Synthesis and properties of polycarbonate‐poly(methyl methacrylate) graft copolymers by polycondensation of macromonomers

Polycarbonates (PCs) having poly(methyl methacrylate)s (PMMAs) as graft chains were prepared by the polycondensation of PC oligomers bearing chloroformate groups as the end groups with dicarboxyl‐terminated PMMA macromonomers, which were prepared by the radical polymerization of methyl methacrylate in the presence of thiomalic acid as a chain transfer. The resulting PC‐PMMA graft copolymers were transparent in comparison with PC/PMMA blend polymers, and had higher Vickers hardness than blend polymers when both of them had the same PMMA content. According to the results of multiple regression analysis, the improvement of Vickers hardness was conducive to length (46%) and number (37%) of PMMA branches. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2670–2675, 2001     

Synthesis and characterization of amphiphilic graft copolymer poly(ethylene oxide)-graft-poly(methyl acrylate)

A novel well-defined amphiphilic graft copolymer of poly(ethylene oxide) as main chain and poly(methyl acrylate) as graft chains is successfully prepared by combination of anionic copolymerization with atom transfer radical polymerization (ATRP). The glycidol is protected by ethyl vinyl ether first, then obtained 2,3-epoxypropyl-1-ethoxyethyl ether (EPEE) is copolymerized with EO by initiation of mixture of diphenylmethyl potassium and triethylene glycol to give the well-defined poly(EO-co-EPEE), the latter is deprotected in the acidic conditions, then the recovered copolymer [(poly(EO-co-Gly)] with multi-pending hydroxyls is esterified with 2-bromoisobutyryl bromide to produce the ATRP macroinitiator with multi-pending activated bromides [poly(EO-co-Gly)_(ATRP)] to initiate the polymerization of methyl acrylate (MA). The object products and intermediates are characterized by NMR, MALDI-TOF-MS, FT-IR, and SEC in detail. In solution polymerization, the molecular weight distribution of the graft copolymers is rather narrow (M_w/M_n < 1.2), and the linear dependence of Ln [M₀]/[M] on time demonstrates that the MA polymerization is well controlled.     

含规整 PMMA支链的 PBA合成及其力学性能

研究了聚甲基丙烯酸甲酯大单体与丙烯酸丁酯在苯中的共聚，该大单体由甲基丙烯酸甲酯在巯基乙酸链转移剂存在下聚合，用甲基烯酸缩不甘油酯封端，研究了共聚速率、大单体相对分子质量、大单体与小单体投料比、引发剂用量、单体浓度及共聚温度对接枝效率及共聚物相对分子质量的影响。用分级沉淀法精制共聚物。用凝胶渗透色谱法、红外光谱法及差示扫描量热法对共聚物进行表征，用蒸汽压式渗透压力计及膜渗透压测定了结构参数，结果表明，平均接枝数随转化率增加而降低，在一定的组成范围内，共聚物呈热塑性弹性体行为。     

Synthesis and characterization of starch‐poly(methyl methacrylate) graft copolymers

The graft copolymerization was carried out by methyl methacrylate with starch in which azobisisobutyronitrile was used as an initiator. The grafting reactions were carried out within a 65–95°C temperature range, and the effect of the monomer, initiator concentrations, and the amount of starch on the graft yield were also investigated. The maximum graft yield was obtained at a azobisisobutyronitrile concentration of 2.0 × 10^?3 mol/L. The overall rate activation energy of the reaction was found to be 89.42 kJ/mol. The grafted starches were characterized with infrared spectroscopy, scanning electron microscopy, and thermogravimetry. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 53–57, 2002     

Synthesis of poly(epichlorohydrin‐g‐methyl methacrylate) graft copolymers by the combination of cationic and atom transfer radical polymerization

