苯乙烯/N-苯基马来酰亚胺共聚物分子量测定和模型

从内聚能的角度建立了含共聚组成、序列不均匀性的共聚物分子量及分布理论,导出其计算式.将凝胶渗透色谱(GPC)与紫外吸收光谱(UV)和示差折光仪(DR)串接,测定苯乙烯(St)/N-苯基马来酰亚胺(PMI)共聚物的分子量.根据St/PMI共聚合原理,对St-PMI共聚物的分子量进行模型化,该模型能较好地预测引发剂、单体配比、转化率对共聚物分子量的影响.     

乙烯基单体/N-苯基马来酰亚胺共聚物组成预测、控制和优化

采用递推方法成功地预测了乙烯基单体/N-苯基马来酰亚胺(PMI)共聚物组成随转化率的变化.选择共聚单体种类和用量,控制和优化共聚物组成.针对氯乙烯(VC)/PMI/丙烯腈(AN)三元悬浮共聚合特殊体系的聚合特点和工艺,得到该三元体系的单体选择范围.     

氯乙烯/N-取代马来酰亚胺共聚竞聚率及共聚物组成

研究了氯乙烯(VC)与多种N-取代马来酰亚胺的溶液共聚合,求得各对单体的竞聚率.结果表明,各种马来酰亚胺的竞聚率都远高于VC的竞聚率,即N-取代马来酰亚胺单体的活性均比VC单体活性高.计算得到N-取代马来酰亚胺Q和e值.由于苯环的共轭效应,N-苯基及N-取代苯基马来酰亚胺具有较大的Q值.各对单体的e值差别较大,表明有形成交替共聚物的倾向.此外,还考察了聚合过程中共聚物组成的变化,用递推法预测了这类体系共聚物瞬时和累积组成随转化率的变化.     

N-(对甲苯基)马来酰亚胺的自由自聚合与光敏诱导聚合及共聚合

N-烷基与N-芳基马来酰亚胺,是属于1,2-二取代乙烯结构的单体,文献[1—3]报道这类单体能进行自由基聚合与共聚合。但对于N-(对甲苯基)马来酰亚胺(PMPMI)的自由基聚合与共聚合中,溶剂对聚合物分子量的影响尚未有详细报道。至于N-烷基与N-芳基马来酰亚胺分别和丙烯酸甲酯(MA)、甲基丙烯酸甲酯(MMA)的共聚合也有一些报道,由竞聚率的测定,计算出N-芳基马来酰亚胶的e值是2.12—2.29和1.35—1.75。表明N-芳基马来酰亚胺是一缺电子的单体,即负性单体。我们研究室曾报道N,N-二甲基-对甲苯胺(DMT)和其它芳胺能光诱导引发负性单体丙烯腈聚合。PMP-     

苯乙烯与N-取代马来酰亚胺的可逆加成-断裂链转移交替共聚合

研究了二硫代苯甲酸酯存在下偶氮二异丁腈引发苯乙烯(St)、St与N-对羟基苯基马来酰亚胺(HPM)、St与N-对(2-氯/溴丙酰氧基)苯基马来酰亚胺(CPPM/BPPM)的可逆加成-断裂链转移(RAFT)均/共聚,聚合物的结构由紫外-可见光(UV-Vis)与凝胶渗透色谱(GPC)表征.结果表明,St的RAFT均聚以及St与N-取代马来酰亚胺的RAFT共聚均呈现活性聚合特征,分子量随着转化率上升而增加,且分子量分布较窄.对于St的RAFT均聚,由于双基终止,聚苯乙烯(PSt)链中"戴帽效率"随着转化率上升逐渐下降.对于St与N-取代马来酰亚胺的RAFT共聚合,电荷转移复合物的形成显著地提高了共聚反应速度,并促进交替结构的形成.随后进行了以P(St-alt-BPPM)引发St的原子转移自由基聚合以制备梳型PSt,结果表明在强极性溶剂中进行的聚合过程失去可控性,所得产物分子量极宽,而在本体聚合中所得聚合物分子量相对较窄,有一定的可控性.     

聚[N-(4-二甲氨联苯基)马来酰亚胺]单体的合成及其聚合

N-取代的马来酰亚胺是缺电子的负性单体[1],它很容易进行自由基聚合或共聚合[2,3],特别是能够与负性单体如丙烯腈共聚合[4].如果在缺电子的N-取代马来酰亚胺单体中引入给电子生色基团,即给电子生色基团与受电子基团于一体,能够表现出较好的光化学性能[5].本文中报道了聚[N-(4-二甲氨联苯基)马来酰亚胺]及其单体的合成,聚合物的光化学性能将在另文报道.     

