乳液共聚反应过程与聚合物结构关系及13C－NMR对聚合物结构的表征

 用间歇法和半连续法进行了丙烯酸丁酯（ＢｕＡ）与醋酸乙烯酯（ＶＡｃ）乳液共聚合．^１３Ｃ－ＮＭＲ对共聚产物分子结构测试表明，在间歇法共聚合中随着反应进行其组成及结构发生很大变化，而半连续法确能制得成份及结构均匀一致的Ｐ（ＢｕＡ－ＶＡｃ）共聚物．由于ＢｕＡ水溶性小于ＶＡｃ，而其竟聚率远大于ＶＡｃ，间歇法共聚合反应初期只有少量ＶＡｃ参加共聚合．通过对间歇法共聚合中不同反应时间聚合物的^１３Ｃ－ＮＭＲ测试，表明反应初期聚合的ＶＡｃ以单链节或二元序列形式存在于主要由ＢｕＡ单元构成的分子链中，而并未形成较长ＶＡｃ链段．对上述试样玻璃化转变温度的测试结果与^１３Ｃ－ＮＭＲ实验结果颇为一致．     

MoO_2Br_2体系催化丁二烯聚合中烯丙基卤素的作用

ＭｏＯ２Ｂｒ２－Ａｌ（ｉ－Ｂｕ）２ＯＰｈＣＨ３（－ｍ）体系催化丁二烯１，２－聚合过程中添加Ｃ３Ｈ５Ｘ（Ｘ＝Ｃｌ、Ｂｒ和Ｉ）对聚合物分子量有较好的调节作用，其中以Ｃ３Ｈ５Ｂｒ的调节作用最强，Ｍｎ从１７．５×１０５降至３．５×１０５，但对催化活性有一定的影响．在测定催化体系的ＵＶ光谱、（１３）Ｃ－ＮＭＲ谱、聚合活性和聚合动力学参数的基础上，讨论了Ｃ３Ｈ５Ｘ在催化体系中的行为．     

用SN型催化剂合成苯乙烯－丙烯嵌段共聚物的研究II．共聚物的结构表征与性能

报道用稀土化合物改性的钛系截体催化剂（ＳＮ催化剂）进行苯乙烯和丙烯顺序嵌段共聚合（Ｓｅｑｕｅｎｔｉａｌｂｌｏｃｋｃｏｐｏｌｙｍｅｒｉｚａｔｉｏｎ）的研究，通过对初生嵌段共聚产物进行溶剂萃取与分级，并用１３Ｃ－ＮＭＲ、ＷＡＸＤ．ＤＳＣ，ＤＭＡ和电子显微镜进行表征，推断共聚物为具有等规聚苯乙烯链和等规聚丙烯链段的Ａ－Ｂ型二嵌段共聚物，且各段均能结晶。发现嵌段共聚物比相应的均聚物具有较好的综合力学性能和热性能，而且对ｉＰＳ／ｉＰＰ共混具有良好的增容作用。     

壳聚糖负载稀土催化剂催化甲基丙烯酸甲酯聚合

对壳聚糖负载稀土配合物（Ｃｓ．ＲＥ）与三异丁基铝，ε－己内酯（ＣＬ）催化甲基丙烯酸甲酯的聚合进行了研究，综合考察了Ｃｓ．Ｙ－Ａｌ（ｉ－Ｂｕ）３－ＣＬ体系催化甲基丙烯酸甲酯聚合特征，聚合动力学，聚合物的分子量和其分布，甲基丙烯酸甲酯与苯乙烯共聚合行竟聚率，推测聚合反应属于配位阴离子机理，用ＩＲ，ＤＳＣ，＾１ＨＮＭＲ和＾１３ＣＮＭＲ表征了聚甲基丙烯酸甲酯的微结构，其间同立构含量达８６．４％，玻璃化转变     

异戊二烯/甲基丙烯酸甲酯嵌段共聚物的合成与微结构研究

用稀土催化剂ＲＥ（Ｐ２０４）３ （ｉ Ｂｕ）３Ａｌ ＢｒＣＨ２ＣＨ２Ｂｒ（ＲＥ＝Ｎｄ,Ｐｒ,Ｙ等）合成嵌段共聚物Ｐ（ＩＰ ｂ ＭＭＡ）．系统考察了共聚合反应特征,以ＤＳＣ,１Ｈ ＮＭＲ,１３Ｃ ＮＭＲ技术研究了该嵌段共聚物的微结构．发现以二溴乙烷为添加剂的稀土催化体系是制备Ｐ（ＩＰ ｂ ＭＭＡ）的良好催化剂,共聚物含２个玻璃化转变温度,分别为－７５６℃和１２９℃,嵌段共聚物的结构规整,（ＩＰ）ｍ段以ｃｉｓ １,４结构为主,其含量为９７％左右,３,４ 结构为３％左右,链节间以头 尾方式连接．（ＭＭＡ）ｎ段以间同立构为主,其含量达７４％．     

