单分散亚微米级聚合物微球的研究进展

本文综述了单分散亚微米级聚合物微球的自由基聚合主要制备方法,包括分散聚合、RAFT分散聚合、乳液聚合和无皂乳液聚合,讨论了溶剂、引发剂、单体、分散剂、乳化剂、搅拌和温度的选择及其对聚合物微球粒径和单分散性的影响以及粒径控制机理.     

N-(α-甲基-丁酯基)马来酰亚胺微乳液聚合的动力学研究

以十二烷基硫酸钠为乳化剂，过硫酸钾为引发剂，使N-(α-甲基-丁酯基)马来酰亚胺的微乳液聚合。并对其动力学进行了研究。考察了引发剂浓度、乳化剂浓度、单体浓度对聚合的影响，得到三者的曲线斜率分别为0．5，1．17，1．22。     

高固含量聚丙烯酰胺反相微乳胶的制备

依据绘制的Span 80/Tween 80-煤油-水(丙烯酰胺水溶液)拟三元相图,选择高单体质量分数〔如w(丙烯酰胺)=39.2%〕微乳液体系,在反应温度为40℃,引发剂用量为单体质量0.2%的条件下,通过反相微乳液聚合反应,制得了w(聚丙烯酰胺)=39.0%,相对分子质量为5.8×106(引发剂为过硫酸铵)和7.6×106(引发剂为偶氮二异丁腈)的透明、稳定的聚丙烯酰胺微乳胶。考察了相关因素对丙烯酰胺微乳液聚合反应的影响。发现所得聚丙烯酰胺的相对分子质量随着单体、乳化剂质量分数的增加而增大;随反应温度的升高而减小,随引发剂质量分数和反应时间的增加呈现先增大后减小的变化趋势。     

自交联型丙烯酸酯微乳液的研制

采用反应型乳化剂和阴非离子型乳化剂进行复配,以过硫酸钾作为热引发剂,通过半连续种子乳液聚合法制得了性能优异的自交联型丙烯酸酯微乳液.研究发现混合乳化剂用量占单体总量3%(其中种子阶段的乳化剂用量为2.5%)、丙烯酸用量2%、电解质用量0.15%、引发剂用量0.3%(其中种子阶段的引发剂用量为0.225%),中和率在70%～75%时,微乳液固含量高(47.5%)、粒径小(<70 nm)、凝胶量低且漆膜光泽高.     

木器涂料用环保型苯丙微乳液的研制

采用反应性乳化剂通过种子乳液聚合制备木器涂料用苯丙微乳液。研究了乳化剂配比、功能性单体、引发剂体系对乳液和涂膜的影响，并用傅里叶红外光谱仪(FT-IR)对乳液组成进行表征。研究发现反应型乳化剂可制备稳定性良好的纳米级乳液，涂膜有较好的耐水性；采用热引发与氧化-还原引发剂体系组成复合引发剂，可使单体转化率达到99．2％。     

高固含量苯丙微乳液的制备

采用种子半连续微乳液聚合法合成苯丙微乳液。以苯乙烯、丙烯酸丁酯和丙烯酸为单体,辛基酚聚氧乙烯醚(OP-10)和十二烷基硫酸钠(SDS)为乳化剂,过硫酸钾为引发剂,考察了乳化剂、引发剂、丙烯酸单体和电解质对聚合反应的稳定性和粒径大小及其分布的影响,并由此确定了适宜的合成条件,制备了固含量在48%左右,粒径在60~70 nm的苯丙微乳液。     

复合乳化剂体系对氯乙烯微乳液聚合速率的影响

以十二烷基硫酸钠／十六醇复合体系为乳化剂，以三元氯化还原体系作引发剂，进行氯乙烯微乳液聚合，用自行开发的气相色谱－示踪剂检测系统测定转化率，在保持聚合温度和引发剂浓度一定的条件下，着重研究了复合乳化剂用量，配比以及种子对于微乳液聚合速率的影响并从机理上对变化规律作了解释。     

纳米级高固含量室温交联型丙烯酸酯微乳液的研制

采用了反应型乳化剂和阴非离子型乳化剂进行复配,以热引发剂和氧化还原引发剂作为复合引发剂,通过半连续种子乳液聚合法制得了性能优异的纳米级高固含量的丙烯酸酯微乳液。研究表明,复合乳化剂在用量2.8%时,合成的微乳液固含量达到了46.8%,平均粒径65 nm,单体转化率高于99%。在引入5%的含有特殊官能团的交联单体后,合成的纳米级微乳液可实现室温交联,涂膜硬度高,综合性能好。并对微乳液进行了粒径大小及分布、相对分子质量大小及分布(GPC)、透射电镜(TEM)的表征。     

煤用微乳液助滤剂的研制

以表面活性剂SLL(自制乳化剂)及SLL和Span85复配物为乳化剂,醇为助乳化剂,煤油为分散介质,研究了制备丙烯酰胺反相微乳液的条件,并在水溶性引发剂的引发下进行了微乳液聚合.用聚合后的体系对6种不同变质程度的煤进行了煤泥真空过滤脱水实验,实验结果表明,经聚合得到的复合体对六种煤泥都具有很好的助滤脱水效果.     

