Copolymerization of aromatic polyamide macromonomers with methyl methacrylate

Summary Graft copolymers of end methacrylate-functionalized[MacroAM] or styrene-functionalized[MacroAS] polyamide macromonomers with methyl methacrylate(MMA) were prepared by radical copolymerization, and their thermal, dynamic properties, and miscibility with matrix PMMA have been investigated. The glass transition temperature(Tg)s of the copolymers were significantly elevated with the increase of the macromonomer content in the copolymer. Storage modulus E of the graft copolymers began to decrease at around 85°C, which is close to Tg of PMMA, irrespective of the macromonomer content in the copolymers. As the macromonomer content and its degree of polymerization became higher, the drop in E became significant.     

Poly(dimethylsiloxane)urethane‐co‐poly(methyl methacrylate) with 2,4‐toluene diisocyanate and m‐xylene diisocyanate. I. Compatibility and impact strength of copolymers

In this study, slightly crosslinked poly(dimethylsiloxane)urethane‐co‐poly(methyl methacrylate) (PDMS urethane‐co‐PMMA) graft copolymers based on two diisocyanates, 2,4‐toluene diisocyanate (2,4‐TDI) and m‐xylene diisocyanate (m‐XDI), were successfully synthesized. Glass‐transition behaviors of the copolymers were investigated. Results confirm that PDMS–urethane and PMMA are miscible in the 2,4‐TDI system, but are only partially miscible in the m‐XDI system. The methylene groups adjoining the isocyanate in the m‐XDI system show increased phase‐separation behavior over the 2,4‐TDI system, in which the benzene ring adjoins the isocyanate. The functional group of PDMS–urethane improves the impact strength of the copolymers. The toughness depends on the compatibility of PDMS–urethane and PMMA segments in the copolymers. In the m‐XDI system, the impact strength of the copolymer containing 3.75 phr macromonomer achieves a maximum value (from 13.02 to 22.21 J/m). The fracture behavior and impact strength of the copolymers in the 2,4‐TDI system are similar to that of PMMA homopolymer, although they are independent of the macromonomer content in the copolymer. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1875–1885, 2002     

Surface modification of polymethyl methacrylate by graft copolymers

Summary Graft copolymers composed of poly(methyl methacrylate) branches and different backbones of poly(fluoroalkyl acrylate(FA)-co-methyl methacrylate(MMA)), poly (hydroxyethyl methacrylate(HEMA)-co-MMA), and poly(FA-co-HEMA) were prepared by macromonomer technique to study their application as a surface modifier for PMMA films. Contact angle of water droplet on PMMA film specimens containing various amounts of these graft copolymers cast on glass slides from THF solution was found to change considerably with the graft copolymer concentration, depending on their backbone component. And there was considerable difference in contact angle between air and glass side of the film surfaces. These results were considered in terms of the surface accumulation of graft copolymers during the solvent evaporation.     

Effects of compatibilizing agents in poly(n-butyl acrylate)/poly(methyl methacrylate) composite latexes

Graft copolymers with poly(n-butyl acrylate) (PBA) backbones and poly(methyl methacrylate) (PMMA) macromonomer side chains are used as compatibilizing agents for PBA/PMMA composite latexes. The composite latexes are prepared by seeded emulsion polymerization of methyl methacrylate (MMA) in the presence of PBA particles. Graft copolymers were already incorporated into the PBA particles prior to using these particles as seed via miniemulsion (co)polymerization of n-butyl acrylate (BA) in the presence of the macromonomers. Comparison between size averages of composite and seed particles indicates no secondary nucleation of MMA during seeded emulsion polymerization. Transmission electron microscopy (TEM) observations of composite particles show the dependence of particle morphologies with the amount of macromonomer (i.e., mole ratio of macromonomer to BA and molecular weight of macromonomer) in seed latex. The more uniform coverage with the higher amount of macromonomer suggests that graft copolymers decrease the interfacial tension between core and shell layers in the composite particles. Dynamic mechanical analysis of composite latex films indicates the existence of an interphase region between PBA and PMMA. The dynamic mechanical properties of these films are related to the morphology of the composite particles, the arrangement of phases in the films, and the volume of the interphase polymer. © 1997 John Wiley & Sons, Inc.     

