Synthesis of well‐defined responsive membranes with fixable solvent responsiveness

A versatile method is described to synthesize a new family of solvent‐responsive membranes whose response states can be not only tunable but also fixable via ultraviolet (UV) irradiation induced crosslinking. The atom transfer radical polymerization (ATRP) initiator 2‐bromoisobutyryl bromide was first immobilized on the poly(ethylene terephthalate) (PET) track‐etched membrane followed by room‐temperature ATRP grafting of poly(2‐hydroxyethyl methacrylate) (PHEMA) and poly(2‐hydroxyethyl methacrylate‐co‐2‐(dimethylamino)ethyl methacrylate) (P(HEMA‐co‐DMAEMA)) respectively. The hydroxyl groups of PHEMA were further reacted with cinnamoyl chloride (a photosensitive monomer) to obtain photo‐crosslinkable PET‐g‐PHEMA/CA membrane and PET‐g‐P(HEMA/CA‐co‐DMAEMA) membrane. The length of grafted polymer chains was controllable by varying the polymerization time. X‐ray photoelectron spectroscopy, Fourier transform infrared spectroscopy in attenuated total reflection and thermogravimetric analysis were employed to characterize the resulting membranes. The various membrane surface morphologies resulting from different states of the grafted chains in water and dimethylformamide were characterized by scanning electron microscopy. It was demonstrated that the grafted P(HEMA/CA‐co‐DMAEMA) chains had more pronounced solvent responsivity than the grafted PHEMA/CA chains. The surface morphologies of the grafted membranes could be adjusted using different solvents and fixed by UV irradiation crosslinking. © 2014 Society of Chemical Industry     

Surface‐graft hyperbranched polymer via self‐condensing atom transfer radical polymerization from zinc oxide nanoparticles

We present the synthesis of hyperbranched polymer grafted zinc oxide (ZnO) hybrid nanoparticles by self‐condensing vinyl polymerization (SCVP) via surface‐initiated atom transfer radical polymerizations (SI‐ATRP) from ZnO surfaces. ATRP initiators were covalently linked to the surfaces of ZnO particles, followed by SCVP of an initiator‐monomer (“inimer”) which has both a polymerizable group and an initiating group in the same molecule. Well‐defined polymer chains were grown from the surfaces to yield hybrid nanoparticles comprised of ZnO cores and hyperbranched polymer shells having multifunctional chlorobenzyl functional end groups. The percentage of grafting (PG%) achieved 429% in 6 h, calculated from the elemental analysis results. The hybrid nanoparticles were also characterized using Fourier transform infrared spectroscopy, UV–vis absorption spectroscopy, thermogravimetric analysis, X‐ray photoelectron spectroscopy, and transmission electron microscopy. POLYM. ENG. SCI., 47:1296–1301, 2007. © 2007 Society of Plastics Engineers     

Surface‐initiated atom‐transfer radical polymerization (SI‐ATRP) of methyl methacrylate from carbon fibre

Surface modification of carbon fibre (CF) by well‐defined polymer brushes was carried out using the ‘grafting from’ method. Poly(methyl methacrylate)‐grafted carbon fibre (CF‐PMMA) was successfully prepared by surface‐initiated atom‐transfer radical polymerization (SI‐ATRP) of methyl methacrylate (MMA) from the macro‐initiator, bromo‐acetic ester‐modified carbon fibre (CF‐BrA), with the complex of 1,10‐phenanthroline and Cu(I)Br as catalyst. The percentage of grafting (PG%) and the conversion of monomer (C%) increased linearly with increasing of polymerization time, and reached 24.0 % and 6.7 %, respectively, after a polymerization time of 6 h, calculated from the elemental analyses (EA). The structural and surface morphological analyses were conducted with Fourier‐transform infrared (FTIR) spectroscopy, X‐ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Copyright © 2005 Society of Chemical Industry     

Preparation and characterization of grafting polyacrylamide from PET films by SI‐ATRP via water‐borne system

