Synthesis And Mechanism Of Multihollow Macromolecule Microspheres Under Microwave Irradiation

Multihollow macromolecule microspheres were synthesized by seeded emulsion polymerization and subsequently alkali/acid or alkali/cooling treatment under microwave irradiation. These multihollow particles were poly(styrene-methylmeth- acrylate-acrylic acid), poly (styrene-methylmethacrylate-methacrylic acid), poly (styrene-methylacrylate-acrylic acid),poly(styrene-ethylacrylate-acrylic acid) and poly(styrene-butylacrylate-methacrylic acid). The polymer conversion was deter- mined by gravimetrically analytical method and the particles were characterized using TEM, IR, GPC and DTA. The copolymer which was prepared by seeded emulsion polymerization almost containing no new particles was gained by the control of the seed concentration, amount of unsaturated monomer, monomer addition velocity and initiator addition method, etc. The suitable conditions for the preparation of multihollow particles with controllable diameter and hollow size were investigated by changing the factors such as initial alkali treatment pH value, alkali treatment time, initial acid treatment pH value, acid treatment time and temperature.The multihollow particle formation mechanism was discussed. It was considered the swelling of the particles, the movement of molecule segment and small water pool existed in the alkali treatment process were crucial step for the formation of multihollow particle. Subsequently, these small water pools would form larger water pool by coagulation through acid treatment or cooling process, which resulted in multihollow structure. The whole treatment process was connected with the interfacial free energy of polymer and water.