Graft copolymerization of sodium acrylate onto organophilic montmorillonites initiated by potassium diperiodatonickelate (IV) and application of graft copolymer in water‐superabsorbent

The graft copolymerization of sodium acrylate (SA) onto organophilic montmorillonites (OMMT) initiated by redox reaction of potassium diperiodatonickelate (IV) [Ni(IV)] with reactive groups on OMMT substrate was studied in alkaline medium. The grafting parameters have been investigated as a function of the ratio of monomer to OMMT, the concentration of initiator, temperature, and pH value. The structure of the graft copolymer (OMMT‐g‐PSA) was systematically characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscope (SEM). It was found that [Ni(IV)] belongs to a highly efficient initiator for graft copolymerization of SA onto OMMT via the redox iniation (grafting efficiency > 95%). Furthermore, the experimental results also showed that the graft copolymer gels synthesized under optimal condition exhibited a maximum water absorbency of 1104 g/g in distilled water and 111 g/g in 0.2 wt % NaCl solution, respectively, and its water retention ability is more than 91% after centrifugal separation for 2 h. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Graft copolymerization of 2-hydroxyethylmethacrylate onto carboxymethyl chitosan using CAN as an initiator

O-Carboxymethyl chitosan (CMCH) was prepared and characterized by FTIR spectroscopy. Graft copolymerization of 2-hydroxyethylmethacrylate (HEMA) onto CMCH using ceric ammonium nitrate (CAN) as an initiator was carried out in an aqueous solution. Evidence of grafting was confirmed by comparison of FTIR spectra of CMCH and the grafted copolymer as well as scanning electron micrograph (SEM) of the products. The effects of concentration of CAN, HEMA, reaction time and temperature on graft copolymerization were studied by determining the grafting percentage, grafting efficiency. With keeping other condition constant, the optimum grafting conditions was obtained as following: CMCH, 2 g; CAN, 0.2 M; and HEMA, 0.384 mol/l; reaction temperature, 40 °C; and reaction time, 4.5 h.     

Synthesis and Characterization of Carboxymethyl Chitosan Grafted Methacrylic Acid Initiated by Ceric Ammonium Nitrate

O-carboxymethyl chitosan (CMCH) was prepared and characterized by FTIR spectroscopy and X-ray diffraction. Grafting of methacrylic acid (MA) onto CMCH using ceric ammonium nitrate (CAN) as an initiator was carried out under nitrogen atmosphere in aqueous solution. Evidence of grafting was confirmed by comparison of FTIR spectra of CMCH and the grafted copolymer as well as scanning electron micrograph (SEM) and X-ray diffraction of the products. The effects of concentration of CAN, MA, reaction time and temperature on graft copolymerization were studied by determining the grafting percentage and grafting efficiency. Keeping other conditions constant, the optimum grafting conditions were obtained as follows: CMCH = 2 gm, CAN = 0.2 M and MAA = 0.581 mol/L, reaction temperature = 40°C and reaction time = 4.5 hr.     

Optimization of synthesis and characterization of cassava starch‐graft‐poly(acrylonitrile) using response surface methodology

Graft copolymerization of poly(acrylonitrile) onto cassava starch was carried out with potassium persulphate (PPS) as the free radical initiator using a response surface Box–Behnken design. Different levels of monomer concentration, initiator concentration, and temperature were used, and regression models were generated in terms of these factors, which can be used to predict the grafting level and efficiency at a given level of the factors. The grafted starches were characterized by FTIR, XRD, and SEM analyses and determination of %grafting (%G), N‐content, thermal properties, water and saline solution retention, and rheological properties. Under the conditions used, %G was found to depend only on the temperature used for the reaction. The maximum %G of 120.1 was obtained for the sample synthesized under the following conditions: weight of AN = 0.753 mol/10 g starch, weight of PPS = 0.284 g and temperature = 55°C, and the grafting efficiency was 30.03%. The absorption bands at 2243 cm^?1 for the nitrile group (? CN) in the FTIR spectra of the products confirmed the grafting reaction. There was a decrease in crystallinity and disappearance of the granular structure after grafting of the starch. The melting temperatures of the graft copolymers determined by differential scanning calorimetry analysis were higher than that of the native starch. The grafted starches exhibited very high thermal stability as observed from the thermogravimetric analysis. The superabsorbent polymer prepared from the grafted starch by alkali saponification exhibited a maximum water absorbency of 636 g/g. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Graft copolymerization of n-vinyl-2-pyrrolidone on dimethyl sulfoxide pretreated poly(ethylene terephthalate) films using azobisisobutyronitrile initiator

