Some observations on kinetic and steric limitations to specific interactions in miscible polymer blends

This note describes the application of infrared spectroscopy to determine the proportion of ester groups of poly(ϵ‐caprolac‐tone) which are involved in specific interactions with the hydroxyl groups of the poly(2‐hydroxypropyl ether of bisphenol A) (Phenoxy, Union Carbide) in a series of miscible blends of the two polymers, Even with a fifteen‐fold excess of hydroxyl groups, only about 50 percent of the ester groups of poly(ϵ‐caprolactone) are hydrogen‐bonded, presumably reflecting steric restrictions to the ester‐hydroxyl interactions. Partially miscible blends of these two polymers may also be prepared by a suitable choice of casting solvent, and infrared spectroscopy may then be used to follow the kinetics of miscibility when the partially miscible blend is heated.