丁苯胶乳的合成研究

以丁二烯和苯乙烯为单体、十二烷基硫醇为乳化剂,通过一步法合成了大粒径丁苯胶乳（SBR）.结果表明：乳化剂浓度、电解质浓度、固含量及单体加入方式是控制丁苯胶乳粒径大小的关键因素.通过适时补加乳化剂,选取适宜的电解质浓度、固含量及采用种子半连续加料方式有利于控制SBR粒径大小及分布.     

淀粉乳液形成过程主要影响因素的耗散粒子动力学模拟与实验

以环己烷为油相、淀粉乳液为水相、Span60和Tween60为乳化剂, 用耗散粒子动力学(DPD)方法研究了淀粉乳液形成过程及油水比、乳化剂用量等因素对淀粉乳液形成的影响. 结果表明, 模拟6000步时, 体系达到平衡状态; 乳滴的粒径随乳化剂含量的增加先减小而后增加, 随淀粉含量的增加而增加, 随环己烷含量的减小而增加; 形成稳定淀粉乳液体系的参数范围: 7＜油水比≤20, 9%＜乳化剂用量≤18%. 实验结果表明, 乳化剂含量为11%～15%时, 微球的粒径随乳化剂含量的增大而减小; 乳化剂含量大于15%时, 微球的粒径反而增大. 实验与模拟的结果吻合.     

小粒径无皂阳离子PMMA胶乳粒子的制备与表征

采用溶剂热法,以AIBA为引发剂制得小粒径无皂阳离子PMMA胶乳纳米粒子。讨论了单体用量、引发剂用量和反应温度对胶乳粒径及乳液的粒径分布的影响;用^1H—NMR、TEM、FTIR、GPC、DTA等对聚合物进行了表征。结果表明：采用溶剂热法制得的无皂阳离子胶乳粒子粒径约为35nm,分散均匀;随着温度的升高,粒径逐渐减小;间同、无规、全同立构的相对含量分别为：55．3％、37．8％、6．9％;乳液的抗电解质稳定性好。     

淀粉微球形成过程的介观模拟及实验

以环己烷为油相、淀粉乳液为水相、Span60和Tween60为乳化剂,对淀粉微球的形成过程进行了耗散粒子动力学(DPD)模拟及实验研究.模拟结果表明,淀粉微球的形成过程存在四个阶段,即淀粉与乳化剂分子无规则分散阶段、小聚集体形成阶段、球状聚集体形成阶段和稳定平衡阶段,并且发现油水比是影响聚集体是否能形成球状的关键因素.油水比小于7的条件下,油水两相分离较难,水相呈现片状、十字型状、柱状及椭球状等形状;当油水比增加到8,水相能形成微球且微球粒径随油水比增加而减小.同时实验结果表明,油水比为8时,微球粘连,几乎看不清球状形貌,油水比为10～20时,微球的粒径随油水比的增大而减小.实验结果很好地吻合了模拟结果.     

不同尺寸（0.02—0.5μm）单分散聚苯乙烯乳液微球的制备

通过对苯乙烯乳液聚合微观动力学以及聚合过程中胶粒直径及其分布随时间变化的理论分析,并通过实验验证,比较了不同乳化剂种类、不同反应温度和不同单体用量条件下,产物胶乳的粒径分布,发现乳液聚合最终产物的粒径分布与成核期长短没有直接联系,而是取决于自由基进入胶粒的速率常数、稳态增长时间、胶粒中的平均自由基数目和胶粒的体积增长速率,胶乳单分散性随这些参量的增大而提高,从而解释了采用高温、高引发剂浓度以及长时间反应的条件对最终的胶粒尺寸分布的影响。本文还通过实验,找到了在20～500nm范围内控制粒径大小及粒径分布的方法。在20～100nm的范围内,用一步法乳液聚合,通过改变单体用量和乳化剂浓度,制备了一系列粒径的单分散聚苯乙烯胶乳;在100～500nm的范围内,运用种子乳液聚合,通过改变溶胀单体与种子胶乳的用量比,也制得了不同粒径的单分散聚苯乙烯胶乳。     

溶剂热法制备无皂P(St-MMA)纳米胶乳粒子

采用溶剂热法,在密闭容器内,以异丙醇-水为分散介质,过硫酸钾为引发剂引发苯乙烯(St)和甲基丙烯酸甲酯(MMA)共聚,制得了粒径约为60 nm的无皂聚(苯乙烯-甲基丙烯酸甲酯)纳米胶乳粒子[P(St-MMA)]。探讨了异丙醇用量和反应温度对P(St-MMA)粒径的影响,并对异丙醇-水和丙酮-水体系中的聚合速率进行了比较。实验结果表明:随着异丙醇用量的增加,P(St-MMA)粒径逐渐减小;随着反应温度的升高,P(St-MMA)粒径先减小后增大;异丙醇-水体系的聚合速率比丙酮-水体系的聚合速率快。     