氯乙烯/N-苯基马来酰亚胺共聚物的玻璃化温度研究

研究了单体配比、聚合温度、转化率和加料方式对氯乙烯(VC)/N-苯基马来酰亚胺(PMI)共聚物的玻璃化温度的影响.用序列模型模拟了玻璃化温度与转化率的关系,可较好地反映变化趋势.分批加料可使共聚物的耐热性能提高,却使其颗粒特性变差.     

乙烯基单体-N-取代马来酰亚胺共聚物玻璃化温度研究

用差示扫描量热仪对乙烯基单体/N-取代马来酰亚胺共聚物的玻璃化温度(T_g)进行测定.研究了共聚物组成、序列结构、乙烯基单体和N-取代马来酰亚胺种类对共聚物T_g的影响.提出了含共聚物组成和序列结构的T_g预测方程,该方程不仅适合于无规共聚物,还适合于具有严重交替倾向的共聚物.     

苯乙烯与N-对位取代苯基马来酰亚胺的乳液共聚

合成了苯乙烯(St)与 N-对位取代基马来酰亚胺的3种二元共聚物乳液.在苯乙烯与N-对位取代苯基马来酰亚胺(N-p-RPhMI)的最大共聚比内,通过种子滴加乳液聚合制得高稳定性、高固含量(40%)、低粘度的共聚物乳液.研究了 N-p-RPhMI 苯环对位上取代基团对共聚物乳液的性能以及共聚物热性能影响.结果表明:N-p-RPhMI 的加入提高了乳液的产率,并且随着取代基团极性的增强,乳液产率提高,乳胶粒的平均粒径增大,乳液的表观粘度降低;共聚物的热分解温度随着取代基团极性的增加而提高,但取代基极性对共聚物的玻璃化转变温度(Tg)的影响明显.同时,St/N-对甲氧基马来酰亚胺(N-p-MOPhMI)体系中助溶剂的加入对共聚物乳液性能影响很大,使共聚物的热起始分解温度升高,但对共聚物的 Tg 基本无影响.     

两种耐高温紫外正型光刻胶成膜树脂的制备及性能

分别通过N-(p-羟基苯基)甲基丙烯酰胺与N-苯基马来酰亚胺、N-苯基甲基丙烯酰胺与N-(p-羟基苯基)马来酰亚胺的共聚合,制备了两种聚合物树脂聚N-(p-羟基苯基)甲基丙烯酰胺共N-苯基马来酰亚胺(poly(HPMA-co-PMI))和聚N-苯基甲基丙烯酰胺共N-(p-羟基苯基)马来酰亚胺(poly(MPA-co-HPMI)).结果表明,这两种聚合物都是按1∶1的摩尔比交替共聚的,它们都具有良好的溶解性、成膜性和亲水性,并且它们的玻璃化温度Tg都在280℃以上.将它们分别与感光剂2,1,5-磺酰氯的衍生物、助剂二苯甲酮等复配成两种紫外正型光刻胶,初步光刻实验表明,其最大分辨率都可以达到1μm,并且都可以耐270℃的高温.     

有电荷转移络合物参与的共聚体系竞聚率

从有电荷转移络合物参与的共聚体系增长基元反应出,提出一种有ＣＴＣ参与的共聚体系竞聚率的求法,从中得到４个竞聚率,自由单体和ＣＴＣ的相对活性等信息。     

Solubilization of oligosaccharides into chloroform by their incorporation into polystyrene as pendant groups

Solubilization of hydrophilic saccharide chains into organic solvents has been attempted by incorporating saccharide-substituted styrene unit into polystyrene main chain. Lactose-, maltopentaose, and amylose-substituted styrene monomers were copolymerized with styrene. Resulting chloroform-soluble copolymers were characterized, and structural formation was investigated. Copolymers of lactose-substituted styrene and maltopentaose-substituted styrene with styrene were dissolved into chloroform. The chloroform-soluble polymers contained about 12 disaccharide lactose chains or 1.7 maltopentaose chains as the pendant groups in one polystyrene molecule. Chloroform-insoluble methyl orange was dissolved into chloroform with the help of chloroform-soluble polystyrene having some saccharide chains. On the other hand, when an amylose-substituted styrene unit was inserted in a polystyrene chain, the resulting polymer became insoluble into chloroform. Amylose polysaccharide of DP_n = ∼24 was not dissolved into chloroform by this method.     

