Qiu Fang-Yi, Song Cheng-Cheng, Zhang Mei, Du Fu-Sheng, Li Zi-Chen
Beijing National Laboratory for Molecular Sciences, Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, Center for Soft Matter Science and Engineering, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
ACS Macro Lett. 2015 Nov 17;4(11):1220-1224. doi: 10.1021/acsmacrolett.5b00533. Epub 2015 Oct 21.
We report a new type of oxidation-promoted fast-degradable aliphatic poly(carbonate)s (PCs) prepared by the ring-opening polymerization (ROP) of a six-membered cyclic carbonate containing a phenylboronic pinacol ester. The ROP of this monomer catalyzed by 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) proceeded rapidly at ambient temperature with a good control over molecular weight and polydispersity at high monomer conversion. The HO-induced decomposition of this cyclic monomer and its noncyclic carbonate analogue was first studied by H NMR in order to clearly demonstrate the degradation mechanism of the PCs. The results of H NMR, GPC, and Nile Red fluorescence measurements revealed that the PC nanoparticles formulated by the o/w emulsion method were stable in neutral buffer, but upon triggering with HO, they underwent rapid surface degradation via the consecutive processes of oxidation, 1,6-elimination, release of CO, and intramolecular cyclization. The degradation rates of the nanoparticles were dependent on the concentration of HO, and the nanoparticles were even sensitive to 0.5 mM of HO.
我们报道了一种新型的氧化促进快速降解脂肪族聚碳酸酯（PCs），它是通过含苯基硼酸频哪醇酯的六元环状碳酸酯的开环聚合（ROP）制备的。由1,8-二氮杂双环[5.4.0]十一碳-7-烯（DBU）催化的该单体的ROP在室温下快速进行，在高单体转化率下对分子量和多分散性有良好的控制。为了清楚地证明PCs的降解机理，首先通过1H NMR研究了HO诱导的这种环状单体及其非环状碳酸酯类似物的分解。1H NMR、凝胶渗透色谱（GPC）和尼罗红荧光测量结果表明，通过水包油乳液法制备的PC纳米颗粒在中性缓冲液中是稳定的，但在用HO触发后，它们通过氧化、1,6-消除、CO释放和分子内环化的连续过程经历快速的表面降解。纳米颗粒的降解速率取决于HO的浓度，并且纳米颗粒对0.5 mM的HO甚至也很敏感。
