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Titolo:
Structure of a spread film of a polybutadiene-poly(ethylene oxide) linear diblock copolymer at the air-water interface as determined by neutron reflectometry
Autore:
Bowers, J; Zarbakhsh, A; Webster, JRP; Hutchings, LR; Richards, RW;
Indirizzi:
Univ London Queen Mary & Westfield Coll, Dept Chem, London E1 4NS, EnglandUniv London Queen Mary & Westfield Coll London England E1 4NS S, England Rutherford Appleton Lab, ISIS Facil, CLRC, Didcot OX11 0QX, Oxon, England Rutherford Appleton Lab Didcot Oxon England OX11 0QX 1 0QX, Oxon, England Univ Durham, Interdisciplinary Res Ctr Polymer Sci & Technol, Durham DH1 3LE, England Univ Durham Durham England DH1 3LE ci & Technol, Durham DH1 3LE, England
Titolo Testata:
LANGMUIR
fascicolo: 1, volume: 17, anno: 2001,
pagine: 131 - 139
SICI:
0743-7463(20010109)17:1<131:SOASFO>2.0.ZU;2-H
Fonte:
ISI
Lingua:
ENG
Soggetto:
POLY(ETHYLENE OXIDE); AIR/WATER INTERFACE; LIGHT-SCATTERING; SURFACE MICELLES; MONOLAYERS; ORGANIZATION; REFLECTION; ADSORPTION; BEHAVIOR; CHAIN;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
41
Recensione:
Indirizzi per estratti:
Indirizzo: Zarbakhsh, A Univ London Queen Mary & Westfield Coll, Dept Chem, Mile End Rd, London E14NS, England Univ London Queen Mary & Westfield Coll Mile End Rd London England E1 4NS
Citazione:
J. Bowers et al., "Structure of a spread film of a polybutadiene-poly(ethylene oxide) linear diblock copolymer at the air-water interface as determined by neutron reflectometry", LANGMUIR, 17(1), 2001, pp. 131-139

Abstract

The structure of a film of a linear diblock copolymer of polybutadiene-poly(ethylene oxide) with a molecular mass of similar to 60 000 g mol(-1) and containing similar to 50 mol % poly(ethylene oxide) PEO spread on water hasbeen investigated using neutron reflectometry. The reflectivity data have been analyzed using the optical matrix method and the kinematic approximation. From the optical matrix analysis it is found that at low surface concentrations (Gamma = 0.45, 0.83 mg m(-2)), the reflectivity data are well described using a two-layer model, indicating that even at low concentrations the blocks of the copolymer are segregated. According to this model the polybutadiene (PB) block resides in a thin similar to3-5 Angstrom layer containing similar to 50% (by volume) polymer and indeterminate quantities of water and PEG. The PEG is accommodated in a slightly thicker layer (similar to6-11 Angstrom), and this solvated layer contains similar to 30% PEG and a negligible amount of PB. The amount of material in these layers determined from the reflectivity data agrees well with the spread amount. At higher surface concentrations (Gamma = 2.06 mg m(-2)), however, st more complex model is required to represent the data. Superficially, the two-layer model is modified by accommodating similar to 13% of PB in the PEG-enriched layer and by adding a third similar to 100 Angstrom layer containing a mixture of PB (10%) and PEO (15%). From this model it can be inferred that at this surface concentration any PEO brushlike structure is accompanied by a higher-level structure containing "submerged" PB. It is feasible that surface aggregates of copolymer are incorporated into the region underlying the segregated monolayer structure; this is suggested by an inflection or "nonhorizontal" transition in the surface-pressure isotherm. This behavior is not dissimilar to that found for adsorbed films of polystyrene-b-poly(ethylene oxide) atthe air-water interface. Analysis using the kinematic approximation supports and reinforces the observations supplied by the optical matrix fitting.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 20/09/20 alle ore 05:00:46