Journal ArticleDOI
Kinetics of swelling of gels
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TLDR
In this article, a theory of the kinetics of the swelling of polyacrylamide gels is presented, which is based on the assumption that the swelling time is determined by the diffusion coefficient of the fluid molecules.Abstract:
We present a theory of the kinetics of the swelling of a gel. The characteristic time of swelling is proportional to the square of a linear dimension of the gel and is also proportional to the diffusion coefficient of the gel network, which is defined as D=E/f where E is the longitudinal bulk modulus of the network, and f is the coefficient of friction between the network and the gel fluid. This constitutes an essential difference between the present theory and the previous theory which is based on the assumption that the swelling time is determined by the diffusion coefficient of the fluid molecules. Experimental data are shown for spheres of 5% polyacrylamide gels and are analyzed using the present theory. The value of the diffusion coefficient obtained from the macroscopic swelling experiments shows excellent agreement with that obtained microscopically using laser light scattering spectroscopy.read more
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Stimuli-responsive hydrogel microfibers with controlled anisotropic shrinkage and cross-sectional geometries
TL;DR: Stimuli-responsive microfibers are fabricated by extruding mixed solutions of poly(N-isopropylacrylamide-co-acrylic acid) (pNIPAM-AAc) and sodium alginate using a microfluidic spinning system that shrink and swell with temperature and/or pH.
Journal ArticleDOI
Poly(NIPAAm-co-β-cyclodextrin) microgels with drug hosting and temperature-dependent delivery properties ☆
TL;DR: Microgels obtained by cross-linking polymerization of the corresponding monomers possess a relative rapid swelling/deswelling rate around the human body temperature and have showed a low degradation rate, the erosion occurring especially at the surface.
Journal ArticleDOI
Smart copolymeric nanohydrogels : Synthesis, characterization and properties
TL;DR: In this paper, a smart pH-sensitive copolymeric hydrogels have been synthesized by inverse microemulsion polymerization of p -nitro phenol acrylate (NPA) and N -isopropylacrylamide (NIPA) using Aerosol (AOT) as a surfactant and ELDMA as a crosslinking agent.
Journal ArticleDOI
Poly(N-isopropylacrylamide) Gel Prepared Using a Hydrophilic Polyrotaxane-Based Movable Cross-Linker
TL;DR: A novel type of thermosensitive polymer gel was fabricated using a hydrophilic polyrotaxane as a movable cross-linker and N-isopropylacrylamide (NIPA) as a monomer to achieve unprecedentedly fast thermosensitivity and mechanical softness.
Journal ArticleDOI
Swelling and deswelling kinetics of poly(N-isopropylacrylamide) gels.
TL;DR: The value of thecritical exponent for the correlation length suggests that the universality class for the volume phase transition of the critical PNIPA gel belongs to the class forThe classical theory.
References
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Journal ArticleDOI
Statistical-Mechanical Theory of Irreversible Processes : I. General Theory and Simple Applications to Magnetic and Conduction Problems
TL;DR: In this paper, a general type of fluctuation-dissipation theorem is discussed to show that the physical quantities such as complex susceptibility of magnetic or electric polarization and complex conductivity for electric conduction are rigorously expressed in terms of timefluctuation of dynamical variables associated with such irreversible processes.
Journal ArticleDOI
Spectrum of light scattered from a viscoelastic gel
TL;DR: In this paper, the spectrum of light scattered from thermally excited displacement fluctuations in polyacrylamide gels was measured using optical mixing spectroscopy, and the correlation function for the displacements having wave vector q is predicted for these gels to have the form of an exponential decay: exp(− Γt).
Journal ArticleDOI
An Introduction to the Theory of Elasticity
P. G. Appleby,R. J. Atkin,N. Fox +2 more