Poly(ethylene terephthalate) (PET) films were grafted with n-vinyl-2-pyrrolidone (n-VP) using an azobisisobutyronitrile (AIBN) initiator. Films were pre-treated in dimethyl sulfoxide (DMSO) for 1 h at 140°C before the polymerization reaction was carried out. Variations of graft yield with time, temperature, initiator, and monomer concentrations were investigated. The optimum temperature and polymerization time was found to be 70°C and 4 h, respectively. Increasing monomer concentration from 0.28 to 1.22M and initiator concentration from 1.77 × 10⁻³ to 4.20 × 10⁻³M enhanced the percent grafting. The effects of monomer and initiator diffusion on PET films were also studied. The overall activation energy for grafting was calculated as 11.5 kcal/mol. Further changes in properties of PET films such as water-absorption capacity and intrinsic viscosity were determined. The grafted films were characterized with FTIR and scanning electron microscopy (SEM). © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1437–1444, 1997     

乙酸乙烯酯接枝改性海藻酸钙凝胶微球

为了降低海藻酸钙凝胶微球的溶胀度,以乙酸乙烯酯（VAc)对海藻酸钠进行自由基接枝共聚,进而制备具有较低溶胀度的聚乙酸乙烯酯改性海藻酸钙(Ca-SA-PVAc)凝胶微球。红外光谱表明,改性之后海藻酸钙的分子上生成新的化学键;热重分析表明,改性微球受热失水行为发生变化,热稳定性提高;扫描电镜表明,改性微球结构孔隙结构发达;接枝反应条件如反应温度、VAc的浓度、引发剂用量、海藻酸钠浓度、钙离子浓度及反应时间等对改性凝胶微球在生理盐水中的抗溶胀性具有不同程度的影响。通过改变反应条件以控制接枝反应参数,可以获得溶胀行为可控的改性海藻酸钙凝胶微球。     

Grafting of vinyl acetate onto low density polyethylene—starch biodegradable films for printing and packaging applications

Starch‐based biodegradable low‐density polyethylene (LDPE) films were used for graft copolymerization of vinyl acetate with ceric ammonium nitrate (CAN) in aqueous acidic medium as redox initiator with nitric acid. The extent of grafting was examined by Fourier‐transform infrared (FTIR) spectroscopy, attenuated total reflectance (ATR) spectroscopy, X‐ray diffraction (XRD) and scanning electron microscopy (SEM). The objective behind the grafting of vinyl acetate onto the LDPE–starch biodegradable films is to make these suitable for printing and packaging applications without affecting the biodegradability of the original films. Copyright © 2004 Society of Chemical Industry     

Studies on graft copolymerization of cyclohexyl methacrylate onto chloroprene rubber

Graft copolymerization of cyclohexyl methacrylate (CMA) onto chloroprene rubber (CR) was carried out in toluene using benzoyl peroxide as an initiator. The graft copolymer was isolated from the gross polymer by extracting it with a butanone solution. Infrared (IR) spectra of the graft copolymer showed the occurrence of grafting. Optimization of various parameters of the grafting, namely, time, temperature, and initiator concentrations, was performed. The mechanical adhesive properties of the graft copolymer, CR-g-CMA, were measured and compared with those of the graft copolymer of methyl methacrylate (MMA) onto CR, CR-g-MMA. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1733–1737, 1997     

Photograft copolymerization of methyl methacrylate on viscose fiber using titanium(III) chloride–potassium persulfate redox initiator in a limited aqueous system