甲基丙烯酸二甲氨基乙酯溴代烷季铵盐与苯乙烯共聚合的研究

以甲基丙烯酸二甲氨基乙酯溴代乙烷（ Ｍ Ａ Ｅ Ｂ） 或丁烷（ Ｍ Ａ Ｂ Ｂ） 季胺盐与苯乙烯（ Ｓｔ）为单体,采用溶液自由基共聚合方法,合成了一类新型阳离子两亲共聚物．详细地研究了聚合条件及共聚物的溶解性．共聚物“亲油”和“亲水”单元的无规结构被 Ｉ Ｒ、１ Ｈ Ｎ Ｍ Ｒ 及１３ Ｃ Ｎ Ｍ Ｒ所证实．最后,用线性化（ Ｙ Ｂ Ｒ） 法分别求得 Ｍ Ａ Ｅ Ｂ／ Ｓｔ 和 Ｍ Ａ Ｂ Ｂ／ Ｓｔ 的单体竞聚率,ｒ Ｍ Ａ Ｂ Ｂ ＝０４４ ,ｒ Ｓｔ ＝ ０１５ ,ｒ Ｍ Ａ Ｅ Ｂ＝ ０６６ ,ｒ Ｓｔ＝ ０３６ ．     

致孔剂对HP（MA—VAc—MMA）载体孔结构的影响

以二乙烯苯和双丙烯酸多缩乙二醇酯为交联剂、聚醋酸乙烯酯（ＰＶＡｃ）或它与醋酸丁酯（ＢＡＣ）的混合物为致孔剂、ＢＰＯ为引发剂，用悬浮聚合随后水解的方法制得了部分水解聚（丙烯酸甲酯－醋酸乙烯酯－甲基丙烯酸甲酯）［ＨＰ（ＭＡ－ＶＡｃ－ＭＭＡ）］多孔载体，研究了ＰＶＡｃ及（ＰＶＡｃ＋ＢＡＣ）用量、分子量及混合比对ＨＰ（ＭＡ－ＶＡｃ－ＭＭＡ）孔结构的影响。结果表明，当ＰＶＡｃ的Ｍ＞２．５×１０５，ＰＶＡｃ／ＢＡＣ为２．３，用量为１０～２０％时，可制得孔隙率较高，孔径分布较窄，孔表面积较大的多孔载体。这种载体适用于微生物固定化。     

RELATIVE CONFORMER STABILITY OF OPEN-CHAIN PHOSPHANE:A PM3 STUDY

ＲＥＬＡＴＩＶＥＣＯＮＦＯＲＭＥＲＳＴＡＢＩＬＩＴＹＯＦＯＰＥＮ－ＣＨＡＩＮＰＨＯＳＰＨＡＮＥ：ＡＰＭ３ＳＴＵＤＹ￥ＦｕＪｉａｎｇＤＩＮＧ；ＬｉａｎｇＦｕＺＨＡＮＧ（ＣｈｅｎｇｄｕｉｎｓｔｉｔｕｔｅｏｆｏｒｇａｎｉｃＣｈｅｍｉｓｔｒｙ，Ａｃａｄｅｍｉ...     

FERROMAGNETIC INTERACTION BETWEEN GADOLINIUM（Ⅲ） AND COPPER （Ⅱ）IONS IN N，N＇－BIS（2－AMINOPROPYL）OXAMIDO COPPER（Ⅱ） BRIDGED BINUCLEAR Gd（Ⅲ）－Cu（Ⅱ） COMPLEX

ＦＥＲＲＯＭＡＧＮＥＴＩＣＩＮＴＥＲＡＣＴＩＯＮＢＥＴＷＥＥＮＧＡＤＯＬＩＮＩＵＭ（Ⅲ）ＡＮＤＣＯＰＰＥＲ（Ⅱ）ＩＯＮＳＩＮＮ，Ｎ＇－ＢＩＳ（２－ＡＭＩＮＯＰＲＯＰＹＬ）ＯＸＡＭＩＤＯＣＯＰＰＥＲ（Ⅱ）ＢＲＩＤＧＥＤＢＩＮＵＣＬＥＡＲＧｄ（Ⅲ）－Ｃｕ...     

