An effective strategy for enhancing the heat resistance of polystyrene(PS)with regard to its glass transition temperature(T_(g))involves the anionic solution copolymerization of a-methylstyrene(AMS)with styrene(St),ty...An effective strategy for enhancing the heat resistance of polystyrene(PS)with regard to its glass transition temperature(T_(g))involves the anionic solution copolymerization of a-methylstyrene(AMS)with styrene(St),typically requires much lower temperature(-25℃)and multistep monomer feeding to achieve higher number-average molecular weight(M_(n))block copolymers.However,the anionic copolymerization of AMS and St under the mild temperature remains largely unexplored.This study systematically investigated the anionic copolymerization of AMS and St using n-BuLi in nonpolar solvent(-25℃ to 25℃)through both one-step and two-step approaches.We demonstrated that one-step copolymerization at 25℃ yielded only 1-3 terminal AMS units,with higher feed ratios(5 wt%-20 wt%)increasing AMS incorporation but reducing the exact molecular weight(MW)due to enhanced depolymerization,as evidenced by MALDI-TOF MS.Temperature-controlled AMS conversion at-15℃ achieved 98%AMS conversion(5 wt% feed)by suppressing side reactions and lowering the[M]_(e),while 50℃(near T_(C))almost prevented incorporation.Despite t-BuOK regulation induced broader PDI(1.24)via reactive[(polymer-Li)OR]K intermediates,while other systems showed narrow distributions,t-BuOK outperformed THF in enhancing AMS incorporation via efficient ion pair dissociation.In comparison,the two-step polymerization approach demonstrated superior performance,achieving both higher AMS conversion efficiency and preferential incorporation at the initiation end.At a 20 wt%AMS feed ratio,this method yielded copolymer chains containing up to 6 AMS units on average.Thermal analysis revealed a composition-dependent single T_(g),which exhibited a systematic increase with higher AMS incorporation content.These results collectively demonstrate the precise control over AMS incorporation and heat resistance achievable through the manipulation of polymerization conditions.展开更多
基金financially supported by the National Natural Science Foundation of China(No.52373052)Fundamental Research Funds for the Central Universities(No.DUT24MS011)。
文摘An effective strategy for enhancing the heat resistance of polystyrene(PS)with regard to its glass transition temperature(T_(g))involves the anionic solution copolymerization of a-methylstyrene(AMS)with styrene(St),typically requires much lower temperature(-25℃)and multistep monomer feeding to achieve higher number-average molecular weight(M_(n))block copolymers.However,the anionic copolymerization of AMS and St under the mild temperature remains largely unexplored.This study systematically investigated the anionic copolymerization of AMS and St using n-BuLi in nonpolar solvent(-25℃ to 25℃)through both one-step and two-step approaches.We demonstrated that one-step copolymerization at 25℃ yielded only 1-3 terminal AMS units,with higher feed ratios(5 wt%-20 wt%)increasing AMS incorporation but reducing the exact molecular weight(MW)due to enhanced depolymerization,as evidenced by MALDI-TOF MS.Temperature-controlled AMS conversion at-15℃ achieved 98%AMS conversion(5 wt% feed)by suppressing side reactions and lowering the[M]_(e),while 50℃(near T_(C))almost prevented incorporation.Despite t-BuOK regulation induced broader PDI(1.24)via reactive[(polymer-Li)OR]K intermediates,while other systems showed narrow distributions,t-BuOK outperformed THF in enhancing AMS incorporation via efficient ion pair dissociation.In comparison,the two-step polymerization approach demonstrated superior performance,achieving both higher AMS conversion efficiency and preferential incorporation at the initiation end.At a 20 wt%AMS feed ratio,this method yielded copolymer chains containing up to 6 AMS units on average.Thermal analysis revealed a composition-dependent single T_(g),which exhibited a systematic increase with higher AMS incorporation content.These results collectively demonstrate the precise control over AMS incorporation and heat resistance achievable through the manipulation of polymerization conditions.
