SURFACE FORCE STUDIES OF LANGMUIR-BLODGETT CELLULOSE FILMS

The interactions between cellulose surfaces, between chitosan-coated s urfaces, and between one cellulose surface and one chitosan-coated sur face have been studied using the interferometric surface force apparat us (SFA). The cellulose surfaces were prepared by depositing trimethyl silyl cellulose on hydrophobized mica using the Langmuir-Blodgett tech nique. The surfaces were desilylated in a humid HCl atmosphere to obta in regenerated cellulose. ESCA measurements and wetting studies demons trated that the desilylation process was effective. Scanning force mic roscopy studies showed the cellulose surfaces to be smooth with a root -mean-square roughness of 0.16 nm. Surface force and ellipsometry meas urements illustrate that the cellulose film swells considerably in hum id air and in water, suggesting that it is mostly amorphous. The inter action between two cellulose surfaces is dominated by a steric repulsi on caused by a few dangling tails. On separation an attractive force w as present both between two cellulose surfaces and between one cellulo se surface and one chitosan surface. The long-range interaction betwee n cellulose and chitosan was shown to be attractive. (C) 1997 Academic Press.