The grafted homopolymer and comb‐shaped copolymer of polyacrylamide were prepared by combining the self‐assembly of initiator and water‐borne surface‐initiated atom transfer radical polymerization (SI‐ATRP). The structures, composition, properties, and surface morphology of the modified PET films were characterized by FTIR/ATR, X‐ray photoelectron spectroscopy (XPS), contact angle measurement, and scanning electronic microscopy (SEM). The results show that the surface of PET films was covered by equable grafting polymer layer after grafted polyacrylamide (PAM). The amount of grafting polymer increased linearly with the polymerization time added. The GPC date show that the polymerization in the water‐borne medium at lower temperature (50°C) shows better “living” and control. After modified by comb‐shaped copolymer brushes, the modified PET film was completely covered with the second polymer layer (PAM) and water contact angle decreased to 13.6°. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Surface initiated ATRP of acrylic acid on dopamine‐functionalized AAO membranes

A facile method for surface‐initiated atom transfer radical polymerization (ATRP) on the anodic aluminum oxide (AAO) membranes has been developed. The AAO membrane was firstly functionalized by poly(dopamine), the bromoalkyl initiator was then immobilized on the poly(dopamine) functionalized AAO membrane surface in a two‐step solid‐phase reaction, followed by ATRP of acrylic acid in a aqueous solution. The poly(acrylic acid) (PAAc)‐grafted AAO membranes were characterized by X‐ray photoelectron spectroscopy, fourier transform infrared spectroscopy and scanning electron microscopy. The XPS and FTIR results indicated that PAAc was successfully grafted on the AAO membrane surface. The degree of grafting increases linearly with the increase of monomer concentration, and it reaches a plateau when the reaction time up to 4 h. The results indicate that the thickness of the grafted polymer inside the isocylindrical pores of AAO membranes could be well controlled by changing the reaction time and monomer concentration. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis of pH‐responsive polyethylene terephthalate track‐etched membranes by grafting hydroxyethyl‐methacrylate using atom‐transfer radical polymerization method

pH‐responsive polyethylene terephthalate (PET) track‐etched membranes were synthesized by grafting 2‐hydroxyethyl‐methacrylate (HEMA) on the surface of the membrane via atom transfer radical polymerization. The controllability of grafting polymerization of HEMA on membrane surface is systematically investigated. The pH‐responsive characteristics of PET‐g‐poly(2‐hydroxyethyl‐methacrylate) (PHEMA) gating membranes with different grafted PHEMA chain lengths are measured by tracking the permeation of water solution with different pH values. The results show that the grafting polymerization is controllable, and the permeation of grafted membranes is affected by the grafted PHEMA chain lengths on the surface of membrane. The results also demonstrate that the grafted PET membranes exhibit reversible pH‐response permeation to environmental pH values. Desired pH‐responsive membranes are obtained by controlling the grafted PHEMA chain lengths via atom transfer radical polymerization method. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40912.     

Synthesis and characterization of poly(γ‐methacryloxypropyltrimethoxysilane)‐grafted silica hybrid nanoparticles prepared by surface‐initiated atom transfer radical polymerization

Poly(γ‐methacryloxypropyltrimethoxysilane) (PMPTS)‐grafted silica hybrid nanoparticles were prepared by surface‐initiated atom transfer radical polymerization (SI‐ATRP). The resulting PMPTS‐grafted silica hybrid nanoparticles were characterized using Fourier transform infrared spectroscopy (FTIRS), nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), X‐ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), scanning electron microscopy (SEM), static water contact angle (WCA) measurement, and thermogravimetric analysis (TGA). Combined FTIRS, NMR, XPS, SEM, and TGA studies confirmed that these hybrid nanoparticles were successfully prepared by surface‐initiated ATRP. SEM and AFM studies revealed that the surfaces of the nanoparticles were rough at the nanoscale. In addition, the results of the static WCA measurements showed that the nanoparticles are of low surface energy and their surface energy reaches as low as 6.10 mN m^?1. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Surface‐initiated atom transfer radical polymerization (ATRP) of styrene from silica nanoparticles under UV irradiation

