Studies on Graft Copolymerization of Acrylic Acid onto Ramie Fibers with Chromic Acid Initiation System

The graft copolymerization of acrylic acid (AA) with unswollen and swollen ramie fibers using chromic acid (H 2CrO 4) as the initiator has been studied in the presence of air. The effects of initiator concentration, monomer concentration, perchloric acid (HClO 4) concentration, time of polymerization, reaction temperature, and amount of ramie fibers on the graft percentage have been found out. The graft copolymer was characterized by IR spectra, scanning electron microscopy(SEM), differential thermal analysis (DTA), and thermogravimertric analysis (TGA).

GRAFT COPOLYMERIZATION OF VINYL MONOMERS ONTO STARCH INITIATED BY TRANSITION METAL-THIOUREA REDOX SYSTEMS

In this paper, the capabilities of grafting acrylonitrile (AN) onto starch initiated by Fe(III)-TU, V(V)-TU, Cr(VI)-TU, Mn(VII)-TU redox systems were compared in the presence of sulfuric acid of different concentrations. It was shown that the grafting capability of Mn(VII)-TU is the highest in these initiating systems. Using Mn (VII-TU as initiator, the effects of various acids (HClO4, H2SO4, HNO3, HCl) on the graft copolymerization of acrylonitrile onto starch were discussed, and the capabilities of graft copolymerization of methyl methacrylate (MMA), acrylamide (AM), acrylic acid (AA) onto starch were investigated. The experimental results show that the order of the influences of different acids is HClO4 > H2SO4 > HNO3 > HCl, and the order of grafting capabilities of different monomers grafted onto starch is MMA > AN > AM > AA. The structure and morphology of graft, copolymers were studied with infrared spectroscopy and scanning electron microscopy. The size, shape and roughness of surface of the grafted starch granules are changed after grafting.

MODIFICATION OF SILK FIBER via EMULSION GRAFT COPOLYMERIZATION WITH FLUOROACRYLATE

2,2,3,3,4,4,5,5-Octafluoropentyl acrylate was grafted onto silk fiber in a two-step heterogeneous system through the vinyl bonds of acryloyloxyethyl isocyanate modified on the silk.The grafted copolylner was analyzed by FTIR and WAXD,and the results revealed that the fluoroacrylate was successfully grafted onto silk fiber and the crystalline structure of silk fibroin withβ-sheet structure was not changed after graft copolymerization.The FT-IR corrected method was used to simulate the grafting yield onto sil...

Graft copolymerization of cellulose and 2-hydroxyethyl methacrylate in an ionic liquid

Dissolution and homogeneous graft copolymerization of cellulose were performed in an ionic liquid 1-allyl-3-methylimidazolium chloride （AmimCl） with 2-hydroxyethyl methacrylate. The synthesized AmimCl and cellulose graft copolymers were characterized by FTIR, ^1 H-NMR and XRD spectroscopy. The results show that AmimCl dissolved cellulose directly by destroying intermolecular and intramolecular hydrogen bonds in cellulose and the crystalline form of cellulose was transformed from cellulose Ⅰ to cellulose Ⅱ after regeneration from AmimCl. The best synthetic condition of the cellulose-graft-P （2-hydroxyethyl methacrylate） was that cellulose 0.5 g, 2-hydroxyethyl methacrylate 3.00 g and initiator ammonium persulfate 0.05 g reacted for 180 min at 60℃; the rate of grafting reached 77.3%.

