We investigated the radical polymerization of N-n-propylmethacrylamide (NNPMAAm) in the presence of alkali metal bis(trifluoromethanesulfonyl)imides (MNTf 2 ), in particular LiNTf 2 . The addition of MNTf 2 led to a significant improvement in the yield and molecular weight of the resulting poly(NNPMAAm)s. Furthermore, the solvent employed influenced stereospecificity in the presence of LiNTf 2 . The stoichiometry of the NNPMAAm-Li + complex appeared to be critical for determining the stereospecificity in the NNPMAAm polymerization. The 1 : 1-complexed monomer in protic polar solvents provided syndiotacticrich polymers, whereas the 2 : 1-complexed monomer in aprotic solvents gave heterotactic-rich polymers. Stereochemical analyses revealed that m-addition by an r-ended radical was the key step in the induction of heterotactic specificity in the aprotic solvents. Spectroscopic analyses suggested that the Li + cation played a dual role in the polymerization process, with Li + stabilizing the propagating radical species and also activating the incoming monomer. Kinetic studies with the aid of electron spin resonance spectroscopy revealed that the addition of LiNTf 2 caused a significant increase in the k p value and a decrease in the k t value. The stereoregularity of poly(NNPMAAm)s was found to influence the phase transition behavior of their aqueous solutions. In a series of syndiotactic-rich polymers, the phase-transition temperature decreased gradually with increase in the rr triad content. Furthermore, heterotactic-rich poly-(NNPMAAm) exhibited high hysteresis, which increased in magnitude with increasing mr triad content. † Electronic supplementary information (ESI) available: 13 C NMR spectra of the CvO group of NNPMAAm in the presence of MNTf 2 , changes in the chemical shifts of 1 H NMR spectra of the vinylidene group of NNPMAAm in the presence of LiNTf 2 , relationship between the radical concentration and time, additional ESR spectra and relationship between the ΔT c and n r values. See

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