fraction was calculated from the insoluble part and found as ≥93%. Swelling and contact angles were measured, and all increased with the increasing amount of PTMG‐IEM in network formulations. In vitro degradation studies were performed at 37 °C in phosphate‐buffered saline (pH 7.4). Collagen‐modified polymers were also prepared and introduced as a bioactive moiety to modify the polymer to enhance cell affinity. To compare the cell adhesion affinity to the polymer with and without collagen, cell growth experiments were performed. The results showed that collagen improves the cell adhesion onto the polymer surface. With the increasing amount of collagen, cell viability increases 86% (ECV304, p < 0.05) and 83% (3 T3, p < 0.05). Copyright © 2011 John Wiley & Sons, Ltd.     

Modification of polyethersulfone membranes using terpolymers engineered and integrated antifouling and anticoagulant properties

In this study, random terpolymers of methoxy poly(ethylene glycol)‐poly(sodium styrene sulfonate‐co‐methyl methacrylate) (MPEG‐P(SSNa‐co‐MMA)) integrated with antifouling and anticoagulant properties were synthesized by atom transfer radical polymerization (ATRP) for the first time and confirmed by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and gel permeation chromatography (GPC). The terpolymers with desired antifouling and anticoagulant segments were then used as amphiphilic additives to modify polyethersulfone membranes by an engineering blended approach. Water contact angle (WCA) results indicated that the surface hydrophilicity of the modified membranes enhanced. Protein ultrafiltration experiments showed that the antifouling ability of the modified membranes increased. In addition, the modified membranes showed decreased protein adsorption (bovine serum albumin, BSA), suppressed platelet adhesion, and prolonged activated partial thromboplastin time (APTT). Copyright © 2013 John Wiley & Sons, Ltd.     

Preparation of dual stimuli‐responsive PET track‐etched membrane by grafting copolymer using ATRP

A dual stimuli‐responsive (pH and thermo) polyethylene terephthalate (PET) track‐etched membrane has been prepared using atom transfer radical polymerization (ATRP). First, ATRP initiator 2‐bromoisobutyryl bromide was anchored onto the membrane surface. Then, 2‐hydroxyethyl‐methacrylate (HEMA) and N‐isopropylacrylamide (NIPAAm) were grafted onto the membrane surface using ATRP. X‐ray photoelectron spectroscopy, ATR‐Fourier transform infrared spectroscopy, scanning electron microscopy and thermogravimetric analysis were used to characterize the membrane structure and thermal properties; water flux measurement was used to investigate the double stimuli‐responsive property of the obtained membrane. The results indicate that the PHEMA and PNIPAAm binary grafted PET track‐etched membrane has double environmental responsiveness. This method provides a potential modification method for preparing functional membranes. Copyright © 2012 John Wiley & Sons, Ltd.     

Synthesis of a polyurea from a glucose‐ or mannose‐containing N‐alkyl urea peptoid oligomer

N‐alkyl urea peptoid oligomers containing glucose or mannose have been synthesized and characterized. The oligomers were subsequently polymerized using a step‐growth polymerization with hexamethylene diisocyanate. Equal moles of both monomers were used to guarantee high‐molecular weight polymers. The polymers were characterized by gel permeation chromatography, nuclear magnetic resonance, and Fourier‐transform infrared spectroscopy, and contact angle measurements of solvent cast thin films. Sulfation of the final polymers was achieved using a SO₃/pyridine complex in pyridine to afford the heparin biomimetics. The average degree of sulfation was calculated to be 3.5 sulfates per saccharide as measured by elemental analysis. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 5230–5238     

Preparation and characterization of a new class of poly(ether‐block‐amide)s via solvent free reactive processing

Novel poly(ether‐co‐amide) block copolymers (PEA) with polyamide‐6 as hard segments and different polyether (polyoxytetramethylene glycol [PTMG]/polyethylene glycol [PEG]) as soft segments were prepared via reactive processing. The chemical structure, crystalline properties, mechanical properties, water resistance, and thermal stability of as‐prepared PEAs were extensively studied by Fourier transform infrared spectroscopy, X‐ray diffraction, differential scanning calorimetry, dynamic mechanical analysis, tensile testing, water contact angle, water absorption, and thermal gravity analysis. Fourier transform infrared spectroscopy confirmed the chemical structure and composition of PEAs. The X‐ray diffraction and differential scanning calorimetry showed that PEAs consist of obvious crystalline polyamide‐6 hard segments and that the crystalline structure of PEG will be significantly changed with the addition of PTMG. Dynamic mechanical analysis and tensile testing showed that the obtained PEAs exhibit classical elastomeric rubber plateau and tensile behavior. Meanwhile, the introduction of PTMG will improve the mechanical properties of PEAs. PEA with PEG as soft segments exhibited extremely surface hydrophilicity and high water absorption of 127%; the increasing of PTMG content in soft segments will reduce the surface hydrophilicity and improve the water resistance. In addition, the obtained PEAs exhibited good thermal stability, which will meet requirement of multiple processing.     