The graft copolymerization of methyl methacrylate (MMA) onto viscose fibers were studied under photoactive conditions with visible light using titanium(III) chloride—potassium persulfate as redox initiator in a limited aqueous system. Polymerization carried out in the dark at 40 ± 1°C produced little graft copolymer whereas that in the presence of light at 40 ± 1°C produced significant grafting. Percent grafting, percent total conversion, and grafting efficiency (%) were studied by varying time, initiator concentration, monomer concentration, solvent composition, and pH of the medium. High percent grafting (～ 200%), high grafting efficiency (～ 98%), and percent total conversion (～ 47%) were obtained with little homopolymer formation. A suitable mechanism for grafting has been discussed and also the characterization of the grafted fibers were studied by Fourier transform infrared (FTIR) spectroscopy, thermogravimetry and scanning electron microscopy (SEM). © 1992 John Wiley & Sons, Inc.     

Grafting Study and Antifungal Activity of a Carboxymethyl Cellulose Derivative

Graft copolymerization of appropriate monomers onto cellulose and its derivatives can enhance their characteristics and consequently expand their potential applications. Carboxymethyl cellulose (CMC) was prepared and characterized by FTIR spectroscopy and XRD. Graft copolymerization of acrylic acid sodium salt (AAs) onto CMC using ammonium persulfate (APS) as a free radical initiator was carried out under nitrogen atmosphere in aqueous solution. Occurrence of grafting was confirmed by comparison of FTIR spectra of CMC and the graft copolymers as well as the XRD patterns and thermal analysis. The effects of concentration of AA, temperature, concentration of APS and reaction time on the grafting yield were investigated by determining the grafting percentage and grafting efficiency. With other conditions kept constant, the obtained optimum grafting conditions were: CMC = 0.2 g, [AAs] = 2 mM, [APS] = 7.5 mM, temperature = 70°C and reaction time = 2 h. A preliminary study was then carried out to evaluate the antifungal activity of the prepared graft copolymer. This preliminary investigation of the prepared graft copolymers showed that they may be tailored and exploited to expand the utilization of these systems in medical applications.     

马铃薯废渣/聚丙烯酸/坡缕石黏土高吸水树脂的制备及表征

采用马铃薯废渣(PWR,粒径<180目)作为纤维素和淀粉源,过硫酸钾(KSB)为引发剂,N,N'-亚甲基双丙烯酰胺(MBA)为交联剂,复配坡缕石(PGS)黏土,与部分中和的丙烯酸(AA)通过自由基引发在水溶液中接枝共聚制备低成本PWR-g-PAA/PGS高吸水树脂。借助扫描电镜(SEM)、红外光谱(FTIR)及热重分析(TGA)对高吸水树脂的形貌、结构及热稳定性进行了表征和分析,并测试其吸液性能。结果表明,当坡缕石黏土和马铃薯废渣的用量占反应体系总质量的17.5%时,WPR-g-PAA/PGS高吸水树脂对w(NaCl)=0.9%水溶液、蒸馏水的最大吸收量分别为41.0、538.6 g/g,保水率为96.1%,凝胶强度达11.3 kPa。通过高吸水树脂的吸水溶胀过程确定了材料的吸水动力学行为符合non-Fickon扩散模型。     

Grafting of poly(vinyl chloride) and polypropylene with styrene in a supercritical CO2 solvent medium: Synthesis and characterization

Graft copolymerization of styrene onto poly(vinyl chloride) (PVC) and polypropylene (PP) was carried out in a supercritical CO₂ medium using AIBN as a free radical initiator. The supercritical CO₂ medium served as a reaction medium in addition to being a solvent for the styrene monomer and the free radical initiator. The reaction temperature and pressure were kept above the critical points of the solvent‐monomer mixture to form a homogeneous single‐phase medium. The resulting graft copolymers were characterized using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and nuclear magnetic resonance (NMR) techniques. The weight percent of grafting was determined using IR absorbance ratio technique. TGA results showed that the thermal stabilily of grafted copolymer of PVC was better than that of PVC, while grafted copolymer of PP had poorer thermal stability than PP. DSC results showed that glass transition temperatures (T_g's) of the grafted copolymers were higher than those of the starting polymers PVC and PP. The presence of polystyrene attached to the backbone polymer was confirmed by ¹H NMR and ¹³C NMR analyses.     

