Isotactic poly (N-isopropylacrylamides) (PNIPAMs) with a wide range of tacticity exhibit upper critical solution temperature (USCT) type phase transition in an ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([BMIM][TFSI]). The phase transition temperature becomes higher with increasing isotacticity, since more amide groups are aligned along the same side of backbones to form stronger intramolecular hydrogen bonding. Phase diagrams of highly isotactic PNIPAMs show prominent UCST peaks at low concentrations, similar with the typical polymer solution, which implies the dissolution of isotactic PNIPAMs is dominated by the entropy-driven effect. The increase in phase transition temperature with molecular weight is also from the entropic reason. The phenomena above reveal that the phase transition behavior of PNIPAMs in ionic liquids is highly influenced by tacticity effect.

等规聚（N具有宽规整度的β-异丙基丙烯酰胺（PNIPAM）在离子液体1-丁基-3-甲基咪唑双（三氟甲磺酰基）酰亚胺（[BMIM] [TFSI]）中显示出较高的临界溶液温度（USCT）型相变。随着等规度的增加，相变温度变得更高，因为更多的酰胺基团沿着主链的同一侧排列以形成更强的分子内氢键。高等规PNIPAM的相图在低浓度下显示出突出的UCST峰，与典型的聚合物溶液相似，这意味着等规PNIPAM的溶解主要受熵驱动的影响。相变温度随分子量的升高也是出于熵的原因。