Effects of Dendron Generation and Salt Concentration on Phase Structures of Dendritic–Linear Block Copolymers with a Semirigid Dendron Containing PEG Tails
Effects of Dendron Generation and Salt Concentration on Phase Structures of Dendritic–Linear Block Copolymers with a Semirigid Dendron Containing PEG Tails
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DOI：
10.1021/ma300654j
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发表时间：
2012-07
期刊：
影响因子：
5.5
通讯作者：
Huanhuan Cai;Guoliang Jiang;Zhihao Shen;Xinghe Fan
中科院分区：
文献类型：
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作者：
Huanhuan Cai;Guoliang Jiang;Zhihao Shen;Xinghe Fan
通过氮氧自由基聚合（NMRP）制备了一系列具有半刚性Percec型树枝状分子和聚苯乙烯（PS）线性聚合物的树枝状-线性嵌段共聚物（DLBCP）。由于DLBCPs通过酯键连接，通过水解，通过凝胶渗透色谱和MALDI-TOF MS精确表征DLBCPs的分子量。差示扫描量热法，小角X射线散射，和透射电子显微镜被用来研究DLBCPs的相行为。结果表明，在第二次升温过程中，半刚性树枝化分子的PEG尾部出现了冷结晶峰和熔融峰，而纯DLBCP的PEG尾部结晶完全被抑制，仅观察到PS嵌段的玻璃化转变温度（Tg）。然而，通过与LiCF_3SO_3络合，可以观察到树枝化块的Tg，这表明，通过使DLBCP与LiCF_3SO_3络合，可以观察到树枝化块的Tg。
We prepared a series of dendritic–linear block copolymers (DLBCPs) bearing a semirigid Percec-type dendron with ionophilic poly(ethylene glycol) (PEG) tails and a polystyrene (PS) linear polymer by nitroxide-mediated living radical polymerization (NMRP). As the DLBCPs are connected by an ester linkage, through hydrolysis the molecular weights of the DLBCPs were precisely characterized by gel permeation chromatography and MALDI-TOF MS. Differential scanning calorimetry, small-angle X-ray scattering, and transmission electron microscopy were used to investigate the phase behaviors of the DLBCPs. Results show that the PEG tails of the semirigid dendron display a cold crystallization peak and a melting peak during the second heating process, while for the neat DLBCPs, the crystallization of the PEG tails is completely inhibited, and only the glass transition temperature (Tg) of the PS block is observed. However, Tg of the dendron block can be observed by complexing the DLBCPs with LiCF3SO3, suggesting that mi...