THE REACTION OF（μ_3－CPh）Co_3（CO）_9 WITH TRANSITION METAL CARBONYL ANION M（CO）_3（RCOCp）AND CHARACTERIZATION OF CLUSTERS（μ_3－CPh）CO_2M（CO）_8（RCOCPp）（M＝Mo，W；R＝H，CH_3．C_2H_5O）

ＴＨＥＲＥＡＣＴＩＯＮＯＦ（μ_３－ＣＰｈ）Ｃｏ_３（ＣＯ）_９ＷＩＴＨ　ＴＲＡＮＳＩＴＩＯＮＭＥＴＡＬＣＡＲＢＯＮＹＬＡＮＩＯＮＭ（ＣＯ）_３（ＲＣＯＣｐ）ＡＮＤＣＨＡＲＡＣＴＥＲＩＺＡＴＩＯＮＯＦＣＬＵＳＴＥＲＳ（μ_３－ＣＰｈ）ＣＯ_２Ｍ（ＣＯ）_８（ＲＣＯＣＰｐ）（Ｍ＝Ｍｏ，Ｗ；Ｒ＝Ｈ，ＣＨ_３．Ｃ_２Ｈ_５Ｏ）Ａｕｔｈｏｒｔｏｗｈｏｍｃｏｒｍｓｐｏｎｄｅｎｃｅｓｈｏｕｌｄａｄｄｒｅｓｓｅｄ．ＥｘｐｅｒｉｍｅｎｔａｌｓｅｃｔｉｏｎＧｅｎｅｒａｌｐｒｏｃｅｄｕｒｅａｎｄｍａｔｅｒｉａｌＡｌｌｏｐｅｒａｔｉｏｎｗａｓｃａｒｒｉｅｄｏｕｔｕｎｄｅｒｈｉｇｈｌｙｐｕｒｅｎｉｔｒｏｇｅｎａｔｍｏｓｐｈｅｒｅｕｓｉｎｇｓｈａｄａｒｄＳｃｈｌｅｎｌｃａｎｄｖａｃｕｕｍｔｅｃｈｎｉｑｕｅｓ．Ｈｅ－ｃａｎｅ，ｂｅｎｚｅｎｅａｎｄｔｅｔｒａｈｙｄｒｏｆｕｒａｎｗｅｒｅｐｒｅｄｒｉｅｄｏｖｅｒｓｏｄｉｕｍｗｉｒｅａｎｄｄｉｓｔｉｌｌｅｄｆｒｏｍｓｏｄｉｕｍ－ｂｅｎｚｏｐｈｅｎｏｎｅｕｎｄｅｒｎｉｔｒｏｇｅｎ．ＮａＭ（ＣＯ）３（ＲＣＯＣＰ）ａｎｄＰｈＣＣｏ３（ＣＯ），ｗｅｒｅｐｒｅｐａｒｅｄａｃｃｏｒｄｉｎｇｔｏｌｉｔｅｒａｔＵｒｅ     

Characterization of particle surface and morphology in vinyl acetate-butyl acrylate emulsion copolymers — Influence of the copolymerization pathway

Surface characterization was investigated in vinyl acetate (VAc) butyl acrylate (BuA) copolymer latexes of various compositions and prepared with four different emulsion polymerization processes: conventionnal batch, composition-controlled batch, core-shell, emulsifier-free semi-continuous. Surface end-groups (sulfate or carboxylic) titration results were first compared and discussed according to the type of process and as a function of conversion. As previously shown [1], it was confirmed that batch latex particles present a heterogeneous structure with a rich VAc outlayer, as in core-shell particles. As expected, semi-continuous and composition-controlled batch particles exhibit surface end-group characteristics revealing a more homogeneous distribution of both monomers within the particles. These differences in particle morphology were corroborated by analyzing water-polymer interface in these latexes using the soap titration method, with the sodium dodecyl sulfate (SDS) or sodium hexadecyl sulfate (SHS) as emulsifier probes. When the BuA was batch-polymerized onto PVAc seed particles, the estimated surface composition seemed to show that probably phase rearrangement occurs in the particle during the synthesis or upon aging. It was also confirmed that SDS displays an abnormal adsorption due to complexation and solubilization in the rich-VAc shell of the particles.     

