M. Monkenbusch et al., AGGREGATING BLOCK-COPOLYMERS AS MODEL SYSTEMS TO STUDY POLYMER BRUSH DYNAMICS, Nuovo cimento della Societa italiana di fisica. D, Condensed matter,atomic, molecular and chemical physics, biophysics, 16(7), 1994, pp. 747-755
A-B block copolymers in a selective solvent-good for the B-species and
bad for the A-species-form micellar aggregates with a compact A-core
with a corona (brush) of B <<hairs>> reaching into the solvent. Wherea
s polystyrene(PS)-polyisoprene(PI) in decane forms spherical micelles
with a PS core of about 10 nm radius, polyethylene(PE)-polyethylenepro
pylene(PEP) forms micellar platelets, the shape of which is goverend b
y the habitus of PE crystallites forming the core. These planar aggreg
ates have large (several hundred nanometers) lateral extension and a c
ore thickness in the range of 10 nm. Both systems are model systems fo
r polymer brushes, either on a spherical surface or planar. Neutron sp
in-echo experiments allow for the investigation of the dynamics of the
brushes which reflects their viscoelastic properties. Results of neut
ron small-angle and spin-echo investigations are reported. The brush d
ynamics is explained using a model based on an idea of de Gennes descr
ibing the brush properties in terms of scaling relations for osmotic p
ressure and viscosity of a semi-dilute solution with inhomogeneous den
sity.