Application of graft copolymers using macromonomer method to two-component polyurethane coatings

Graft copolymers as acrylic polyols in two-component polyurethane coatings were prepared by the free-radical copolymerization of methyl methacrylate, n-butyl methacrylate, n-butyl acrylate, acrylic acid, 2-hydroxyethyl methacrylate and poly(methyl methacrylate)-macromonomers. The poly(methyl methacrylate) macromonomer was prepared by the polymerization of methyl methacrylate in the presence of thiopropionic acid as a transfer agent followed by the reaction with glycidyl methacrylate. These polymers, whose numbers of poly(methyl methacrylate) macromonomer branches and the molecular weights of the poly(methyl methacrylate) macromonomer branches were controlled, offer an advantage over conventional resins with respect to the application/appearance of coatings as well as the final film properties. Some of these advantages were higher solids and a better control of the coating rheology, an increase in the cross-linking reactivity of the polyols with polyisocyanate and improvement in film toughness. The change in the morphological structure of the films under tensile stress was of particular interest.     

用X射线衍射法研究接枝共聚物PSt-g-PEO和PMA-g-PEO及其金属盐络合物的结晶性能

采用广角X射线衍射法研究了以聚苯乙烯(PSt)或聚丙烯酸甲酯(PMA)为主链,聚环氧乙烷(PEO)为支链的接枝共聚物及其金属盐络合物的结晶性能。结果表明,在PEO支链分子量相同,且含量相近的情况下,PMA-g-PEO的结晶度(x_0)比PSt-g-PEO小;在金属盐与EO的络合比及其他条件相同的情况下,不同金属盐降低x_0的能力为LiClO_4>KSCN>FeCl_2;接枝共聚物及其金属盐络合物的x_0均随着PEO支链含量的增加而增加。     

Syntheses of polyamide-poly(methyl methacrylate) graft copolymers by polycondensation reactions of macromonomers

Summary Dicarboxyl-terminated macromolecular monomers (macromonomers) were synthesized by radical polymerization of methyl methacrylate in the presence of thiomalic acid as a chain transfer agent. This macromonomer and sebacic acid were condensed with diamines (p,p-diaminodiphenyl ether, p,p-diaminodiphenylmethane and m-phenylenediamine) by triphenylphosphitepyridine system. Thus, graft copolyamides of well-defined structure and composition were readily prepared. This is the first example of the polycondensation reactions of macromonomers.     

Copolymerization of polyvinylpyridine macromonomers with styrene

Summary Free radical Copolymerization of ( -methylstyryl) poly (2-vinylpyridine) macromonomers with styrene was performed. After separation of residual macromonomer the graft copolymers were submitted to a careful characterization.The copolymers were generally of rather low molecular weight and the average number of grafts per backbone chain was found close to unity. Nevertheless, these polymeric species tend to give aggregates and/or emulsions in selective solvents of the grafts, a typical behaviour of graft copolymers.     

Intermolecular and intramolecular hydrogen bonding of poly(dimethylsiloxane)urethane‐graft–poly(methyl methacrylate) copolymers based on 2,4‐TDI and m‐XDI

In this study, poly(dimethylsiloxane)urethane–graft–poly(methyl methacrylate) (PDMS urethane–g–PMMA) copolymers with low crosslinking density were synthesized. Glass transition temperatures of the copolymers were investigated by dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC). Results confirm that PDMS urethane–g–PMMA is miscible in the 2,4‐TDI (2,4‐ toluene diisocyanate) system, whereas it is partially miscible in the m‐XDI (m‐xylene diisocyanate) system. Free, intra‐ (urethane–urethane), and inter‐ (urethane–ester) association hydrogen bonding exist in the urethane group of copolymers. The inter‐association hydrogen bonding can improve the compatibility of the copolymer components. The relationship between the frequency shift and enthalpy confirm the distribution of hydrogen bonding in the macromonomer and copolymer. Ninety percent of the hydrogen bonding is by interassociation in the 2,4‐TDI system. The intra‐association hydrogen bonding in the m‐XDI system is higher than that in the 2,4‐TDI system. Consequently, aggregation may occur easily in the siloxane‐grafted chain in the m‐XDI system. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 962–972, 2002     

Synthesis of ABA block Co-Oligomers of polymethylmethacrylate and poly (dimethylsiloxane)

A methoxysilyl macromonomer containing an acrylic chain is obtained by telomerization of methyl methacrylate with mercaptopropylmethyldimethoxysilane. This macromonomer is then reacted with a polydimethylsiloxane hydroxytelechelic leading to new block Co-Oligomers with acrylic and siloxane moieties.     