Preparation and Characterization of Starch-g-Polymethacrylamide Copolymers

In this article, methacrylamide was successfully grafted onto starch using benzoyl peroxide as a radical initiator in aqueous medium. The extent of grafting was found to be affected by the initiator, monomer, starch concentration, and temperature. The optimum initiator concentration is 2.0×10⁻³ mol/L. The graft yield was observed to increase with the monomer concentration and temperature. No optimum values for the monomer concentration and temperature were found. The overall activation energy for graft copolymerization was obtained. The grafted starches were characterized by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). TGA thermograms showed that the thermal stability of starch increased as a result of grafting. SEM micrographs showed that the granular structure of starch was not maintained after graft copolymerization. The water uptake and moisture retainment values of starch graft copolymers were investigated.     

Surface modification of cellulose filter paper by glycidyl methacrylate grafting for biomolecule immobilization: Influence of grafting parameters and urease immobilization

Graft copolymerization of glycidyl methacrylate (GMA) onto cellulose filter paper (CFP) was carried out by a free‐radical initiating process using ceric ammonium nitrate (CAN) as an initiator. Optimum conditions pertaining to different grafting percentages were evaluated as a function of monomer and initiator concentrations, polymerization time and temperature. CFP with various graft levels of GMA was characterized by fourier transform infrared (FTIR) spectroscopy and thermo gravimetric analysis (TGA). Surface morphology of ungrafted and grafted CFP was evaluated by scanning electron microscopy (SEM). Attenuated total reflectance (ATR)‐FTIR spectral analysis provided the evidence of grafting of GMA onto CFP. The maximum grafting of 102% was achieved by using 4 × 10^?3 molL^?1 CAN and 5% of GMA (w/v) monomer at 60°C in 25 min. The CFP‐g‐GMA surfaces with different graft levels were evaluated as a support for immobilization of biomolecules. Urease was selected as the model enzyme to be covalently coupled through the surface epoxy groups of the CFP‐g‐GMA discs. Immobilized discs were further studied for urea estimation and their reusability. Although the highest degree of urease immobilization was observed at 100% (162‐μg urease/disc) graft level, the urease immobilized on discs with 70% (105‐μg urease/disc) graft level gave the maximum activity of the enzyme. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Graft copolymerization of N‐isopropylacrylamide onto poly(vinyl chloride)

Poly(vinyl chloride) (PVC) was dehydrochlorinated in alkali solution and then grafted with N‐isopropylacrylamide (NIPAM) using benzoyl peroxide as an initiator under a nitrogen atmosphere. The results show that grafting of NIPAM onto dehydrochlorinated PVC (DHPVC) by means of chemical initiation is easily performed. The influence of various reaction conditions such as NIPAM concentration, reaction time, initiator concentration, and PVC content on the grafting copolymerization was investigated. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1234–1241, 1999     

Structural characterization of alpha methyl styrene‐butyl acrylate‐grafted polyetheretherketone films

Radiation‐induced graft copolymerization of alpha methyl styrene (AMS)‐butyl acrylate (BA) mixture onto poly(etheretherketone) (PEEK) was carried out to develop films of varying copolymer compositions. The characterization of films was carried out with fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), X‐ray diffraction analysis (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The presence of AMS and BA units within the film matrix was confirmed by FTIR. The intensity of the characteristic peaks for AMS and BA increased with the increasing grafted component in the films. The crystallinity of the films as observed from DSC and XRD decreased with the increasing graft levels. On the other hand, the melting temperature of the base polymer was almost unaffected by irradiation and the grafting process. The glass transition temperature (T_g) of the grafted film increased as compared to the virgin PEEK. Ungrafted film showed a stable thermogram up to ～500°C. However, the grafting introduced a new decomposition range in the copolymer, due to the presence of the AMS/BA. AFM images showed the formation of domains on the grafted PEEK film surface. The SEM also showed domain formation of the grafted component within the PEEK matrix. However, the fracture analysis did not show any prominent phase separation. Mechanical characterization of films in terms of tensile strength, elongation, and modulus was also carried out. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Chemical grafting of polyaniline onto nylon66 fiber in different media

