MONOLAYER FORMATION OF CHITINU DERIVATIVES CONTAINING PMMA SIDE-CHAINS

The monolayer behaviour of poly(methyl methacrylate) (PMMA)-grafted ch itin derivatives was studied on an air-water interface by measuring su rface pressure-area isotherms. The formation of a stable monolayer ind icates the well-defined packing and orientation of the chitin derivati ve, which can be regulated by the main-chain length under appropriate experimental conditions. The isotherms exhibit a transition point from a liquid expanded phase to a condensed phase at a surface pressure of approximately 15 mN/m for almost all monolayers examined. The transit ion pressure decreases with increase of temperature from 10 to 20-degr ees-C. The properties of the sub-phase affected the formation of a mon olayer greatly. The collapse of a surface film takes place at lower pr essure on the sub-phase of a 0.1 M NaCl solution. After introducing ly sozyme at a concentration at 2.4 x 10(-8) M to the sub-phase, the mono layer showed an extensively expanded phase with a longer transition re gion. This indicates that the monolayer was degraded by the lysozyme, resulting in a disordered structure. The results are contrasted with t hose of an aqueous phase where N-acetylglucosamine residues may be ina ccessible to lysozyme so that the degradation of the chitin derivative occurs at a very slow rate.