Synthesis of amphiphilic network copolymers based on poly(ester dimethacrylates)

Poly(ester dimethacrylate) has been synthesized by condensation of the ɛ-caprolactone-based macromonomer and 2-hydroxyethyl methacrylate with dicyclohexylmethane diisocyanate. Network copolymers of different compositions capable of swelling in water, THF, and toluene are obtained by the free-radical copolymerization of poly(ester dimethacrylate) with N-isopropylacrylamide or 2-hydroxyethyl methacrylate. The rate constants and equilibrium swelling indices of network copolymers in these solvents are measured. The amphiphilic properties of the network copolymers can vary in a wide range depending on the composition of copolymers and the nature of a hydrophilic monomer. The copolymers of poly(ester dimethacrylate) with N-isopropylacrylamide are characterized by pronounced thermal sensitivity.     

Synthesis of poly(tetrahydrofuran-b-ε-caprolactone) macromonomer via the Sml2-induced transformation

Summary A novel well-defined macromonomer consisting of different types of monomers in polymerization mechanisms was synthesized for the first time through the SmI₂-induced transformation. The macromonomer, -methacryloylpoly-(tetrahydrofuran-b--caprolactone), was prepared by the reaction of methacryloyl chloride with living poly(tetrahydrofuran-b--caprolactone) [poly(THF-b-CL)] which was obtained by the two-electron reduction of the cationic growing center of poly(THF) by samarium iodide (SmI₂) followed by the polymerization of CL. ¹H NMR analysis indicated the quantitative introduction of the methacryloyl group onto the polymer end. The molecular weight distribution of the macromonomer was relatively narrow, and the unit ratio of THF to CL could be controlled by both polymerization time of THF and the amount of CL, resulting from the living nature of both CL- and THF-polymerizations. Radical copolymerization of the produced macromonomers with methyl methacrylate in the presence of AIBN resulted in a polymethacrylate backbone grafted with poly(THF-b-CL) block copolymers.     

Copolymerizations of macromonomer prepared by addition-fragmentation chain transfer polymerization of methyl acrylate trimer

Summary An oligomer of the methyl acrylate unsaturated trimer bearing 2-carbomethoxy-2-propenyl ω-end group (M _n = 1300, M _w/M _n = 1.7, and functionality > 0.7) was copolymerized as a macromonomer (0.02 mol/L) with styrene (1.0 mol/L) in benzene at 60 °C. The amounts of monomer and macromonomer in the feed simultaneously decreased with increasing time to indicate copolymer formation, and the macromonomer was found to be as reactive as styrene toward poly(styrene) radicals. The M _ns of the copolymers were 13900–22000 depending on conversion. No resonance due to the unsaturated <ω-end group bound to the poly(styrene) chain was detected by ¹H-NMR spectroscopy, indicating that no fragmentation of adduct radical of the end group to expel the poly(methyl acrylate trimer) radical. Polymerization of ethyl methacrylate (1.0 mol/L) in the presence of the macromonomer (0.02 mol/L) resulted in a mixture of the unreacted macromonomer and homopolymer of ethyl methacrylate. No end group bound to the poly(ethyl methacrylate) was detected by ¹H-NMR spectroscopy, excluding the possibility of addition fragmentation chain transfer to the macromonomer to expel an oligomer radical of the methyl acrylate trimer. Addition of the poly(methacrylate) radical to the macromonomer is extremely slow under the present conditions of copolymerization. Received: 27 March 2003/Revised version: 30 April 2003/ Accepted: 30 April 2003 Correspondence to Bunichiro Yamada     

ESR studies of the photodegradation of cellulose graft copolymers

Ultraviolet light induced free radicals in cellulose and cellulose graft copolymers were studied by means of ESR spectroscopy. At least six kinds of free radicals were formed in cellulose when the polymer was irradiated with ultraviolet light. Polystyrene and poly(methyl methacrylate) are more resistant to ultraviolet light than cellulose; however, the cellulose graft copolymers of polystyrene and poly(methyl methacrylate) were degraded by ultraviolet light. ESR studies revealed that photoinduced free radicals in cellulose graft copolymers were formed at the grafting branches of the copolymers rather than the cellulose backbone. The mechanisms of light stabilization and energy transfer reactions of cellulose and cellulose graft copolymers are discussed.     