Batch and semicontinuous emulsion copolymerization of vinyl acetat–butyl acrylate. I. Bulk,surface, and colloidal properties of copolymer latexes

Vinyl acetate (VAc)–butyl acrylate (BuA) comonomer mixtures with various composition were polymerized by batch and semicontinuous emulsion polymerization processes. PVAc and PBuA homopolymer latexes as well as the (VAc-BuA) copolymer latexes were characterized with respect to particle size, molecular weight, acid end groups on particle surfaces, and colloidal stability against electrolytes. The surface and colloidal properties of these latexes were also compared before and after aging and acid hydrolysis. The average particle size of batch latexes was independent of copolymer composition, whereas for semicontinuous latexes it decreased with increasing BuA content and was always lower than that of the corresponding batch latex. The molecular weight distribution (MWD) for batch latexes was narrower and much less dependent on composition than that of the semicontinuous latexes; bimodal MWD was found in most semicontinuous latexes with a substantial amount of low MW fraction. The total weak and strong acid end groups on particle surfaces for semicontinuous latexes is higher, and more dependent on composition, than the batch latexes. Acid-induced hydrolysis results in a drastic change in the type and concentration of the surface groups of the semicontinuous latex particles. Colloidal stability against electrolytes showed that both electrostatic (due to surface acid groups) and steric [due to surface poly(vinyl alcohol)] mechanisms are contributing. However, for semicontinuous latexes, increasing PVAc content above 50 mol % resulted in a proportional increase and ultimately dominant role of steric stabilization. The results were interpreted in terms of differences in reactivity ratios and water solubilities of the two monomers and their effects on the locus of initiation and growth in the two polymerization processes, as well as the monomer sequence within the polymer chain and degree of homogeniety of the copolymer composition within the particle.     

乳液聚合共聚物玻璃化转变温度及其理论计算

从共聚单体的竞聚率、油相水相分布系数出发,通过动力学模拟计算了丙烯酸丁酯与醋酸乙烯酯乳液共聚物的链结构,并用Johnson公式对其玻璃化转变温度(T_g)进行了理论计算,给出了共聚物T_g及其对应聚合物的重量分布图。发现半连续共聚物有1个T_g,其值随共聚物组成而变化;但一步法共聚物有两个T_g:低温区T_g代表富丙烯酸丁酯共聚物,高温区T_g则代表PVA均聚物。计算结果与实验十分吻合。     

Effect of graft copolymer on demixing of immiscible polymers in solution

The effect of graft copolymer on the demixing of solutions of two immiscible homopolymers and critical conditions for emulsion formation were studied. The graft copolymer used in the present work consists of one backbone poly(vinyl acetate) (PVAc) and one branch polystyrene (PS). PVAc and PS of various degrees of polymerization were used as immiscible homopolymers. The common solvent was benzene. When the concentration of homopolymer blend was not sufficiently higher than the critical concentration for demixing of the blend solution, no stable emulsion was formed, even when a considerable amount of graft copolymer was present, and the added graft copolymer merely reduced the demixing rate. However, as the blend concentration was increased, a stable emulsion could readily be obtained by addition of rather small amounts of graft copolymer. The radius of emulsion droplets was inversely proportional to the weight ratio of the graft copolymer to the dispersed component polymer, in accordance with the theoretical prediction. It was concluded that the emulsions were stabilized against coagulation by graft copolymer molecules fixed strongly as a monolayer on the interface of the emulsion.     

Miniemulsion copolymerization of vinyl acetate and butyl acrylate. I. Differences between the miniemulsion copolymerization and the emulsion copolymerization processes

Differences between the emulsion copolymerization and miniemulsion copolymerization processes, in terms of emulsifier adsorption, emulsion stability, polymerization kinetics, copolymer composition and dynamic mechanical properties were studied for the comonomer mixture of 50:50 molar ratio vinyl acetate (VA+)—butyl acrylate (BuA), using sodium hexadecyl sulfate (SHS) as a surfactant and hexadecane (HD) as a co-surfactant. The use of hexadecane with the appropriate SHS initial concentration led to a higher adsorption of surfactant, smaller droplet size, higher stability of the emulsions, lower polymerization rates, and larger latex particle size. The copolymer composition during the initial 70% conversion was found to be less rich in Vac monomer units for the miniemulsion process. The dynamic mechanical properties of the copolymer films showed less mixing between the BuA-rich core and the VAc-rich shell in the miniemulsion latexes compared to the conventional latex films.     