Photo-Grafting Copolymerization of PP Nonwoven Fabric and Its Application for Acidic Dye Adsorption and Filtration

The monomer methacrylamido propyl trimethy ammonium chloride( MAPTAC) was copolymerized onto the fiber surface of polypropylene( PP) nonwoven fabric under ultroviole radiation. The weak acid red GN dye adsorption and adsorptive filtration performance of the resulted PP fabrics were investigated.The results showed that the grafting copolymerization preferred to happen in the inner layer of the fabrics. The water flux of the grafted fabrics decreases with the increase of grafting yield. The collapse of the grafted polymer chains causes the flux increase in acidic condition,or vice versa at alkaline version. The coiling of the polyelectrolyte chains upon the dye adsorption seems to violate the routine assumption of the rigid substrate, and this gets the adsorption energy constant negative. The static adsorption process follows the Lagergren's pseudo-second order kinetic equation. The removals of circa( ca.) 100% of the total permeation volume3 500 mL simulated dye wastewater was reached during permeation.The dye adsorbed fabrics were regenerated by the mixed media of the cationic surfactant / ethanol /water. The grafted fabric assumes stable fabric integrity and stability during permeation,and presents excellent dye adsorption capacity,easy desorption, and repeatable utilization.

THE EFFECTS OF MAGNETIC FIELD ON GRAFT COPOLYMERIZATION OF METHYL METHACRYLATE ONTO POLYVINYL ALCOHOL IN THE PRESENCE OF BENZOPHENONE DURING UV IRRADIATION

The effects of magnetic field on the graft ratio and stereoregularity of grafts of PVA-g-MMA in the presence ofbenzophenone during UV irradiation are discussed. By means of IR, it was found that the graft ratio was increased with the increment of magnetic field strength. Furthermore, application of relative weak magnetic field of 0.4 Tesla had been shown to substantially enhance the stereo-regularity of graft copolymer. The maximum stereo-regularity appeared when the graft ratio approached to 85% with the magnetic field of 1.2 Tesla (T). The resistance to moisture and heat resistance of the grafted copolymer in the presence of magnetic field were also improved.

Modification of Natural Rubber Latex by Graft Copolymerization of 2-Ethylhexyl Acrylate and Methacrylic Acid

Natural rubber(NR)grafted with 2-ethylhexyl acrylate(2-EHA)and methacrylic acid(MAA,collectively NR-g-PEHA/MAA)was synthesized by emulsion polymerization.Tetraethylenepentamine and cumene hydroperoxide were used as redox initiators.The successful grafting of 2-EHA and MAA onto NR was confirmed by Fourier transform infrared spectroscopy.The morphology of the NR latex particles was observed by transmission electron microscopy.The effects of reaction temperature,initiator dosage,feeding mode,and hard monomer content on the mechanical properties of the modified NR film were investigated.Grafted polymer chains were unevenly wrapped on the outside of NR particles,and smaller particles were more easily grafted.Crosslinking was characterized using a toluene swelling method.Thermal stability and glass transition temperature were examined by differential scanning calorimetry and thermogravimetric analysis.The results showed that the thermal stability of NR-g-PEHA/MAA had been improved,and the glass transition temperature(Tg)was unchanged.

Studies on the Graft Copolymerization of Methyl Acrylate and Ethyl Acrylate onto Corn Starch Using Potassium Persulfate-Sodium Thiosulphatc as Initiation System

Grafting copolymerizations of methyl acrylate(MA) and ethyl acrylate(EA) onto corn starch, respectively, initiated by potassium persulfate-sodium thiosulphate (KPS-STS) redox system, were studied. The structures of poly(MA)-g-starch and poly(EA)-g-starch were characterized by IR, SEM and X-ray diffraction. Experimental results show that KPS-STS is an efficient initiation system for grafting of MA and EA onto corn starch. The maximum percent grafting was obtained at [KPS] of 6.0× 10~3 mol/L, [STS] of 1.8× 10 5 mol/L, [M] of 6. 0× 101 mol/L, S:L=4:100 at 40℃ for 6 h. The reactivity order is MA>EA.

