4-乙烯基苄氯/苯乙烯细乳液制备及其稳定性

以4-乙烯基苄氯(p-CMS)为模型单体,采用超声细乳化的方法制备了系列p-CMS/苯乙烯(St)细乳液。利用纳米粒度仪研究了乳化剂用量、超声时间、超声功率和助稳定剂等对细乳液制备及p-CMS/St质量比值对细乳液稳定性的影响。结果表明,在乳化剂用量为10 g/L、超声24 min、超声功率400 W、助稳定剂用量为单体质量的5%时,制得细乳液的液滴平均粒径约为99 nm,粒径多分散指数为0.12;细乳液的稳定性随着p-CMS/St质量比值的增大而下降,Ostwald熟化作用可能是p-CMS/St细乳液失稳的主要原因。     

甲基丙烯酸3-三甲氧基硅丙酯/苯乙烯细乳液共聚合乳胶粒稳定性

研究了各聚合条件对甲基丙烯酸3-三甲氧基硅丙酯（MPS）和苯乙烯（St）细乳液共聚合体系乳胶粒稳定性的影响,聚合条件包括引发剂类型、MPS/St比例、乳化剂用量、共稳定剂用量和体系pH值。通过动态激光光散射测定初始液滴和乳胶粒的尺寸,气相色谱测定苯乙烯的转化率,总转化率由重量法测定。研究发现,油溶性引发剂偶氮二异丁腈（AIBN）引发的体系,MPS/St比例为1∶4时,聚合过程中乳胶粒尺寸基本不变,最终乳胶粒数与初始液滴数比值为0.97。相同MPS/St比例,水溶性引发剂过硫酸钾（KPS）引发的体系,随聚合反应进行乳胶粒尺寸增加,最终乳胶粒数和初始液滴数比值仅为0.55,乳胶粒发生明显聚并。随MPS/St比例增加,乳胶粒稳定性变差,乳化剂和共稳定剂量变化对乳胶粒数和初始液滴数比值影响不大。在酸性或碱性介质中,由于水解反应加剧,乳胶粒聚并严重,最终粒子数只占初始粒子数的0.25。     

低皂高稳丙烯酸酯单体细乳液的制备 Ⅰ.乳液稳定性影响因素

研究在低乳化剂浓度 (约 0 .2 %,基于水 )条件下 ,丙烯酸酯细乳液稳定性的影响规律及高稳定细乳液的制备方法。结果表明乳化剂的优劣顺序为十六烷基硫酸钠 >十六烷基三甲基溴化铵 >十二烷基硫酸钠 >十二烷基聚十五氧乙烯醚 ;与乳化剂碳链长度相近的助乳化剂优于其他助乳化剂 ;当用搅拌乳化时脂肪醇优于同碳链的烃 ,当用超声波乳化时 ,结果相反 ;加分散相前的分散强度愈高 ,时间愈长 ,乳液稳定性愈高 ;加分散相后的乳化强度一定时 ,乳液稳定性有一最大值 ,达到最大稳定性的时间有一最佳值 ,乳化强度愈高 ,这一最大值愈大 ,达到最大值所需时间愈短 ;分散相水溶性愈大的乳液稳定性愈差 ;乳化与贮存温度也对乳液稳定性有很大影响。     

2-苄基-4-氯苯酚的合成研究

2-苄基-4-氯苯酚是一种强力的杀菌剂。本文以对氯苯酚和氯化苄为原料,在催化剂三氯化铁的存在下,搅拌加热20min,制得2-苄基-4-氯苯酚,收率为77%～78%。经过两次真空蒸馏的产品纯度为97 78%(摩尔),熔点43 30℃～46 10℃。研究了反应的影响因素并确定了最佳反应条件。     

乙烯基聚硅氧烷乳液的制备及性能研究

以十六烷基三甲基溴化铵(CTAB)和辛基酚聚氧乙烯醚(OP-10)为复合乳化剂、KOH为催化剂、八甲基环四硅氧烷(D<,4>)和四甲基四乙烯基环四硅氧烷(D<'Vi><,4>)为单体,制备了乙烯基聚硅氧烷乳液.考察了CTAB用量、CTAB与OP-10的质量比、聚合温度对乳液性能的影响,并对制备的聚硅氧烷进行了红外(IR)与热失重(TG)表征.结果表明,D<,4>与D<'Vi><,4>发生了共聚反应;当CTAB用量为单体质量的3.2%,CTAB与OP-10的质量比为1:6,聚合温度为80℃时,可制得单体转化率为88.5%、乳胶粒粒径为74.82 nm、机械、高温、稀释与电解质稳定性都较好的乙烯基聚硅氧烷乳液.热失重分析(TGA)表明,292℃以前乙烯基聚硅氧烷的质量损失率为17.2%,然后快速分解至442℃,乙烯基聚硅氧烷的质量损失率为97.2%.     

