Difference in lower critical solution temperature behavior between random copolymers and a homopolymer having solvatophilic and solvatophobic structures in an ionic liquid.
Difference in lower critical solution temperature behavior between random copolymers and a homopolymer having solvatophilic and solvatophobic structures in an ionic liquid.
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DOI：
10.1021/jp0670900
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发表时间：
2007-02
期刊：
影响因子：
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通讯作者：
T. Ueki;T. Karino;Y. Kobayashi;M. Shibayama;M. Watanabe
中科院分区：
文献类型：
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作者：
T. Ueki;T. Karino;Y. Kobayashi;M. Shibayama;M. Watanabe
研究了聚（甲基丙烯酸苄酯）（PBzMA）和聚（苯乙烯-co-甲基丙烯酸甲酯）（P（St-co-MMA））在疏水性离子液体1-乙基-3-甲基咪唑双（三氟甲烷砜）酰亚胺（[C（2）mim][NTf（2）]）中的溶解度和相行为，作为温度的函数。虽然这两种聚合物的结构中都含有疏溶剂苯基和亲溶剂甲基丙烯酸酯基团，但它们在聚合物链上的分布却有很大的不同。在PBzMA中，两种结构都被引入到每个单体单元中，而在P（St-co-MMA）s中，分布由St和MMA的单体竞聚率在统计学上确定。[C（2）mim][NTf（2）]中的两种聚合物溶液随着温度的升高而变得浑浊（低临界溶解温度（LCST）行为）。PBzMA在100 ° C下发生急剧的浊度变化，而P（St-co-MMA）s的浊度变化缓慢。P（St-co-MMA）s的LCST型相分离温度随St组成的增加而降低。P（St-co-MMA）s的缓慢相分离是由于聚合物链上沿着排列的MMA序列在一定程度上抑制了St的聚集。PBzMA的动态光散射（DLS）测量显示，PBzMA的流体动力学半径在100 ℃时突然变化;低于此温度时，未观察到聚集。这个结果强烈地暗示了线圈到坍缩的转变是一阶的。研究表明，聚合物链上亲溶剂和疏溶剂基团的分布对聚合物在离子液体中的LCST型相分离有很大的影响。
The solubility and phase behavior of poly(benzyl methacrylate) (PBzMA) and poly(styrene-co-methyl methacrylate) (P(St-co-MMA)) in a hydrophobic ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethane sulfone)imide ([C(2)mim][NTf(2)]), have been explored as a function of temperature. Although both polymers have solvatophobic phenyl groups and solvatophilic methacrylate groups in the structure, their distribution on the polymer chains is quite different. In PBzMA, both structures are incorporated in each monomer unit, whereas in P(St-co-MMA)s the distribution is statistically determined by the monomer reactivity ratio of St and MMA. Both polymer solutions in [C(2)mim][NTf(2)] become turbid with an increase in temperature (lower critical solution temperature (LCST) behavior). The turbidity change occurs sharply at 100 degrees C for PBzMA, whereas it is sluggish for P(St-co-MMA)s. The LCST-type phase-separation temperature for P(St-co-MMA)s decreases with an increase of the St composition. The sluggish phase separation for P(St-co-MMA)s has been explained in terms of the presence of the MMA sequences along the polymer chain, which inhibits the St aggregation to a certain extent. The dynamic light scattering (DLS) measurements for PBzMA reveal that the hydrodynamic radius of PBzMA suddenly changes at 100 degrees C; below this temperature, no aggregation is observed. This result strongly implies that the coil-to-collapse transition is of the first-order type. It has been demonstrated that the LCST-type phase separation of the polymers in an ionic liquid is greatly affected by the distribution of the solvatophilic and solvatophobic groups on the polymer chains.