Solid state {sup 1}H and {sup 13}C NMR structural investigation of a poly(ethylene oxide) hydrogel
- Univ. of Strathclyde, Glasgow (United Kingdom)
A cross-linked poly (ethylene oxide)/polyurethane hydrogel cross-linked with 1,2,6 hexane-triol and designated PEG4050/1HT [measured M{sup n} of 4050 for poly (ethylene oxide) glycol (PEG) and a mole ratio of 1:1 for the PEG to the 1,2,6 hexane-triol] has been characterized by high resolution {sup 1}H and {sup 13}C NMR. {sup 1}H thermal (T{sub 1}) and rotating frame (T{sub 1{rho}}) and {sup 13}CT{sub 1} relaxation times were determined for the powdered dry and swollen hydrogel with the standard variants of the cross-polarization pulse sequence which was used in conjunction with magic-angle spinning (MAS). The rotating frame relaxation measurements confirmed that crystalline and amorphous regions were present in the dry hydrogel but showed unabiguously that the crystalline regions are confined to the poly (ethylene oxide) chains, Upon hydration, there is a decrease in the cross polarization efficiency from the enhanced mobility by the poly (ethylene oxide) chains are affected to a much greater extent that the urethane and hexane segments, the characteristic time constant, T{sub CH} increasing by more than order of magnitude compared to no more than a factor of two for the latter. Clearly, the hydration involves hydrogen bonding between the water and principally the oxygens in the poly (ethylene oxide) chains. The {sup 1}H MAS spectra of the dry and hydrated samples confirmed that considerable averaging of the dipolar interactions occurs on hydration to give a well-resolved spectrum.
- OSTI ID:
- 141791
- Report Number(s):
- CONF-930304-; TRN: 93:003688-1477
- Resource Relation:
- Conference: 205. American Chemical Society national meeting, Denver, CO (United States), 28 Mar - 2 Apr 1993; Other Information: PBD: 1993; Related Information: Is Part Of 205th ACS national meeting; PB: 1951 p.
- Country of Publication:
- United States
- Language:
- English
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