The burgeoning ethylene production in the Asia-Pacific region has led to a substantial oversupply of butadiene as a byproduct,and it is highly important to develop new butadiene-based materials.Butadiene-maleic anhydride copolymer,characterized by its amphiphilic nature,shows potential applications in adhesives,emulsifiers,etc.However,the Diels-Alder(DA)reaction of butadiene and maleic anhydride competes with the polymerization,limiting the copolymer yield.In this study,the kinetics of the DA reaction and copolymerization between butadiene and maleic anhydride were examined,and the influence of various reaction conditions on the copolymer yield was investigated.We found that the DA reaction in the induction period of the radical polymerization was the critical factor in limiting copolymer yield.Therefore,we proposed the two-step method to suppress the DA reaction and achieve high-yield production(~85%)of cross-linked microspheres with controllable particle size(175-800 nm)by self-stabilized precipitation polymerization.This work enables an efficient synthesis of conjugated diolefin-maleic anhydride cross-linked microspheres,offering a novel approach to address the issue of butadiene overcapacity.
Hong-Yi QiChen-Xi LiangMing-Sen ChenYan-Bin HuangWan-Tai Yang
Volatile Organic Compounds(VOCs)are highly harmful to human beings and other organisms,and thus the elimination of VOCs is extremely urgent.Here,La-Si co-doped TiO_(2)microsphere photocatalysts,which were prepared by a hydrothermal method,exhibited high photocatalytic activity in the decomposition of formaldehyde compared with TiO_(2).The improved activity can be attributed to the promoted separation efficiency and density of the charge carriers,as verified by the electrochemical results in combination with density functional theory calculations.In addition,the Si dopant changed the microstructure and surface acidity,while the addition of La promoted the separation efficiency of charge carriers.More interestingly,it was found that singlet oxygen was the key species in the activation of molecular dioxygen,and it played a pivotal role in the photocatalytic decomposition of formaldehyde.This work provides a novel strategy for the selective activation of dioxygen for use in the decomposition of formaldehyde.
为实现电石渣资源化利用,以电石渣为原料,表面活性剂为模板剂,采用复分解法制备出碳酸钙空心微球。利用扫描电子显微镜和X射线衍射对样品的形貌、晶型进行了表征,发现碳酸钙微球的粒径在0.5~2μm之间,呈现出空心结构。考察了表面活性剂种类及用量、反应温度、搅拌速度等工艺参数对碳酸钙形貌的影响,研究结果表明:以25 mL 0.1 mol/L十二烷基磺酸钠和15 mL 0.04 mol/L吐温-80表面活性剂为模板剂,在25℃水浴温度下,搅拌速度为500 r/min,反应时间1.5 h,得到分散性较好的方解石型碳酸钙空心微球。