RAFT‐mediated synthesis and temperature‐induced responsive properties of poly(2‐(2‐methoxyethoxy)ethyl methacrylate) brushes

Well‐defined, high‐density poly(2‐(2‐methoxyethoxy)ethyl methacrylate) [poly(MEO₂MA)] brushes were fabricated through a reliable strategy by the combination of self‐assembly of a monolayer of 3‐aminopropyltrimethoxy silane on silicon surface to immobilize 4‐cyano‐4‐(dodecylsulfanylthiocarbonyl)sulfanyl pentanoic acid chain transfer agent and reversible addition‐fragmentation chain transfer‐mediated polymerization of MEO₂MA. The whole fabrication process of the poly(MEO₂MA) brushes was followed by water contact angle, grazing angle‐Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, and atomic force microscopy. Characterization of the poly(MEO₂MA) brushes, such as molecular weight and thickness determination, were measured by gel permeation chromatography and ellipsometry, and the grafting density was estimated. The temperature‐responsive property of the poly(MEO₂MA) brushes was further investigated and the result verified the brush‐to‐mushroom phase transition of the poly(MEO₂MA) chains from low to high temperature. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

超支化聚酯低压纳滤膜的制备与表征

通过超支化聚酯(HPE)末端的羟基与戊二醛(GA)之间的羟醛缩合反应,采用简单的浸涂-交联方法,制备了一种以聚砜超滤膜为支撑层,交联的HPE为活性分离层的复合纳滤膜.采用衰减全反射红外光谱(ATR-FTIR)、接触角测定、扫描电子显微镜(SEM)对纳滤膜的表面化学组成、亲水性和膜形貌进行了表征.考察了HPE溶液浓度、GA溶液浓度对膜分离和渗透性能的影响,优化的HPE和GA溶液浓度分别为9.8 g/L和7.4 g/L,此时在0.4 MPa下膜的水通量达69.6 L/(m2.h),对Na2SO4脱除率为93.2%,表现出低操作压力、高通量、高脱盐率的优异性能.纳滤膜对无机盐的截留顺序为Na2SO4>NaCl>MgSO4>MgCl2,呈现明显的荷负电特征.     

Remarkable reduction of irreversible fouling and improvement of the permeation properties of poly(ether sulfone) ultrafiltration membranes by blending with pluronic F127

Hydrophilic modification of ultrafiltration membranes was achieved through blending of Pluronic F127 with poly(ether sulfone) (PES). The chemical composition and morphology changes of the membrane surface were confirmed by water contact angle, X-ray photoelectron spectroscopy, scanning electron microscopy, and protein adsorption measurements. The decreased static water contact angle with an increase in the Pluronic F127 content indicated an increase of surface hydrophilicity. XPS analysis revealed enrichment of PEO segments of Pluronic F127 at the membrane surface. The apparent protein adsorption amount decreased significantly from 56.2 to 0 microg/cm(2) when the Pluronic F127 content varied from 0% to 10.5%, which indicated that the blend membrane had an excellent ability to resist protein adsorption. The ultrafiltration experiments revealed that the Pluronic F127 content had little influence on the protein rejection ratio and pure water flux. Most importantly, at a high Pluronic F127 content membrane fouling, especially irreversible fouling, has been remarkably reduced. The flux recoveries of blend membranes reached as high as 90% after periodic cleaning in three cycles.     

Photochemical modification of diamond films: introduction of perfluorooctyl functional groups on their surface

Photolysis of perfluoroazooctane with diamond films led the chemical modification of the surface to introduce perfluorooctyl functional groups, confirmed by means of Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and time-of-flight secondary ion mass spectrometry measurements. Diamond films modified with fluorine moieties showed improved frictional property and reduction of surface energy, as evaluated by contact angle to water, compared with a pristine diamond film. The contact angle and friction coefficient of chemically modified diamond film are 118 degrees and 0.1, respectively. The results of the value of the contact angle depending on irradiation times are consistent with those of the F/C ratio of fluorinated diamond films by monitoring with XPS.     

Modification of polyethylene with Pluronics F127 for improvement of blood compatibility

In order to improve blood compatibility of polyethylene (PE) film, the Pluronics F127 additives in the PE film were then crosslinked to be stably entrapped in the PE matrix. The crosslinking was done by free radicals produced from the decomposition of dicumyl peroxide (DCP) in the film through heating (120 °C). Surface properties of the Pluronics F127 additive-containing PE films were investigated by Fourier transform infrared spectroscopy (FTIR), electron spectroscopy for chemical analysis (ESCA) and water contact angle (WCA) measurements. The blood compatibility of the Pluronics F127 additive-containing films was evaluated by platelet-rich plasma and blood-cell adhesion tests, respectively. And the results were observed by scanning electron microscopy. The blood compatibility of the prepared Pluronics F127 additive-containing film is better than that of blank PE film. These results suggest that the blood compatibility of Pluronics F127 additive-containing films make them suitable biomaterials for some applications.