微波辐照下无皂阳离子聚(St-MMA)高分子纳米粒子的制备和表征

讨论了微波辐照下 ,以丙酮 水为分散介质 ,利用阳离子型自由基引发剂偶氮二异丁基脒盐酸盐(AIBA)引发苯乙烯 (St)和甲基丙烯酸甲酯 (MMA)共聚 ,合成出表面带正电荷的P(St MMA)共聚物纳米粒子 ,考察了丙酮用量、单体和引发剂浓度对纳米粒子粒径、粒径分布和乳液稳定性的影响 .结果表明 ,丙酮 水的体积比由 0增加到 1 2 6∶1时 ,粒子的平均水化半径从 12 2 2 1nm降低到 2 4 6 8nm ,粒径分布变宽 ,乳液抗电解质稳定性逐渐增强 ;增加引发剂和共聚单体MMA的浓度 ,粒子的水化半径逐渐减小 ,粒径分散系数增大 .     

溶剂热法制备小粒径无皂MMA/St共聚纳米胶乳粒子

溶剂热法制备小粒径无皂MMA/St共聚纳米胶乳粒子;溶剂热法;无皂乳液聚合;纳米粒子;聚(苯乙烯甲基丙烯酸甲酯)     

溶剂热法制备无皂阳离子P(MMA-St)纳米胶乳粒子

运用溶剂热法,以丙酮-水为分散介质,偶氮二异丁基脒盐酸盐(AIBA)引发苯乙烯(St)和甲基丙烯酸甲酯(MMA)共聚,制得粒径约为40nm的无皂阳离子聚(苯乙烯-甲基丙烯酸甲酯)纳米胶乳粒子[P(MMA-St)],其结构经TEM,FT-IR,TG和DTA表征。讨论了不同引发剂[AIBA与KPS(过硫酸钾)],AIBA浓度{[AIBA]},单体总浓度{[M0]}对聚合速率的影响。结果表明:相同条件下AIBA引发聚合速率比KPS的快;随着[AIBA]的增大,聚合速率先增大后减小,而粒径先减小后增大;随着[M0]的增大,聚合速率增大;得到[M0]和[AIBA]影响聚合速率的动力学方程为:RP=kP·[M0]0.59[AIBA]0.77;[P(MMA-St)]的热稳定性显著提高。     

月桂醇微小球制作及缓释机理的研究

本文用溶剂蒸发法制备了月桂醇缓释微小球。阐述了微球粒径与搅拌速度、温度、核心材料与基质材料比例以及乳化剂浓度、油水相体积比等制备条件的关系。测定了它在乙醇介质与空气中的释放速率;证明了它的释放机制属于整体型扩散渗透体系并用扫描电镜(SEM)观察了微球表现形态。     

Polymerization of acrylamide in nonionic microemulsions: Characterization of the microlatices and polymers formed

Free radical polymerization of acrylamide was carried out in nonionic microemulsions of water, an isoparaffinic oil, Isopar M and a blend of nonionic emulsifiers: a sorbitan sesquioleate and a polyoxyethylene sorbitol hexaoleate (HLB of the mixture: 9.3). The size and the stability of the latex particles formed after polymerization were studied as a function of monomer, emulsifier and electrolyte concentration. High emulsifier and high monomer contents favor obtaining high molecular weight polyacrylamides. It is shown that both the number of polymer chains contained in each latex particle and the size of the particles are essentially controlled by the acrylamide/emulsifier weight ratio.     

Synthesis and Characterization of Hydrogel Nanoparticles Through Inverse Microemulsion Polymerization of 2-Acrylamido-2-methyl-1-propanesulfonic Acid

Nanosized hydrogel particles prepared through inverse microemulsion polymerization of 2-acrylamido-2-methyl-1-propanesulfonic acid, using the combination of an oil soluble emulsifier (SPAN80) with a water soluble emulsifier (TWEEN 80), and precise determination of HLB range related to the formation of stable single phase microemulsions.

The effect of crosslink density, water phase to oil phase ratio, and the hydrophilic-lipophilic balance (HLB) value on polymerization rate, particle size, and swelling ratio were investigated. It found that polymerization rate and particle size are strongly dependent on the water phase to oil phase ratio. Hydrogel samples prepared using oil soluble and water soluble initiators and the results showed that the initiator type had a great influence on monomer conversion and particle size. Effect of pH on equilibrium swelling of hydrogels was studied by dynamic light scattering and hydrogels showed pH-independent swelling behavior in a broad range of pH values. We also reported and discussed the crosslink density distribution in nanogels prepared by inverse microemulsion polymerization.     

明胶微球粒径控制的研究

采用乳化-凝聚法,在油包水(w/o)的体系中对明胶微球(GMs)粒径、微球的形态和分散性等进行了研究.扫描电子显微镜(SEM)和粒径分布曲线的结果表明在乳化体系中,提高明胶溶液的浓度或水油比例,明胶微球的粒径增大;增加乳化剂的用量,微球的粒径减小;选择合适的乳化时间和搅拌速率,可以改善微球的分散性和表面光滑程度.同时,通过调控实验条件,在明胶溶液浓度0.100 g/mL,水油比1/5,乳化剂浓度0.05g/mL时研制出了平均粒径为3.58μm的表面光滑、分散性好的明胶微球.     

