Promotion of morphology transition of di-block copolymer nano-objects via RAFT dispersion copolymerization
Promotion of morphology transition of di-block copolymer nano-objects via RAFT dispersion copolymerization
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通过RAFT分散共聚促进二嵌段共聚物纳米物体的形貌转变
DOI：
10.1039/c6py00164e
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发表时间：
2016
影响因子：
4.6
通讯作者：
Pan Caiyuan
中科院分区：
文献类型：
--
作者：
Zhou Jiemei;Zhang Wenjian;Hong Chunyan;Pan Caiyuan
以聚丙烯酸羟乙酯（PHEA）为大分子链转移剂（macro-CTA），在甲醇中进行了苯乙烯（St）和甲基丙烯酸甲酯（MMA）的可逆加成-断裂链转移（RAFT）分散共聚合。与一般的大分子CTA介导的St醇分散聚合相比，St与MMA的RAFT分散共聚能促进两嵌段共聚物纳米粒子的形态转变。通过改变St/MMA的摩尔比，绘制了3个相图，以反映P（St-co-MMA）的聚合度（DP）、固相浓度和所得纳米材料形貌之间的关系，发现St/MMA的摩尔比对相图有一定的影响。采用超灵敏差示扫描量热法（US-DSC）测定了聚合物纳米体在甲醇中的玻璃化转变温度（Tg），结果表明，随着共聚物中MMA单元摩尔含量的增加，Tg值降低。在疏溶剂嵌段中引入甲基丙烯酸甲酯（MMA）单元可以提高其在甲醇中的流动性，有利于嵌段共聚物纳米粒子的形貌转变。
Reversible addition–fragmentation chain transfer (RAFT) dispersion copolymerization of styrene (St) and methyl methacrylate (MMA) is conducted in methanol using poly(2-hydroxyethyl acrylate) (PHEA) as a macro chain transfer agent (macro-CTA). Compared with the general macro-CTA mediated alcoholic dispersion polymerization of St, RAFT dispersion copolymerization of St and MMA can promote the morphology transition of di-block copolymer nano-objects. Three phase diagrams are constructed by changing the molar ratio of St/MMA to reflect the relationship between the degree of polymerization (DP) of P(St-co-MMA), solids concentration and morphology of obtained nano-materials, and it is found that the phase diagrams could be affected by the molar ratio of St/MMA. Ultra-sensitive differential scanning calorimetry (US-DSC) is employed to determine the glass transition temperature (Tg) of polymeric nano-objects in methanol, and the result shows that the Tg values decrease with the increase of the molar content of MMA units in copolymers. Introduction of MMA units into the solvophobic block can enhance its mobility in methanol, which is beneficial for the morphology transition of di-block copolymer nano-objects.