K. Grundke et al., LIQUID-FLUID CONTACT-ANGLE MEASUREMENTS ON HYDROPHILIC CELLULOSIC MATERIALS, Colloids and surfaces. A, Physicochemical and engineering aspects, 116(1-2), 1996, pp. 79-91
Contact angle measurements with captive bubbles have been used to quan
tify the wettability of different cellulosic materials in contact with
pure water or aqueous protein solutions. The application of a new con
tact angle technique (axisymmetric drop shape analysis) in combination
with atomic force microscopy permits new insights into the wetting be
haviour of these hydrophilic surfaces: It was found that the unmodifie
d cellulose membrane has a very smooth and homogeneous surface in the
water-swollen state. There is almost no hysteresis between the advanci
ng and receding water contact angles. The chemical modification of the
cellulose with diethylaminoethyl groups results in a smooth but heter
ogeneous water-swollen membrane surface with fewer hydrophilic propert
ies. A water-swollen cellulose acetate film was used as a model surfac
e for wetting measurements with buffered protein solutions. It was fou
nd that different proteins (human serum albumin, fibrinogen) yielded d
ifferent contact angles in their adsorbed state; after the adsorption
of fibrinogen the contact angle of the pure aqueous buffer solution on
the cellulose acetate was lower than the contact angle measured after
the adsorption of human serum albumin.