Characterization and degradation of the poly(methylphenylsiloxane)–poly(methyl methacrylate) graft copolymer

Poly(methylphenylsiloxane)–poly(methyl methacrylate) graft copolymers (PSXE-g-PMMA) were prepared by condensation reaction of poly(methylphenylsiloxane)-containing epoxy resin (PSXE) with carboxyl-terminated poly(methyl methacrylate) (PMMA), and they were characterized by gel permeation chromatography (GPC), infrared (IR), and ²⁹Si and ¹³C nuclear magnetic resonance (NMR). The microstructure of the PSXE-g-PMMA graft copolymer was investigated by proton spin–spin relaxation T₂ measurements. The thermal stability and apparent activation energy for thermal degradation of these copolymers were studied by thermogravimetry and compared with unmodified PMMA. The incorporation of poly(methylphenylsiloxane) segments in graft copolymers improved thermal stability of PMMA and enhanced the activation energy for thermal degradation of PMMA. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2521–2530, 1998     

Synthesis and characterization of random copolymers of (2,2-dimethyl-1,3-dioxolan-4-yl)methyl methacrylate and 2,3-dihydroxypropyl methacrylate

Poly[(2,2-dimethyl-1,3-dioxolan-4-yl)methyl methacrylate)] [poly(solketal methacrylate) (PSMA)] was synthesized by free radical polymerization. By partial hydrolysis of the acetal group, random copolymers of SMA with 2,3-dihydroxypropyl methacrylate (DHPMA) were synthesized whereas complete cleavage lead to poly(2,3-dihydroxypropyl methacrylate) (PDHPMA). The copolymer composition was determined by ¹H NMR spectroscopy. FTIR spectroscopy indicates the synthesis of random copolymers with different degrees of hydrogen bonding as measured by a shift of the OH vibration bands. The glass transition temperature of the random copolymers increases linearly with increasing DHPMA content, resulting in a positive deviation from the Fox equation. The thermal degradation of both homopolymers and their random copolymers has been studied. Finally, the solution behaviour of the copolymers and PDHPMA in water studied by dynamic light scattering showed a strong tendency of the polymer chains to form clusters in the size range of 15-62 nm. The size and the kind of associating interactions within the clusters strongly depend on the copolymer composition.     

Free Radical Initiated Polymerization of N-[4-N′ -{(4-chlorophenyl) amino-carbonyl} phenyl] Maleimide and Characterization of Homopolymer and Copolymers with MMA

N-[4-N′ -{(4-chlorophenyl) amino-carbonyl} phenyl] maleimide (N-CPACPMI) was prepared. It was homopolymerized and copolymerized with methyl methacrylate (MMA) in order to study the effect of imide ring in polymer backbone. The copolymer composition was determined by nitrogen element analysis. The monomer reactivity ratio was determined by the Fineman-Ross method. The molecular weight was determined by GPC. The thermal behavior was studied by thermogravimetric analysis. The initial decomposition temperature of polymers were in the 255 to 299°C range.     

Thermal and flammability behaviour of copolymers of N-(2, 4, 6-tribromophenyl)maleimide with some acrylates

The copolymers of N-(2, 4, 6-tribromophenyl)maleimide (TBPMI) with methyl acrylate, methyl methacrylate and acrylonitrile of different composition were prepared by free radical polymerization at low conversion. Their thermal behaviour was established by TGA measurements in helium atmosphere and flammability properties were determined by limiting oxygen index method. The higher TBPMI content in the copolymer led to a higher thermal stability and lower flammability particularly when Sb₂O₃ was used as a synergist.     

Thermal and photo induced reactions in blends of polypropylene and poly(methyl methacrylate)

Thermal Volatilization Analysis (TVA) demonstrates that poly(methyl methacrylate) (PMMA) is stabilized by blending with polypropylene (PP). Although well-defined radical reactions occur in both polymers under 2537 Å radiation, there is no evidence of the formation of block or graft copolymers when blends of the two are irradiated. Preirradiation suppresses the amount of monomeric methyl methacrylate formed on subsequent thermal degradation. The missing methyl methacrylate units appear in the chain fragment fraction. The characteristics of the thermal degradation of blends of unirradiated PP with preirradiated PMMA are similar to those of unirradiated rather than pre-irradiated blends, thus emphasizing the importance of the PP component in determining the thermal stability of blends after irradiation. These observations are discussed mechanistically.     

