Tailoring of water‐soluble cellulose‐g‐ copolymers in homogeneous medium using single‐electron‐transfer living radical polymerization

Cellulose‐graft‐polyacrylamide and cellulose‐graft‐poly(N,N‐dimethylacrylamide) copolymers were prepared by single‐electron‐transfer living radical polymerization (SET‐LRP) in homogeneous medium. Cellulose macroinitiators for SET‐LRP, with different numbers of initiating sites along the cellulose backbone, were successfully synthesized by direct acylation of cellulose with 2‐bromoisobutyryl bromide in LiCl/dimethylacetamide. Dynamic light scattering revealed that cellulose macroinitiator molecules in dimethylsulfoxide (DMSO) exist primarily as individual chains with a certain amount of intermolecular aggregates. SET‐LRP of acrylamide and N,N‐dimethylacrylamide with the cellulose macroinitiators was carried out in DMSO solution. Formation of cellulose‐graft‐copolymers was confirmed using attenuated total reflectance Fourier transform infrared, ¹H NMR and ¹³C NMR spectroscopy, and the products were water‐soluble. High content of poly(N,N‐dimethylacrylamide) in the copolymers enhanced the thermal stability relative to that of cellulose. Scanning electron microscopy studies of cellulose‐based particles formed from the copolymers using the aerosol flow reactor method revealed spherical nanoscale structures. Copyright © 2011 Society of Chemical Industry     

Graft copolymerization of methylmethacrylate with N‐substituted maleimide‐styrene copolymer by ATRP

Atom transfer radical polymerization (ATRP) was employed to prepare graft copolymers having poly(MBr)‐alt‐poly(St) copolymer as backbone and poly(methyl methacrylate) (PMMA) as branches to obtain heat resistant graft copolymers. The macroinitiator was prepared by copolymerization of bromine functionalized maleimide (MBr) with styrene (St). The polymerization of MMA was initiated by poly(MBr)‐alt‐poly(St) carrying bromine groups as macroinitiator in the presence of copper bromide (CuBr) and bipyridine (bpy) at 110°C. Both macroinitiator and graft copolymers were characterized by ¹H NMR, GPC, DSC, and TGA. The ATRP graft copolymerization was supported by an increase in the molecular weight (MW) of the graft copolymers as compared to that of the macroinitiator and also by their monomodal MW distribution. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

“Smart” membrane materials: Preparation and characterization of PVDF‐g‐PNIPAAm graft copolymer

In this research, a smart membrane material of graft copolymer of poly(vinylidene fluoride) with poly(N‐isopropylacrylamide) (PVDF‐g‐PNIPAAm) was synthesized by atom transfer radical polymerization (ATRP) using poly(vinylidene fluoride) (PVDF) as a macroinitiator and direct initiation of the secondary fluorinated site PVDF facilitates grafting the N‐isopropylacrylamide comonomer. The copolymers were characterized by Fourier transform infrared (FTIR), ¹H NMR, gel‐permeation chromatography (GPC), and X‐ray photoelectron spectroscopy (XPS). The temperature‐sensitive membrane was prepared from the PVDF‐g‐PNIPAAm graft copolymers by the phase inversion method. The effects of temperature on the flux of pure water of membrane was investigated. The results showed that alkyl fluorides were successfully applied as ATRP initiators in the synthetic condition and the flux of pure water through the PVDF‐g‐PNIPAAm membrane depended on the temperature change. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1482–1486, 2007     

Water‐soluble dual responsive polythiophene‐g‐poly(methoxyethoxy ethyl methacrylate)‐co‐poly(N,N‐diethylamino ethyl methacrylate) for different applications

Polythiophene (PT) based dual responsive water‐soluble graft copolymer (PT‐g‐[poly(methoxyethoxy ethyl methacrylate)‐co‐poly(N,N‐diethylamino ethyl methacrylate)]) (PT‐g‐P(MeO₂MA‐co‐DEAEMA)) (PTDE) has been synthesized by random copolymerization of methoxyethoxy ethyl methacrylate (MeO₂MA) and N,N‐diethylamino ethyl methacrylate (DEAEMA) at 30 °C on the 2,5‐poly(3‐[1‐ethyl‐2‐(2‐ bromoisobutyrate)] thiophene) (PTI) macroinitiator using the Cu based atom transfer radical polymerization technique. The PTDE graft copolymer was characterized by gel permeation chromatography and ¹H NMR techniques and it exhibits thermo‐reversible solubility in water showing a lower critical solution temperature of ca 42 °C in neutral aqueous solution. The PTDE graft copolymer contains a fluorescent PT backbone, and interestingly the system exhibits doubling of fluorescence intensity with rising temperature over the temperature range 41–45 °C at pH 7. The PTDE system therefore acts following the principle of the polymeric AND logic gate and it is also found to be effective in sensing of nitroaromatics, particularly picric acid. The influence of chain hydrophobicity on the logic operation and on the sensing of nitroaromatics is discussed. © 2014 Society of Chemical Industry     

