Synthesis of Amphiphilic and Double Hydrophilic Star-like Block Copolymers and the Dual pH-Responsiveness of Unimolecular Micelle
Synthesis of Amphiphilic and Double Hydrophilic Star-like Block Copolymers and the Dual pH-Responsiveness of Unimolecular Micelle
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两亲双亲水星状嵌段共聚物的合成及单分子胶束的双pH响应性
DOI：
10.1021/acs.macromol.0c00918
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发表时间：
2020
期刊：
影响因子：
5.5
通讯作者：
Lin, Zhiqun
中科院分区：
文献类型：
--
作者：
Harn, Yeu-Wei;He, Yanjie;Wang, Zewei;Chen, Yihuang;Liang, Shuang;Li, Zili;Li, Qiong;Zhu, Lei;Lin, Zhiqun
以β-环糊精为引发剂，采用原子转移自由基聚合（ATRP）方法合成了一系列具有良好分子结构、分子量和窄分散性的两亲性星形三嵌段共聚物。这些星形三嵌段共聚物由作为第一嵌段的聚（4-乙烯基吡啶）（P4 VP）、作为第二嵌段的聚（丙烯酸叔丁酯）（PtBA）和作为第三嵌段的聚苯乙烯（PS）、聚（甲基丙烯酸甲酯）（PMMA）或聚（环氧乙烷）（PEO）（分别表示为P4 VP-b-PtBA-b-PS、P4 VP-b-PtBA-b-PMMA和P4 VP-b-PtBA-b-PEO）组成。值得注意的是，通过有意加入线性引发剂[即，α-溴异丁酸乙酯（EBiB）]进入聚合反应中（即，合成星形P4 VP-嵌段-PtBA;表示为P4 VP-b-PtBA），可以实现合适浓度的Cu 2+。这抑制了星状聚合物的活性链端之间的进一步终止反应，从而使得能够更好地控制星状P4 VP-b-PtBA二嵌段共聚物的生长（多分散性指数; PDI < 1.2）。研究了PtBA聚合反应的动力学，考察了添加和不添加线性引发剂EBiB的情况.重要的是，星形P4 VP-b-PtBA二嵌段共聚物ATRP的活性性质只有在加入线性引发剂时才能获得。随后，通过使用星形P4 VP-b-PtBA作为大分子引发剂分别经由ATRP（对于疏水性PS和PMMA）和点击反应（对于亲水性PEO）合成星形P4 VP-b-PtBA-b-PS、P4 VP-b-PtBA-b-PMMA和P4 VP-b-PtBA-b-PEO，进一步证实了表面化学的可调谐性（即，星形三嵌段共聚物的外嵌段）。最后，将PtBA水解为聚丙烯酸（PAA），研究了双亲水性星形P4 VP-b-PAA嵌段共聚物的双重pH响应行为。除了双重pH响应性之外，我们在本研究中开发的基于通过环糊精作为引发剂的顺序ATRP的策略可以方便地合成多种其他刺激响应性单分子星形嵌段共聚物，其包含pH响应性、热响应性或光响应性的不同嵌段。因此，它们可以为智能运载工具，传感器和纳米材料可调模板的基础研究和应用提供独特的平台。
A series of amphiphilic star-like triblock copolymers with well-defined molecular architectures, molecular weight, and narrow polydispersity were successfully synthesized by sequential atom transfer radical polymerization (ATRP) using β-cyclodextrin as the initiator. These star-like triblock copolymers are composed of poly(4-vinyl pyridine) (P4VP) as the first block, poly(tert-butyl acrylate) (PtBA) as the second block, and either polystyrene (PS), poly(methyl methacrylate) (PMMA), or poly(ethylene oxide) (PEO) as the third block (denoted as P4VP-b-PtBA-b-PS, P4VP-b-PtBA-b-PMMA, and P4VP-b-PtBA-b-PEO, respectively). Notably, by deliberate addition of a linear initiator [i.e., ethyl α-bromoisobutyrate (EBiB)] into the polymerization reaction when growing the second PtBA block (i.e., synthesis of star-like P4VP-block-PtBA; denoted as P4VP-b-PtBA), a suitable concentration of Cu2+can be achieved. This suppresses further termination reactions between active chain ends of star-like polymer, thus rendering the ability to better control the growth of star-like P4VP-b-PtBA diblock copolymer (polydispersity index; PDI < 1.2). Kinetic studies of PtBA polymerization with and without the addition of linear initiators of EBiB were conducted. Importantly, the living nature of ATRP of star-like P4VP-b-PtBA diblock copolymer can only be attained when the linear initiator was added. Subsequently, star-like P4VP-b-PtBA-b-PS, P4VP-b-PtBA-b-PMMA, and P4VP-b-PtBA-b-PEO were synthesized by using star-like P4VP-b-PtBA as the macroinitiator via ATRP (for hydrophobic PS and PMMA) and click reaction (for hydrophilic PEO), respectively, further confirming the tunability of surface chemistry (i.e., the outer block of star-like triblock copolymers) in this system. Finally, after hydrolyzing PtBA into poly(acrylic acid) (PAA), the dual pH-responsive behaviors of double hydrophilic star-like P4VP-b-PAA diblock copolymer were explored. In addition to dual pH-responsiveness, the strategy we developed based on sequential ATRP via cyclodextrin as the initiator in this study may conveniently enable the synthesis of a rich variety of other stimuli-responsive unimolecular star-like block copolymers comprising dissimilar blocks that are either pH-responsive, thermo-responsive, or photo-responsive. As such, they may afford a unique platform for fundamental research and applications in smart delivery vehicles, sensors, and tunable templates for nanomaterials.
影响因子：
5.5
作者：
Youliang Zhao;X. Shuai;and Chuanfu Chen;F. Xi
通讯作者：
Youliang Zhao;X. Shuai;and Chuanfu Chen;F. Xi
影响因子：
3.4
作者：
Iatridi, Zacharoula;Tsitsilianis, Constantinos
通讯作者：
Tsitsilianis, Constantinos