Type

Journal Article

Authors

Michael A. Morris
Justin D. Holmes
Timothy W Collins
Parvaneh Mokarian-Tabari

Subjects

Physics

Topics
cyclical evolution phase separation thin films thick films high pressure morphology kinetics

Cyclical "flipping" of morphology in block copolymer thin films. (2011)

Abstract We studied the kinetics of nanopattern evolution in (polystyrene-b-polyethylene oxide) diblock copolymer thin films. Using scanning force microscopy, a highly unexpected cylindrical flipping of morphology from normal to parallel to the film plane was detected during solvent annealing of the film (with average thickness of 30 nm) at high vapor pressure. Using an in situ time-resolved light scattering device combined with an environmental cell enabled us to obtain kinetic information at different vapor pressures. The data indicated that there is a threshold value for the vapor pressure necessary for the structural transition. We propose a swelling and deswelling mechanism for the orientation flipping of the morphology. The cyclic transition occurs faster in thick films (177 nm) where the mass uptake and solvent volume fraction is smaller and therefore the driving force for phase separation is higher. We induced a stronger segregation by confining the chains in graphoepitaxially patterned substrates. As expected, the cyclic transition occurred at higher rate. Our work is another step forward to understanding the structure evolution and also controlling the alignment of block copolymer nanocylinders independently of thickness and external fields.
Collections Ireland -> University College Cork -> PubMed

Full list of authors on original publication

Michael A. Morris, Justin D. Holmes, Timothy W Collins, Parvaneh Mokarian-Tabari

Experts in our system

1
Michael A. Morris
University College Cork
Total Publications: 164
 
2
Justin D. Holmes
University College Cork
Total Publications: 287
 
3
Timothy W Collins
University College Cork
Total Publications: 13
 
4
Parvaneh Mokarian-Tabari
University College Cork
Total Publications: 9