Synthesis of cleavable multi-functional mikto-arm star polymer by RAFT polymerization: example of an anti-cancer drug 7-ethyl-10-hydroxycamptothecin(SN-38) as functional moiety

Multi-functional mikto-arm star polymers containing three different arms [hydrophilic, SN-38-P（OEGMAs_9）11, cationizable, SN-38-P（DMAEMA）3s and hydrophobic, SN-38-P（BMA）26] were prepared by RAFT polymerization via an arm-first approach using a cleavable cross-linker. The star polymers were cleaved to the linear arms with tributylphosphine as a reducing agent. The decrease in molecular weight observed is consistent with the initial stars having approximately five arms, Blue fluorescence was observed when a solution of mikto-arm star was irradiated under a 365 nm light proving the retention of the SN-38 moiety during star formation by RAFT polymerization. Thus these polymer-drug conjugates can be considered as potential delivery vehicles for cancer therapy. The P（DMAEMA） arms can be quaternized using iodomethane, allowing star polymers to bind negatively charged small interfering RNA （siRNA） and potentially be used as a carrier for that material.

杂臂星型低聚物的合成及其增韧环氧树脂研究

以六氯环三磷腈和对羟基苯甲醛反应合成了六（对醛基苯氧基）环三磷腈,再将其与油胺反应合成了星型化合物,将该星型化合物的亚胺还原为仲胺,与环氧低聚物反应得到了一种杂臂星型低聚物。采用红外光谱和核磁共振光谱表征了产物的结构。将该产物加入到环氧-酸酐体系中,通过示差扫描量热分析、热重分析及动态热力学分析考察了其对环氧体系热固化过程的影响,以及不同添加量对环氧固化物力学性能及热性能的影响。结果表明,杂臂星型低聚物的加入不会显著影响环氧树脂的固化过程以及固化物的玻璃化转变温度。加入杂臂星型低聚物可显著提升环氧树脂的耐冲击性,当添加质量分数为5%时,固化物的冲击强度最佳,较纯环氧固化物提升约150%,且材料的拉伸强度、热稳定性和耐水性均有一定程度的提高。