Phase diagram of water soluble semirigid polymers as a function of chain hydrophobicity

The phase behavior in water of hydroxypropylcellulose (HPC) and HPC partial ly esterified with methacryloyl chloride (HPCM) has been studied by measuri ng the variation of solution turbidity in the temperature range -5 to 46 de grees C. The resulting phase diagram is compared to previous results on HPC /water system and a qualitative agreement is observed. The HPCM phase diagr am shifts towards lower values of temperature and polymer concentration; wh ich may be mainly explained by the presence of hydrophobic residues introdu ced along the HPC chain. The progressive loss of the structure of water mol ecules around these groups as temperature or concentration increase reduces the area of the isotropic region with respect to that of the anisotropic p hase. (C) 2000 Elsevier Science Ltd. All rights reserved.