Ionomers made from terpolymers with uniform poly(methyl methacrylate) grafts

Terpolymers with uniform poly(methyl methacrylate) (PMMA) grafts were prepared by terpolymerization of PMMA macromonomer, butyl acrylate, and acrylic acid in benzene using AIBN as initiator. During terpolymerization the macromonomer polymerizes faster than the monomers at the beginning but slower at the latter stage. The terpolymers were purified by solvent extraction and fractional precipitation. The average grafting number per chain of the terpolymers was determined to be 3–8. Ionomers were obtained by neutralization of the terpolymers with alkali hydroxide or metallic acetate. Dynamic mechanical spectrum of the ionomer shows the existence of two T_g's, which implies the occurence of microphase separation. The ionomer exhibits high damping over a temperature range from ?25 to 100°C. Both PMMA grafts and metallic carboxylate content raise the tensile strength of the ionomer and lower the ultimate elongation. The tensile strength of ionomers neutralized with different metallic ions decreases in the following order: Pb²⁺ > Zn²⁺ > Na⁺ > Ca²⁺ > Mg²⁺ > K⁺. The ionomers with uniform PMMA grafts show much better mechanical properties than the terpolymer without neutralization or the ionomer without PMMA grafts.     

Thermoplastic blends of physically crosslinked multiblock copolymers and copolymers with uniform grafts

Two multiblock copolymers of styrene and propylene oxide and four acrylate copolymers with uniform polystyrene grafts were prepared and blended. The blends are melt processable and their properties varied from thermoplastic elastomers to toughened plastics. The relationship between mechanical properties and composition of the thermoplastic blends indicated that all the blends exhibited a synergism, which is probably due to the increase of miscibility between the components caused by the same physical crosslinks — the glassy domains aggregated from both the polystyrene grafts and polystyrene blocks. The synergistic effect seemed more evident when two different graft copolymers were blended together than when one multiblock copolymer was blended with one graft copolymer. In all cases a maximum tensile strength appeared at the blend with 90 wt.-% of the component, possessing higher tensile strength and ultimate elongation.     

Synthesis and properties of amphiphilic copolymers of butyl acrylate and methyl methacrylate with uniform polyoxyethylene grafts

Amphiphilic copolymers of butyl acrylate (BA) and methyl methacrylate (MMA) with uniform polyoxyethylene (PEO) grafts were synthesized by the copolymerization of BA and MMA with a methacrylate‐terminated PEO macromer in benzene with azobisisobutyronitrile as an initiator. The effects of various copolymerization conditions on the grafting efficiency and molecular weight of the copolymers, as well as the effect of the copolymerization time on the conversions of the macromer and the monomers, were reported. The copolymers, with uniform PEO grafts, were purified by successive extractions with water and ether/acetone (3/7) to remove unreacted macromer and ungrafted copolymers of MMA and BA, respectively. The purified graft copolymers were characterized with IR, ¹H‐NMR, membrane osmometry, gel permeation chromatography, and differential scanning calorimetry. The highest grafting efficiency was about 90%, and molecular weight of the copolymers varied around 10⁵. The average grafting number of the copolymer was about 10. A study of the crystalline properties, emulsifying properties, phase‐transfer catalytic ability, and mechanical properties of the graft copolymers showed that the emulsifying volume decreased with the increasing molecular weight of the PEO grafts but increased with the PEO content. The conversion of potassium phenolate in the Williamson solid–liquid reaction obviously increased with an increasing PEO content of the graft copolymers. The crystallinity of the graft copolymers increased with the PEO content of the graft copolymers or the molecular weight of the macromer used. The copolymers, prepared under certain conditions, behaved as thermoplastic elastomers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2982–2988, 2003     