Poly(epichlorohydrin) possessing chloromethyl side groups in the main chain was used in the atom transfer radical polymerization of methyl methacrylate and styrene to yield poly(epichlorohydrin‐g‐methyl methacrylate) and poly(epichlorohydrin‐g‐styrene graft copolymers. The polymers were characterized by ¹H NMR spectroscopy, gel permeation chromatography, differential scanning calorimetry, and fractional precipitation method. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2725–2729, 2006     

Synthesis and characterization of poly(hydroxamic acid) chelating resin from poly(methyl acrylate)‐grafted sago starch

A new chelating ion‐exchange resin containing the hydroxamic acid functional group was synthesized from poly(methyl acrylate) (PMA)‐grafted sago starch. The PMA grafted copolymer was obtained by a free‐radical initiating process in which ceric ammonium nitrate was used as an initiator. Conversion of the ester groups of the PMA‐grafted copolymer into hydroxamic acid was carried out by treatment of an ester with hydroxylamine in an alkaline solution. The characterization of the poly(hydroxamic acid) chelating resin was performed by FTIR spectroscopy, TG, and DSC analyses. The hydroxamic acid functional group was identified by infrared spectroscopy. The chelating behavior of the prepared resin toward some metal ions was investigated using a batch technique. The binding capacities of copper, iron, chromium, and nickel were excellent and the copper capacity was maximum (3.46 mmol g⁻¹) at pH 6. The rate of exchange of the copper ion was very fast that is, t_1/2 < 5 min. It was also observed that the metal ion‐sorption capacities of the resin were pH‐dependent and its selectivity toward the metal ions used is in the following order: Cu²⁺ > Fe³⁺ > Cr³⁺ > Ni²⁺ > Co²⁺ > Zn²⁺ > Cd²⁺ > As³⁺ > Pb²⁺. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1256–1264, 2001     

Physical properties of poly(vinyl chloride)–grafted N‐isopropylacrylamide graft copolymers and corresponding polyblends

The physical properties of poly(vinyl chloride) (PVC) and poly(N‐isopropylacrylamide) [poly(NIPAAm)] blend systems, and their corresponding graft copolymers such as PVC‐g‐NIPAAm, were investigated in this work. The compatible range for PVC–poly(NIPAAm) blend systems is less than 15 wt % poly(NIPAAm). The water absorbencies for the grafted films increase with increase in graft percentage. The water absorbencies for the blend systems increase with increase in poly(NIPAAm) content within the compatible range for the blends, but the absorbencies decrease when the amount of poly(NIPAAm) is more than the compatible range in the blend system. The tensile strengths for the graft copolymers are larger than the corresponding blends. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 170–178, 2000     

Studies with gradient polymers of polystyrene and poly(methyl acrylate)

A series of [net-polystyrene]-ipn-[net-poly(methyl acrylate)] systems with gradients of poly(methyl acrylate) in a polystyrene matrix are prepared and tested mechanically. The results showed no distinct differences from that of corresponding interpenetrating polymer network (IPN) samples with similar compositions, in contrast to the substantially improved fracture strains obtained for [net-poly(methyl methacrylate)]-ipn-[-net poly(methyl acrylate)] gradient systems and their nongradient IPN's in our previous work. Hence, it is concluded that the toughening effect of gradient structure observed is not universally applicable for all gradient systems but it is unique for the acrylic system studied. Moduli-temperature responses and dynamic mechanical spectra of gradients and IPN's prepared in the current study are also presented. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1721–1725, 1999     

聚丙烯酸甲酯接枝改性纳米纤维素

利用羰基二咪唑(CDI)的高活性活化纳米纤维素(NCC),使NCC表面带有高反应活性的碳碳双键。再以2-溴异丁酸乙酯为引发剂,铜丝为催化剂,制备出低分子量的聚丙烯酸甲酯(PMA)。然后采用活性自由基聚合将PMA接枝到活化的NCC表面,制备出PMA接枝改性的NCC。采用凝胶渗透色谱测定合成的PMA的分子量及分子量分布;通过傅立叶变换红外光谱及X射线衍射分析等测试方法对改性前后的NCC的结构和性能进行了分析。实验结果表明,通过单电子转移活性自由基聚合法合成的PMA分子量为2 000,分子量分布窄(分布指数为1.14),并且其成功接枝到NCC表面。     

