The Preparation Of Hollow Polymer Latex Particles

This paper was aimed at preparing cross-linked hollow polymer particles. We synthesized hollow polymer particles through two different ways based on two different mechanism. One is based on phase separation and another is by osmotic swelling. We researched the recipes of these two different methods and some effects on the forming of hollow polymer particles.In the preparation of cross-linked hollow polymer particles by the phase separation, the PST seed with low molecular weight was synthesized firstly, then use the monomer of MMA and DVB to swell the seed particle at high temperature. Polymerization was allow to continue at 80℃with the initiator for 5~10h, after the PST seed was highly swollen with monomer at 80℃ for 30min.The morphology of polymer particles depends on the the molecular weight of the seed polymer and the composition of DVB and MMA in the monomer. When the molecular weight of the seed polymer was under 8000, the hollow particle can be formed; At the MMA:DVB=9/1~6/4, hollow particles were obtained. Following the process of polymerization we get the hollow forming mechanism. It is likely that the stress concentration of the polymerization shrinkage must have occurred at the interface of the seed polymer on the inside of the cross-linked polymer particle, so that a void is developed.In the preparation of the hollow polymer particle by osmotic swelling, MAA and MMA was used as core monomers in order to prepare a acid seed polymer, which can be hydrated and swelled by adding volatile base. MMA-BA-MAA and ST-MMA were used as first and second shell monomers separately to cover the acid seed to obtain the core-shell latex particles with the more hydrophilic polymer in the core and the more hydrophobic polymer in the shell. After the first shelling polymerization, use volatile base such as ammonia to hydrate the core-shell latex particles. Results showed that the hydration degree and the morphology of the latex particle were affected by the MAA content of the seed emulsion, the neutralization degree of the base, time, base type, and the cross-linking of the seed particle. Compared with the solid core-shell polymer film, the film adding hollow polymer particle has good opaquing properties and whiteness because of its hollow structure. The highly cross-linked hollow polymer have an excellent thermal stability, the research of the UV-absorbing ability of the film showed that it has a strong absorption between 275nm to 400nm.