Solid-State NMR Investigations of the Unusual Effects Resulting from the Nanoconfinement of Water within Amphiphilic Crosslinked Polymer Networks



Two types of solid-state 19F NMR spectroscopy experiments are used to characterize phase-separated hyperbranched fluoropolymer–poly(ethylene glycol) (HBFP–PEG) crosslinked networks. Mobile (soft) domains are detected in the HBFP phase by a rotor-synchronized Hahn echo under magic-angle spinning conditions, and rigid (hard) domains by a solid echo with no magic-angle spinning. The mobility of chains is detected in the PEG phase by 1H → 13C cross-polarization transfers with 1H spin-lock filters with and without magic-angle spinning. The interface between HBFP and PEG phases is detected by a third experiment, which utilized a 19F → 1H–(spin diffusion)–1H → 13C double transfer with 13C solid-echo detection. The results of these experiments show that composition-dependent PEG inclusions in the HBFP glass rigidify on hydration, consistent with an increase in macroscopic tensile strength.