Controlled release of carboxylic‐containing herbicides by starch‐g‐poly(butyl acrylate)

The use of starch‐g‐poly(butyl acrylate) as a new material for encapsulating carboxylic‐containing herbicides such as 2,4‐dichlorophenoxyacetic acid and 2,4,5‐trichlorophenoxyacetic acid for controlled release was studied. The herbicides were individually encapsulated within the modified starch substrate, which was graft‐copolymerized with a small amount of butyl acrylate. The modification of starch induced a hydrophobic behavior in the matrix, made it swell less, and caused the release rate to slow, especially for herbicides with higher water solubility. Therefore, the survival life of the starch products for controlled release could be expected to extend to some extent compared with that of natural starch. In addition, the effects of the molecular weight, herbicide content, and particle size on the swellability and release behavior were also investigated. Scanning electron microscopy revealed that the herbicides encapsulated within the starch matrix were dispersed in the form of tiny cell. Consequently, the herbicides encapsulated were released through diffusion. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1535–1543, 2001     

Microwave polymerization of poly(methyl acrylate): Conversion studies at variable power

Methyl acrylate (MA) was polymerized by microwave radiation at three different powers, namely, 200, 300, and 500 W. The percentage conversion of the reaction was followed by Fourier transform infrared (FTIR) spectroscopy. The specimen temperature during the polymerization process was measured to select a suitable temperature for comparison with the conventional method. The results indicate that a similar comparable temperature of about 52° was found for all the microwave power settings tested. The microwave polymerization process was compared with that of the thermal method at 52(±1)° under comparable reaction conditions. The reaction rate enhancement of the microwave polymerization compared to the thermal method was found to be as follows: 275% for the 500 W, 220% for the 300 W, and 138% for the 200 W, indicating a significant correlation between the reaction rate enhancement and the level of microwave power used.     

The study of surface segregation and the formation of gradient domain structure at the blend of poly(methyl methacrylate)/poly(dimethyl siloxane) graft copolymers and acrylate adhesive copolymers

The effect of siloxane chain length on surface segregation of poly(methyl methacrylate)‐grafted poly(dimethyl siloxane) (PMMA‐g‐PDMS)/poly(2‐ethylhexyl acrylate‐co‐acrylic acid‐co‐vinyl acetate) [P(2EHA‐AA‐VAc)] blends was investigated. The blends of PMMA‐g‐PDMS with P(2EHA‐AA‐VAc) showed surface segregations of PDMS components. The surface enrichments of PDMS in the blends depended significantly on the PDMS chain length. Also, this blend showed the gradient domain structure. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 375–380, 2003     

Effect of poly(ethylene methyl acrylate) copolymer on thermal,morphological, and mechanical properties of polypropylene copolymer blown films

Blends of polypropylene copolymer (PP‐cp) and poly(ethylene methyl acrylate) [poly(EMA)] copolymer blends were processed by blown film extrusion. The orientation and crystallinity of PP‐cp matrix in the blend did not change significantly with the addition of EMA. The low machine direction and transverse direction tear strengths, which are observed for neat polypropylene blown films more than doubled at 6 wt % or higher content of EMA. The increase in tear properties was mainly attributed to a fine dispersion of EMA in the matrix with an average particle size of 100–500 nm and the formation of elongated domains. The dispersed nonrounded EMA domains, resulting from the blown‐film process, enhance better energy dissipation mechanism with the formation of an extended plastic zone in the blend films as compared with that in pure PP‐cp films. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of poly(methylphenylsilylene)–poly(ethylene oxide) and poly(methylphenylsilylene)–polyisoprene multiblock copolymers

