Thermosensitive biodegradable poly(organophosphazene) gels and their blends

Abstract

Thermo-sensitive poly(organophosphazene) hydrogels with hydrophilic α-amino-ω-methoxy-poly(ethyleneglycol) (AMPEG), hydrophobic amino acid esters (L-isoleucine ethyl ester) and glycine lactate ethyl ester as a side group have been synthesized. The poly(organophosphazenes) were characterized by 1H-, 31P-NMR spectroscopies and GPC. The viscosities of the gels were measured by viscometer along with the temperature changes. The poly(organophosphazenes) synthesized form solutions in water at low temperature while they form gels as the temperature increases showing lower critical solution temperature. To control the gelation properties we have studied polymer blends system. We grouped the polymers synthesized in two group such as hard polymers with low Tmax and high Vmax and soft polymers with high Tmax and low Vmax. When these polymers were blended at the appropriate ratio, the blended aqueous solution changed into a transparent hydrogel at the targeted body temperature. According to DSC and IR measurements, the two polymers were blended homogeneously.