Hydroxyethyl nylon, a new flexible superpolyamide derivative

Abstract

Abstract Interesting new derivatives of nylon with unusual properties were prepared by treating nylon with ethylene oxide. These graft copolymers have greatly enhanced flexibility but still retain the high melting character of the original nylon. A hydroxyethyl 6‐6 nylon containing 50% combined ethylene oxide was found to be flexible and useful over a very large temperature range, the polymer having a melting point of 221°C. and an apparent second‐order transition point below −40°C. Analyses, carried out to study the distribution of combined ethylene oxide residues in these materials, indicated a tendency toward limited substitution of the nylon backbone and rather long average polyethylene glycol branch lengths. The distributions of the combined ethylene oxide residues are correlated with the nature of the starting materials. Synthetic methods, analyses, infrared spectra, solubilities, viscosity behavior, melting point and second‐order transition point data, stress‐elongation results, and moisture permeabilities of these materials are reported. The hydroxyethyl derivatives are more hydrophilic than the unsubstituted linear nylons. Hydroxyethyl nylon should also be considerably more stable than Type 8 nylon since it does not contain the labile N ‐methoxymethyl linkage. A striking contrast in properties exists between hydroxyethyl nylon and derivatives of nylon prepared in solution under homogeneous conditions. This difference in properties is attributed to a nonrandom distribution of branch sites along the chain in the case of hydroxyethyl nylon. This nonrandomness is due to the heterogeneous nature of the ethylene oxide‐nylon reaction and to the formation of primary hydroxyl groups which are more reactive toward ethylene oxide than the original amide NH groups.