Optimization of Phytosterols Dispersion in an Oil/Water Emulsion Using Mixture Design Approach

Major problems related to enrichment of products with phytosterols are high melting temperature, chalky taste and low solubility in water phase. Dispersion of phytosterols in an emulsion was optimized using a mixture design with four components (phytosterols, emulsifier, soy oil, and water). It was found that the particle size of the dispersed phase decreased with the increase in emulsifier concentration. The appearance viscosity was increased with decreasing particle size. The stability of these emulsions could be correlated with the decrease in surface tension and particle size by using oil and emulsifier as components of oil phase.     

The size of solid lipid nanoparticles: an interpretation from experimental design

This study aimed to investigate the role of different factors affecting the size of solid lipid nanoparticles (SLN), prepared by the emulsification-solvent evaporation method. A double factorial design was conducted so as to cover a wide range of sizes, highlighting zones with different behaviour with respect to changes in the controlled variables: lipid concentration, solvent:lipid ratio and emulsifier concentration. The solvent:lipid ratio constituted the main factor influencing particle size. Increasing the amount of solvent induced a decrease in the size. This was a general trend, essentially independent from solvent and lipid type. The amount of emulsifier had a non-trivial impact on size, depending on whether systems were located below, above or close to the optimal surface coverage. The amount of lipid had a limited influence upon particle size, being more relevant for lower lipid concentrations. An optimal formulation was selected for intermediate levels of the three variables. Sonication reduced both particle size and polydispersity. These particles were also tested as drug carriers using simvastatin as a model of lipophilic drug. SLN were able to entrap a high amount of simvastatin, with little effect upon size and zeta potential, constituting a promising carrier for lipophilic drugs.     

Microemulsion polymerization of butyl acrylate. IV. Effect of emulsifier concentration

The oil/water microemulsion polymerizations of butyl acrylate initiated by a water (ammonium peroxodisulfate, APS) or oil (dibenzoyl peroxide, DBP) soluble radical initiator at different emulsifier concentrations were investigated. The rate of polymerization vs. conversion curve shows two intervals. The rate of polymerization is found to decrease with the emulsifier concentration. This finding was discussed in terms of the decrease of both radical and monomer concentration, the chain transfer to emulsifier, desorption of chaintransferred radicals, and the contribution of solution polymerization. The polymerization is faster with APS. In the APS system the rate per particle or the number of radicals per particle increases exponentially with increasing particle size. The particle size and number increase during the whole polymerization. This behavior was discussed in terms of the nucleation of monomer-containing micelles and agglomeration of primary particles during the whole polymerization. © 1995 John Wiley & Sons, Inc.     

Synthesis of monodisperse, large scale and high solid content latexes of poly(n-butyl acrylate) by a one-step batch emulsion polymerization

Seeded emulsion polymerization and agglomerating method were well-known techniques for the production of polymeric latexes with large particle size and high solid content. Obtaining latexes with monodisperse and particle size above 300 nm scale, however, was time-consuming and difficult by means of these methods. Here, stable, monodisperse latexes with the controlled particle diameter (55–650 nm) and high solid content (60 wt%) were synthesized via one-step in batch emulsion polymerization. Experimental investigations show that the particle size increased with decreasing emulsifier concentrations and increasing monomer/water ratios or electrolyte concentrations. The latex particle coagulation was considered as the dominant particle formation and growth method, which could be proved by the evolutions of particle number as well as dimension against conversion. Latex particle coagulation occurred if the particle surface covered ratio dropped between the critical surface covered ratio (θ _crit?=?0.59) and the lowermost surface covered ratio (θ _low?=?0.38). In addition,θ _crit and θ _low were increased with electrolyte concentrations.     

Preparation of Monodispersed Polymer Microspheres by SPG Membrane Emulsification‐Solvent Evaporation Technology

The membrane emulsification coupled with solvent evaporation was adopted to prepare monodispersed polystyrene (PS) microspheres. Firstly, stable oil‐in‐water emulsion has been successfully obtained by pressing PS solution through SPG membrane into continuous phase at appropriate pressures. Then monodispersed PS microspheres with size of 2–20 µm were obtained following the removal of solvent. The size of the PS microspheres was strongly dependent on the mean pore size of SPG membrane and concentration of PS solution. Furthermore, the effect of emulsion stability, operation pressure and emulsifier on the size and size distribution of microspheres were systemically investigated. Finally, the surface character of PS microspheres was examined via SEM.     

(2-甲基丙烯酰氧乙基)三甲基氯化铵-丙烯酰胺反相微乳液共聚合特性研究

选用SPAN80与OP10复合乳化剂、K₂S₂O₈-Na₂SO₃氧化还原引发剂,进行(2-甲基丙烯酰氧乙基)三甲基氯化铵-丙烯酰胺反相微乳液共聚合反应.研究了单体配比、电解质浓度和乳化体系的油水比对共聚物分子量及离子度的影响,考察了该共聚合体系的反应特性.