Graft copolymerization of methyl methacrylate with an N‐substituted maleimide–liquid‐crystalline copolymer by atom transfer radical polymerization

The synthesis of novel copolymers consisting of a side‐group liquid‐crystalline backbone and poly (methyl methacrylate) grafts were realized by the use of atom transfer radical polymerization (ATRP). In the first stage, the bromine‐functional copolymers 6‐(4‐cyanobiphenyl‐4′‐oxy)hexyl acrylate and (2,5‐dioxo‐2,5‐dihydro‐1H‐pyrrole‐1‐yl)methyl 2‐bromopropanoate were synthesized by free‐radical polymerization. These copolymers were used as initiators in the ATRP of methyl methacrylate to yield graft copolymers. Both the macroinitiator and graft copolymers were characterized by ¹H‐NMR, gel permeation chromatography, differential scanning calorimetry, and thermogravimetric analysis. The ATRP graft copolymerization was supported by an increase in the molecular weight of the graft copolymers compared to that of the macroinitiator and also by their monomodal molecular weight distribution. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis of poly(aryl ether sulfone)‐graft‐polystyrene and poly(aryl ether sulfone)‐graft‐[polystyrene‐block‐poly(methyl methacrylate)] through atom transfer radical polymerization

A new graft copolymers poly(aryl ether sulfone)‐graft‐polystyrene (PSF‐g‐PS) and poly(aryl ether sulfone)‐graft‐[polystyrene‐block‐poly(methyl methacrylate)] (PSF‐g‐(PS‐b‐PMMA)) were successfully prepared via atom transfer radical polymerisation (ATRP) catalyzed by FeCl₂/isophthalic acid in N,N‐dimethyl formamide. The products were characterized by GPC, DSC, IR, TGA and NMR. The characterization data indicated that the graft copolymerization was accomplished via conventional ATRP mechanism. The effect of chloride content of the macroinitiator on the graft copolymerization was investigated. Only one glass transition temperature (T_g) was detected by DSC for the graft copolymer PSF‐g‐PS and two glass transition temperatures were observed in the DSC curve of PSF‐g‐(PS‐b‐PMMA). The presence of PSF in PSF‐b‐PS or PSF‐g‐(PS‐b‐PMMA) was found to improve thermal stabilities. © 2002 Society of Chemical Industry     

Thermoresponsive poly(ϵ‐caprolactone)‐graft‐poly(N‐isopropylacrylamide) graft copolymers prepared by a combination of ring‐opening polymerization and sequential azide–alkyne click chemistry

A straightforward strategy is described to synthesize poly(?‐caprolactone)‐graft‐poly(N‐isopropylacrylamide) (PCL‐g‐PNIPAAm) amphiphilic graft copolymers consisting of potentially biodegradable polyester backbones and thermoresponsive grafting chains. PCL with pendent chlorides was prepared by ring‐opening polymerization, followed by conversion of the pendent chlorides to azides. Alkyne‐terminated PNIPAAm was synthesized by atom transfer radial polymerization. Then, the alkyne end‐functionalized PNIPAAm was grafted onto the PCL backbone by a copper‐catalyzed azide–alkyne cycloaddition. PCL‐g‐PNIPAAm graft copolymers self‐assembled into spherical micelles comprised of PCL cores and PNIPAAm coronas. The critical micelle concentrations of the graft copolymers were in the range 7.8–18.2 mg L^?1, depending on copolymer composition. Mean hydrodynamic diameters of micelles were in the range 65–135 nm, which increased as the length of grafting chains grew. PCL‐g‐PNIPAAm micelles were thermosensitive and aggregated upon heating. © 2014 Society of Chemical Industry     

pH and thermo‐responsive poly(N‐isopropylacrylamide) copolymer grafted to poly(ethylene glycol)

