Influence of the structure of nanoscopic building blocks on the assembly of micropatterned surfaces

The effect of solution-state nanoscale structures on the assembly of micropatterns by solvent evaporation was explored with a novel amphiphilic diblock copolymer synthesized by reversible addition-fragmentation chain transfer polymerization. A copolymer of the structure poly(styrene-alt-maleic anhydride)(75)-b-isoprene(84) was assembled into inverse micelles in toluene, and covalently stabilized in the core by reactive amidation of maleic anhydride residues with 2,2'-(ethylenedioxy)bis(ethylamine) to create core-crosslinked nanoparticles (CCNPs) or in the shell by the photoinitiated radical crosslinking reactions of isoprene units to create large crosslinked aggregates (LCAs) of heterogeneous sizes and shapes. Micropatterned films were prepared by the deposition of the diblock copolymer as a solution in acetone and the nanoscale structures (inverse micelle, crosslinked aggregate, and CCNP) as solutions in toluene onto trimethylysilyl chloride treated glass microscope slides under ambient conditions. An analysis by optical microscopy and tapping-mode atomic force microscopy (AFM) indicated that the nanoscale surface topology could be controlled by the pre-establishment of the block copolymer phase segregation into well-defined core-shell nanoassemblies in solution. The most interesting films resulted from the evaporative deposition of inverse micelle and CCNP solutions, which afforded uniform, straplike micropatterns of similar dimensions on the microscale and low surface roughness on the nanoscale (roughness = 4 +/- 1 and 6 +/- 1 nm by AFM). (c) 2006 Wiley Periodicals, Inc.