有机硅单体细乳液的制备及其性能

以DNS525和DNS500为复合乳化体系(质量比为1∶1),采用机械搅拌辅助超声均质的方法制备了γ-甲基丙烯酰氧丙基三(三甲基硅氧基)硅烷(TRIS)的单体细乳液,考察了机械搅拌时间、超声时间、乳化剂用量、油水比对其稳定性和粒径性能的影响。当机械搅拌60 min,超声均质15 min,乳化剂用量为6%,油水比为2∶3时,在该条件下制得的TRIS均聚细乳液外观呈白色、泛蓝光、均一,凝胶率为0.62%,转化率为98.32%,粒径为226.4 nm,分布宽度系数为0.143。     

Pd/C催化水合肼还原法制备4-氨基苄醇

在优化实验条件下,即0.60 gw(Pd)=10%的Pd/C催化下,2.94 g质量分数为85%的水合肼还原3.83 g4-硝基苄醇,在80~85℃下反应3.5 h后,反应产物用乙醇-水重结晶得4-氨基苄醇2.788 g,收率为90.67%。3次扩大10倍实验的平均收率为88.56%。     

β-胡萝卜素乳液的制备及其稳定性比较

以吐温80和变性淀粉为乳化剂,将β-胡萝卜素制成水溶性乳液,比较两种乳化剂制备乳液的光、热稳定性。结果发现,两种乳液在光照条件下稳定,但对热的稳定性有一定差异,吐温80制备的乳液热稳定性较差。显微照片和乳液粒径分布可知,吐温80乳液较纯胶乳液稳定。     

4-(4-氯苯基)环己醇及4-(4-氯苯基)环己酮的合成研究

以氯苯、环己烯、乙酰氯为原料,通过Friedel-Crafts反应、Baeyer-Villiger反应、水解反应得到4-(4-氯苯基)环己醇。通过正交试验得到Friedel-Crafts反应和Baeyer-Villiger反应优化后的工艺条件。4-(4-氯苯基)环己醇总收率达12.9%,较文献收率提高了6%以上。所得醇经次氯酸钠氧化,得到4-(4-氯苯基)环己酮,氧化收率87%,产品的结构经1HNMR、GC-MS鉴定。     

低皂高稳丙烯酸酯单体细乳液的制备Ⅱ.乳液稳定性机理

在前文研究影响丙烯酸酯细乳液稳定性众多因素的基础上 ,测定加分散相前乳化剂与助乳化剂所形成的复合胶束和加分散相后的细乳液的单体液滴粒径大小及乳液水相乳化剂浓度 ,提出在低乳化剂浓度下制备高稳定细乳液的机理 ,并进一步归纳出制备高稳定细乳液的最佳工艺。     

氢化松香/丙烯酸酯复合细乳液的制备及其性能研究

以氢化松香(HR)作为增黏树脂,采用细乳液聚合法制备了HR/丙烯酸酯复合细乳液。探讨了乳化剂、HR等因素对该乳液及其胶膜性能的影响。结果表明:与常规乳液聚合相比,细乳液聚合制得的乳液粒径更小、粒径分布更窄、单体转化率更高、凝聚率更低、Zeta电位更高且体系更稳定;HR能有效改善PSA(压敏胶)的粘接性能,并且当w(HR)=5%时,PSA的初粘力(9#钢球)、180°剥离强度(11.2 N/25 mm)和持粘力(47 min)相对较好。     

Interfacially confined RAFT miniemulsion copolymerization of styrene and butadiene

In this study, ammonolyzed poly(styrene‐alt‐maleic anhydride) terminated with dithioester group can be self‐assembled into an amphiphilic macro‐reversible addition‐fragmentation chain transfer (RAFT) agent, and RAFT group will be located in the interface of oil and water. RAFT polymerization of styrene (S) and butadiene (B) will be confined in the interface. The main work is to study the effect of degree of aminolysis, reaction temperature, and ratio of S/B on the polymerization kinetics and living characters. The experimental results revealed that aminolysis of dithioester group would lead to retardation and loss of living characters under higher degree of aminolysis. Interfacially confined RAFT miniemulsion polymerizations were of relatively good controlled/living characters under lower degree of aminolysis before gelation. Increase of reaction temperature and ratio of S/B will accelerate the formation of gelation. Finally, styrene/butadiene copolymer nanoparticles with uniform particle size were formed, and because of microphase segregation “core–shell” morphology with polybutadiene core and polystyrene shell was seen obviously. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Coagulative stability of miniemulsion droplets

