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Continuous Equilibrated Growth of Ordered Block Copolymer Thin Films by Electrospray Deposition.
MedLine Citation:
PMID:  23451911     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Deposition of block copolymer thin films is most often accomplished in a serial process where material is spin coated onto a substrate and subsequently annealed, either thermally or by solvent vapor, to produce a well-ordered morphology. Here we show that under appropriate conditions, well-ordered block copolymer films may be continuously grown under substrate equilibrated conditions by slow deposition of discrete sub-attoliter quantities of material using electrospray. We conduct time-resolved observations and investigate the effects of process parameters that underpin film morphology including solvent selectivity, substrate temperature, block-substrate selectivity and flow rate of the feed solution. For a PEO cylinder-forming poly(styrene-b-ethylene oxide) block copolymer, we uncover a wide temperature window from 90 ºC to 150 ºC and an ideal flow rate of 2 µL/min for ordered film deposition from dilute acetone solutions. PEO cylinders aligned with their long axes perpendicular to the film-air interface at optimal spray conditions. Using poly(styrene-b-methyl methacrylate) deposited onto neutrally selective surfaces, we show that the substrate-equilibrated process results in vertically oriented microdomains throughout the film, indicating a preservation of the initial substrate-dictated morphology during the film deposition. Electrospray offers a new and potentially exciting route for controlled, continuous growth of block copolymer thin films and manipulation of their microstructure.
Authors:
Hanqiong Hu; Sofia Rangou; Myungwoong Kim; Padma Gopalan; Volkan Filiz; Apostolos Avgeropoulos; Chinedum O Osuji
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2013-3-4
Journal Detail:
Title:  ACS nano     Volume:  -     ISSN:  1936-086X     ISO Abbreviation:  ACS Nano     Publication Date:  2013 Mar 
Date Detail:
Created Date:  2013-3-4     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101313589     Medline TA:  ACS Nano     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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