聚苯乙烯大单体和丙烯酸辛酯的规整接枝共聚物

采用聚苯乙烯大单体和丙烯酸辛酯进行自由基溶液共聚合反应，得到规整接枝共聚物。产物通过萃取法提纯后，用IR表征其结构。研究了共聚合反应条件：聚苯乙烯大单体的投料质量分数，引发剂用量，反应温度对接枝效率的影响；并测定了丙烯酸辛酯在不同反应时间的竞聚率，接枝共聚物的稀溶液性质以及物理机械性能。结果表明，当聚苯乙烯大单体的投料质量分数在40％左右时，此接枝共聚物是一种性能良好的热塑性弹性体。     

软段含离子的聚氨酯离聚物

概述了一系列新型的软段含离子的聚氨酯离聚物的合成、性能、研究进展,以及这类离聚物对聚氨酯离聚物离子簇解离现象的贡献。     

Comparison of properties of segmented copolyetheresteramides containing uniform aramid segments with commercial segmented copolymers

The thermal (using differential scanning calorimetry), dynamic mechanical (using a dynamic mechanical analyzer), and mechanical properties of segmented copolyetheresteramides with aramid units of uniform length (TΦT) and poly(tetramethylene oxide) (PTMO) segments were compared to those of commercial segmented copolyetheresters (PBT–PTMO) and thermoplastic polyurethanes. The hard segments in TΦT‐containing polymers were found to crystallize almost completely, unlike the hard segments of Arnitel and Desmopan. Consequently, the glass‐transition temperature of TΦT‐containing polymers is lower and the melting temperature higher than those of Arnitel and Desmopan. Furthermore, the rubbery plateau of the TΦT‐containing polymers is temperature independent, making the service temperature range wider. In TΦT‐containing polymers a lower concentration of hard segment is needed to obtain dimensionally stable polymers with a high melting temperature. No melt phasing occurs during polymerization and therefore long PTMO segments can be used, producing very soft and elastic materials. The polymers crystallize faster than do commercial materials. The elasticity of the TΦT‐containing polymers is comparable to the elasticity of Desmopan and better than that of Arnitel. TΦT–(PTMO₁₀₀₀/DMT) copolymers are transparent and the solvent resistance is high. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1372–1381, 2001     

含均匀聚氧乙烯支链的两亲性(丙烯酸丁酯-甲基丙烯酸甲酯)共聚物的结构及结晶性

由聚氧乙烯(PFO)大单体、丙烯酸丁酯(BA)、甲基丙烯酸甲酯(MMA)共聚合成的产物经水及乙醚/丙酮(体积比3/7)分别萃取得取了纯化的两亲性接枝共聚物,用凝胶渗透色谱仪、红外光谱仪、核磁共振仪对接枝共聚物进行了表征,用蒸气渗透压计、膜渗透压计、X射线衍射仪及偏光显微镜研究了接枝共聚物的结构参数平均相对分子质量(M-nb)为9.1×103～15.2×103;随着共聚时间的延长,Ng有所下降,M-nb有所增加,接枝共聚物的结晶度为0～49.5%,且随着PEO含量及其相对分子质量的增加而增大;接枝物呈现球晶结构,且随着PEO含量的减少,球晶变小且不规整.     

聚苯乙烯大单体/丙烯酸辛酯规整接枝共聚物的结构、性能与增容作用

用傅里叶变换红外光谱、透射电子显微镜和差示扫描量热仪表征了聚苯乙烯大单体和丙烯酸辛酯规整接枝共聚物(POA-g-PS)的结构,测定了其物理机械性能,并研究了POA-g-PS作为聚苯乙烯/丙烯酸酯橡胶体系的共混增容剂时,共混物组成、接枝物用量及接枝物组成对共混物物理机械性能的影响。结果表明,POA-g-PS属于两相态,存在微观相分离结构;当聚苯乙烯大单体的质量分数在40%左右时,POA-g-PS是一种具有较大拉伸强度、较大扯断伸长率及较小永久变形的热塑性弹性体;扫描电镜和差示扫描量热分析表明接枝共聚物促进了聚苯乙烯/丙烯酸酯橡胶共混体系的互容,起到了增容剂的作用。     