pH and thermo‐responsive graft copolymers are reported where thermo‐responsive poly(N‐isopropylacrylamide) [poly(NIPAAm), poly A ], poly(N‐isopropylacrylamide‐co‐2‐(diethylamino) ethyl methacrylate) [poly(NIPAAm‐co‐DEA), poly B ], and poly(N‐isopropylacrylamide‐co‐methacrylic acid) [poly(NIPAAm‐co‐MAA), poly C ] have been installed to benzaldehyde grafted polyethylene glycol (PEG) back bone following introducing a pH responsive benzoic‐imine bond. All the prepared graft copolymers for PEG‐g‐poly(NIPAAm) [ P‐N1 ], PEG‐g‐poly(NIPAAm‐co‐DEA) [ P‐N2 ], and PEG‐g‐poly(NIPAAm‐co‐MAA) [ P‐N3 ] were characterized by ¹H‐NMR to assure the successful synthesis of the expected polymers. Molecular weight of all synthesized polymers was evaluated following gel permeation chromatography. The lower critical solution temperature of graft copolymers varied significantly when grafted to benzaldehyde containing PEG and after further functionalization of copolymer based poly(NIPAAm). The contact angle experiment showed the changes in hydrophilic/hydrophobic behavior when the polymers were exposed to different pH and temperature. Particle size measurement investigation by dynamic light scattering was performed to rectify thermo and pH responsiveness of all prepared polymers. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effect of dimethyl sulfoxide on synthesis of thermoplastic cellulose‐Graft‐poly(l‐lactide) copolymer using ionic liquid as reaction media

In this study, ring‐opening graft polymerization of l ‐lactide onto cellulose was carried out homogeneously in ionic liquid (IL)/dimethyl sulfoxide (DMSO) co‐solvent as a reaction media. Through the effective control of high viscosity and steric hindrance caused by the interaction between the IL and the hydroxyl group of cellulose by adding DMSO as a co‐solvent, cellulose‐graft‐poly(l ‐lactide) (Cell‐g‐PLLA) copolymer with higher substitution efficiency was successfully prepared, at relatively low concentration of l ‐lactide. The maximum values of molar substitution, degree of lactyl substitution, and degree of polymerization of poly(l ‐lactide) in the copolymer were 3.76, 1.74, and 2.16, respectively, determined by ¹H‐NMR. The prepared cell‐g‐PLLA copolymers showed thermal plasticization with a glass transition temperature of 155°C. In addition, the thermal processibility could be improved as the amount of grafted PLLA in the copolymer increased. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41331.     

Thermoresponsive and biocompatible poly(vinyl alcohol)‐graft‐poly(N,N‐diethylacrylamide) copolymer: Microwave‐assisted synthesis,characterization, and swelling behavior

Novel thermoresponsive poly(vinyl alcohol)‐graft‐poly(N,N‐diethylacrylamide) (PVA‐g‐PDEAAm) copolymers were prepared by microwave‐assisted graft copolymerization using a potassium persulfate/N,N,N′,N′‐tetramethylethylenediamine (KPS/TEMED) initiator system. The structures of PVA‐g‐PDEAAm copolymers were characterized by ¹H‐NMR, Fourier transform infrared spectroscopy, differential scanning calorimetry/thermogravimetric analysis, gel permeation chromatography, X‐ray diffraction, and scanning electron microscopy. The effects of various process parameters on grafting were systematically studied: microwave power, KPS, monomer and PVA concentrations, and ultraviolet irradiation. Under optimal conditions, the maximum grafting percent and graft efficiency were 101% and 93%, respectively. Furthermore, a lower critical temperature of copolymers was measured in the range 29–31 °C by ultraviolet spectroscopy. The swelling behavior of graft membranes was carried out at various temperatures, and the results showed that the swelling behavior of membranes was dependent on the temperature. In vitro cell culture studies using L929 fibroblast cells confirmed cell compatibility with the PVA‐g‐PDEAAm copolymer and its membrane, making them an attractive candidate for drug delivery systems. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45969.     

Synthesis of graft copolymers. II. Synthesis of polystyrene‐g‐poly(methyl methacrylate)

The thermolysis of labile 1,2‐bis(trimethylsilyloxy)tetraphenylethane groups pendant along polystyrene chains in the presence of various vinyl monomers leads to the direct synthesis of graft copolymers. Depending on the monomer chosen, the polymerization temperature, and the number of active sites by the macroinitiator molecule, crosslinked or total soluble graft copolymers can be prepared. Several conditions were studied in order to attain soluble polystyrene‐g‐poly(methyl methacrylate) copolymers under a controlled polymerization mechanism. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 12–18, 2002     

Grafted polysaccharides based on acrylamide and N,N‐dimethylacrylamide: Preparation and investigation of their flocculation performances

