A Solid-State NMR Study of Boric Acid Doped in Poly(vinyl alcohol)

A multinuclear solid-state NMR study of boric acid doped in poly(vinyl alcohol) (PVA) is presented. The experiments used for PVA films include 1 H windowed Phase-Modulated Lee-Goldburg (wPMLG), and 11 B Magic-Angle Spinning (MAS), 11 B stationary NMR, 11 B Multiple-Quantum MAS, and 1 H- 11 B CP and HETCOR at 14.1 and/or 21.6 T. The present analysis strongly suggests the possibility that the boric acid serves as a crosslinker with a coordination number other than four.