带有两性离子和离子液体垂体的均聚物的结构变异，以实现可调节的多刺激响应性和分层纳米聚集体,Macromolecules

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带有两性离子和离子液体垂体的均聚物的结构变异，以实现可调节的多刺激响应性和分层纳米聚集体
Macromolecules ( IF 5.1 ) Pub Date : 2017-12-12 00:00:00 , DOI: 10.1021/acs.macromol.7b02106
Yajnaseni Biswas ₁ , Tarun K. Mandal ₁

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设计并合成了包含具有咪唑鎓溴化离子液体（IL）和具有不同烷基间隔基的两性离子咪唑烷基羧酸酯部分的单元的一系列单体。这些单体的RAFT聚合产生一类新型的离子均聚物，称为聚（两性离子离子液体）（PZIL），其行为与聚（离子液体）以及聚（两性离子）相同，具体取决于溶液的pH值。此类PZIL在pH 5.7时表现出等电点（pI），并以两性离子形式存在，使其对pH和温度均具有双重响应。在pH高于5时，由于形成各种形态的不溶性分层纳米聚集体（NA），例如小球，大球，花状，树突状，取决于溶液的pH和PZIL的结构。加热时聚集体的溶解和冷却后聚集体的溶解表明，pH 5以上存在可逆的上临界溶液温度（UCST）型相变。由于存在阳离子IL部分，pH 5以下时，PZIL水溶液显示出对透明的透明性。由于在Hofmeister系列中添加了各种离液阴离子，形成了各种树突状形态的阴离子诱导的NA，从而导致了浑浊的转变。加热后，这种胶状混浊悬浮液变得透明，显示出独特的UCST型相变，并且该过程是可逆的。通过更改各种参数（例如分子量，浓度，PZIL的结构，

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Structural Variation in Homopolymers Bearing Zwitterionic and Ionic Liquid Pendants for Achieving Tunable Multi-Stimuli Responsiveness and Hierarchical Nanoaggregates

A series of monomers comprising units bearing both imidazolium bromide ionic liquid (IL) and zwitterionic imidazolium alkyl carboxylate moieties with different alkyl spacer groups are designed and synthesized. RAFT polymerization of these monomers produces a new class of ionic homopolymers, named poly(zwitterionic ionic liquid)s (PZILs), which behave like poly(ionic liquid)s as well as poly(zwitterion)s depending on the solution pH. Such PZILs exhibit an isoelectric point (pI) at pH 5.7, where they exist in their zwitterionic form, making them dual responsive to both pH and temperature. Above pH 5, the aqueous transparent solution of PZIL transforms into turbid suspension due to the formation of insoluble hierarchical nanoaggregates (NAs) of various morphologies such as small spheres, large spheres, flower-like, dendrite-shaped, and dendritic fibril-like depending upon the solution pH and PZILs’ structures. The dissolution of aggregates upon heating and reaggregation upon cooling suggests existence of reversible upper critical solution temperature (UCST)-type phase transition above pH 5. Below pH 5, owing to the presence of cationic IL moieties, aqueous PZIL solution exhibits transparent-to-turbid transition due to the formation of anion-induced NAs of various dendritic morphologies upon addition of various chaotropic anions within the Hofmeister series. Upon heating, this colloidal turbid suspension becomes transparent, showing a distinct UCST-type phase transition, and the process is reversible. It is easily possible to fine-tune the cloud point and morphologies of the NAs by changing various parameters such as molecular weight, concentrations, structure of PZILs, nature and concentration of anions, and solution pH.

更新日期：2017-12-12

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