The graft copolymerization of N,N‐dimethylacrylamide (DMA) and acrylamide (AM) were carried out onto different polysaccharide backbones separately. The graft copolymers were synthesized by ceric ion induced redox polymerization technique. Three polysaccharides were used, namely hydroxyethyl starch (HES), hydroxyethyl cellulose (HEC) and Amylopectin (AP), for the grafting reactions. Among the three polysaccharides, HEC has linear structure, while HES and AP have a branch one. The graft copolymers were characterized by intrinsic viscosity measurements, FTIR spectroscopy, NMR (both ¹H and ¹³C) spectroscopy, and thermal analysis. Flocculation performances of the graft copolymers were evaluated in 1 wt % kaolin and in 0.25 wt % iron ore suspensions. A detailed comparative study of the flocculation properties of the synthetic graft copolymers was also made. It showed that graft copolymers based on DMA were better flocculants than those based on AM. Among the synthetic graft copolymers, HES‐g‐Poly (DMA) performed best when compared with the other synthetic graft copolymers as well as to the commercial flocculants in the same suspensions. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

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.     

Graft copolymers from commercial chlorinated polypropylene via Cu(0)‐mediated atom transfer radical polymerization

Commercially available chlorinated polypropylene has been used as a macroinitiator for the Cu(0)‐mediated atom transfer radical polymerization of methyl methacrylate and tert‐butyl acrylate to obtain well‐defined graft copolymers. The relatively narrow molecular weight distribution in the graft copolymers and linear kinetic plots indicated the controlled nature of the copolymerization reactions. Both Fourier transform infrared and ¹H NMR studies confirmed that the graft reactions had taken place successfully. After graft copolymer formation, tert‐butyl groups of poly(tert‐butyl acrylate) side chains were completely converted into poly(acrylic acid) chains to afford corresponding amphiphilic graft copolymers. © 2016 Society of Chemical Industry     

Synthesis,characterization, flocculation,and rheological characteristics of hydrolyzed and unhydrolyzed polyacrylamide‐grafted poly(vinyl alcohol)

Graft copolymers of poly(vinyl alcohol) and polyacrylamide (PVA‐g‐PAM) were synthesized using a ceric ion–induced solution polymerization technique at 28°C. Three grades of graft copolymers were synthesized with varying acrylamide concentrations. Three grades of hydrolyzed products of PVA‐g‐PAM were synthesized with varying concentrations of sodium hydroxide solution. Hydrolyzed and unhydrolyzed PVA‐g‐PAM were characterized by viscometry, X‐ray diffractometry, infrared spectroscopy, and thermal analysis. Rheological investigation was also carried out on the aqueous solutions of various samples. The flocculation characteristics of various materials were investigated by the use of jar and settling tests in 0.25 and 5 wt %, respectively, using kaolin and iron ore suspensions. Among the series of graft copolymers, the one with fewest but longest PAM chains showed superior performance. The flocculation characteristics of the best‐performing graft copolymer were compared with those of various commercially available flocculants in the two suspensions under investigation. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2109–2122, 2006     

Poly(ε‐caprolactone)‐graft‐poly(N‐isopropylacrylamide) amphiphilic copolymers prepared by a combination of ring‐opening polymerization and atom transfer radical polymerization: Synthesis,self‐assembly,and thermoresponsive property

Thermoresponsive graft copolymers of ε‐caprolactone and N‐isopropylacrylamide were synthesized by a combination of ring‐opening polymerization and the sequential atom transfer radical polymerization (ATRP). The copolymer composition, chemical structure, and the self‐assembled structure were characterized. The graft length and density of the copolymers were well controlled by varying the feed ratio of monomer to initiator and the fraction of chlorides along PCL backbone, which is acting as the macroinitiator for ATRP. In aqueous solution, PCL‐g‐PNIPAAm can assemble into the spherical micelles which comprise of the biodegradable hydrophobic PCL core and thermoresponsive hydrophilic PNIPAAm corona. The critical micelle concentrations of PCL‐g‐PNIPAAm were determined under the range of 6.4–23.4 mg/L, which increases with the PNIPAAm content increasing. The mean hydrodynamic diameters of PCL‐g‐PNIPAAm micelles depend strongly on the graft length and density of the PNIPAAm segment, allowing to tune the particle size within a wide range. Additionally, the PCL‐g‐PNIPAAm micelles exhibit thermosensitive properties and aggregate when the temperature is above the lower critical solution temperature. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41115.     

