聚合诱导自组装制备形貌多样的ABA型三嵌段共聚物微/纳米粒子

Synthesis of ABA Triblock Copolymer Micro/Nano-Objects with Versactile Morphologies via Polymerization-Induced Self-Assembly

以聚N,N-二甲基丙烯酰胺(PDMA)为大分子链转移剂、苯乙烯(St)为单体,采用可逆加成-断裂链转移(RAFT)分散聚合制备了PDMA-b-PS-b-PDMA两亲性三嵌段共聚物胶束。考察了固含量和疏、亲溶剂链段比对胶束尺寸、形貌的影响。固含量为25%和30%时,胶束形貌转化过程是从球状、蠕虫状向囊泡状胶束发展,最终得到大小2种尺寸的嵌段共聚物形貌囊泡。固含量为30%,疏、亲溶剂链段比为300∶32和400∶32时,分别获得平均粒径约为900/310 nm和400/210 nm的大小囊泡;固含量为25%,疏、亲溶剂链段比为400∶32时,大小囊泡的尺寸分别约为520 nm和200 nm。固含量为35%和40%时,胶束形貌则由球状逐渐向海绵状、复合囊泡,大复合胶束转变,最终得到微米级大复合胶束。

PDMA-b-PS-b-PDMA amphiphilic triblock copolymers were synthesized via reversible-addition fragmentation chain transfer(RAFT)disperse polymerization with poly(N,N-dimethylacrylamide)(PDMA)as macro-CTA and styrene(St)as monomer in ethanol/water mixed solvent.The parameters affecting the morphology and size of the nano-objects,including solid contents and the ratio of hydrophobic and hydrophilic chain segments,were investigated.When the solid contents are 25%and 30%,the morphologies of copolymer micelles undergo a transition from spheres,worms to vesicles,and vesicles with two different sizes are obtained.When the solid content is 30%and the ratios of hydrophobic and hydrophilic chain segments are 300∶32 and 400∶32,vesicles with average particle sizes of about 900/310 nm and 400/210 nm are attained,respectively.When the ratio of hydrophobic and hydrophilic chain segments is 400∶32,the sizes of the large and small vesicles at 25%solid content are approximately 520 nm and 200 nm,respectively.When the solid contents are 35%and 40%,the morphologies of the micelles evolve from spheres to sponges,large composite vesicles and large composite micelles,and the final micelles are large composite micelles with size of micrometer.