DILATATIONAL PROPERTIES OF POLY(D,L-LACTIC ACID) AND BOVINE SERUM-ALBUMIN MONOLAYERS SPREAD AT THE AIR-WATER-INTERFACE

Dynamic behavior of monolayers of a biodegradable polymer (poly(D,L-la ctic acid), PLA50) and a protein (bovine serum albumin, BSA) spread at the air/water interface are studied to clarify the organization of th e films with regard to the composition and the state of compression. A theological approach based on the Maxwell's model was found to be use ful to discriminate the influence of each constituent in the monolayer . Before the transition phase of PLA50, theological properties of the mixed monolayer are governed by the PLA50 which constitutes probably t he continuous phase of the system. During the transition phase of PLA5 0, condensation of the PLA50 segments allow the formation of a continu ous phase mainly constituted from BSA. After the transition phase of P LA50, theological properties of the mixed monolayer were shown to be i dentical to the properties of a pure BSA monolayer. This indicates tha t BSA is present between PLA50 aggregates and prevents the connection of these domains at least until the higher studied pressure (i.e. 21 m N/m). The obtained results suggest that BSA could be an efficient stab ilizer of the interfacial region during preparation of PLA50 particles by an emulsion technique.