Stable dispersions of highly anisotropic nanoparticles formed by cocrystallization of enantiomeric diblock copolymers

Stable dispersions of anisotropic particles with nanometer dimensions can be prepared in a selective solvent through cocrystallization (stereocomplexation) between two enantiomeric poly(lactide) block copolymers: poly(L-lactide)-poly(epsilon-caprolactone) and poly(D-lactide)-poly(epsilon-caprolactone). In the conditions of the experiment, no unspecific aggregation of the homochiral polylactide blocks occurs. The only driving force for self-assembly is between PLLA and PDLA. The good colloidal stability of the dispersion makes it possible to study the evolution of the particle shape and dimensions with time. The formation of these highly anisotropic particles was studied by a combination of techniques (infrared spectroscopy, light scattering, small angle neutron scattering, and atomic force microscopy).