Poly(styrene peroxide) and Poly(methyl methacrylate peroxide) for Grafting on Unsaturated Bacterial Polyesters

A new soluble terephthaloyl oligoperoxide (OTP) was synthesized by the reaction of terephthaloyl peroxide and 2,5‐dimethyl 2,5‐dihydroperoxy hexane. Thermal polymerization of vinyl monomers (styrene, methyl methacrylate) with OTP yielded poly(styrene peroxide) (PS‐P) and poly(methyl methacrylate peroxide) (PMMA‐P) which are used in the grafting reactions onto medium chain length unsaturated bacterial polyester obtained from soybean oily acids with Pseudomonas oleovorans poly(3‐hydroxy alkanoate), (PHA). PS‐g‐PHA and PMMA‐g‐PHA graft copolymers isolated from related homopolymers were characterizated by ¹H NMR spectrometry, FT‐IR spectroscopy, thermal analysis and gel permeation chromatographic (GPC) techniques. Swelling measurement of the crosslinked graft copolymers were also measured to calculate q_v values.     

Syntheses and polymerizations of novel chiral poly(acrylamide) macromonomers and their chiral recognition abilities

Chiral poly(acrylamide) macromonomers (PMB‐1, PMB‐2, PPAE‐1, and PPAE‐2) were synthesized from 2‐methacryloyloxyethyl isocyanate and prepolymers, that is, poly[(S)‐methylbenzyl acrylamide] or poly(L ‐phenylalanine ethylester acrylamide with a terminal carboxylic acid or hydroxy group. Radical homopolymerizations of poly(acrylamide) macromonomers were carried out under several conditions to obtain the corresponding optically active polymers. A strong temperature dependence on the specific optical rotation was observed for poly(PPAE‐2) in comparison with that for the corresponding prepolymer. This might have resulted from a change in the conformation caused by hydrogen bonds between polymer‐graft branches in the polymacromonomer. Radical copolymerizations of poly(acrylamide) macromonomers with styrene and methyl methacrylate were performed with azobisisobutyronitrile in tetrahydrofuran at 60 °C. Chiroptical properties of the copolymers were slightly influenced by comonomer units. Chiral stationary phases were prepared by the radical polymerization of poly(acrylamide) macromonomers in the presence of silica gel containing vinyl groups on the surface. Some racemic compounds such as menthol and mandelic acid were resolved on the chiral stationary phases for high‐performance liquid chromatography. The conformation based on hydrogen bonds between polymer‐graft branches in the polymacromonomers may play an important role in chiral discrimination. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1726–1741, 2002     

Thermal degradation of bromine-containing polymers. Part 3—Blends of poly(2-bromoethyl methacrylate) and poly(methyl acrylate)

Films of a blend of equal weights of poly(2-bromoethyl methacrylate) (P2BEM) and poly(methyl acrylate) (PMA) were prepared by evaporation of a solution in acetone. The principal characteristics and products of the thermal degradation of the blend were established by the application of thermal analysis and infra-red and mass spectrometric techniques. Similarities to the degradation behaviour of copolymers of 2-bromoethyl methacrylate (2BEM) and methyl acrylate (MA) were noted.     

A Study on End Group Characterization of Poly(phenacyl methacrylate) Polymer Produced by Free Radical Polymerization

Free‐radical homopolymerization and copolymerization of phenacyl methacrylate (PAMA) with methyl methacrylate (MMA) was done using 2,2′‐azobis(isobutyronitrile) (AIBN) as the initiator in 1,4‐dioxane at 60°C. ¹H‐NMR and FT‐IR spectroscopy confirmed the existence of OCH₂ and CH signals and unsaturated structure and CN stretch at the chain end of low molecular weight poly(phenacyl methacrylate)[poly(PAMA)], respectively. The six‐membered ring with both ester and ether at the end group was detected by ¹H‐NMR. In the poly(PAMA), the end groups formed due to chain transfer reactions were found in large concentrations. The mechanism of the formation of end groups has been presented. The behavior of free radical polymerization of PAMA was compared with that of phenoxycarbonylmethyl methacrylate (PCMMA). The molecular weight distribution of the homo and copolymers was determined using gel permeation chromatography. Thermal properties of the polymers were determined using differential thermal analysis (DTA) and thermogravimetric analysis (TGA).     

A Study on End Group Characterization of Poly(phenacyl methacrylate) Polymer Produced by Free Radical Polymerization

Free‐radical homopolymerization and copolymerization of phenacyl methacrylate (PAMA) with methyl methacrylate (MMA) was done using 2,2′‐azobis(isobutyronitrile) (AIBN) as the initiator in 1,4‐dioxane at 60°C. ¹H‐NMR and FT‐IR spectroscopy confirmed the existence of OCH₂ and CH signals and unsaturated structure and CN stretch at the chain end of low molecular weight poly(phenacyl methacrylate) [poly(PAMA)], respectively. The six‐membered ring with both ester and ether at the end group was detected by ¹H‐NMR. In the poly(PAMA), the end groups formed due to chain transfer reactions were found in large concentrations. The mechanism of the formation of end groups has been presented. The behavior of free radical polymerization of PAMA was compared with that of phenoxycarbonylmethyl methacrylate (PCMMA). The molecular weight distribution of the homo and copolymers was determined using gel permeation chromatography. Thermal properties of the polymers were determined using differential thermal analysis (DTA) and thermogravimetric analysis (TGA).     

