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Water sorption kinetics in light‐cured poly‐HEMA and poly(HEMA‐ co ‐TEGDMA); determination of the self‐diffusion coefficient by new iterative methods
Author(s) -
Sideridou Irini D.,
Papanastasiou Georgios E.
Publication year - 2007
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.26693
Subject(s) - methacrylate , sorption , triethylene glycol , extrapolation , diffusion , materials science , polymer chemistry , copolymer , fick's laws of diffusion , thermodynamics , analytical chemistry (journal) , polymer , chemistry , mathematics , physics , composite material , chromatography , adsorption , mathematical analysis
The present investigation is concerned with the determination of self‐diffusion coefficient ( D ) of water in methacrylate‐based biomaterials following Fickian sorption by two new methods: the Iterative and the Graphical methods. The D value is traditionally determined by means of the initial slope of the corresponding sorption curve and the so‐called Stefan's approximation. The proposed methods using equations without approximations and data resulting from the whole sorption range reach to accurate values of D , even when the sorption curve does not present an initial linear portion. In addition to D , the Graphical method allows the extrapolation of the mass of the sorbed water at equilibrium ( M ∞ ), even when the equilibrium specimen's mass fluctuates around its limited value ( m ∞ ). The test of the proposed procedures by means of ideal and Monte Carlo simulated data revealed that these methods are fairly applicable. The obtained D values compared with those determined by means of the Stephan's method revealed that the proposed methods provide more accurate results. Finally, the proposed methods were successfully applied to the experimental determination of the diffusion coefficient of water (50°C) in the homopolymer of 2‐hydroxyethyl methacrylate (HEMA) and in the copolymer of HEMA with triethylene glycol dimethacrylate (98/2 mol/mol). These polymers were prepared by light curing (λ = 470 nm) at room temperature in presence of camphorquinone and N,N ‐dimethylaminoethyl methacrylate as initiator. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007