Monolayer formation of chitin derivatives containing PMMA side‐chains

The monolayer behaviour of poly(methyl methacrylate) (PMMA)‐grafted chitin derivatives was studied on an air–water interface by measuring surface pressure–area isotherms. The formation of a stable monolayer indicates the well‐defined packing and orientation of the chitin derivative, 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 15mN/m for almost all monolayers examined. The transition pressure decreases with increase of temperature from 10 to 20°C. The properties of the sub‐phase affected the formation of a monolayer greatly. The collapse of a surface film takes place at lower pressure on the sub‐phase of a 0.1 M NaCI solution. After introducing lysozyme at a concentration at 2.4 × 10−8M to the sub‐phase, the monolayer showed an extensively expanded phase with a longer transition region. This indicates that the monolayer was degraded by the lysozyme, resulting in a disordered structure. The results are contrasted with those of an aqueous phase where N‐acetylglucosamine residues may be inaccessible to lysozyme so that the degradation of the chitin derivative occurs at a very slow rate.