PAMS微球制备过程中电解质的影响

为调控固化过程中双重乳液内径的变化和降低聚-α-甲基苯乙烯(PAMS)微球的表面粗糙度,研究了双重乳液固化过程中内外水相中电解质浓度对水在油相液膜中迁移和分相行为的影响。结果表明:仅在外水相中添加电解质时,内水相的渗透压高于外水相,使得内相水向外水相迁移,导致固化后的微球表面起皱。当在内外水相同时添加电解质时,由于平衡了三相之间水的化学势,抑制了水在油相液膜中的迁移和分相,导致PAMS微球壳壁内气泡体积和数量显著降低。同时,在内外水相中同时添加不同浓度的电解质,还可显著改善双重乳液三相之间的密度匹配度,从而提高微球的球形度和壁厚均匀性。

Influences of electrolyte in fabrication process of poly(α-methyl styrene) capsules by microencapsulation

To control the inner diameter change of double emulsions and to improve the surface finish of the resulting poly(-methyl styrene) (PAMS) capsules, the effects of electrolyte in the inner and outer water phases on the water migration and phase separation behaviors in the oil phase layer during curing process were investigated. The results show that addition of electrolyte only in the inner water phase leads to a migration of the water from the inner to the outer water phase and thus results in a shrinking of the double emulsions, potentially wrinkling the resulting PAMS capsules. When adding electrolyte into the inner and outer water phases at the same time, the chemical potential of the inner water phase balances with that of the outer water phase, so that the generation of water microdroplets and the migration of water in the oil phase layer during the curing process are suppressed and then the vacuoles in the shell wall of the resulting PAMS capsules are reduced. Moreover, through adjusting the concentrations of electrolyte in the inner and outer water phases, the densities of the three phases of the double emulsions can also be matched for improving the sphericity and wall thickness uniformity of the resulting PAMS capsules.