Nanostructure fabrication from block copolymers in my group normally involves polymer design

synthesis

self-assembly

selective domain crosslinking

and sometimes selective domain removal. Preparation of thin films withnanochannels was used to illustrate the strategy we took. In this particular case

a linear triblock copolymer polyisoprenc-block-poly(2-cinnamoylethyl methacrylate)-block-poly(t-butyl acrylate)

PI-b-PCEMA-b-PtBA

was used. Films

25 to50 μm thick

were prepared from casting on glass slides a toluene solution of PI-b-PCEMA-b-PtBA and PtBA homopolymer

hPtBA

where hPtBA is shorter than the PtBA block.At the hPtBA mass fraction of 20% relative to the triblock or the total PtBA (hPtBA and PtBA block) volume fraction of 0.44

hPtBA and PtBA formed a seemingly continuous phase in the matrix of PCEMA and PI.Such a block segregation pattern was locked in by photocrosslinking the PCEMA domain.Nanochannels were formed by extracting out hPtBA with solvent.Alternatively

larger channels were obtained from extracting out hPtBA and hydrolyzing the t-butyl groups of the PtBA block.Such membranes were not liquid permeable but had gas permeability constants-6 orders of magnitude higher than that of low-density polyethylene films.