以非离子型水性聚氨酯为囊壁材料乳液聚合制备相变纳米胶囊

在无外加乳化剂的情况下,用非离子型聚氨酯作为乳化剂和囊壁材料,以石蜡为芯材,制备了一系列稳定分散在水中的相变纳米胶囊(PCMN),经动态光散射(DLS),透射电镜(TEM),差示扫描量热(DSC)和热重分析(TGA)等手段对PCMN的粒径,形态,热稳定性和相变性能进行研究。通过对乳液聚合转化率的跟踪测试,考察了引发体系、引发剂用量和反应温度对乳液聚合的影响。制备的相变纳米胶囊在透射电镜下有核壳型和聚氨酯粒子型两种粒子。调节囊壁材料和芯材的比例可以得到具有不同相变焓的纳米胶囊,其相变焓可以达到89J/g。热失重分析表明相变纳米胶囊的热稳定性随着交联单体含量的增加而增加。

Preparation of Phase Change Material Nanocapsules by Emulsion Polymerization with Nonionic Water-Borne Polyurethane as the Shell Materials

A series of phase changed materials nanocapsules(PCMN) with paraffin as core materials and nonionic polyurethane as emulsifier and shell materials were prepared without any additional emulsifiers.The PCMNs were able to be stably dispersed in water.The particle size,morphology,thermal stability and phase change properties were characterized by dynamic light scattering(DLS),TEM,DSC,and TGA.The cross-linked shells of PCMNs were formed by emulsion polymerization and the conversions of cross-linker during emulsion polymerization were measured.The influence of the redox-initiaion system,initiator dosage,and reaction temperature on the emulsion polymerization was investigated.The PCMN with cross-linked shell had two kinds of particle structures under transmission electron microscope: core-shell structure and polyurethane particle.PCMNs with different phase change enthalpy were obtained by adjusting the mass ratio of core to shell.The phase change enthalpy of PCMN was able to reach 89 J/g.It was indicated by the thermogravimetric analysis that the thermal stability of PCMN becomes better with the increase of the cross-linker content.