Diethyldithiocarbamyl‐modified silica nanoparticles were prepared and used as macroinitiator for the surface‐initiated atom transfer radical polymerization (SI‐ATRP) of styrene under UV irradiation. Well‐defined polymer chains were grown from the nanoparticle surfaces to yield particles composed of a silica core and a well‐defined, densely grafted outer PS layer with a mass ratio of styrene to silica, or percentage grafting, of 276.3% after an UV irradiation time of 5 h. Copyright © 2004 Society of Chemical Industry     

Novel comb‐structured‐polymer‐grafted carbon black by surface‐initiated atom transfer radical polymerization and ring‐opening polymerization

Novel comb‐structured‐polymer‐grafted carbon black (CB) was synthesized with a combination of surface‐initiated atom transfer radical polymerization and ring‐opening polymerization. First, poly(2‐hydroxyethyl methacrylate) (PHEMA) was grafted onto the CB surface by surface‐initiated atom transfer radical polymerization. The prepared CB‐g‐PHEMA contained 35.6–71.8% PHEMA, with the percentage depending on the molar ratio of the reagents and the reaction temperature. Then, with PHEMA in CB‐g‐PHEMA as the macroinitiator, poly(?‐caprolactone) (PCL) was grown from the CB‐g‐PHEMA surface by ring‐opening polymerization in the presence of stannous octoate. CB‐g‐PHEMA and CB‐g‐(PHEMA‐g‐PCL) were characterized with Fourier transform infrared, ¹H‐NMR, thermogravimetric analysis, dynamic light scattering, and transmission electron microscopy. The resultant grafted CB had a shell of PHEMA‐g‐PCL. On the whole, the CB nanoparticles were oriented in dendritic lamellae formed by these shells. This hopefully will result in applications in gas sensor materials and nanoparticle patterns. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis of PLLA‐PEOMA comb‐block‐comb type molecular brushes based on AGET ATRP and ring‐opening polymerization

BACKGROUND: Molecular brushes are types of macromolecules with densely grafted side chains on a linear backbone. The synthesis of macromolecular brushes has stimulated much interest due to their great potential in applications in various fields. Poly(L ‐lactide)–poly(ethylene glycol) methyl ether methacrylate (PLLA‐PEOMA) comb‐block‐comb molecular brushes with controlled molecular weights and narrow molecular weight distributions were successfully synthesized based on a combination of activator generated by electron transfer (AGET) atom transfer radical polymerization (ATRP) and ring‐opening polymerization. The synthetic route is a combination of the ‘grafting through’ method for AGET ATRP of the PEOMA comb block and the ‘grafting from’ method for the synthesis of the PLLA comb block. Poly(2‐hydroxyethyl methacrylate) (PHEMA) was synthesized by ATRP, and PLLA side chains and PEOMA side chains were grown from the backbones and the terminal sites of PHEMA, respectively. RESULTS: The number‐average degrees of polymerization of PLLA chains and poly[poly(ethylene glycol) methyl ether methacrylate] (PPEOMA) comb blocks were determined using ¹H NMR spectroscopy, and the apparent molecular weights and molecular weight distributions of the brush molecules were measured using gel permeation chromatography. The crystallization of the components in the comb‐block‐comb copolymers was also investigated. The crystallization of PLLA side chains is influenced by PLLA chain length and the content of PPEOMA in the molecular brushes. The comb‐block‐comb copolymer composed of hydrophobic PLLA and hydrophilic PEOMA can self‐assemble into a micellar structure in aqueous solution. CONCLUSION: A combination of AGET ATRP and ring‐opening polymerization is an efficient method to prepare well‐defined comb‐block‐comb molecular brushes. The physical properties of the molecular brushes are closely related to their structures. Copyright © 2009 Society of Chemical Industry     

Grafting of titanium dioxide microspheres with a temperature‐responsive polymer via surface‐initiated atom transfer radical polymerization without the use of silane coupling agents

