有机硅改性聚氨酯-丙烯酸酯共聚乳液的研究

以十二烷基硫酸钠、OP-10为乳化剂，采用预乳化的方法，将甲基丙烯酸丙酯基三甲氧基硅烷（KH-570）-丙烯酸酯-聚氨酯进行乳液共聚，制得了稳定的聚合物乳液。采用红外光谱、透射电镜对共聚物结构及其乳胶粒子形态进行了表征；研究了KH-570的用量，反应温度、pH值对共聚反应聚合速率的影响。结果表明：采用乳液共聚法合成的聚合物分子链七带有硅氧烷基团；乳胶粒子为粒径在50-100nm之间的球形粒子；体系聚合速率随KH-570用量的增加而降低；随体系温度的升高而增加；KH-570的引入明显提高了涂层的耐水性。     

用阴离子Gemini 9 B-6-9 B乳化剂合成苯乙烯-丙烯酸丁酯共聚物纳米乳液

以壬基酚、1,6-二溴己烷、氯磺酸为主要原料合成的阴离子Gemini磺酸盐表面活性剂9 B-6-9 B为乳化剂,苯乙烯(St)、丙烯酸丁酯(BA)为单体,合成了乳胶粒径小于100 nm且分布均匀的苯乙烯-丙烯酸丁酯共聚物纳米乳液,考察了聚合温度、乳化剂用量、引发剂用量、单体配比、单体含量对乳液的影响,探讨了乳胶粒子成核机理。结果表明,随着温度的升高,乳胶粒子的平均粒径减小,转化率与凝胶率增大;随着乳化剂或引发剂用量的增加,乳胶粒子的平均粒径和凝胶率减小,转化率增大;随着软单体比例的增加,乳胶粒子的平均粒径与转化率增大,粒径分布变宽,凝胶率减小;单体用量增大,乳胶粒子的平均粒径与凝胶率增大,转化率降低;乳胶粒子的粒径呈单峰分布,可能是按胶束成核机理形成的。     

苯乙烯／甲基丙烯酸β羟乙酯乳液共聚合研究

采用十二烷基硫酸钠为乳化剂,将甲基丙烯酸羟乙酯／苯乙烯进行乳液共聚。研究了单体配比、引发剂浓度、单体浓度、乳化剂浓度、反应温度等因素对聚合速率（Rp）的影响。结果表明,聚合速率随着引发剂浓度、乳化剂浓度、单体浓度、反应温度的增加而增加．随着单体HEMA配比的增加而增加。该体系的表观活化自由能为73．36kJ／mol,Rp=K[M]^1.24[I]^0.61[E]^0.24。     

核壳结构聚硅氧烷/丙烯酸酯复合乳液(Ⅰ)乳化剂对乳液聚合过程及粒径分布和粒子形态的影响

采用种子乳液半连续法合成了具有高有机硅含量的聚硅氧烷/丙烯酸酯核壳结构复合乳液,研究乳化剂的种类、复配比例及质量浓度对有机硅／丙烯酸酯壳核乳液性能与乳胶粒径、分布和结构的影响.结果表明：阴离子乳化剂十二烷基硫酸钠(SDS)、十二烷基磺酸钠(SDS-2)、十二烷基苯磺酸钠(SDBS)所合成的乳胶粒子粒径依次增大,SDS与非离子型乳化剂OP-10复配使用时,随OP-10质量分数的增加,聚合速率和转化率降低,化学稳定性增加,乳胶粒子粒径增大,分布变宽,确定了复合乳化剂的最佳配比.随复合乳化剂浓度的增加,聚合速率加快、转化率增加,乳胶粒子粒径减小而分布加宽.通过改变乳化剂加入方式可减小乳胶粒子的粒径分布.为减少壳层聚合物新粒子的产生,需严格控制乳化剂的浓度,使加入的壳层单体处于“饥饿”状态,在乳胶粒子表面富集、引发聚合,形成表层“过渡层”,最终形成核壳结构复合粒子.     

