title: Nanopatterning in Langmuir-Blodgett monolayers of a thermoresponsive double hydrophilic block copolymer studied by atomic force microscopy.
abstract: The microphase-separation of Langmuir-Blodgett (LB) monolayers of a rhodamine B (RhB) end-labeled double hydrophilic block copolymer (DHBC), RhB-Poly(N,N-dimethylacrylamide)-b-poly(N,N-diethylacryl-amide) (RhB-PDMA(207)b-PDEA177) and the 1:1 segmental mixture of PDEA and RhB-PDMA 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 degrees 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.
authors.affiliation: Centro de Química Estrutural, Instituto Superior Técnico, Av. Rovisco Pais, P-1049-001 Lisboa, Portugal.
authors.forename: Rute I S
authors.initials: RI
authors.lastname: Romão
authors.forename: Quirina
authors.initials: Q
authors.lastname: Ferreira
authors.forename: Jorge
authors.initials: J
authors.lastname: Morgado
authors.forename: José M G
authors.initials: JM
authors.lastname: Martinho
authors.forename: Amélia M P S Gonçalves
authors.initials: AM
authors.lastname: da Silva
mesh_terms: D008422:Materials Testing; D008567:Membranes, Artificial; D018625:Microscopy, Atomic Force / Q000379:methods*; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D011109:Polymethacrylic Acids / Q000737:chemistry*; D013499:Surface Properties; D013696:Temperature
chemical_list: D008567:Membranes, Artificial; D011109:Polymethacrylic Acids; C523088:poly(2-(dimethylamino)ethyl methacrylate)-block-poly(2-(diethylamino)ethyl methacrylate)