Synthesis And Applications Of Styrene-allyl Alcohol Copolymer

Styrene-allyl alcohol copolymer, hereinafter referred to as SAA, are resinous polyols with high performance and can be used as performance-enhancing resin modifiers in coating and ink systems or be used to synthesize a series of functional polymer materials. SAA has a vast market potential and applications prospect. However, the documents concerning on SAA are rare. The systematic study concerned on the free-radical copolymerization of styrene and allyl alcohol has not seen reported in literature yet. In this paper, the free radical copolymerization of styrene and allyl alcohol has been studied emphatically. By exploring the suitable reaction conditions of this copolymerization, the process parameters of diffrient compositions of styrene-allyl alcohol copolymers were obtained. Then, the motheds of improving the conversion of allyl alcohol during the copolymerization were studied. In the end, we also investigated the applications of SAA as the solid skeleton in solid-solid phase change materials. The results were listed as follows:First, the free-radical copolymerization of styrene and allyl alcohol has been studied in detail. The effects of polymerization conditions, which included the type of initiators, reaction temperature, monomers ratio and feeding mode were investigated. The results showed that high temperature initiators, such as DCP and DTBP are more preferable to this copolymerization. Suitable reaction temperature is between 130 and 165 ℃, the proper amount of initiator is 3 wt%(by weight of momomers) and the reaction time can be 1～3h according to the practical situation. When adopted a monomer molar ratio of St to AA is 0.18:0.82 by one-stage addition of monomers, copolymers with high bound styrene content (0.8 molar percent) can be obtained. While, by using the method of stage-addition of active monomers, which is styrene, copolymers with more bound allyl alcohol units can be prepared. By adopting a monomer molar ratio of St to AA is 0.19:0.81 or 0.10:0.90, copolymers with 0.7 molar percent of bound styrene or 0.6 one can be pepared respectively. SAA with 0.8 molar percent of bound styrene can also be obtained by using a molar ratio of St to AA is 0.35:0.65. The results of thermal analysis showed that SAA has a good thermo-stability which can satisfy the needs of extensive application. The copolymers of different compositions showed distinct dissolubility in the same solvent.The methods of improving allyl alcohol units in the copolymers were explored since the monomer reactivity ratio of allyl alcohol is rather low. The experimental results indicate that increasing the reaction temperature or gradual addition of a free-radical initiator during the course of the polymerization can increase the conversion of allyl alcohol. And the best way is the two combine. However, the reaction temperature should not exceed about 180℃ because the boiling point of allyl aocohol is only 97℃, or operational risk will increase. The suitable mount of initiator can be 3-6 wt%. For commercial production, no more than 15 wt% of initiator should be used.Last, the innovative application of SAA was explored. A series of novel solid-solid phase materials were synthesized with stearic acid, stearyl alcohol and polyethylene glycol as phase change substance and styrene-co-allyl alcohol copolymer as solid skeleton via graft copolymerization respectively. The experimental results show that SAA is an excellent solid skeleton for solid-solid phase change materials (SSPCMs). All the grafted copolymers synthesized have a perfect durability and thermo-stability, which can be potentially used as SSPCMs in different thermal energy storage applications such as building exterior wall thermal insulation or greenhouse.