丁苯乳液共聚合动力学的研究

本文详细考察了高转化率下各种因素对丁苯乳液共聚合速率的影响。以过硫酸钾为引发剂,岐化松香皂和硬脂酸钾的混合物为乳化剂,正十二硫醇为链转移剂,在5升不锈钢高压釜中进行了丁苯乳液共聚合实验。随着乳化剂和引发剂浓度的增大、乳化剂中硬脂酸钾相对量的增加以及温度的升高,聚合速率均加快;加入少量电解质可以提高聚合速率;加入少量硫醇与完全不加硫醇相比,聚合速率有很大提高。另外,还发现氧对聚合有明显的阻聚作用、水油比对单体转化速率影响不大。同时理论推导了乳胶粒数随时间的变化关系,并在自由基聚合机理,乳胶粒中单体浓度连续下降等假设的基础上推导了高转化率下乳液聚合的数学模型,对于丁二烯、苯乙烯共聚体系,模型计算值与实验值能较好的吻合。     

VAc-BA-AA三元乳液共聚合研究

用 (NH4) 2 S2 O8-Na2 SO3氧化还原体系引发醋酸乙烯 (VAc) -丙烯酸丁酯 (BA) -丙烯酸 (AA)三元乳液共聚合 ,研究了引发剂、乳化剂、聚合反应条件对聚合转化率 ,乳液粘度和乳液稳定性的影响。实验结果表明体系动力学与经典 Smith-Ewart的乳液合理论不一致。反应速率 (Rp)随着乳化剂浓度的增加而增大 ,乳液的稳定性受乳化剂浓度的影响。聚合温度、引发剂浓度、丙烯酸的浓度对三元共聚乳液的稳定性也有影响     

聚甲基丙烯酸甲酯预聚物作为助稳定剂的细乳液聚合速率研究

以聚甲基丙烯酸甲酯(PMMA)预聚物为助稳定剂、十二烷基硫酸钠为乳化剂、十六醇为助乳化剂和过硫酸钾为引发剂,研究甲基丙烯酸甲酯(MMA)的细乳液聚合反应速率.考察乳化剂浓度、助乳化剂浓度、引发剂浓度、预聚物浓度、预聚物分子量以及反应温度对聚合速率的影响.结果表明:聚合速率RP随着乳化剂浓度或反应温度的提高而增加,随着助乳化剂浓度的提高而减小,引发剂浓度对RP影响不明显.在相同条件下,加入预聚物的细乳液体系聚合速率RP在聚合反应前期比常规细乳液有明显提高:PMMA(MH=520000)浓度为2×10-3mmol·L-1时,RP的最大峰值为1.84×10-2mol·L-1·min-1.预聚物PMMA在MMA细乳液聚合体系中,可以提高聚合速率和增加体系稳定性.     

苯乙烯/丙烯酸丁酯交联体系乳液聚合动力学研究

以十二烷基苯磺酸钠(SDBS)为乳化剂,过硫酸钾(KPS)引发苯乙烯/丙烯酸丁酯(St/BA)乳液共聚,加入二甲基丙烯酸乙二醇酯(EGDMA)、聚丁二烯生胶(PB)作为交联剂,研究了聚合温度、引发剂浓度、乳化剂浓度、单体配比对聚合速率的影响。实验结果表明,共聚体系的表观活化能为70.67kJ/mol,聚合初始速率与引发剂浓度的0.43次方、乳化剂浓度的0.56次方和单体BA的0.49次方成正比。     

脂肪酸甲酯磺酸钠作乳化剂的丙烯酸酯乳液聚合研究

以甲基丙烯酸甲酯、丙烯酸丁酯、丙烯酸为单体,脂肪酸甲酯磺酸钠C16-MES为乳化剂,通过乳液聚合制备了丙烯酸酯共聚物乳液.根据Davies法计算了C16-MES的HLB值在12.8左右,并且考察了乳化剂用最、引发剂种类及用量、单体配比对聚合稳定性及乳液稳定性的影响规律.实验结果表明,以C16-MES为乳化剂制备的不同单体配比的丙烯酸酯共聚物乳液稳定,随着乳化剂用量的增加,聚合反应速率增大;引发剂用量相同时,氧化还原引发体系引发的丙烯酸酯乳液聚合速率大于热引发体系.乳胶粒的粒径都在103～200 nm.     

醋酸乙烯酯-叔碳酸乙烯酯乳液共聚动力学研究

以十二烷基硫酸钠为乳化剂,聚乙烯醇为保护胶体,过硫酸钾为引发剂,进行醋酸乙烯酯-叔碳酸乙烯酯(VAc-VeoVa10)乳液共聚.研究了引发剂含量、乳化剂含量、单体配比和聚合温度等对VAc-VeoVa10乳液共聚速率的影响.结果表明:共聚体系的总表观活化能为106.55 kJ/mol,单体组成对共聚速率的影响不明显,Ⅱ阶段共聚合速率同引发剂浓度的0.658次方,乳化剂浓度的0.371次方成正比.     

