乙烯基螺环原酯(VS)和马来酸酐(MA)的交替光共聚

PHOTOINDUCED ALTERNATING POLYMERIZATION OF VINYL SPIRO ORTHOESTER(VS) WITH MALEIC ANHYDRIDE

乙烯基螺环原酯(VS) 2 亚甲基 1 ,4 ,6 三氧螺 [4,4 ]壬烷和马来酸酐 (MA)的光聚合反应 ,通过形成电荷转移络合物反应中间体 ,按烯类加聚方式生成线性交替共聚物 .在温和条件下 ,VS和MA的光聚合反应仅在自由基光引发剂存在时才发生 ,聚合速度取决于溶剂极性和两种单体的投料比 .而共聚物的组成与单体投料比无关 ,保持等摩尔比值 .采用UV吸收光谱进一步研究了VS和MA等摩尔CT络合物的形成 ,并测定了它们在不同极性溶剂中的络合常数(K) ,另外用IR和1HNMR波谱进一步测定了VS/MA共聚合产物的结构 .得到的结果清楚表明 ,所得共聚物是一种规整的线性交替共聚物 ,在VS单元上保留着原有的三氧螺环 .另外对VS和MA自由基交替光聚合的反应机制亦作了讨论 .

Photoinduced copolymerization of vinyl spiro orthoester(VS) (2 methylene 1,4,6 trioxaspiro[4,4] nonane)with maleic anhydride(MA) proceeds via formation of the charge transfer(CT) complex as reactive intermediate to produce linearly alternating copolymer, poly(VS alt MA) by vinyl type radical polymerization way. It was found that in the mild condition the photopolymeriztion occurs only in the present of radical photoinitiator. The solvent polarity and feed ratio of two monomers significantly affect the polymerization rate, but does not effect on the composition of polymer products. The formation CT complex between VS and MA was further verified by UV absorption spectra. The association constant( K ) of CT complex was estimated to be 0.22 mol -1 ·L (THF) and 0.19 mol -1 ·L(CH 3CN).The small value of K indicates that VS and MA interact to construct a weak CT complex, which is easily affected by polarity of solvents and temperature. The structure of VS/MA copolymer obtained was further determined by IR and 1HNMR spectra. The results measured clearly demonstrated that the copolymer product possesses a regular alternating structure with original trioxaspiro ring at VS unit in polymer chain. The mechanism of radical alternating photopolymerization of VS with MA was also discussed.