Batch and semicontinuous emulsion copolymerization of vinyl acetate–butyl acrylate. II. Morphological and mechanical properties of copolymer latex films

Vinyl acetate/(VAc)-butyl acrylate/(BuA) copolymer latex films of various copolymer compositions were investigated for their morphological properties by electron microscopy techniques, and for their mechanical properties by dynamic mechanical spectroscopy (DMS), differential scanning calorimetry (DSC), and tensile strength measurements. Batch copolymer latex films showed domains of PBuA dispersed in PVAc matrix; the domain sizes were increased with increased BuA content. Semicontinuous latex films were homogeneous in composition. Glass transition temperatures T_g determined from DMS and DSC indicated the presence of two, low and high, transition temperatures for batch latex films. The two temperatures approached the individual homopolymers, with increased PBuA content up to 51 mol %. Semicontinuous latex films showed only one single T_g. Tensile properties of the batch copolymer films showed a higher ultimate tensile strength, higher Young's modulus, and lower percent elongation to break compared to semicontinuous latex films. These differences were found to reflect the effect of mode of monomer addition during the emulsion copolymerization process on the particle morphology, and confirmed earlier data on bulk, colloidal, and surface properties of the same copolymer latexes.     

Activated Rubber Crumb in Waterborn Surface Coating

This study investigates the properties of a matt finishing paint formulated using Vinyl acetate (VAc) - Butyl acrylate (BuA) copolymer latex (water based resin system) and activated rubber crumb (matting agent). Vinyl acetate - Butyl acrylate copolymer prepared by semicontinuous emulsion polymerization. The copolymer emulsion mixed with dispersion of rubber crumb to make the surface coating. Presence of rubber crumb may actively resist the attack of chemicals and climate conditions.     

醋酸乙烯酯-丙烯酸丁酯乳液共聚乳胶粒形态演化过程的模拟

将簇迁移动力学拓展应用到共聚形态的研究中，对醋酸乙烯酯 丙烯酸丁酯从间歇到不同加料速率下的半连续乳液共聚实验的乳胶粒形态演化过程进行了模拟，模拟从共聚 均聚转折点开始．结果说明：半连续加料时，随着加料速率加快，相分离程度增加，间歇反应时形成了核壳结构．乳胶粒形态模拟结果与文献对此共聚乳胶粒形态的实验表征结果类似．     

Characterization of poly(vinyl alcohol) during the emulsion polymerization of vinyl acetate using poly(vinyl alcohol) as emulsifier

During the emulsion polymerization of vinyl acetate (VAc) using poly(vinyl alcohol) (PVA) as stabilizer and potassium persulfate as initiator, the VAc reacts with PVA forming PVA-graft-PVAc. When the grafted polymer reaches a critical size it becomes water-insoluble and precipitates from the aqueous phase contributing to the formation of polymer particles. Since particle formation and therefore the properties of the final latex will depend on the degree of grafting, it is important to quantify and to characterize the grafted PVA. In this work, the quantitative separation and characterization of the grafted water-insoluble PVA was carried out by a two-step selective solubilization of the PVAc latex, first with acetonitrile to separate PVAc homopolymer, followed by water to separate the water-soluble PVA from the remaining acetonitrile-insoluble material. After the separation, the water-soluble and water-insoluble PVA were characterized by Fourier Transform Infrared (FTIR) spectroscopy and ¹H and ¹³C nuclear magnetic resonance (NMR) analyses, from which the details of the PVA-graft-PVAc structure were obtained. © 1996 John Wiley & Sons, Inc.     

Synthesis of Polyvinylacetate‐Sodium Montmorillonite Hybrids by Emulsion Polymerization in the Presence of Anionic Surfactants

The emulsion polymerisation of vinyl acetate (VAc) in presence of sodium dodecylsulphate (SDS) and sodium montmorillonite (NaMMT) is used in order to achieve polymer‐clay hybrids. The influence of the polyvinylacetate (PVAc), SDS, and PVAc‐SDS complex on the NaMMT structure also was investigated. The VAc emulsion polymerization rate exhibits a maximum as the NaMMT concentration increases. The XRD patterns correspond to hybrids with intercalated structure. If a water soluble comonomer, ammonium sulphato ethylmethacrylate (ASEMA) is used for copolymerization with VAc, a exfoliated hybrid structure (from XRD spectra) is obtained. The solid materials were analysed by TGA, FTIR, XRD, SEM, and TEM.