苯乙烯/γ-甲基丙烯酰氧丙基三甲氧基硅烷乳液共聚动力学研究

以苯乙烯（St）、γ-甲基丙烯酰氧丙基三甲氧基硅烷（TMSPMA）为单体,十二烷基硫酸钠和辛基酚聚氧乙烯醚为复合乳化剂,通过乳液聚合法制备了St-TMSPMA共聚物。用傅里叶变换红外光谱仪对共聚物进行了表征,1090 cm-1处Si－O－Si键的吸收峰和1723 cm-1处羰基的伸缩振动吸收峰表明TMSPMA与St发生了共聚反应;并研究了反应温度、引发剂浓度、乳化剂浓度和TMSPMA浓度对乳液共聚反应速率的影响,结果表明,升高反应温度、增大引发剂或乳化剂浓度以及降低TMSPMA浓度都可以提高聚合反应速率。     

Statistical experimental strategies approach to emulsion copolymerization of styrene and n-butyl acrylate

A batch emulsion copolymerization for the preparation of styrene-n-butylacrylate (St/BA) copolymer latexes is investigated. A series of n-butylacrylate-styrene copolymer latexes were obtained by emulsion copolymerization in the presence of K₂S₂O₈ (KPS) as initiator and with/without emulsifier (sodium lauryl sulfate). The effect of such preparation conditions as initiator concentration, the St/BA ratio, reaction temperature, agitation rate, and emulsifier concentration on the polymerization rate, particle size of copolymer latex, and molecular weight distribution of the resulting copolymer (∼ 80% conversion), respectively, is systematically studied using fractional factorial design methodology. Fractional factorial analysis indicates that the effects of the St/BA ratio, reaction temperature, emulsifier concentration, as well as the two-factor interaction of temperature and emulsifier concentration, are the key variables influencing the polymerization rate. At ∼ 80% monomer conversion, statistical analysis clearly isolates emulsifier concentration as the dominant factor affecting average particle size of copolymer latex; results also indicate that the effects of the St/BA ratio, reaction temperature, and emulsifier concentration are major effects influencing the polydispersity of polymer molecular-weight distribution. For 7.30 g KPS/100 g monomer and 500 rpm agitation rate, the conditions for minimizing molecular-weight distribution (∼ 80% conversion) occur for a reaction temperature, St/BA ratio, and surfactant concentration of 70°C, ∼ 3.59/1, and ∼ 2.08 g/100 g monomer, respectively, generating a minimum molecular-weight polydispersity of ∼ 3.0. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 551–563, 1998     

偏氯乙烯／丙烯酸甲酯乳液共聚合研究

以过硫酸钾／亚硫酸氢钠（ＫＰＳ／ＳＨＳ）为引发体系，十二烷基苯磺酸钠（ＳＤＢＳ）或十二烷基硫酸钠／聚氧乙烯基辛基酸醚（ＳＬＳ／ＯＰ）为乳化剂或复合乳化剂，于５０℃或６０℃下进行偏氯乙烯／丙烯酸甲酯（ＶＤＣ／ＭＡ）的乳液共聚合。实验结果表明，采用乳化剂ＳＤＢＳ或复合乳化剂ＳＬＳ／ＯＰ，加入适量离子型第三单体和ｐＨ值调节剂，可以制得总固物含量大于５０％的稳定性好、粒径适宜、阻透和涂敷性能良好的ＶＤＣ／     

Mechanism and kinetics of emulsion copolymerization of vinylidene chloride—Critical conversion at the end of interval 2 and rate of polymerization

In this paper, the change of vapour pressure in the emulsion copolymerization of vinylidene chloride (VDC) was determined. It was observed that the vapour pressure drops at conversion about 60% when VDC/comonomer = 90/10 (wt). The types of emulsifier, concentrations of emulsifier and initiator, temperature do not effect these conversion values significantly. According to the principle of phase equilibrium, that the critical conversion at the end of Interval 2 in the emulsion copolymerization of VDC is about 60% was suggested. The effects of types of emulsifier, concentrations of emulsifier and initiator, temperature, types and concentrations of comonomer on rate of copolymerization were also studied. It was found that the different types of comonomer will have no great effect on the copolymerization rate and intrinsic viscosity of a VDC copolymer. And a common route and recipe can be adopted for producing different grades of PVDC latex.     

