Surface modification of cellulose using fluoroalkyl end-capped oligomeric silanes were studied. With increase in modification temperature and time, both the dispersive and polar components of surface free energy, γs
d and γs
p, of modified cellulose decreased. All the values of γs
d were ranged in 20_??_25mJ/m
2, which proved that the fluoroalkylation by those silanes affords good oil repellency to the cellulose surface. On the other hand, with respect to γs
p of modified surface, the silane having small fluoroalkyl group (C
3F
7) changed the cellulose surface to water repellent (γs
p_??_3mJ/m
2), but the silanes having longer fluoroalkyl groups decreased γs
p only in the range of 10_??_20mJ/m
2 and could not bring the complete water repellency.
Based on the ESCA measurements, the difference in water repellency or γs
p values was interpreted in terms of the amounts of fluoroalkyl groups on the cellulose surface. Several possible mechanisms of modification by the fluoroalkyl silanes were also discussed.
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