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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Photon transmission technique for monitoring drying processes in acrylamide gels formed with various crosslinker contents
Selim Kara,Önder Pekcan +1 more
TL;DR: In situ photon transmission experiments were performed using UV-visible (UVV) spectrometer during the drying of polyacrylamide (PAAm) gels.
Journal ArticleDOI
High frequency poroelastic waves in hydrogels
TL;DR: In this article, a model for high frequency poroelastic longitudinal waves in hydrogels is presented, where a viscoelastic force describing the interaction between the polymer network and bounded water present in such materials is introduced.
Journal ArticleDOI
Prediction of the appropriate size of drug molecules that could be released by a pulsatile mechanism from pH/thermoresponsive microspheres obtained from preformed polymers.
Gheorghe Fundueanu,Marieta Constantin,Ionela Oanea,Valeria Harabagiu,Paolo Ascenzi,Bogdan C. Simionescu +5 more
TL;DR: The synthesis of pH/thermoresponsive cross-linked microspheres based on N-isopropylacrylamide and N-alloc-ethylenediamine is reported, using a chromatographic method developed to predict the appropriate size of drug molecules that could be loaded and then released in a pulsatile manner.
Journal ArticleDOI
Diffusion coefficient in a semi-dilute solution measured by concentration gradient technique and compared to quasielastic light scattering results
M. Adam,M. Delsanti,G. Pouyet +2 more
TL;DR: In this paper, it was shown that the diffusion coefficient of a semi-dilute solution does not depend on the time scale over which the measurement is made, whereas the response is purely viscous if the observation is made in an interval greater than TR.
Journal ArticleDOI
Synthesis and characterization of pH-sensitive microgels by derivatization of npa-based reactive copolymers
TL;DR: In this paper, the pH-sensitivity of the final microgels has been studied by the determination of the hydrodynamic diameters by QELS as a function of pH, and the results showed that the systems underwent a swelling transition near the estimated apparent p K a according to the introduced pendant groups.
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