乳液稳定性对溶剂挥发法制备微胶囊的影响

Effect of Emulsion Stability on Preparation of Microcapsules by Solvent Evaporation Method

为了研究微胶囊型潜伏性固化剂的制备方法及工艺,以二氨基二苯甲烷(diaminodiphenylmethane,DDM)为芯材、聚甲基丙烯酸甲酯(polymethylmethacrylate,PMMA)为壁材,采用溶剂挥发法制备了DDM-PMMA微胶囊固化剂.讨论了溶剂挥发法制备微胶囊的工艺过程中,乳化方法及表面活性剂和分散剂对乳液稳定性及微胶囊成形过程的影响.通过定时拍照记录的方式,记录并对比了不同乳液体系的静态沉降时间长短,用于评价乳液的稳定性.采用红外光谱法(infrared spectra analysis,IR)和热重分析法(thermogravimetric analysis,TGA)分别对微胶囊的表面化学组成和芯材质量分数进行了表征,并采用扫描电子显微镜(scanning electron microscopy,SEM)对微胶囊的表面形貌进行了表征.结果表明,以十二烷基硫酸钠(sodium dodecyl sulfate,SDS)和聚酰胺650为表面活性剂、聚乙烯醇(polyvinyl alcohol,PVA)为分散剂时,采用相反转乳化方法可得到较稳定的乳液,制备的微胶囊接近球形,表面光滑无粘连,且粒径分布较均匀.

To investigate the preparation technology of the microencapsulated latent curing agent,the curing agent diaminodiphenylmethane-polymethylmethacrylate(DDM-PMMA)microcapsule was prepared by solvent evaporation method with DDM as the core material and PMMA as the wall material.The effects of emulsification methods,surfactants and dispersants on the stability of the emulsion and the forming of the microcapsules were discussed for the preparation of microcapsules by solvent evaporation method.The stability of the emulsion was evaluated by recording the precipitation of the emulsion without stirring.The chemical composition of the surface phase of the microcapsule was characterized by infrared spectra analysis(IR),and the core content was estimated based on the thermogravimetric analysis(TGA)results.The surface morphology of the microcapsule was observed by scanning electron microscopy(SEM).Results show that stable emulsion can be prepared by inversion emulsification with sodium dodecyl sulfate(SDS)and polyamide 650 as the surfactants and polyvinyl alcohol(PVA)as the dispersant.The prepared microcapsule has a spherical appearance,smooth surface,and uniform particle size distribution.