State Key Laboratory of Fine Chemicals,Dalian University of Technology
采用金属铬配合物/双-(三苯基正膦基)氯化铵/叔丁醇锂组成的三组分催化体系,实现了多种环氧烷烃与γ-硫代丁内酯(TBL)高活性开环共聚。发现聚合过程中叔丁醇锂可以有效稳定链末端硫负离子,抑制其回咬,保证了反应的活性以及聚合物的分子量。采用1H NMR、13C NMR、ESI-MS以及FTIR对聚合物结构进行了表征,通过DSC和TGA考察了不同结构聚酯硫醚的热性能。结果表明,聚酯硫醚均具有完全交替结构且呈现无定形态,玻璃化转变温度(Tg)处于?53~?18 °C之间,5%热失重温度在258~300 °C之间。通过氧化反应进一步获得含亚砜和砜结构单元的含硫聚合物,使得Tg大大提高。以叔丁基缩水甘油醚与TBL的共聚物为例,其硫醚结构被氧化为亚砜和砜结构后聚合物Tg分别提高了49和60 °C。
The highly active ring-opening copolymerization of epoxides with γ-thiobutyrolactone (TBL) was achieved by using a three-component catalytic system consisting of chromium complex, bis(triphenylphosphine)iminium chloride and lithium tert-butoxie (tBuOLi). In the polymerization process, tBuOLi can effectively stabilize the negative sulfur anions at the chain ends and suppress backbiting reaction to ensure the reaction activity and molecular weight of the polymer. The copolymer structure were characterized by 1H NMR, 13C NMR, ESI-MS and FTIR. The thermal properties of the resulting poly(ester-thioether)s were investigated by DSC and TGA methods. The resultant copolymers display perfect alternating structures and amorphous forms, with glass transtion temperatures (Tg) ranging from ?53 ℃ to ?18 ℃ and the decomposition temperatures at 5% weight loss between 258 and 300 ℃, showing good thermal stability. Further oxidation of thioether units resulted in the formation of the polymers containing sulfoxide and sulfone structures, which show enhanced Tgs. Taking the copolymer of tert-butyl glycidyl ether and TBL as an example, the thioether was oxidized to sulfoxide and sulfone structure, and the Tg was increased by 49 and 60 ℃, respectively.