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The European Physical Journal B
ISSN: 1434-6028 (printed version)
ISSN: 1434-6036 (electronic version)
Abstract Volume 1 Issue 3 (1998) pp 359-369
From molecular flexibility to shape, curvature and thermotropic transitions in pure surfaces
B. Bassetti (1) (a), C.A. Mantica (1), P. Jona (2)
(1) Università degli Studi di Milano, Dipartimento di Fisica, Via Celoria 16, 20123 Milano, Italia
(2) Politecnico di Milano, Dipartimento di Fisica, Piazza Leonardo da Vinci 32, 20123 Milano, Italia
Received: 13 November 1996 / Revised: 9 May 1997 / Received in final form: 4 November 1997 / Accepted: 10 November 1997
Abstract: A material surface of pure constituents with a flexible molecular chain (amphiphilics) is considered; thermodynamic behaviour is studied in the chain length-temperature plane. The Hamiltonian of the system is modelled as the sum of a formation term which refers to the polymer nature of the chain, and of a fluctuation term with a specific elastic form. For closed systems the model exhibits phases with uniform curvature and conformational order/disorder or, alternatively, modulated phases; a critical chain length is found for the existence of modulated phases; the dependence of transition temperature on energy parameters is determined. A critical region is found for open systems, where conformational disorder drives spontaneous generation of curvature; this lies above a characteristic chain length and around the shape transition temperature.
PACS. 64.60.-i General studies of phase transitions- 68.35.Rh Phase transitions and critical phenomena- 87.22.-q Physics of cellular and physiological processes
(a) email: bassetti@mi.infn.it
Online publication: February 24, 1998
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