Simultaneous determination of the styrene unit content and assessment of molecular weight of triblock copolymers in adhesives by a size exclusion chromatography method

The content of styrene units in nonhydrogenated and hydrogenated styrene‐butadiene‐styrene and styrene‐isoprene‐styrene triblock copolymers significantly influences product performance. A size exclusion chromatography method was developed to determine the average styrene content of triblock copolymers blended with tackifier in adhesives. A complete separation of the triblock copolymer from the other additives was realized with size exclusion chromatography. The peak area ratio of the UV and refraction index signals of the copolymers at the same effective elution volume was correlated to the average styrene unit content using nuclear magnetic resonance spectroscopy with commercial copolymers as standards. The obtained calibration curves showed good linearity for both the hydrogenated and nonhydrogenated styrene‐butadiene‐styrene and styrene‐isoprene‐styrene triblock copolymers (r  = 0.974 for styrene contents of 19.3–46.3% for nonhydrogenated ones and r  = 0.970 for the styrene contents of 23–58.2% for hydrogenated ones). For copolymer blends, the developed method provided more accurate average styrene unit contents than nuclear magnetic resonance spectroscopy provided. These results were validated using two known copolymer blends consisting of either styrene‐isoprene‐styrene or hydrogenated styrene‐butadiene‐styrene and a hydrocarbon tackifying resin as well as an unknown adhesive with styrene‐butadiene‐styrene and an aromatic tackifying resin. The methodology can be readily applied to styrene‐containing polymers in blends such as poly(acrylonitrile‐butadiene styrene).     

Recent developments in cellulose grafting chemistry utilizing Barton ester intermediates and nitroxide mediation

Esters or carbonates of N‐hydroxypyridine‐2‐thione (Barton esters) were appended to either carboxymethyl or hydroxypropyl cellulose. Irradiation of the cellulose bound Barton esters in monomer initiated free radical graft copolymerization with minimal concomitant homopolymerization. Grafting of styrene to carboxymethyl cellulose was accompanied by backbone cleavage. The hydroxypropyl spacer group minimized backbone degradation; styrene, acylamide and N‐isopropyl acrylamide could be grafted to hydroxypropyl cellulose in tetrahydrofuran solution. Treatment of Barton carbonate modified hydroxypropyl cellulose with styrene in the presence of TEMPO afforded corresponding TEMPO adducts, which can be used to promote the controlled radical graft polymerization of styrene. Grafts were analyzed independently after hydrolysis of the cellulose backbone.     

Cationic Copolymerization of 2-Chloroethyl Vinyl Ether with Styrene Derivatives. III. Solvent and Catalyst Effects on Relative Reactivity

Abstract

The change in relative reactivity in the cationic copolymerization of 2-chloroethyl vinyl ether and styrene derivatives was investigated with various catalysts and solvents. p-Methoxystyrene, p-methylstyrene, and a-methyl-styrene were used as styrene derivatives. The styrene content in the co-polymer increased when a polar solvent and/or a strong catalyst was used. The change of relative reactivity in the copolymerization of 2-chloroethyl vinyl ether with styrene derivatives was much greater than that in the copolymerization between vinyl ethers or styrene derivatives. When nitro-ethane was used as a solvent, not only the polarity but also the nucleophilicity influenced the copolymer composition. The results were discussed by two energies, E^π and E_rs, which are measures of complex formation between monomer and carbonium ion, and stabilization energy in the transition state, respectively.     

Distribution of emulsified monomers with different water solubility

The location and distribution of acrylic acid and styrene in emulsions made with a cationic surfactant, cetyltrimethylammonium bromide (CTAB), or an anionic surfactant, sodium dodecylsulfate (SDS), were determined with ultra-violet spectroscopy, conductivity, and potentiometry. In these systems, the acrylic acid remains in the aqueous phase near the micelle surface, whereas the styrene is located in the micelles or in emulsified droplets. In the absence of acrylic acid, some of the styrene is solubilized in the micelle interior and some is adsorbed at the micelle inner surface. Upon addition of acrylic acid, all the styrene is displaced to the center of the micelles. The interaction between acrylic acid and CTAB micelles is stronger than that between acrylic acid and SDS micelles. With CTAB, acrylic acid is adsorbed at the micelle surface, whereas with SDS, acrylic acid remains in the intermicellar solution. These differences can account for the differences reported in the emulsion copolymerization of acrylic acid and styrene using CTAB or SDS.     