Preparation and Swelling Kinetic Analysis of Poly (HPMC-co-AA-co-AM) Super Absorbent Resin

Super absorbent resin(SAR)is prepared by aqueous high temperature polymerization using hydroxypropyl methylcellulose(HPMC)as monomer backbone material,acrylic acid(AA)and acrylamide(AM)as the graft copolymer monomer,potassium persulfate(KPS)as the initiator to generate free radicals,and N,N`-methylenebisacrylamide(MBA)as cross-linking agent for cross-linking reaction.Simutaneously,the influence of individual factors on the water absorption is investigated,and these factors are mainly AA,AM,KPS,MBA,HPMC,and reaction temperature.The optimized conditions are obtained by the experiment repeating for several times.The water absorption multiplicity and salt absorption multiplicity under the conditions are 782.4 and 132.5 g/g,respectivity.Furthermore,the effects of different temperatures and salt concentrations on its water absorption,as well as the swelling kinetics of SAR are studied.It is indicated the water-absorbing swelling process is mainly caused by the difference in water osmotic pressure and Na+concentration inside and outside the cross-linked molecular structure of the resin,which is not only consistent with the quasi-secondary kinetic model,but also with the Fick diffusion model.

Study on PVC Grafted with Acrylic Rare Earths

The copolymers were formed by the graft copolymerization of PVC with acrylic rare earth. The principle and method of the graft copolymerization of PVC and acrylic rare earth were discussed. The graft copolymers were characterized by FT-IR spectra and scanning electron microscope (SEM).The thermal stability of the graft-copolymers was studied by thermogravimetric analysis (TG). The experiment results show that the thermal resistance and toughness of the graft copolymers are obviously enhanced.

SYNTHESIS AND CHARACTERIZATION OF AMPHIPHILIC GRAFT COPOLYMER CONTAINING MICROPHASE SEPARATED AND LONG POLY(ETHYLENE OXIDE) SIDE CHAIN STRUCTURES

Acryloyl terminated Poly (ethyleneoxide)macromonomers (PEO-A) with different PEO chain lengths have been prepared by deactivation of PEO alkoxide with acryloyl chloride. A new kind of amphiphilic polystyrene-g-poly (ethylene oxide)graft copolymer containing both microphase separated and PEO side chain structures has been synthesized from radical copolymerization of PEO-A macromonomer with styrene. After careful purification by a newly-developed method called 'selective dissolution', the well-defined structure of the purified copolymers was confirmed by IR, ~1H-NMR and GPC. Various experimental parameters controlling the copolymerization were studied in detail. The results indicated that the feed ratio of styrene to macromonomer(S/M) was the most important determining factor for the composition of the copolymers. A detailed 'comb- model' was proposed to describe the molecular structure of the graft copolymers. Finally, this amphiphilic graft copolymers may readily form microphase separated structures as clearly indicated by transmission electron microscopy.

Determination of Crosslinking and Grafting in Polyurethane-acrylic Hybrid Material and Their Theoretical Calculations

A theoretical method to calculate the mode of polyurethane（PU） prepolymers grafted to polyacrylic（PAC） was presented. Using hydroxyethyl acrylate（HEA） as coupling agent, polyurethane-acrylics（PU-AC） hybrid latexes were prepared with varying HEA level and the reaction of HEA with PU prepolymers at different temperatures, and PU grafted to PAC was experimentally determined. The results show that PU grafted to PAC regularly increased, and the non-grafted and linear free PU regularly decreased with increase in HEA/NCO（isocyanate group）. The grafted PU on PAC was not proportional to HEA. More than half of linear PU prepolymers were grafted to PAC when HEA was at a low level with HEA/NCO at 0.33. While grafted PU increased to 84.80%（mass fraction）, when HEA/NCO increased to 1.0. The results were interpreted based on the theoretical calculation of PU grafted to PAC by the present method.

