Morphologies and release behavior of polyurea microcapsules from different polyisocyanates

摘要

Polyurea microcapsules were prepared byemulsion polymerization after adding an aqueous solution withpoly(vinyl alcohol) as protective colloid into an organic solutionwith migrin oil as core material, 1,4-diamino anthraquinone(DAA) as penetrator, and different molar ratios of isophoronediisocyanates (IPDI) and toluene diisocyanates (TDI) as wallmaterials. The effects of diisocyanate types on the morphologiesand release behavior of the resultant microcapsules wereinvestigated. The transmittance(%) of the completely dissolvedmicrocapsule in dimethyl acetamide (DMAc) by UV/visiblespectrophotometer decreased with the content of aliphatic IPDIin the wall by increasing the wall thickness due to its inferiorreactivity compared to aromatic TDI. Also in SEM images,these polyurea microcapsules from higher TDI content hadrougher surfaces. In conclusion, the release profiles of themicrocapsules in extraction solution showed that release rate ofDAA depended on the roughness of the microcapsules.