Effect of polyethylene glycol (PEG) length on the association properties of temperature-sensitive amphiphilic triblock copolymers (PNIPAAMm-b-PEGn-b-PNIPAAMm) in aqueous solution

摘要: Effects of temperature on the association behavior in aqueous solutions a series thermosensitive poly(N-isopropylacrylamide)-block-poly(ethylene glycol)-block-poly(N-isopropylacrylamide) triblock copolymers (PNIPAAMm-b-PEGn-b-PNIPAAMm) with length PNIPAAM block fixed (m ≈ 67) and different lengths PEG (n = 23, 34, 77, 165) have been studied aid turbidity, dynamic light scattering (DLS), Monte Carlo simulations. The turbidity results show that sharp transition to high values is shifted higher temperatures when spacer increased from 23 whereas no observed for longest block. These findings are consistent DLS results, which suggest formation large structures at well above cloud point. simulation indicate long PEG-block portion separating blocks copolymer reduces tendency polymer forming interchain associations elevated temperatures. Simulation shows spacer, moiety rather extended even temperatures, short thermoresponsive undergoes an compact conformation.