Chitosan-graft-poly(L-glutamic acid) Hybrid Material and Its Self-assembly

Chitosan-graft-poly（L-glutamic acid）（CS-g-PGA） copolymer was successfully synthesized by grafting polymerization of γ-benzyl-L-glutamate N-carboxyanhydride onto the modified chitosan chains. The self-assembly behavior of such a CS-g-PGA amphiphilic copolymer was studied. The results show that spherical nanoparticles have been formed. The size of CS-g-PGA nanoparticles is found to be controlled by the grafting ratio of PGA. These bio-based polysaccharide/polypeptide hybrid nanoparticles with controllable size may have great potential application in biomedical fields, such as drug delivery systems.

SYNTHESIS OF GRAFT COPOLYMERS WITH POLYISOBUTYLENE BRANCH CHAINS

The copolymerization of 4-vinylbenzyl chloride （VBC） and vinyl acetate （VAC） was carried out in toluene at 75℃ via radical polymerization using 2,2＇-azo-bis-（isobutyronitrile） （AIBN） as an initiator. The random copolymers of poly（4-vinylbenzyl chloride-co-vinyl acetate） （P（VBC-co-VAC）） with number average molecular weight （Mn） from 2000 to 6900, relatively narrow molecular weight distribution （MWD, Mw/Mn ca. 2.0） and with different copolymer composition of 4-vinylbenzyl chloride （VBC） from 17 mol% to 62 mol% could be obtained. The P（VBC-co-VAC） copolymers with an average number of 7 to 13 initiating sites of benzyl chloride per macromolecule could be used for the cationic polymerization of isobutylene （IB）. The cationic polymerizations of IB were further conducted by using P（VBC-co-VAC） copolymers as macroinitiators in conjunction with TICl4 at -40℃ in CH2Cl2. The effects of VBC/TiCl4 （molar ratio） on monomer conversion, Mn and MWD of the resultant copolymers were investigated under 3 sets of conditions. It is found that P（VBC-co-VAC）-g-PIB copolymers with relatively narrow MWD （Mw/Mn ca. 2.0） and with terminal tert-chlorine functional groups in branched PIB chains could be successfully synthesized when VBC/TiCl4 （molar ratio） was set in the range from 0.10 to 1.12. The unimodal GPC curve of the P（VBC-co-VAC）-g-PIB copolymers by RI detector was almost in harmony with the GPC curve by UV detector. The TEM image of the P（VBC-co-VAC）-g-PIB copolymer stained by RuO indicated that the copolymer formed a two-phase morphology with P（VBC-co-VAC）-rich domains of 20-100 um in size tethered by PIB branch segments.

Synthesis and characterization of biodegradable amphiphilic PEG-grafted poly(DTC-co-CL)

A novel biodegradable copolymer, poly（5,5-dibromomethyltrimethylene carbonate-co-ε-caprolactone） （poly（DBTC-co-CL）） with pendant bromine groups, was synthesized via ring-opening polymerization （ROP） of ε-caprolactone （CL） and 5,5- dibromomethyltrimethylene carbonate （DBTC） using stannous octoate （Sn（Oct）2） as catalyst. Then the pendant bromine groups were completely converted into azide form, which permitted ＂click＂ reaction with alkyne-terminated polyethylene （A-PEG） by Huisgen 1,3-dipolar cycloadditions preparing biodegradable amphiphilic poly（DTC-co-CL）-g-PEG graft copolymer. The graft copolymer was characterized by nuclear magnetic resonance （NMR） and size-exclusion chromatography （SEC）.