Titania microspheres with narrow size distribution and diameters of about 1 µm were prepared and subsequently functionalized using surface‐initiated atom transfer radical polymerization (ATRP) of N‐isopropylacrylamide. The ATRP initiator was immobilized on the particle surface via acylation of surface hydroxyl groups with α‐bromoisobutyryl bromide. Subsequently, an established ATRP reaction system was used for the preparation of titania surface‐grafted poly(N‐isopropylacrylamide) (PNiPAAm). Characterization was performed with electron microscopies, X‐ray diffraction, infrared spectroscopy and dynamic light scattering. It was found that the particle size in aqueous dispersions changed reversibly with temperature as expected for a shell of PNiPAAm, a polymer with a lower critical solution temperature at 32 °C. This confirmed the successful preparation of functional, stimuli‐responsive TiO₂ microparticles via a straightforward controlled surface‐initiated polymerization method.     

Modification of polysulfone membranes via surface‐initiated atom transfer radical polymerization and their antifouling properties

Surface‐initiated atom transfer radical polymerization (ATRP) was used to tailor the functionality of polysulfone (PSF) membranes. A simple one‐step method for the chloromethylation of PSF under mild conditions was used to introduce surface benzyl chloride groups as active ATRP initiators. Covalently tethered hydrophilic polymer brushes of poly(ethylene glycol)monomethacrylate and 2‐hydroxyethyl methacrylate and their block copolymer brushes were prepared via surface‐initiated ATRP from the chloromethylated PSF surfaces. A kinetic study revealed that the chain growth from the membranes was consistent with a controlled process. X‐ray photoelectron spectroscopy was used to characterize the surface‐modified membrane after each modification stage. Protein adsorption experiments revealed substantial antifouling properties of the grafted PSF membranes in comparison with the those of the pristine PSF surface. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Surface‐initiated nitroxide‐mediated radical polymerization of 4‐vinylpyridine on magnetite nanoparticles

Poly (4‐vinylpyridine) (P4VP) brushes had been prepared by the surface‐initiated nitroxide‐mediated radical polymerization of 4‐VP on the surface of 3‐methacryloxyproyltrimethoxysilane (3‐MPS)‐modified magnetite nanoparticles with an average diameter of 30 nm. The grafting polymerization was accomplished by nitroxide‐mediated polymerization of 4‐VP, using 4‐hydroxyl‐2,2,6,6‐tetramethyl‐1‐piperidinyl‐oxy (HTEMPO·) free radical as capping agent and benzoyl peroxide (BPO) as initiator. X‐ray photoelectron spectra (XPS) measurement demonstrated that the alkoxysilane initiator layer had formed on the magnetite surface. Gel permeation chromatograph analysis and XPS measurement suggested that the amount of grafted P4VP increases with increasing grafting time. The amount of P4VP grafted on the surface could be determined to be 0.09 chains/nm² by thermogravimetric analysis. The P4VP‐grafted magnetite particles exhibited the characteristics of multidomain system, distinct from the single domain attributes of the pure magnetite particles. Atomic force‐microscopy analysis revealed the diameter of the grafted P4VP magnetic latex particles is in the range of 120 nm to 150 nm. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Surface‐initiated atom transfer radical polymerization of regenerated cellulose membranes with thermo‐responsive properties

Using atom transfer radical polymerization (ATRP), thermo‐responsive regenerated cellulose membranes were synthesized. Regenerated cellulose membranes were firstly modified by reacting the hydroxyl groups on the surface with 2‐bromoisobutyryl bromide, followed by grafting with poly(N‐isopropylacrylamide). The membranes had obvious thermally modulated permeability properties. Analysis was carried out by means of X‐ray photoelectron spectroscopy, attenuated total reflection Fourier transform infrared spectroscopy, scanning electron microscopy and thermogravimetric analysis. The results showed that N‐isopropylacrylamide had been grafted successfully on the surface of the regenerated cellulose membranes. The thermally modulated permeability properties of the grafted membranes were studied using water flux measurements. It was found that the thermally modulated permeability properties of a cellulose surface can be tailored by the use of the ATRP method. Copyright © 2010 Society of Chemical Industry     

Controlled grafting of polymer brushes on poly(vinylidene fluoride) films by surface‐initiated atom transfer radical polymerization

