The polymerisation of styrene in lyotropic liquid-crystalline (LC) phases o
f dioctadecyldimethylammonium bromide (DODAB) in water is explored. Amphiph
ile concentrations between 20 and 50 wt % are employed. The study is set ou
t as a model study for polymerisation reactions in nonstabilised, nonfuncti
onal bilayer systems. X-ray characterisation was used to assess the phase b
ehaviour of the lyotropic mesophases before. during and after polymerisatio
n. The DODAB/water system forms the lamellar phase within the concentration
range considered. Addition of styrene to the lamellar phase of DODAB at an
equimolar ratio induces a phase shift to a bicontinuous cubic phase at ele
vated temperatures near the phase-transition temperature. Upon polymerisati
on within this cubic phase, the phase structure is maintained if the system
is kept at constant temperature; however, if the polymer/amphiphile phase
is cooled, the lamellar phase, being typical of the DODAB/water system, is
restored. It is concluded that, as a result of phase separation between the
polymer and the amphiphile phase, the polymerisation in lyotropic LC phase
s does not provide a stable copy of the templating amphiphile phase. This i
s in analogy to the observations for polymerisations in other lyotropic pha
ses.