核交联型双亲聚合物胶体粒子的制备及其乳化性能

以三硫代碳酸酯为链转移剂,合成了端羧基聚(丙烯酸-r-苯乙烯)(P(AA-r-St))大分子链转移剂;将其用于二乙烯基苯的可逆加成-断裂链转移自由基(RAFT)聚合,一步制备了以交联聚二乙烯基苯为内核、P(AA-r-St)为核外大分子链的双亲聚合物胶体粒子。通过红外光谱、核磁共振氢谱和凝胶渗透色谱确定了大分子链转移剂的化学结构;采用纳米粒度仪、扫描电子显微镜和水接触角测试对胶体粒子的尺寸、形貌及亲-疏水性进行了表征。研究了核外大分子链的化学组成、水相pH、油-水体积比以及油相类型对胶体粒子乳化性能的影响,并通过油相固化的方式考察了胶体粒子在油-水界面的形貌。结果表明:改变核外大分子链的化学组成可有效调控胶体粒子的尺寸、亲-疏水性及乳化性能;当核外大分子链中疏水基元St的物质的量分数为11%时,胶体粒子能够在较宽的pH范围(3~11)稳定水包油型乳液,最大油相体积分数达66.7%;胶体粒子吸附于油-水界面上,有效阻止了乳液滴的聚并;此外,胶体粒子可长效稳定多种油-水体系,作为颗粒乳化剂具有良好的普适性。

Preparation and Emulsifying Performance of Core Cross-Linked Amphiphilic Polymeric Colloidal Particles

The hydroxyl carboxyl-terminated poly(acrylic acid-r-styrene)(P(AA-r-St))-based macro-molecular chain transfers were synthesized using trithiocarbonate as a chain transfer agent,which were further applied in the RAFT polymerization of divinyl benzene to prepare the amphiphilic polymeric colloidal particles with crosslinked poly(divinyl benzene)as the core and P(AA-r-St) as outer copolymer chains.The chemical structure of the macromolecular chain transfers was characterized by infrared spectroscopy,proton nuclear magnetic resonance,and gel permeation chromatography.The size,morphology,and amphipathicity of the as-prepared colloidal particles were characterized by particle size analyzer,scanning electron microscopy,and water contact angle tests,respectively.The effects of the chemical constitution of outer copolymer chains,pH value in aqueous phase,volume ratio of oil to water,and oil type on the emulsifying performance of the colloidal particles were studied.The configuration of the colloidal particles on the oil-water interface was also investigated by solidifying the oil phase.Results show that the size,amphipathicity,and emulsibility of the colloidal particles could be regulated effectively by varying the chemical constitution of the outer macromolecular chains.The colloidal particles,with the mole fraction of St units in the outer macromolecular chains of 11%,could well stabilize the oil-in-water emulsions at a wide pH range(3-11),and the maximum volume fraction of oil in emulsions could reach 66.7%.The packed colloidal particles at oil-water interface effectively prevented the emulsion droplets from coalescence.In addition,the colloidal particles demonstrated their ability to stabilize a variety of water-oil systems to form fine oil-in-water Pickering emulsions for long time,indicating their versatility as particulate emulsifiers.