Influence of natural inorganic impurity on the synthesis of poly(L -lactic acid), properties and nanofabrication

Abstract

This work is focused on determination of the effect of a calcium-based inorganic impurity originating from biotechnological L-lactic acid production from cheese whey on the synthesis of poly(L-lactic acid). The influence of the impurity was investigated in the range of 0 to 1 wt % and the product properties were studied by analytical techniques GPC, FTIR-ATR, acid end group analysis and DSC. The final product was used to prepare submicron particles, which were analyzed by dynamic light scattering and electron microscopy. Results show a moderate reduction in molecular weight in connection with an increase in the amount of the impurity up to 0.75 wt %. Further increase in the concentration of the impurity caused decomposition. Investigating the thermal properties reveals a noticeable reduction in the melting temperature and a slight decrease in glass transition temperature. The prepared submicron particles had a Z-average diameter of between 280 and 520 nm, depending on the emulsifying system, and the presence of the inorganic impurity seems to play no role during particle formation. © 2013 Wiley Periodicals, Inc.