Strained polycarbonate-polyurethanes with linear and branched diisocyanates
Subtitle: an in vitro biodegradation study.
Published: 2005
Language: eng
Number of pages: 131
Description: This thesis investigates linear (hexane diisocyanate, HDI) versus branched (lysine diisocyanate, LDI) hard segments, and strain effects on hydrogen bonding (HB) and biodegradation in two 14C-materials. One contained pure HDI hard-segments (100%HDI) and the other (75%HDI) was a 3:1 blend of two polymers: 100%HDI and 100%LDI (polymer containing only LDI hard-segments). HB was determined using infrared spectroscopy (under strain, 0-15%). Biodegradation was conducted by exposing polymer films at the above strains to a macrophage-like cell line and 14C-release monitored. With higher molecular weight materials (>105 polystyrene equiv.), 75%HDI degraded &lt; 100%HDI (p &lt; 0.05). With lower molecular weight materials than the above, 75%HDI degraded six times > 100%HDI (p &lt; 0.05). No statistical differences in degradation were found for the strain levels despite their evident differences in HB. Mathematical modeling of intramolecular interactions suggested that chain rearrangements for hard and soft segments accounted for the observations in the degradation studies.
Notes: Source: Masters Abstracts International, Volume: 44-02, page: 0958.

Thesis (M.A.Sc.)--University of Toronto, 2005.

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