Dynamical mechanical behavior of copolymers made of styrene and methyl methacrylate: Random, alternate and diblock copolymers

The dynamics of copolymers made of styrene and methyl methacrylate and of different architecture (three diblock, two random and one alternate) have been studied using a dynamic mechanical spectroscopy technique (DMTA). The scanning calorimetric results indicate that there is only one glass transition except for two of the diblock copolymers. In addition, only one broad mechanical relaxation is observed in all the copolymers studied in this work. However, it has not been possible to build master curves for the complex Young modulus E* for the copolymers. In fact the relaxation spectra calculated from E* are bimodal. In order to describe the relaxation functions of the samples, it has been necessary to use two Kohlraush-Williams-Watts functions at each of the temperatures studied. The relaxation times of the two dynamic contributions can be described by Arrhenius laws, which is probably due to the relatively narrow temperature range for which the relaxation can be studied within the frequency range experimentally accessible. The stretching parameters increase linearly with T, which indicates that both dynamic transitions broaden as T is decreased.     

以POA-g-PS为增容剂的丙烯酸酯橡胶/聚苯乙烯的共混

研究了在含有规整聚苯乙烯支链的聚丙烯酸辛酯存在下丙烯酸酯橡胶与聚苯乙烯的共混.结果表明,在质量分数为2%～3%的此种接枝物存在下,共混物的拉伸强度提高了1倍.DSC,SEM的测试结果表明,此种接枝物增加了共混物的相容性.     

Synthesis,characterization, and properties of amphiphilic poly(ethyl acrylate) with uniform polyoxyethylene grafts

Amphiphilic copolymers of ethyl acrylate (EA) with uniform polyoxyethylene (PEO) grafts were synthesized by copolymerization of EA with methacrylate terminated PEO macromer in benzene using azobisisobutyronitrile as the initiator. The effects of the molecular weight of the macromers, the charging weight ratio of the macromer to EA, the total monomer concentration, and the amount of initiator on the grafting efficiency (GE) were reported as was the molecular weight of the copolymers. The highest GE reached to above 90% and the molecular weight of the copolymers varied from (5–15) × 10⁴. The reactivity ratio of EA with the macromer was determined to be 0.83. The graft copolymers were purified with extractions and the purified products were characterized with IR, ¹H‐NMR, gel permeation chromatography, differential scanning calorimetry, and membrane osmometry. The average grafting number of the copolymer varied from 2 to 11. The glass‐transition temperature of the poly(EA) in the copolymer was increased because of the partial compatibility of the two components. The crystalline property, emulsifying property, and dilute solution viscosity of the graft copolymers, as well as ionic conductivity of their complexes with alkali metal salts, were studied. The emulsifying volume decreased with the increasing molecular weight of the PEO grafts. The addition of NaOH to the emulsion affected the emulsifying volume only slightly, whereas the addition of HCl changed the oil in water type emulsion into a water in oil type. The conductivity of the LiClO₄ complex of the copolymer with an oxyethylene/Li ratio of 20 reached 3.7 × 10^?5 S/cm at 27°C. The lower the crystallinity of the complex, the higher was the conductivity. The dilute solution viscosity showed the existence of intramolecular microphase separation. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 903–912, 2001     

Model development for semicontinuous production of ethylene and norbornene copolymers having uniform composition

Terminal and penultimate models for controlling copolymer composition distribution (CCD) in ethylene and norbornene (NB) copolymerization were developed by taking into account the variation of active site concentration with the initial comonomer ratio. The models were validated by batch polymerization experimental data. The terminal model gave better correlation with the composition data whereas the penultimate model had a better fit to the rate data. The terminal model was then used to design NB feeding policies in semicontinuous processes for targeted CCD profiles. Based on the model results, a series of ethylene‐NB copolymers with various NB contents were prepared. With the same NB content, the semicontinuous process produced a uniform composition, whereas the batch process yielded broad CCD. The batch samples had lower T_g values and broader transition ranges, even yielded crystalline materials. In contrast, the semicontinuous samples overcame the disadvantages. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

