PHASE-BEHAVIOR OF TELECHELIC POLYISOBUTYLENE (PIB) IN SUBCRITICAL AND SUPERCRITICAL FLUIDS .2. PIB SIZE, SOLVENT POLARITY, AND INTER-ASSOCIATION AND INTRA-ASSOCIATION EFFECTS FOR BLANK, MONOHYDROXY, AND DIHYDROXY PIB(11K) IN ETHANE, PROPANE, CARBON-DIOXIDE, AND DIMETHYL ETHER

Cloudpoints for monohydroxy, dihydroxy, and nonfunctional (referred tb as blank) telechelic polyisobutylene df molecular weight 11000 g/mol (PIB(11K)) were measured up to 200 degrees C and 2000 bar in ethane, propane, and dimethyl ether and compared to those for polyisobutylene of molecular weight 200 g/mol (PIB(200)) and 1000 g/mol (PIB(1K)). The PIB size, solvent polarity,and,hydroxy group density were found to influence the balance of self-association, cross-association, or intra-association. Each of these types of association uniquely shifts the cloud-point curves relative to the nonassociating system. The statistical associating fluid theory (SAFT) rigorously accounts for these shifts if they are due to intermolecular association. If these shifts are due to intramolecular association as found in polar solutions, effective SAFT sites and parameters have to be used to fit the experimental data.