单一乳化剂制备聚苯乙烯乳液条件探究

以苯乙烯(St)为单体,十二烷基硫酸钠(SDS)为单一乳化剂,过硫酸铵为引发剂,通过乳液聚合制备聚苯乙烯乳液。系统地研究了引发剂用量及质量比、乳化剂浓度、反应时间和反应温度对乳液聚合过程和乳液性能的影响。结果表明,引发剂质量比为0. 25%,乳化剂浓度为0. 1 mol/L,反应时间3 h,反应温度为70℃时,乳液性能最为优良。利用红外和SEM对所得产品的结构和粒径进行了表征。     

Photoinitiated dispersion polymerization using polyurethane based macrophotoinitiator as stabilizer and photoinitiator

Polyurethane based macrophotoinitiator (PU-PI) had been designed and synthesized, and applied to photoinitiated dispersion polymerization of methyl methacrylate as both photoinitiator and stabilizer, with ethanol/water mixture as reaction medium. Monomer conversion over 90% was achieved within 25 min of UV irradiation at room temperature, and monodisperse PMMA microspheres were obtained. The structure of the microspheres had been analyzed by XPS, showing that about 50% of surface of the microspheres were covered with the stabilizer. PU-PI effectively stabilized the polymeric particles in photoinitiated dispersion polymerization due to the unique stabilization process. The size and size distribution of the microspheres became insensitive to the reaction condition such as stabilizer/initiator concentration, initial monomer concentration and reaction medium. The size of the microspheres obtained changed in the range from 0.88 μm to 1.06 μm at different reaction condition, with polydispersity index as low as 1.011. The research may provide a quick and facile approach to prepare monodisperse microspheres with tailored functional surface.     

Preparation and characterization of monodisperse magnetic poly(styrene butyl acrylate methacrylic acid) microspheres in the presence of a polar solvent

Magnetic poly(styrene butyl acrylate methacrylic acid) [P(St–BA–MAA)] microspheres were prepared by emulsifier‐free emulsion polymerization in the presence of a polar solvent and a ferrofluid prepared by a coprecipitation method. The effects of some polymerization parameters, such as the medium polarity, reaction temperature, initiator content, and surfactant content in the ferrofluid, on the particle diameter and particle size distribution of magnetic P(St–BA–MAA) microspheres were examined in detail. The results showed that the electrostatic repulsion in the polymerization system significantly affected the monodispersity of the resulting magnetic polymer microspheres. The proper electrostatic repulsion, achieved through changes in the medium polarity and amount of surfactant in the polymerization system, improved the monodispersity, but a higher or lower repulsion led to a decrease in the monodispersity. Although the existence of surfactant and magnetite particles reduced the monodispersity more or less, the polymerization behavior of an emulsifier‐free emulsion polymerization in the presence of the ferrofluid was analogous to that of a conventional emulsifier‐free emulsion polymerization. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1733–1738, 2003     

Heterocoagulation behavior of carbon black with surface encapsulation through emulsion polymerization

Nanocomposite microspheres containing styrene–acrylate resin, wax, and carbon black (CB) with desired CB dispersion were prepared through heterocoagulation. The CB surface was modified using conventional anionic emulsifier and anionic dispersants with different lengths of nonionic chains and reactivities or through polymer encapsulation via emulsion polymerization to regulate the dispersion and concentration of CB in the microspheres. Experimental results showed that anionic dispersants with long nonionic chains effectively dispersed and stabilized CB particles. Polystyrene (PS) was then encapsulated on the CB surface by using a reactive dispersant and a water‐soluble initiator of polymerization. The CB particles exhibited comparable pH stability with other heterocoagulation components. Overall, encapsulation through emulsion polymerization can be used to obtain not only high CB content but also improved CB distribution in the resulting microspheres. High coagulation efficiency can also be achieved using polystyrene‐encapsulated dispersed CB because of its high affinity to emulsifiers and reactive dispersants during dispersion. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43516.     

无皂乳液聚合法合成单分散性阴离子聚苯乙烯微球

采用无皂乳液聚合法制备了粒径大小可控且均一的聚苯乙烯微球,研究了反应过程中SDS加入量、反应温度、引发剂加入量及反应介质对聚苯乙烯微球粒径大小及分布的影响。利用傅立叶变换红外光谱仪对微球结构进行了表征。     

One-stage photoinitiated RAFT dispersion polymerization – Reaction parameters for achieving high particle size uniformity

