Ultrasonic Induced Emulsion And Microemulsion Polymerization Of Methyl Methacrylate And Preparation Of Composites With Inorganic Nanoparticles

Novel materials are the bases of the development of high technology. New technology provides methods for the preparation of novel materials. In this paper, ultrasonic irradiation was employed to initiate the emulsion and microemulsion polymerization of methyl methacrylate (MMA) and preparation of composites with some inorganic nanoparticles. Some novel materials with special structure and properties were prepared.1. Ultrasonic induced emulsion polymerization of MMAUltrasonic induced batch emulsion polymerization of MMA was realized. The experimental results showed that surfactant sodium dodecyl sulfonate (SDS) played a very important role for high yield, in absence of SDS, the monomer conversion was near zero. The surfactant served as initiator as well as interfacial modifier in this system (MMA/I^O), monomer conversion increased significantly with increase of SDS concentration. An increase in reactor temperature leaded to an increase of monomer conversion. There was a peak value of power output for the conversion of MMA. Conversion of MMA decreased with the increase of reaction system volume and monomer concentration. The parameters stated above also showed complicated effect on the molecular weight and distribution of PMMA.The parameters affecting induction time were investigated in detail. Under the optimized reaction conditions, the induction time was shortened from 5-10 min to less than 1 min; high monomer conversion of about 67%, high molecular weight of about several millions were obtained in a period of about 30 min.The structure of PMMA obtained by ultrasonic induced emulsion polymerization of MMA was charaterized. The PMMA latex was in'nano scale via TEM measurement, indicating a promising technique for the mini-, or micro-emulsion polymerization of MMA. The results of molecular weight characterization showed that polymer chains with high molecular weight were formed at the beginning of polymerization. Generally, the molecular weight of PMMA obtained by ultrasonic induced emulsion polymerization of MMA was as high as 3-4 million.The mechanism of ultrasonic induced emulsion polymerization of MMA was brought out, and compared with conventional emulsion polymerization and ultrasonic induced bulk polymerization of MMA.Ultrasonic induced semi-continuous and continuous polymerizations of MMA were realized. Decreasing the feeding rate of monomer or flowing rate of reaction fluid, monomer conversion was increased.Ultrasonic induced emulsion copolymerization of MMA/BA and MMA/MAA was realized. FTIR spectrum proved the occurring of copolymerization of MMA/MAA. With the increasing of BA content, conversion of co-monomers was increased. The addition of MAA promoted the conversion of MMA, but had little effect on the molecular weight and distribution of PMMA.Ultrasonic induced seed polymerization of MMA (PMMA or PBA as seed) was realized. The experimental results showed that the polymer radicals from the ultrasonic degradation of polymer seeds initiated the copolymerization of added monomers, indicating copolymer latex with core-shell structure is obtained. The mechanism of formation of core-shell structure was discussed.After the systematic study on the ultrasonic induced batch, semi-continuous,continuous emulsion polymerization, emulsion copolymerization and seed emulsion polymerization of MMA, the new technology of ultrasonic induced emulsion polymerization of MMA was established successfully, providing theoretical and experimental foundation for commercializing this new technology, which was also an effective method for controlling the structure and properties of polymers.2. Ultrasonic induced microemulsion polymerization of MMAUltrasonic induced microemulsion polymerization of MMA was realized and the monomer conversion reached about 90% in a short time of about 40 min. The effect of several factors on the polymerization was investigated in detail.The radical scavenger DPPH was used to study the kinetics of ultrasonic induced microemulsion polymerization of MMA. Rate cons...