Synthesis of graft copolymers from a linear polyolefin through a combination of coordination polymerization and atom transfer radical polymerization

This article reports on a facile route for the preparation of methyl acrylate and methyl methacrylate graft copolymers via a combination of catalytic olefin copolymerization and atom transfer radical polymerization (ATRP). The chemistry first involved a transforming process from ethylene/allylbenzene copolymers to a polyolefin multifunctional macroinitiator with pendant sulfonyl chloride groups. The key to the success of the graft copolymerization was ascribed to a fast exchange rate between the dormant species and active radical species by optimization of the various experimental parameters. Polyolefin‐g‐poly(methyl methacrylate) and polyolefin‐g‐poly(methyl acrylate) graft copolymers with controlled architecture and various graft lengths were, thus, successfully prepared under dilute ATRP conditions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

自交联型水性丙烯酸-聚氨酯杂化体的合成

以聚环氧丙烷二醇(PPG)、1,6-丁二醇(HDO)、二羟甲基丙酸(DMPA)、甲苯二异氰酸酯(TDI)及丙烯酸β-羟乙酯(HEA)为主要原料合成水性聚氨酯大单体。用该水性聚氨酯大单体为表面活性剂,用甲基丙烯酸甲酯(MMA)、丙烯酸丁酯(BA)、丙烯酸-β-羟乙酯(HEA)、甲基丙烯酸(MAA)和交联单体等单体,以半连续乳液聚合工艺合成了核壳结构水性丙烯酸-聚氨酯杂化体。讨论了合成工艺对产品性能的影响。     

Effect of temperature on the solution properties in 2-ethoxyethanol of statistical copolymers of methacrylic acid and methyl methacrylate

Summary The temperature dependence of the second virial coefficient and intrinsic viscosity of statistical copolymers of methyl methacrylate and methacrylic acid in 2-ethoxyethanol was investigated. It was found that the -temperatures of copolymers are outside the temperature range given by the -values for poly(methacrylic acid) and poly(methyl methacrylate). Their dependence on the copolymer composition has a discontinuity. Simple theoretical considerations have shown that this behaviour may be expected with copolymers composed of monomer units dissolving, respectively, with absorption and evolution of heat.     

Preparation and characterization of poly(vinyl alcohol-co-methyl methacrylate) copolymers

Summary An investigation is presented of the preparation and characterization of poly(vinyl alcohol-co-methyl methacrylate) copolymers which can be used for the preparation of novel membranes. These polymers were prepared by copolymerization of vinyl acetate and methyl methacrylate by -irradiation, followed by methanolysis of the produced copolymers. IR and ¹H-NMR studies established the structure of the copolymers.On sabbatical leave from the Department of Chemical Engineering, Sung Kyun Kwan University, Suwon 170-00, Republic of Korea.     

Process variables and their effects on grafting reactions of styrene and methyl methacrylate onto natural rubber

The graft copolymerization of styrene and methyl methacrylate onto natural rubber latex was studied under various reaction conditions using a cumene hydroperoxide redox initiator. The monomer conversion, graft copolymer compositions, and grafting efficiency were determined. The synthesized graft copolymers were purified and then characterized by proton nuclear magnetic resonance (¹H‐NMR) analysis and differential scanning calorimetry (DSC). A 2 fractional factorial experimental design was applied to study the main effects on the grafting. The variables investigated in this work were the amount of the initiator and emulsifier, the presence or absence of a chain‐transfer agent, the styrene‐to‐methyl methacrylate ratio, the monomer‐to‐rubber ratio, and the reaction temperature. The measured response for the experimental design was the grafting efficiency. The analysis of the results from the design showed the sequence of the main effects on the observed response of the grafting of styrene and methyl methacrylate onto natural rubber, in ascending order. The amount of the chain‐transfer agent and the reaction temperature in the range of the test had significant effects and one marginally significant effect was the monomer‐to‐rubber ratio. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 63–74, 2003     

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