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Some physical properties of high molecular weight linear poly(N-isopropylacrylamide)s (PNIPAM) having different isotacticities (m, meso dyad = 47, 62, 68, 81, and 88 %) have been studied. The solubility of these polymers in different solvents varied with their isotacticity. Thermal degradation of higher isotactic polymer started slightly earlier. Cloud point of these polymers in water gradually decreased with increase in m up to 68 %. Surface tension of these polymers in N,N-dimethylformamide (DMF) was slightly lower than DMF and almost independent of their isotacticity in the temperature range of 20–60 °C. But it decreased linearly with the increase in temperature. Moreover, for all polymers, it decreased very slightly with the increase in their concentrations in the range of 0.001–0.01 % (w/v). Viscosity of these polymers in DMF increased with (i) the increase in the concentration range of 1–5 % (w/v), (ii) the increase in their m values, and (iii) the decrease in the temperature in the range of 20–60 oC.

Well-defined linear dihydrophilic amphiphilic ABA-type triblock copolymers of e-caprolactone (CL) and N-isopropylacrylamide (NIPAAm) have successfully been synthesized with a high yield by combining the ring opening polymerization (ROP) and xanthate-mediated reversible addition-fragmentation chain transfer (RAFT) polymerization methods. The resulted block copolymer shows the formation of micelles in water as supported by light scattering. The critical micelle concentration (cmc) value of the micelle increases with the increase in the chain length of the poly (N-isopropylacrylamide) (PNIPAAm) block. Cloud point of the block copolymers decreases with the decrease in the PNIPAAm chain length. The TGA analysis shows a one-step degradation and a lower thermal stability of the triblock copolymer than the PNIPAAm. The DSC analysis of the triblock copolymer shows the lowering of glass transition temperature (T g), and melting temperature (T m) peaks possibly due to the partial miscibility of the poly (e-caprolactone) (PCL) block with the amorphous PNIPAAm block through the interaction of ester groups of PCL with the amide groups of PNIPAAm. The XRD pattern of the triblock copolymer shows a broad peak due to the suppression of the crystallization of PCL block owing to the mixing of PNIPAAm block with the PCL block.