Miniemulsion droplets were stabilized with a mixed emulsifier system consisting of an anionic surfactant such as sodium dodecyl sulfate and a costabilizer, which is typically a low-water-soluble, long-chain alkane or alcohol such as hexadecane or hexadecanol. The surfactant, anionic in nature, provided an electrostatic barrier against coagulation, and the costabilizer retarded molecular diffusion of the monomer or Ostwald ripening. The coagulation mechanism operative for the stabilization of the miniemulsion droplets is theoretically considered here. The understanding provides insight into the role of the surfactant. The fate of the miniemulsion droplets during the course of polymerization is also discussed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Ultrasonically initiated miniemulsion polymerization of styrene in the presence of Fe3O4 nanoparticles

Ultrasonically initiated miniemulsion polymerization of styrene was conducted in the presence of Fe₃O₄ nanoparticles. Stable polystyrene (PS)/Fe₃O₄ nanocomposite emulsions were prepared and magnetic PS/Fe₃O₄ composite particles were obtained through magnetic separation. The whole procedure comprised two steps. First, Fe₃O₄ nanoparticles were dispersed in the monomer phase with the aid of stabilizer Span‐80. Second, miniemulsion polymerization of styrene in the presence of Fe₃O₄ nanoparticles was carried out under an ultrasonic field in the absence of a chemical initiator. The affecting factors, including stabilizer concentration, surfactant concentration, hexadecane concentration and the amount of Fe₃O₄, were systematically studied. Stabilizer concentration, surfactant concentration and hexadecane concentration strongly affected the formation of the coagulation. The least amount of coagulation was formed at 2.5 wt% Span‐80 concentration. The addition of Fe₃O₄ nanoparticles drastically increased the polymerization rate owing to the fact that Fe₃O₄ nanoparticles increased the acoustic intensity and Fe²⁺ reacted with H₂O₂ to produce hydroxyl radicals and increase the number of radicals. The increase in cosurfactant concentration and power output also increased the polymerization rate. Copyright © 2005 Society of Chemical Industry     

Particle nucleation and growth mechanisms in miniemulsion polymerization of styrene

Styrene miniemulsion polymerizations stabilized by sodium lauryl sulfate in combination with a reactive costabilizer, lauryl methacrylate (LMA) or stearyl methacrylate (SMA), were studied. A small amount of extremely hydrophobic dye was incorporated into monomer droplets (10² nm in diameter) to investigate particle nucleation and growth mechanisms. In addition to monomer droplet nucleation, particle nuclei generated in the aqueous phase (homogeneous nucleation) also play an important role in both LMA‐ and SMA‐containing polymerization systems. The way that these two nucleation mechanisms compete with each other is closely related to the water solubility of the costabilizer (LMA > SMA). The fraction of latex particles originating from homogeneous nucleation increases with decreasing hydrophobicity of the costabilizer. Zeta potential data of latex particles and the molecular weight and molecular weight distribution of emulsion polymers provide supporting evidence for the proposed competitive particle nucleation and growth mechanisms. © 2002 Society of Chemical Industry     

Double‐miniemulsion preparation of Fe3O4/poly(methyl methacrylate) magnetic latex

Magnetic poly(methyl methacrylate) (PMMA) microspheres were prepared by double‐miniemulsion polymerization. First, oleic acid coated magnetite particles synthesized by means of coprecipitation were dispersed into octane to obtain a ferrofluid. The ferrofluid and MMA were emulsified to form O/W emulsion, respectively. Subsequently two miniemulsions were mixed together for polymerization. The obtained magnetic polymer particles were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, X‐ray powder diffraction, and thermogravimetry. The results showed that oleic acid coated magnetite particles were well encapsulated in PMMA. The effects of initiator dosage and monomer concentration on the conversion of MMA were also investigated. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

3,5-二甲基-4-甲氧基-2-氯甲基吡啶的合成

以3,5-二甲基吡啶为原料经氧化、硝化、甲氧基化、羟甲基化及氯化后制得3,5-二甲基-4-甲氧基-2-氯甲基吡啶。     

2-氯甲基-4-乙氧基吡啶盐酸盐的合成

以2-甲基吡啶为起始原料,经N-氧化、硝化、乙氧基取代、酰化、水解、卤代等步骤,合成了2-氯甲基-4-乙氧基吡啶盐酸盐1,5步总收率为20%。     

纳米二氧化钛/丙烯酸酯复合乳液的制备及反应稳定性研究

采用预乳化及种子乳液聚合方法制备了纳米二氧化钛/丙烯酸酯复合乳液,研究了丙烯酸(AA)、过硫酸钾(KPS)、乳化剂及纳米二氧化钛用量对聚合反应稳定性的影响,并采用红外光谱对复合乳胶膜的结构进行了表征。结果表明:当AA、KPS、乳化剂和纳米二氧化钛的用量分别为3.0%,0.5%,3.3%和2.0%时,体系中的凝胶较少,具有良好的聚合反应稳定性。