Controlled grafting of well‐defined polymer brushes on the poly(vinylidene fluoride) (PVDF) films was carried out by the surface‐initiated atom transfer radical polymerization (ATRP). Surface‐initiators were immobilized on the PVDF films by surface hydroxylation and esterification of the hydroxyl groups covalently linked to the surface with 2‐bromoisobutyrate bromide. Homopolymer brushes of methyl methacrylate (MMA) and poly(ethylene glycol) monomethacrylate (PEGMA) were prepared by ATRP from the α‐bromoester‐functionalized PVDF surface. The chemical composition of the graft‐functionalized PVDF surfaces was characterized by X‐ray photoelectron spectroscopy (XPS) and attenuated total reflectance (ATR)–FTIR spectroscopy. Kinetics study revealed a linear increase in the graft concentration of PMMA and PEGMA with the reaction time, indicating that the chain growth from the surface was consistent with a “controlled” or “living” process. The “living” chain ends were used as the macroinitiator for the synthesis of diblock copolymer brushes. Water contact angles on PVDF films were reduced by surface grafting of PEGMA and MMA. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3704–3712, 2006     

Synthesis of a chiral stationary phase with poly[styrene‐b‐cellulose 2,3‐bis(3,5‐dimethylphenylcarbamate)] by surface‐initiated atom transfer radical polymerization and its chiral resolution efficiency

A chiral stationary phase (CSP) with poly[styrene‐b‐cellulose 2,3‐bis(3,5‐dimethylphenylcarbamate)] was synthesized by the surface‐initiated atom transfer radical polymerization (SI‐ATRP) of cellulose 2,3‐bis(3,5‐dimethylphenylcarbamate)‐6‐acrylate after the SI‐ATRP of styrene on the surface of silicon dioxide supports in pyridine. The successful preparation of the CSP with poly[styrene‐b‐cellulose 2,3‐bis(3,5‐dimethylphenylcarbamate)] was confirmed via Fourier transform infrared spectroscopy, field emission scanning electron microscopy, X‐ray photoelectron spectroscopy, elemental analysis, and thermal analysis. The applicability for the chiral resolution of the CSP with poly[styrene‐b‐cellulose 2,3‐bis(3,5‐diphenylcarbamate)] was evaluated with high‐performance liquid chromatography with 10 racemates under various mobile phases of hexane/alcohol, hexane/tetrahydrofuran (THF), and hexane/chloroform. The results show that the CSP with poly[styrene‐b‐cellulose 2,3‐bis(3,5‐diphenylcarbamate)] could be used in THF and chloroform as eluents. The chiral resolutions of the commercial Chiracel OD, the CSP with cellulose 2,3‐bis(3,5‐dimethylphenylcarabmate), and the CSP with poly[styrene‐b‐cellulose 2,3‐bis(3,5‐dimethylphenylcarbamate)] prepared by SI‐ATRP were examined. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis of chiral stationary phase via surface‐initiated atom transfer radical polymerization of vinylated cellulose 3,5‐dimethylphenylcarbamate

A polysaccharide‐immobilized chiral stationary phase (CSP) was prepared by the surface‐initiated atom transfer radical polymerization (SI‐ATRP), in pyridine, of cellulose 2,3‐bis(3,5‐dimethylphenylcarbamate), having a polymerizable vinyl group, on the surface of SiO₂ support. The successful preparation of the CSP was confirmed via Fourier transform infrared spectroscopy, field‐emission scanning electron microscopy, X‐ray photoelectron spectroscopy, elemental analysis and thermal analysis. The chiral recognition ability of the prepared CSP was evaluated with high‐performance liquid chromatography using 10 racemates with various mobile phases of hexane/alcohol, hexane/tetrahydrofuran and hexane/chloroform. As a result, this CSP prepared using SI‐ATRP can be used in tetrahydrofuran and chloroform solutions as eluents. Copyright © 2011 Society of Chemical Industry     

Shape control synthesis of polymeric hybrid nanoparticles via surface‐initiated atom‐transfer radical polymerization

