We have previously demonstrated that solution-cast films of conjugated polymers with grafted alkyl side chains comprise clearly identifiable domains ca. 10 nm in size upon solvent evaporation. Here we show that these nanodomains indeed serve as basic units for morphological development in poly(9,9-di-n-octyl-2,7-fluorene) (PFO) films during cold crystallization. Results of our microscopic and diffraction observations indicate that the cold crystallization process involves intradomain nucleation and growth, followed by nanodomain alignment and coalescence into fibrils in the sub-micrometer length scale via thermally activated adjustment of nanodomain orientation. An analogy with oriented aggregation (or oriented attachment-coalescence) behavior of nanocrystals of metal oxides is drawn; the relevance to recently proposed models of polymer crystallization via primary nucleation induced at the growth front is addressed.

We have used small-angle neutron scattering (SANS) technique to study the micellization of a series of alternating comb-shaped copolymers, poly[l-alkene-co-(maleic anhydride)], in the fully neutralized state in water with the 1-alkenes ranging from 1-octene to 1-octadecene and weight-average molecular weights from 6000 to 20000. The structural parameters of the amphiphilic aggregates are determined by analyzing the intraparticle structure factor of the SANS intensity data. The analysis has shown that the copolymer derived from 1-octadecene forms cylindrical-shaped micelles while the copolymers derived from lower 1-alkenes form ellipsoidal-shaped micelles with the transition occurring at the 1-hexadecene copolymer. Analysis of the absolute neutron scattering intensity at zero scattering angle has shown a strong dependence of the mass of the aggregates on the side-chain length, namely, there are approximately 200 monomer repeating units per aggregate for the 1-octadecene copolymer versus about 20 monomer repeating units per aggregate for the 1-octene copolymer. The effect of molecular weight on aggregation is not observed possibly due to the polydispersity in the copolymers.