丙烯腈与丙烯酸乙酯乳液共聚合及其表征

用氧化还原引发体系在低温下研究了丙烯腈与丙烯酸乙酯的乳液共聚合。考察了聚合温度、乳化剂浓度和分子量调节剂浓度对聚合的影响 ,结果表明 ,随温度升高 ,乳化剂浓度增大 ,单体转化率和分子量增大 ,乳液更稳定 ;链转移剂十二烷基硫醇浓度增加 ,分子量显著降低 ,转化率有所降低 ,表明十二烷基硫醇在调节分子量的同时也起着缓聚剂的作用。用激光粒径分析仪考察了 2 0℃时聚合过程中乳胶粒子大小的变化 ,发现聚合过程的成核和增长均在胶束中进行的。用凝胶渗透色谱法研究了十二烷基硫醇对聚合物分子量的影响 ,发现聚合时加入分子量调节剂 ,活性链寿命较短并呈单峰分布 :聚合时不加入分子量调节剂 ,活性链寿命较长并呈双峰分布。 DSC结果表明 ,随聚合体系中软单体含量增加 ,共聚物的玻璃化温度降低。     

Dispersion Polymerization of Styrene by Initiation Within Monomer Phase with Lauroyl Peroxide

Dispersion polymerization kinetics of styrene was investigated in this study. A monomer phase soluble initiator, namely lauroyl peroxide, and a water phase soluble emulsifier, namely sodium dodecyl sulfate, were used. the polymerizations were carried out in a magnetic drive, sealed, cylindrical polymerization reactor, in nitrogen atmosphere. Two different fatty alcohols, cetyl and lauryl alcohols, were tried as particle size increasing agents. the effects of initiator, emulsifier concentrations, monomer/water ratio, and the weight ratio of particle size increasing agent to emulsifier on the total monomer conversion, average size, and size distribution of the large latex particles were studied. the agglomeration conditions were tested by changing the polymerization temperature, initiator, and emulsifier concentrations. the results indicated that the polymerization rate and the average size of the latex increased with increasing emulsifier concentration. the average size of the latex was also increased with increasing initiator concentration. the use of cetyl alcohol in the presence of emulsifier resulted in an appreciable increase in the polymerization rate and in the average size of the latex. the effect of fatty alcohols on the polymerization rate in the dispersion polymerization system was completely different than that in the swollen emulsion polymerization. the agglomeration of the large latex particles was increased with decreasing emulsifier and increasing initiator concentrations.     

氯乙烯/异丁基乙烯基醚乳液共聚物的合成

以(NH4)2S2O8／Na2SO3／CuSO4为氧化-还原引发体系、十二烷基硫酸钠(SDS)为乳化剂，采用间歇乳液聚合合成氯乙烯／异丁基乙烯基醚(VC／IBVE)共聚物。结果表明，当投料单体中IBVE质量分数增加时,相同聚合时间的聚合转化率和共聚物特性粘度明显降低。当转化率小于70％时，共聚物平均组成变化不大；聚合温度增加使聚合速率增加，但共聚物特性粘度减小；SDS浓度对聚合速率和共聚物特性粘度的影响很小；随引发体系浓度增加．聚合速率增加，共聚物特性粘度变化不大。     

有机硅氧烷改性丙烯酸酯微乳液的合成与表征

采用种子乳液聚合法,以阴离子乳化剂DF-2和非离子乳化剂OP-10作为复合乳化剂,以FeSO4、K2S2O8和甲醛合次亚硫酸氢钠(SFS)作为氧化-还原引发剂,在65℃合成了有机硅改性丙烯酸酯聚合物微乳液。实验采用单体滴加工艺,用COULTERLS粒度仪和傅里叶变换红外光谱仪分别测定了共聚乳液的粒径分布和产物的结构,研究了加料方式、配方组成及操作方式对聚合稳定性、乳液的粒径分布以及产物性能的影响。结果表明,采用单体滴加工艺能得到平均粒径为50～80nm的单峰窄分布微乳液,并有效地将有机硅氧烷引入到共聚物大分子中。     

Chemical composition and its distribution of emulsion copolymers composed of styrene and ethyl acrylate as hydrophobic and hydrophilic comonomers

Summary Chemical composition and its distribution of styrene (St)-ethyl acrylate (EA) copolymers synthesized by emulsion copolymerization under different monomer ratios and polymerization conditions were examined by ¹H-NMR and high-performance liquid chromatography (HPLC), respectively, and compared with those of bulk copolymers. It was newly found that the chemical composition of copolymer at early stage is affected by the concentration of emulsifier (SDS, sodium dodecyl sulfate) and monomer/water ratio, and is almost independent of the concentration of initiator or polymerization temperature. The EA fraction decreased with the increase of SDS concentration and converged to the value calculated using distribution factor (f_d) when SDS concentration was extrapolated to zero. These results indicate that the EA fraction in micelle decreased compared to the expected value from f_d due to the interaction of EA monomer with emulsifier. From HPLC, it was found that each copolymer showed a sharp single peak at an early stage of polymerization indicating that no homopolymer or copolymer with different composition was produced.