Multiblock copolymers were synthesized through condensation reactions of end‐groups of α,ω‐dichloro‐poly(methylphenylsilylene) with hydroxyl end‐groups of poly(ethylene glycol) or the chain‐ends of ‘living’ polyisoprenyl disodium. Optimum conditions have been sought through kinetic studies and by investigation of model reactions. The overall molecular weight distribution of poly(methylphenylsilylene)‐block‐poly(ethylene oxide) is characterized in terms of Flory's theory of condensation reactions, while the limiting step in the reaction is tentatively attributed to the formation of aggregates. © 2001 Society of Chemical Industry     

Structure development in the phenolic resin/poly(methyl methacrylate-co-ethyl acrylate) copolymer blends

Single-phase mixtures of phenolic derivatives with three poly(methyl methacrylate-co-ethyl acrylate) copolymers [P(MMA-co-EA)s] were cured in the presence of hexamethylenetetramine and the reaction kinetics and phase-separation processes during cure were investigated by differential scanning calorimetry (DSC), light scattering, and optical microscopy (OM). DSC measurements revealed that the higher the fraction of multifunctional phenols in the total phenols the lower the conversion at gelation in the phenolic-rich phase. The time variation of the light-scattering profile during cure demonstrated the characteristic feature for spinodal decomposition. OM observation revealed that a cocontinuous two-phase structure appeared after a certain time lag and coarsened to a spherical domain structure consisting of phenolic resin particles dispersed in the P(MMA-co-EA)s matrix. The periodic distances, Λ_m, in the phase-separated structure changed with curing time: (1) The higher the component of MMA in P(MMA-co-EA)s and (2) the higher the fraction of multifunctional phenols in the total phenols, the smaller the Λ_m. These results may imply that the phase separation is suppressed by the faster gelation in the phenolic-rich phase so that the phase-separated structure can be fixed by the network formation in the phenolic-rich phase at the early stage of spinodal decomposition. This results in a two-phase structure with a shorter periodic distance. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1829–1837, 1998     

Synthesis of poly(methyl methacrylate‐g‐glycidyl azide) graft copolymers using N,N‐dithiocarbamate‐mediated iniferters

A glycidyl azide polymer with pendent N, N‐diethyl dithiocarbamate groups (GAP‐DDC) was prepared by the reaction of poly(epichlorohydrin) (PECH) with pendent N, N‐diethyl dithiocarbamate groups (PECH‐DDC) and sodium azide (NaN₃) in dimethylformamide (DMF). It was then used as a macro‐photoinitiator for the graft polymerization of methyl methacrylate (MMA). Photopolymerization was carried out in a photochemical reactor at a wavelength greater than 300 nm. Conversion was determined gravimetrically and first‐order time conversion plot for the polymerization system showed linear increase with the polymerization time indicating that polymerization proceed in controlled fashion. The molecular weight distribution (M_w/M_n) was in the range of 1.4–1.6 during polymerization. The formation of poly(methyl methacrylate‐g‐glycidyl azide) (PMMA‐g‐GAP) graft copolymer was characterized by gel permeation chromatography, FT‐IR spectroscopy, Thermogravimetric analysis, and differential scanning calorimetry. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Modification of poly(vinyl chloride) by IPN formation with poly(ethyl acrylate)

Semi‐1 and semi‐2 interpenetrating polymer networks (IPNs) of poly(vinyl chloride) (PVC) and in situ formed poly(ethyl acrylate) (PEA) have been synthesized using diallyl phthalate and ethylene glycol dimethacrylate as the crosslinkers of PVC and PEA, respectively. These two types of IPNs have been compared with respect to their physical, mechanical, and thermal properties and an endeavor has been made to find a correlation of these properties with the morphology generated in these systems. The semi‐1 IPNs displayed a decrease in their tensile strength and modulus while in contrast; the semi‐2 IPNs exhibited a marginal increase with increasing crosslinked PEA incorporation. The semi‐1 and semi‐2 IPNs containing 10 and 30 wt % of PEA displayed a two‐stage degradation typical of PVC in their thermogravimetric and DSC studies while confirming the increased stability of the samples with higher percentages of PEA. The softening characteristics as detected by the extent of penetration of the thermomechanical probe as has been detected by thermomechanical analysis are in conformity with their mechanicals. The biphasic cocontinuous systems as explicit from the morphological studies reveal fibrillar characteristics in both the systems. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Glass‐transition temperature of poly(vinylidene fluoride)‐poly(methyl acrylate) blends: Influence of aging and chain structure

