Study On Modification Of Syndiotactic Polystyrene

In this paper, acetylated syndiotactic polystyrene and bromoacetylated syndiotactic polystyrene were synthesized through a heterogeneous process. The grafting copolymers were also prepared with a heterogeneous process using atom transfer radical polymerization (ATRP). The thermal properties of modificated sPS were also investigated. The results indicated that the modificated sPS have different thermal properties compared with the neat sPS. The main contents were as follows:Acetylation of stereoregular syndiotactic polystyrene has been accomplished in a heterogeneous process by using carbon disulfide as the dispersing medium and acetyl chloride, anhydrous aluminum chloride as acetylating agent and catalyst, respectively. The acetylation reaction can be well controlled and carried out to a high degree of acetylation. The resultant polymer was characterized by FTIR and NMR spectroscopy. FTIR analysis indicated that the acetyl group must be predominantly at the para-position. The incorporation of acetyl groups onto syndiotactic polystyrene was found to have an effect on the thermal properties of these new materials. The degree of crystallinity decreased by the presence of acetyl groups, while the glass transition temperature increased as well.The bromoacetylated syndiotactic polystyrene has been synthesized fromthe acid-catalyzed halogenation reaction of partially acetylated syndiotactic polystyrene in a heterogeneous process by using methanol as the dispersing medium. The resultant polymer was characterized by NMR spectroscopy. The results indicated that acetyl groups could be converted to bromoacetyl groups completely when reaction temperature and time were 40 and 24 h, respectively. In bromoacetylated syndiotactic polystyrene due to the large size of the substituent group, the bromoacetylated styrene unit exists only in the amorphous region. Thus, no Tm and Tc were detected for the samples with bromoacetylation level of 25.3 mol% and 42.6 mol%, respectively.Syndiotactic polystyrene graft copolymers, including syndiotactic-polystyrene-graft-poly(glyceryl methacrylate), syndiotactic-polystyrene-graft-atactic-polystyrene, and syndiotactic-polystyrene-graft-poly(methyl methacrylate), were synthesized by atom transfer radical polymerization using bromoacetylated syndiotactic polystyrene as macroinitiator and copper bromide combined with 2,2 '-bipyridine as catalyst. The graft copolymers were characterized by 1H and 13C-NMR spectroscopy.