对甲苯磺酸/活性炭/双氧水体系选择氧化苯乙烯生成苯甲醛(英文)

以双氧水为氧化剂,研究了对甲苯磺酸和活性炭体系选择氧化苯乙烯生成苯甲醛反应性能。考察了反应时间、温度、催化剂用量、苯乙烯和双氧水摩尔比等对苯乙烯选择氧化性能的影响.结果表明,对甲苯磺酸和活性炭的用量和用量比是一个重要因素,但对甲苯磺酸的酸性对氧化反应活性影响不大.对甲苯磺酸和双氧水相互作用,经非自由基过程氧化苯乙烯.通过分解双氧水产生氢氧自由基,活性炭显著提高对甲苯磺酸和双氧水体系氧化苯乙烯活性.在惰性或还原气氛中高温处理活性炭能降低其表面含氧基团数量,增加碱性,有效分解双氧水,产生相对较多的OH自由基.与未处理的活性炭相比,高温处理的活性炭进一步提高了对甲苯磺酸和双氧水体系氧化苯乙烯活性,但降低了苯甲醛选择性.经磺化,在活性炭表面引入的–SO_3H基团比含氧基团(–OH,–COOH)更有效与双氧水作用氧化苯乙烯.     

Copolymerization of styrene and conjugated dienes with half‐sandwich titanium(IV) catalysts: The effect of the ligand structure on the monomer reactivity,monomer sequence distribution,and insertion mode of dienes

The copolymerization of styrene and 1,3‐butadiene (Bd) or isoprene (Ip) was carried out with half‐sandwich titanium(IV) Cp′TiCl₃ catalysts (where Cp′ is cyclopentadienyl 1 , indenyl 2 , or pentamethylcyclopentadienyl 3 ) with methylaluminoxane as a cocatalyst. For the copolymerization with Bd, catalyst 3 gave the copolymers containing the highest amount of Bd among the catalysts used. The resulting copolymers were composed of a styrene–Bd multiblock sequence. High melting points were observed in the copolymers prepared with catalyst 1 . The structures of hydrogenated poly(styrene‐co‐Bd) were studied by ¹³C NMR spectroscopy, and the long styrene sequence length was detected in the copolymers prepared with catalyst 1 . For styrene/Ip copolymerization, random copolymers were obtained. Among the used catalysts, catalyst 1 gave the copolymers containing the highest amount of Ip. The copolymers prepared with catalyst 1 showed a steep melting point depression with increasing Ip content because of the high ratio of 1,4‐inserted Ip units and/or the low molecular weights of the copolymers. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 939–946, 2003     

原子转移自由基聚合制备聚(甲基丙烯酸甲酯-b-苯乙烯)时单体聚合顺序对嵌段效率的影响

采用原子转移自由基聚合研究了聚（ 甲基丙烯酸甲酯 ｂ 苯乙烯） 嵌段共聚物的合成,实验结果表明,当先进行甲基丙烯酸甲酯的聚合,然后再进行苯乙烯的聚合时,得到了完全的嵌段共聚物;反之,如果改变单体的聚合顺序,则嵌段效率很低．用聚合物末端Ｃ—Ｘ（Ｘ＝ Ｃｌ,Ｂｒ） 键的断裂能对实验结果进行了解释．     

Polymeric complex membranes based on styrene–diene–styrene triblock copolymers for oxygen enrichment

Polymers containing a vinylpyridine, vinylimidazole or oxirane group could be used to immobilize cobalt Schiff bases (CoS), which serve as the oxygen carrier in oxygen enrichment. The graft copolymers, based on styrene–butadiene–styrene (SBS) and styrene–isoprene–styrene grafted with 4-vinylpryidine and 1-vinylimidazole, and epoxidized SBS copolymers were prepared to immobilize CoS. The equilibrium constants between CoS and polymeric materials, the oxygen coordination number and the oxygen binding constants were determined. The thermodynamic parameters of oxygen association/dissociation in various complex membranes were determined. The oxygen permeation behavior through various CoS-containing complex membranes was studied and discussed by the dual-mode facilitated transport theory. The permeation properties of oxygen and nitrogen at low pressure were also investigated.