Graft copolymerization of polyaniline (PANI) onto nylon 66 fiber was carried out in two different media, hydrochloric acid and p‐toluene sulfonic acid (PTSA), using peroxodisulfate (PDS) as an initiator. Percentage grafting, percentage efficiency, and rate of grafting were determined. The grafting of PANI onto nylon 66 was confirmed through FTIR spectroscopy, cyclic voltammetry (CV), weight‐loss study, and conductivity measurement. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1283–1296, 2001     

Graft copolymerizaztion of methyl acrylate onto chitosan initiated by potassium diperiodatocuprate (III)

A novel redox system, potassium diperiodatocuprate [Cu (III)–chitosan], was employed to initiate the graft copolymerization of methyl acrylate (MA) onto chitosan in alkali aqueous solution. The effects of reaction variables such as monomer concentration, initiator concentration, pH and temperature were investigated. By means of a series of copolymerization reactions, the grafting conditions were optimized. Cu (III)–chitosan system was found to be an efficient redox initiator for this graft copolymerization. The structures and the thermal stability of chitosan and chitosan‐g‐poly(methyl acrylate) (PMA) were characterized by infrared spectroscopy (IR) and thermogravimetric analysis (TGA). In this article, a mechanism is proposed to explain the formation of radicals and the initiation. Finally, the graft copolymer was used as the compatibilizer in blends of poly(vinyl chloride) (PVC) and chitosan. The scanning electron microscope (SEM) photographs and differential scanning calorimetry (DSC) thermograms indicate that the graft copolymer improved the compatibility of the blend. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2283–2289, 2003     

高粱秸秆-g-聚丙烯基化合物/坡缕石黏土高吸水树脂制备及动力学研究

以天然高粱秸秆(SS, 颗粒直径>180目)作为纤维素源,N, N?亚甲基双丙烯酰胺(MBA)为交联剂,过硫酸钾(KSB)引发剂,复配坡缕石(PGS)黏土,通过与丙烯酰胺(AM)及部分中和的丙烯酸(AA)接枝共聚制备低成本高吸水树脂SS-g-P(AA/AM)/PGS。运用扫描电镜(SEM)和红外光谱(FTIR)对高吸水树脂的形貌及结构进行了表征,并测试了其吸水性能及热稳定性。结果表明,在坡缕石和高粱秸秆的添加量占反应体系的19.8%时,SS-g-P(AA/AM)/PGS对蒸馏水和自来水的最大吸收量分别为273.0g/g和66.7g/g,且热稳定性较好。通过研究树脂的吸水溶胀过程研了材料的吸水动力学行为,结果表明SS-g-P(AA/AM)/PGS吸自来水和蒸馏水的过程分别符合Fickon扩散模型和non-Fickon扩散模型。     

Graft copolymerization of PU membranes with acrylic acid and crotonic acid using benzoyl peroxide initiator

To improve water wettability of polyurethane (PU), graft copolymerization with acrylic acid (AA) and crotonic acid (CA) was performed using a benzoyl peroxide (BO) initiator. The grafting reaction was carried out by placing the membranes in aqueous solutions of AA and CA at constant temperatures. Variations of graft yield with time, temperature, initiator, and monomer concentrations were investigated. The optimum temperature, polymerization time, monomer, and initiator concentrations for AA were found to be 70°C; 3 h; 1.5 M; 5.0 × 10^?2 M, and for CA 70°C; 1 h; 1.5 M; 4.0 × 10^?2 M, respectively. The grafting membranes were characterized by FTIR spectroscopy and scanning electron microscopy (SEM) analysis, and the effect of grafting on equilibrium water content (EWC) of PU membranes was obtained by swelling measurements. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2690–2695, 2001