Sugar-polymer hydrogen bond interactions in lyophilized amorphous mixtures

The objective of this work was to investigate hydrogen bonding interactions between a variety of glass-forming sugars and a model polymer, poly(vinylp yrrolidone) (PVP), in binary amorphous solid solutions, produced by lyophil ization. The glass transition temperatures of the sugars and sugar-PVP coly ophilized mixtures were assessed using differential scanning calorimetry. T he hydrogen bonding interactions between each sugar and PVP were monitored using FT-Raman spectroscopy. Sucrose was found to hydrogen bond to a greate r extent with PVP at a particular sugar:polymer ratio than the other disacc harides studied including trehalose and the trisaccharide raffinose. Maltod extrins showed a decreased tendency to hydrogen bond with the polymer compa red to the lower molecular weight sugars. The extent of hydrogen bonding wa s found to correlate inversely with the glass transition temperature of the sugar, with the tendency to hydrogen bond decreasing as the T-g increased. The importance df hydrogen bonding interactions to the thermodynamics of m ixing in amorphous solids is discussed.