Addition compatibilization of PP/PS blends by tailor‐made copolymers

The thermoplastic polymer blends of commercial interest generally need a phase compatibilization to reduce the interfacial tension, to stabilize the morphology, and to increment the interfacial adhesion. This work deals with the compatibilization of PP/PS blends by addition of a tailor‐made copolymer, which is prepared from the pure homopolymers by a Friedel‐Crafts reaction. This addition compatibilization process comes out as an economic alternative applicable to the recycling of mixed plastics from urban and industrial wastes. The influence of compatibilizer concentration and blending time on the emulsifying effect, morphology, and mechanical properties of the resulting blends are analyzed. The compatibilization process effectiveness is assessed through the improvement in phase adhesion, emulsification and ductility of the compatibilized with respect to the physical blends. An increase of three times in ductility is achieved using very low compatibilizer concentrations (0.5–0.7 wt%). No appreciable detriment in yield strength or modulus is observed in these compatibilized blends. POLYM. ENG. SCI. 46:329–336, 2006. © 2006 Society of Plastics Engineers     

Polyether‐amide segmented copolymers based on ethylene terephthalamide units of uniform length

Segmented copolymers were synthesized using the crystallizable bisesterdiamide segment (N,N′‐bis(p‐carbomethoxybenzoyl)ethanediamine) T2T‐dimethyl (a one‐and‐a‐half repeating unit of nylon 2,T) and poly(tetramethyleneoxide) segments. Poly(tetramethyleneoxide) (PTMO) is amorphous and has a low T_g. The segment length was varied from 650 to 2800 g/mol by extending PTMO₆₅₀ using dimethyl isophthalate. The polymers were synthesized in the melt, and test samples were prepared by injection molding. The melting behavior, as well as the torsion modulus spectrum as a function of temperature, were studied using DSC and DMA, respectively. The T2T‐PTMO polymers were found to have sharp glass (T_g) and flow transitions (T_fl), and the modulus at the rubbery plateau appeared to be virtually temperature independent. The T_g value was found to be independent of the diamide concentration, thus indicating that the T2T segments were fully crystallized. The T_fl was found to decrease with increasing soft segment length; this was ascribed to a “solvent” effect of the amorphous phase of the crystalline T2T units. The difference between the melting and crystallization temperatures was found to be low, thus suggesting that on cooling, there is a high rate of crystallization. When ethanediol was added as a T2T segment extender, amide‐ester‐amide segments were introduced. These amide‐ester‐amide segments form a separate lamellar phase with a much higher melting temperature (>300°C). It was found that the crystallization rate of the T2T units was enhanced by the presence of the amide‐ester‐amide segments, indicating that upon cooling, the crystallized amide‐ester‐amide segments form the nucleation sites for the nonextended T2T segments. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1173–1180, 2001     

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 anionic graft copolymers containing poly(ethylene oxide) grafts

Graft copolymers containing poly(ethylene oxide) side chain attached to maleic anhydride‐alt‐vinyl methyl ether (MA‐VME) copolymer were prepared by coupling MA‐VME and poly(ethylene glycol) monomethyl ether (MPEG) by esterification in DMF at 90°C. MPEG and dodecyl alcohol (DA) were grafted onto MA‐VME copolymer in o‐xylene at 140°C in the presence of p‐toluene sulfonic acid as catalyst. 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. DSC was used to examine thermal properties of the graft copolymers. The analysis indicates that grafts have phase‐separated morphology with the backbone and the MPEG grafts forming separate phases. The properties in aqueous solutions of these grafts were studied with respect to aggregation behavior and viscometric properties. In aqueous solution, the polymers exhibited polyelectrolyte behavior (i.e., a dramatic increase of the viscosity upon neutralization). Graft copolymers with DA have lower viscosities. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1138–1148, 2002