Contact experiments have been performed between an onion lamellar phase and
brine in the SDS/octanol/brine system. Using video microscopy we have stud
ied the non-equilibrium behaviour of the swelling and dissolution process o
f onions. Experiments at T = 20 and 30 degreesC showed that temperature has
a strong effect on their behaviour. At low temperature onions are observed
to diffuse away from the onion phase and only swell slightly. However, by
increasing the temperature we induce the formation of sponge phase (L-3) at
the onion/brine interface. Onions that initially swell then dissolve into
L-3 phase expel a stable core which moves to the micellar phase and remains
there. Over a longer period of time (several days) we have also observed c
oalescence leading to the formation of large onions of up to similar to 100
mum diameter. These huge onions have a radial distribution of domains, or
solvent cavities, within them. (C) 2001 Elsevier Science B.V. All rights re
served.