Silicon-modified surfactants and wetting: III. The spreading behaviour of equimolar mixtures of nonionic trisiloxane surfactants on a low-energy solid surface

The spreading behaviour of binary and ternary equimolar mixtures of siloxan e surfactants of general formula [(CH3)(3)SiO](2)CH3Si(CH2)(3) (OCH2CH2)(n) OCH3, n=3-9, has been investigated. The mixtures show a pronounced temperat ure dependence on the initial spreading rate. Mixtures imitating the averag e oligo-ethylene glycol chain length n = 5 are the fastest spreaders at 15 degrees C. At 23 degrees C and 40 degrees C these mixtures spread fastest s ucking n = 6 and n = 8, respectively. For a given average chain length an i ncreasing length difference between the components of the binary mixtures r educes the initial spreading rate, Nevertheless, substantial differences be tween the phase transition temperature T-c from the lamellar phase (L-alpha ) into the two-phase state (2 Phi) and the actual spreading temperature are tolerated, A clear relation between phase transition temperature T-c and i nitial spreading rate does not exist. Copyright (C) 1999 John Wiley & Sons, Ltd.