Modelling Of Free Radical Polymerization Of Styrene And Synthesis Of Block Copolymer By Multifunctional Initiators

Multifunctional peroxides are new types of initiators for free radical polymerization. They can initiate vinyl monomers to obtain polymers with high molecular weight at high polymerization rate and can also be used to prepare block copolymers. The polymerization processes initiated by multifunctional initiators are more complicated since there are more than one peroxide group with different activity in them. Polyether poly-t-butylperoxy carbonate (JWEB50) and3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxynonane (TETMTPA) were investigated in this paper. Firstly, the kinetic model of styrene bulk polymerization initiated by JEWB50was established. Secondly, the synthesis of block copolymers by conventional free radical polymerization with two initiators were studied.The kinetic model of styrene bulk polymerization initiated by JWEB50was established from the presented elementary reactions according to the study of diffusion-controlled theory. The model was discussed to predicate the changes of various initiator concentrations, various radical concentrations and polymer (including polymer with or without peroxide group) of polymerization system with conversion were also acquired. All relationships to conversion were affected by reaction temperature and initiator concentration. The results calculated from this model is agreement with the experimental very well, what proved that the model can forecast some polymerization characteristics.The special feature of JWEB50is the fact that one initiator contains four peroxide groups which can be sequential decomposed. With the aim of synthesis block copolymers by traditional free radical polymerization, a diblock copolymers, polystyrene-b-poly(methyl methacrylate)(PS-b-PMMA), was prepared by free radical polymerization with a tetra-functional peroxide initiator JWEB50. The polymerization of the formation of the block copolymer was carried out by two stages. First, the polymerization of styrene using JWEB50was investigated and the polystyrene with peroxide was obtained, which was used in the second stage to initiate the second monomer, methyl methacrylate (MMA). Selective solvent extraction was used for separation of the block polymer from the homopolymers. The separation technique was found to be efficient by gel permeation chromatography (GPC). The block copolymer was characterized by GPC,’H-nuclear magnetic resonance (1H-NMR), fourier transform infrared spectrometer (FTIR). The results showed that the polystyrene-b-poly(methyl methacrylate) could be synthesised with JWEB50. The transmission electron microscope (TEM) analysis showed that the polymer could be used as the compatilizer to improve the miscibility of PS/PMMA blends.TETMTPA also has the feature that the three peroxide bonds can be sequential decomposed. The feasibility of synthesis of amphiphilic block copolymer PS-b-PAA with TETMTPA was studied. The polymerization of styrene using TETMTPA was investigated and the polystyrene with peroxide was obtained, which was used in the second stage to initiate the second monomer tert-butyl acrylate. Selective solvent extraction was used for separation of the block polymer from the homopolymers. The separation efficiency was tested by GPC. Then, the copolymer hydrolyzed by trifluoroacetic acid. The polymers was characterized’H-NMR and FTIR. The results showed that tert-butyl acrylate was not blocked to PS and the route proved invalid.