Polymeric hybrid nanoparticles were synthesized via surface‐initiated atom‐transfer radical polymerization (SI‐ATRP) method on the surface of gold nanoparticles in cyclohexanone. Tetraoctyl ammonium bromide (TOAB) as a phase transfer agent was used to transfer the gold nanoparticles into cyclohexanone, which will be replaced by disulfide initiator on the surface of gold nanoparticles. Transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and UV–vis spectroscopy were utilized to characterize the product to make sure the experiment had been conducted. The results showed that the polymeric gold hybrid nanoparticles with different structures could be controlled by adjusting the ratio of initiator and gold nanoparticles in ATRP. If the ratio is very little, asymmetric polystyrene–gold hybrid nanoparticles were synthesized, and a single gold nanoparticle was attached with a polystyrene sphere. If the ratio becomes larger, core–shell polystyrene–gold nanocomposite particles were obtained resulting in gold nanoparticle encapsulated by a uniform polymer shell. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43584.     

Polyimide films with antibacterial surfaces from surface‐initiated atom‐transfer radical polymerization

BACKGROUND: Materials with antibacterial surface properties have attracted extensive scientific interest for research and development in the battle against microbial contamination. The application of antimicrobial polymers minimizes environmental problems and enhances the efficiency, selectivity and lifetime of the antimicrobial agents. In this paper polyimide (PI) films are chosen as the polymeric substrate to be modified due to the good thermal, mechanical and physicochemical properties of PI. The method of preparing PI films with antibacterial surfaces using surface‐initiated atom‐transfer radical polymerization (ATRP) is described. RESULTS: The results from X‐ray photoelectron spectroscopy showed that the surfaces at each stage were modified successfully. The pyridinium groups introduced on the PI surface possessed antibacterial properties and the bactericidal effect of the functionalized PI films on Escherichia coli was evaluated. Quaternization of the pyridine rings of the poly(4‐vinylpyridine) (P4VP) brushes gave rise to a high concentration of quaternary pyridinium groups on the PI film surfaces. The antibacterial efficiency of the modified PI film was dependent on the amount of quaternary pyridinium groups on the surface. CONCLUSION: In this research, functional polymer brushes of P4VP were prepared via surface‐initiated ATRP from PI films, followed by alkylation of the grafted P4VP with hexyl bromide. The surface functionalization method described has the advantage of being effective in conferring antibacterial properties on polymeric materials. Copyright © 2008 Society of Chemical Industry     

Synthesis and characterization of poly(2‐hydroxyethyl methacrylate)‐functionalized Fe‐Au/core‐shell nanoparticles

Disulfide‐bearing poly(2‐hydroxyethyl methacrylate) (DT‐PHEMA) was synthesized by atom transfer radical polymerization technique, which was subsequently immobilized onto core‐shell structured Fe‐Au nanoparticles (Fe‐AuNPs) by applying a “grafting to” protocol to afford new PHEMA‐grafted Fe‐AuNPs (PHEMA‐g‐Fe‐AuNPs). The Fe‐AuNPs having the iron core of 20–22 nm and the gold layer of 1–2 nm were initially prepared by inverse micelle technique and characterized by XRD and high‐resolution transmission electron microscopy (HR‐TEM). The grafting of DT‐PHEMA on the Fe‐AuNPs was confirmed by Fourier transformed infrared spectrophotometer, thermogravimetric (TGA), X‐ray photoelectron spectroscopy, and energy dispersive X‐ray analyses. The average diameter of polymer coated Fe‐AuNPs was determined to be 28 nm by HR‐TEM analysis. The amount of the polymer on the surface of Fe‐AuNPs was calculated to be about 50% by TGA analysis. The studies of magnetic property by the superconducting quantum interference devices indicate the superparamagnetic property of Fe‐AuNPs and PHEMA‐g‐Fe‐AuNPs. The optical property of the PHEMA‐g‐Fe‐AuNPs was recorded by UV–visible absorption spectroscopy, and a redshift in the absorption was observed, which further suggests the PHEMA attachment on the surface of Fe‐AuNPs. The magnetic nanocomposites demonstrate good dispersibility in common polar solvents. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011