Self-organization in aqueous solutions of thermosensitive statistical copolymers based on N-(dimethylamino)ethyl methacrylate

Thermo- and pH-responsive statistical copolymers of N-(dimethylamino)ethyl methacrylate and lauryl methacrylate were synthesized by free radical copolymerization. Obtained samples differed in content of hydrophobic components (3 and 6?mol. %). Their molar masses were close to 30,000?g/mol. Self-organization in buffer solutions of copolymers were studied using light scattering and turbidimetry. It was found that copolymers as well as of poly(N-(dimethylamino)ethyl methacrylate) were thermosensitive at pH?>?7. Phase separation temperatures of investigated solutions decreased with dilution and pH increasing. Growth of lauryl methacrylate content in copolymers caused the decrease in phase separation temperatures.     

Friedel-Crafts acylation reactions in copolymers of methyl methacrylate and styrene and in mixtures of the homopolymers

In the presence of SnCl₄ in 1,2-dichloroethane solution, copolymers of styrene and methyl methacrylate undergo a Friedel-Crafts acylation reaction between the ester groups and the ortho position of adjacent styrene units to form a partial ladder polymer. This has been confirmed by infrared and ultraviolet spectral analysis and by observing the influence of substituted styrenes on the rate of the reaction. A similar reaction can be induced to occur between polystyrene and poly(methyl methacrylate). Thermal analysis measurements demonstrate that the degradation properties of copolymers of styrene and methyl methacrylate are profoundly changed by this treatment.     

Synthesis and characterization of a novel polymer electrolyte based on acrylonitrile/N-[4-(aminosulfonyl)phenyl]acrylamide copolymers

<正>Acrylonitrile/N-[4-(aminosulfonyl)phenyl]acrylamide(AN/ASPAA) copolymers were synthesized and used as a host of lithium ion conducting electrolytes.The composition,molecular weight and molecular weight distribution of AN/ASPAA copolymers were determined,and the influence of copolymer composition on the glass temperature of AN/ASPAA copolymers and the ion conductivity of electrolytes were investigated.The molecular weights of AN/ASPAA copolymers were lower than those of AN and ASPAA homopolymers due to the cross-termination reaction.The glass temperatures of AN/ASPAA copolymers increased as the molar fraction of ASPAA units in copolymers increased.The lithium ion conductivities of the polymer electrolytes increased initially as the molar fraction of ASPAA units in copolymers increased,and a maximum conductivity was achieved when the molar fraction of ASPAA in the copolymer was 16.8%.     

Effect of reaction conditions on the homo and copolymerizations of N-(1-naphthyl)acrylamide

In this work, we studied the influence of time reaction and initiator amount on N-(1-naphthyl)acrylamide (NAM) polymerization, in dioxane and DMF. The same was done with three copolymers with methyl methacrylate (MMA). We found that NAM could be incorporated in high proportions in the copolymer. We also found that, with the same reaction time, the amount of benzoyl peroxide (BPO) has little or no effect on the polymerization degree; however reaction rates and yields were affected in DMF. All homopolymers showed a low dispersion (?), even when they were polymerized in solution. All DPNAMs can be classified as monodisperse.     

Thermal degradation and stability of poly(4-vinylpyridine) homopolymer and copolymers of 4-vinylpyridine with methyl acrylate

The thermal stability and degradation behaviour of poly(4-vinylpyridine) (PVP) homopolymer and copolymers of 4-vinylpyridine and methyl acrylate (VP-MA) have been investigated. The reactivity ratios in the copolymerization were determined using an NMR method. The apparent activation energies of the degradation of the homopolymers and copolymers were calculated using the Arrhenius equation.     