Preparation of cellulose graft copolymers having polypeptide side chains and their blood compatibility

Blood compatibility of cellulose graft copolymers with poly(γ-benzyl-L -glutamate) and poly(N⁵-2-hydroxyethyl-L -glutamine) (Cell-g-PBLG and Cell-g-PHEG) was examined in vivo blood tests. For this purpose, Cell-g-PBLG graft copolymers with PBLG contents ranging from 7 to 60 mol % were prepared by polymerizing N-carboxy-γ-benzyl-L-glutamate(γ-BLG NCA) using aminoethyl cellulose (AE-Cell) with degree of substitution of 0.05 as macroinitiator. Graft copolymerization was carried out under a variety of conditions at 20°C in dimethyl-sulfoxide. Monomer conversion higher than 60% were obtained for all the polymerization runs. The solubility tests revealed that all of the AE-Cell and the polypeptides formed were grafted. The Cell-g-PHEG graft copolymers were prepared by treating Cell-g-PBLG graft copolymers with 2-amino-1-ethanol. Characterization of these graft copolymers were carried out by IR spectroscopy, DSC, and water content measurement. Tests for blood compatibility, in vivo, were made by a method of peripheral vein indwelling suture which was developed by one of the authors. The coating of graft copolymers on the polyester suture was made by casting either from formic acid solution of LiCl/dimethylacetamide solutions using water as the regenerating medium, and the polymer-coated sutures were implanted into a jugular and femoral vein of a dog. The results showed that the graft copolymers examined have excellent antithrombogenic properties.     

Synthesis of water‐soluble polyphenol‐graft‐poly(ethylene oxide) copolymers via enzymatic polymerization and anionic polymerization

Water‐soluble polyphenol‐graft‐poly(ethylene oxide) (PPH‐g‐PEO) copolymers were prepared using grafting‐through methodology. Polyphenol chains were synthesized via enzymatic polymerization of phenols, and the graft chains were synthesized via living anionic polymerization of ethylene oxides. The polymers were characterized using gel permeation chromatography, static light scattering and ¹H NMR, infrared and ultraviolet spectroscopies. The PPH‐g‐PEO graft copolymers are soluble in several common solvents, such as water, ethanol, N,N‐dimethylformamide, tetrahydrofuran and methylene dichloride. The solubility of the PPH‐g‐PEO graft copolymers is improved significantly compared with that of polyphenol. Copyright © 2009 Society of Chemical Industry     

Synthesis,characterization, and flocculation characteristics of polyacrylamide‐grafted glycogen

The synthesis of glycogen‐g‐polyacrylamide (Gly‐g‐PAM) was carried out by a ceric ion‐induced solution polymerization technique. Six grades of graft copolymers were synthesized by the variation of catalyst and monomer concentrations. These graft copolymers were characterized by intrinsic viscosity measurements, FTIR spectroscopy, and X‐ray diffraction techniques. Flocculation performance of these graft copolymers were done in kaolin suspension. Of the above grades, the graft copolymer Gly‐g‐PAM 5, which has longer PAM chains, showed best flocculation performance. The flocculation performance of the graft copolymer was compared with commercial flocculants and other PAM‐grafted flocculants developed so far in the authors' laboratory. In all the cases, it was found that the graft copolymer performed the best. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 773–778, 2007     

The synthesis of PHA‐g‐(PTHF‐b‐PMMA) multiblock/graft copolymers by combination of cationic and radical polymerization

A new and promising method for the diversification of microbial polyesters based on chemical modifications is introduced. Poly(3‐hydroxy alkanoate)‐g‐(poly(tetrahydrofuran)‐b‐poly(methyl methacrylate)) (PHA‐g‐(PTHF‐b‐PMMA)) multigraft copolymers were synthesized by the combination of cationic and free radical polymerization. PHA‐g‐PTHF graft copolymer was obtained by the cationic polymerization of THF initiated by the carbonium cations generated from the chlorinated PHAs, poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV), and poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) (PHBHx) in the presence of AgSbF₆. Therefore, PHA‐g‐PTHF graft copolymers with hydroxyl ends were produced. In the presence of Ce⁺⁴ salt, these hydroxyl ends of the graft copolymer can initiate the redox polymerization of MMA to obtain PHA‐g‐(PTHF‐b‐PMMA) multigraft copolymer. Polymers obtained were purified by fractional precipitation. In this manner, their γ‐values (volume ratio of nonsolvent to the solvent) were also determined. Their molecular weights were determined by GPC technique. The structures were elucidated using ¹H‐NMR and FTIR spectroscopy. Thermal analyses of the products were carried out using differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009