The Optimization of Synthesizing Graft Copolymer of Starch with Vinyl Monomers

The graft copolymerization of acrylamide （ AM ） / acrylic acid （ AA ） onto starch （ St- g-pAA and St-g-p（AA-co-AM） ） was carried out using an orthngonal test method. The combined effects of different reaction conditions on the water absorbency of the graft copolymers were optimized through mathematical statistical methods of range and square variance analysis. The maximum water absorbency was obtained when the ratio of dried starch to distilled water was 1 ： 8 （ w/w ）, the ratio of starch to monomer 1 ： 6 （ w/w ）, the initiator concentration 4.40 × 10^-3 mol/L, the crosslinker concentration 10.86 × 10^-2 mol/L, and the basicity to AA 0. 70（ mol/mol ）. Both the graft copolymers have an excellent water absorption capacity in distilled water aact in 0. 9wt% NaCl solution. It was also found that in distilled water the water absorbency of St-g-pAA was higher than that of St-g-p（ AA-co-AM） , while in 0.9wt% NaCl solution, the situation was just the reverse. The correlation between the water absorbeacy anct the nature of the solution anct the properties of the copolymers, which is related to the properties of the monomers, was discussed. The grafting of AA ancl AM onto starch was confirmed by the IR spectra of St-g-pAA and St-g-p（ AA-co-AM）.

SYNTHESIS AND CHARACTERIZATION OF GRAFT COPOLYMERS BASED ON POLY(p-PHENYLENE TEREPHTHALAMIDE) BACKBONE AND WELL-DEFINED POLYSTYRENE SIDE CHAINS

A novel dualfunctional monomer, 2-（2＇,2＇,6＇,6＇-tetramethyl-piperidinyl-1＇-oxy）methylbenzene-1,4-dioyl chloride hydrochloride, with two acid chloride groups for step-growth polymerization and a nitroxide group for the mediation of living radical polymerization was synthesized. It was first copolymerized with terephthaloyl chloride and p- phenylenediamine at a feed molar ratio of 1：3：4 in N-methyl-2-pyrrolidone containing 10 wt% calcium chloride at -10℃ to yield a poly（p-phenylene terephthalamide） based macroinitiator, which initiated radical polymerization of styrene at 125℃ to obtain a series of poly（p-phenylene terephthalamide）-g-polystyrenes. A combinatory analysis of proton nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, elementary analysis, thermogravimetry and gel permeation chromatography indicated that the macroinitiator induced the radical polymerization of styrene to proceed in a well- controlled way. The molecular weight of side-chains increased with an increase of monomer conversion, and the molecular weight distribution index remained lower than 1.5. The graft copolymers showed a remarkably improved solubility in N- methyl-2-pyrrolidone and much depressed crystallinity in bulk.

Graft Polymerization of Acryloyloxystarch with Poly (D, L-lactide) Macromonomer——A Potential Drug Delivery Carrier for Oral Administration

Starch is the second largest natural biopolymer. Its unique biodegradable and biocompatible properties make it be increasingly applied to the field of biomedicine. As one kind of polysaccharide, starch is easily degraded into small organic molecules by amylase in the alimentary canal. The fact that the activity of amylase is restrained in the high acid environment in stomach provides an opportunity to prepare an intestinal-specific delivery carrier with

Synthesis of Poly(acrylic acid)-Grafted Carboxymethyl Cellulose for Efficient Removal of Copper Ions

Biocompatible and high content grafted carboxymethyl cellulose-g-poly(acrylic acid)powder was successfully synthesized in an aqueous system,and used as adsorbents for the removal of Cu(II)in aqueous solution.The copolymer was characterized by FT-IR and SEM techniques.Graft copolymerization introduced a large number of carboxyl groups in the polymer and caused the micro-surface of the material to be porous.The fundamental adsorption behaviors of the material were studied.The adsorption kinetics was well fitted with pseudo-second order equation,while the adsorption isotherm preferred to be described the Langmuir equation.The maximum adsorption capacity obtained from the Langmuir model was 154.32 mg/g,indicating that the adsorption capacity of carboxymethyl cellulose was improved remarkably after grafting poly(acrylic acid).Moreover,Fourier transform infrared spectroscopy(FT-IR)has been used to investigate the adsorption mechanisms at molecular levels,which revealed that carboxyl groups are facile to form bidentate carboxylates with metal ions.Thus,this environment friendly copolymer will be a promising candidate for application in removal of heavy metal ions.