One-stage photoinitiated RAFT dispersion polymerization (PRDP) has been studied. It was found that the structure of the RAFT agent has a strong influence on the particle morphology. Carboxyl-functionalized trithiocarbonates, including S,S′-bis(α,α′-dimethyl-α″-acetic acid) trithiocarbonate (BDMAT), S-1-dodecyl-S′-(α,α′-dimethyl-α″-acetic acid) trithiocarbonate (DDMAT), S-1-ethyl-S′-(α,α′-dimethyl-α″-acetic acid) trithiocarbonate (EDMAT), were found to be suitable RAFT agents for preparing highly monodisperse microspheres. GPC traces suggested that the polymerization does not follow the typical controlled/living process due to the low RAFT agent concentration in comparison with photoinitiator concentration. Particle size and uniformity changed very little with a wide range of concentrations of the stabilizer and photoinitiator. Highly monodisperse microspheres were obtained even at low stabilizer concentration (5 wt% PVP). Increasing the monomer concentration led to an increase in particle diameter with an exponent of 0.63, which is similar in scale to conventional dispersion polymerization. The microspheres were monodisperse at monomer concentrations ranging from 5 to 15 wt%.     

乳液聚合法制备核(二氧化钛)-壳(聚苯乙烯)复合粒子

研究了乳液聚合技术用于聚苯乙烯(polystyrene,PS)包覆改性二氧化钛(TiO2)纳米粒子.十二烷基硫酸钠(sodium dodecyl sulfate,SDS)作乳化剂,考察了其浓度对复合粒子形态的影响.用Fourier红外光谱、透射电镜和热重分析表征了无机-有机核-壳复合粒子.用沉降实验评价复合粒子的分散性和分散稳定性.实验表明:SDS浓度为0.8mg/mL时,可以实现PS对纳米TiO2粒子的成功包覆.最佳条件下,乳液聚合单体转化率达62.0%:包覆效率为54.0%;复合粒子中PS占62.6%;复合粒子平均粒径为181nm.复合粒子能在乙酸乙酯中形成均匀分散体系.     

Study of kinetics and mechanisms of dispersion polymerization of 2‐hydroxypropyl methacrylate

In the present work, the dispersion polymerization of 2‐hydroxypropyl methacrylate (HPMA) was carried out in No. 120 gasoline/n‐pentanol medium using azobisisobutyronitrile as initiator and a comb‐structured amphipathic polymer as dispersant. The effects of many factors such as the type, structure and concentration of dispersants, and the reaction temperature, on the reaction and the morphology of the polymer microspheres obtained were investigated. It is proposed that the dispersion polymerization of HPMA has two nucleation mechanisms, homogeneous nucleation and inverse mini‐emulsion nucleation. Furthermore, the kinetic of HPMA dispersion polymerization was also studied. © 2001 Society of Chemical Industry     

Preparation of micron‐size monodispersed PS/P(St/MAA) microspheres by seeded dispersion polymerization

Uniform polystyrene (PSt) particles with the size of 1.9 μm were first prepared via dispersion polymerization, and then used as the seeds in a second‐stage dispersion copolymerization of styrene (St) and methacrylic acid (MAA) to produce carboxyl‐carrying microspheres. The PSt seed particles were swollen by monomer mixture of St and MAA, including an oil‐soluble initiator 2,2′‐azobisiso‐butyronitrile (AIBN), before polymerization. Finally, uniform PS/P(St/MAA) (polydispersity index, PDI = 1.02) microspheres with the size of 2.2 μm were obtained. The average particle size and size distribution of the final microspheres were investigated. MAA contents between 54 and 97 mg/g were detected from the PS/P(St/MAA) particles produced under different conditions. Dispersion medium has great influence on the kinetics of polymerization, due to its effect on the partitioning of monomers, solvents, and initiator in the particle phase, probably as well as on the conformation of the dispersion agent on the surface of the particles. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3586–3591, 2006     

苯乙烯改性丙烯酸酯乳液压敏胶的研制

以丙烯酸丁酯、甲基丙烯酸甲酯、苯乙烯、丙烯酸-2-羟乙酯、丙烯酸为反应单体,十二烷基硫酸钠与聚乙二醇辛基苯基醚按质量比2：1组成复合乳化剂,过硫酸钾为引发剂,采用乳液聚合法,制备了苯乙烯改性丙烯酸酯乳液型压敏胶;对乳液型压敏胶进行了粒度分布、初粘性、180°剥离强度测试。研究结果表明,在反应温度为83±2℃、反应时间为6h、复合乳化剂用量为单体总质量的3～5％、引发剂用量为单体总质量的0．6～0．8％、单体质量比BA：MMA：St：HEA：AA为80：5：10：2：3的工艺条件下,可制得粒径分布窄、平均粒径小、初粘性好、剥离强度高的乳液型压敏胶。     

Fe_3O_4/P(ST-AA)核—壳复合微球的制备和表征

本文以磁性氧化铁胶体粒子为种子,运用分散聚合法,制备出具有磁响应性Fe_3O_4/P(SI-AA)核—壳复合微球。考察了复合微球的形态及结构,测定了复合徽球的粒径和磁响应性,研究了分散介质,引发剂,聚合单体和种子粒子等因素对复合徽球形成的影响。适当调整有关反应条件,采用分散聚合法,可以使复合微球粒径达到23.0μm,磁性氧化铁含量达到9.0mg/s。