The glass‐transition temperature (T_g) of the poly(vinylidene fluoride) (PVF₂)‐poly(methyl acrylate) (PMA) blends increase with aging time. The T_g versus log(time) plots are straight lines whose slope values depend on the head to head (H–H) defect content of PVF₂ samples and on the composition of the blends. The values of polymer–polymer interaction parameters (χ) increase with an increase in the H–H defect of PVF₂ for a fixed composition of the blend. Consequently, the T_g of the blend decreases with an increase in the H–H defect of the PVF₂ sample. However, after aging for longer times this decrease of the T_g with H–H defects is lower than those of the unaged blends. The possible reasons are discussed. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1541–1548, 2001     

Preparation of poly(tert‐butyl acrylate)‐poly(acrylic acid) amphiphilic copolymers via radiation‐induced reversible addition–fragmentation chain transfer mediated polymerization of tert‐butyl acrylate

Poly(tert‐butyl acrylate) (PtBA) is a versatile hydrophobic macromolecule usually preferred in the development of new materials for a host of applications. PtBA homopolymers with well‐defined structure and controlled molecular weight in a wide range were successfully synthesized via radiation‐induced reversible addition–fragmentation chain transfer (RAFT) polymerization in the presence of a trithiocarbonate type RAFT agent. The polymerization of tBA was performed under ⁶⁰Co γ‐irradiation in the presence of 2‐(dodecylthiocarbonothioylthio)‐2‐methylpropionic acid (DDMAT) as the RAFT agent in toluene at room temperature with three [tBA]/[DDMAT] ratios (400, 600 and 1000) and different irradiation times. Radiation‐induced polymerization of tBA displayed controlled free radical polymerization characteristics: a narrow molecular weight distribution (M_w/M_n ~ 1.1), pseudo first order kinetics and controlled molecular weights. The system followed the RAFT polymerization mechanism even at very low amounts of RAFT agent ([tBA]/[DDMAT] = 1000), and molecular weights up to 113 900 with narrow dispersity (Ð =1.06) were obtained. PtBA was further hydrolysed into different amphiphilic PtBA‐co‐poly(acrylic acid) (PAA) copolymers by low (27.5%) and high (77.3%) degrees of hydrolysis. The pH sensitivity of the two copolymers was investigated by dynamic light scattering at pH 2 and pH 9 (above and below the pK_a value of PAA) and their hydrodynamic diameters and zeta potential values were determined. © 2020 Society of Chemical Industry     

粒径可控的聚丙烯酸丁酯/聚甲基丙烯酸甲酯核壳乳液的制备及表征

采用种子乳液聚合法制备了聚丙烯酸丁酯(PBA)乳液,然后通过第二单体甲基丙烯酸甲酯的预溶胀法聚合制备了PBA/聚甲基丙烯酸甲酯(PMMA)乳液,用激光散射粒度仪和透射电子显微镜对乳液粒径和结构进行了表征.结果表明,当乳化剂十二烷基硫酸钠质量分数为丙烯酸丁酯的1.5%时,可制备粒径为53.6 nm且分布窄的PBA种子乳液;通过调整补加乳化剂、单体与种子乳液的用量,可制得粒径为53.6～443.8 nm的一系列单分散PBA乳液;PBA/PMMA乳液具有完善的核壳结构,且在核壳两相间存在着一个过渡层.