Ion transport and relaxation in phosphonium poly(ionic liquid) homo- and co-polymers

In the present work, a poly(ionic liquid) (PIL), poly(triphenyl-4-vinylbenzylphosphonium chloride) and a series of its random copolymers with nonionic hydrophobic poly(methyl methacrylate) (PMMA) are synthesized by conventional free radical polymerization (CFRP) and reversible addition-fragmentation chain-transfer (RAFT) polymerization. The understanding of some fundamental aspects about ion transport and relaxation mechanism in PIL and PIL copolymers are investigated using dielectric spectroscopy via several theoretical models. The influence of copolymer compositions, physical blending of neat PIL and PMMA, size of counter anions (Cl⁻ and TFSI⁻) and variation of molecular weights on thermal stability, moisture sensitivity, ionic transport and relaxation properties are also studied. An enhancement of thermal stability and ionic transport property of the PIL copolymer is observed compared to those of the physically mixed blend of two homopolymers with same compositions. The incorporation of hydrophobic PMMA segment definitely decreases the moisture content in PIL copolymers than the PIL itself. In all these PIL- based systems, the temperature dependence of ionic conductivity, relaxation time and ion diffusivity are well described by Vogel-Tammann-Fulcher model. The studies of some fundamental properties of these new PIL copolymers with less moisture sensitivity may help in using them as potential polymer electrolytes in energy storage devices.     

Synthesis and characterization of anionic graft copolymers containing poly(ethylene oxide) grafts

Anionic graft copolymers were synthesized through grafting of poly(ethylene glycol) monomethyl ether (MPEG) onto terpolymers containing succicinic anhydride groups. The backbone polymers were prepared through radical terpolymerization of maleic anhydride, styrene, and one of the following monomers: methyl methacrylate, ethylhexyl methacrylate, and diethyl fumarate. MPEG of different molecular weights were grafted onto the backbone through reactions with the cyclic anhydride groups. In this reaction one carboxylic acid group is formed together with each ester bond. The molecular weights of MPEG were found to influence the rate of the grafting reaction and the final degree of conversion. The graft copolymers were characterized by IR, GPC, and ¹H-NMR. Thermal properties were examined by DSC. Graft copolymers containing 50% w/w of MPEG 2000 grafts were found to be almost completely amorphous, presumably because of crosslinking, and hydrogen bonding between carboxylic acid groups in the backbone and the ether oxygens in MPEG grafts. © 1995 John Wiley & Sons, Inc.     

Thermal degradation of poly(ethyl methacrylate) and its copolymer with poly(ethyl acrylate)

The thermal degradation behaviour of poly(ethyl methacrylate) homopolymers and poly(ethyl methacrylate) and poly(ethyl acrylate) copolymers synthesized by using the benzoyl peroxide-di-methyl aniline redox pair at different temperatures (18–35C) was investigated. Contrary to some reports in the literature, the thermal degradation of PEMA was observed to take place in multi steps. These are assigned to be loss of labile end groups, side chain scission, anhydride formation and main chain degradation steps. Dominating chemical formations at the end of these steps were characterized by FTIR spectroscopy.The homopolymer samples synthesized at 18C showed a greater thermal stability against degradation. Copolymerization with small amounts of ethyl acrylate was observed to impart thermal stability to PEMA by stabilizing mainly the end groups against degradations.     

Direct synthesis of amphiphilic block copolymers, consisting of poly(methyl methacrylate) and poly(sodium styrene sulfonate) blocks through atom transfer radical polymerization

Amphiphilic block copolymers of methyl methacrylate (MMA) and sodium styrene sulfonate (SSNa) were successfully synthesized via direct atom transfer radical polymerization (ATRP) of SSNa. First, poly(sodium styrene sulfonate) (PSSNa) or poly(methyl methacrylate) (PMMA) macroinitiators were prepared using proper ATRP systems for each case. In some cases, functional initiators, which allow further reactions, were used. The macroinitiators were characterized and further used to synthesize PSSNa/PMMA block copolymers, by using proper solvent combinations, such as N,N-dimethylformamide/water or methanol/water at appropriate volume ratios, in order to ensure solubility of the synthesized amphiphilic copolymers. The molecular weight of the copolymers was determined by gel permeation chromatography, using water as eluent. By using a combination of analytical techniques like ¹H NMR, FTIR and thermogravimetry, the chemical structure and the actual copolymer composition were determined. Since, the block copolymers were soluble in water, forming hydrophilic/hydrophobic domains in aqueous solution, their micellization behavior was further studied by pyrene fluorescence probing.     

Characterization and degradation of poly(methylphenylsiloxane)–poly(methyl methacrylate) interpenetrating polymer networks

Poly(methylphenylsiloxane)–poly(methyl methacrylate) interpenetrating polymer networks (PMPS–PMMA IPNs) were prepared by in situ sequential condensation of poly(methylphenylsiloxane) with tetramethyl orthosilicate and polymerization of methyl methacrylate. PMPS–PMMA IPNs were characterized by infrared (IR), differential scanning calorimetry (DSC), and ²⁹Si and ¹³C nuclear magnetic resonance (NMR). The mobility of PMPS segments in IPNs, investigated by proton spin–spin relaxation T₂ measurements, is seriously restricted. The PMPS networks have influence on the average activation energy E_a,av of MMA segments in thermal degradation at initial conversion. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1717–1724, 1999