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Nanopatterning in Langmuir-Blodgett monolayers of a thermoresponsive double hydrophilic block copolymer studied by AFM

Romão, R. I. S. ; Ferreira, Q. ; Morgado, J. ; Martinho, J. ; Gonçalves da Silva, A. M. P. S.

Journal of Nanoscience and Nanotechnology Vol. 11, Nº 4, pp. 3151 - 3161, April, 2011.

ISSN (print): 1533-4880
ISSN (online):

Journal Impact Factor: 1,435 (in 2009)

Digital Object Identifier: 10.1166/jnn.2011.3726

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The microphase-separation of Langmuir-Blodgett (LB) monolayers of a rhodamine B (RhB) endlabeled
double hydrophilic block copolymer (DHBC), RhB-Poly(N,N-dimethylacrylamide)-b-poly(N,Ndiethylacryl-
amide) (RhB-PDMA207b-PDEA177) and the 1:1 segmental mixture of PDEA and RhBPDMA
homopolymers was followed by AFM. The DHBC LB films revealed a loose distribution
of nano-aggregates with variable geometries below the lower critical solution temperature (LCST)
of PDEA (32 C) and low surface pressure (3 mN m−1). By increasing either the temperature
above the LCST of PDEA or the surface pressure beyond the immersion regime of PDMA in the
subphase (7 mN m−1) a dense nanopatterning was obtained. The absence of a corresponding
regular nanopatterning in LB films of mixed homopolymers with the same composition highlights the
role of the covalent bonding between PDEA and PDMA on the self-segregation of the two blocks
at the air–water interface.