In this study, we demonstrate how the diffusion of probe particles in aqueous poly(vinyl alcohol) (PVA) solutions and gels is affected by: (i) the presence of cross-links, (ii) the cross-link density, (iii) the polymer concentration. We apply fluorescence correlation spectroscopy (FCS) to measure the diffusion time of a rhodamine-based fluorescent particle (TAMRA) and TAMRA-labeled dextran in P...

Scleroglucan is a natural polysaccharide that has been proposed for various applications. However there is no investigation on its property variations when the molecular weight of this polymer is reduced. Scleroglucan was sonicated at two different polymer concentrations for different periods of time and the effect of sonication was investigated with respect to molecular weight variations and r...

Background: Polymer gel dosimeters combined with magnetic resonance imaging (MRI) can be used for dose verification of advanced radiation therapy techniques. However, the uncertainty of dose map measured by gel dosimeter should be known. The purpose of this study is to investigate the uncertainty related to calibration curve and MRI protocol for MAGIC (Methacrylic and Ascorbic acid in Gelatin I...

The experimental results of the Brillouin shift and width for poly(vinyl alcohol) and poly(vinyl chloride) gels as a function of gel network volume fraction have been analysed using the theory of Marqusee and Deutch for Brillouin light-scattering from polymer gels, incorporated with a new plausible assumption relating the speed of sound in the gel network with its volume fraction. It has been f...

We report results from experimental studies performed on polyelectrolyte gels to understand the volume transition induced by multivalent cations. Macroscopic osmotic and mechanical measurements are made to determine the effect of ion binding on the elastic and mixing contributions of the network free energy. Small-angle neutron scattering is used to reveal the role of multivalent ions in the or...

Star polymers with a high number of arms, f=263, become kinetically trapped when dispersed in an athermal solvent at concentrations above the overlapping one, forming physical gels. We show that the addition of linear chains at different concentrations and molecular weights reduces the modulus of the gel, eventually melting it. We explain this linear polymer-induced gel-liquid transition in ter...

Bridge-flocculated colloidal gels are used in many important processes and products such as gel casting for advanced ceramics, precursor inks for 3D printing, and waste treatment strategies. An important aspect of polymer bridged gels that makes them excellent candidates for these applications is the precise control it affords for control of rheological properties. Recent studies have shown tha...

Introduction Gels are particularly suitable to study ion-polymer interactions. Monovalent-divalent cation-exchange plays central role in various physiological processes such as nerve excitation and muscle contraction It is natural to use synthetic polyelectrolyte gels as model systems to demonstrate principles, develop and verify new experimental approaches. They are relatively easy to make, th...

Permanently crosslinked polyelectrolyte gels are known to undergo discontinuous first-order volume phase transitions, the onset of which may be caused by a number of factors. In this study we examine the volumetric properties of such polyelectrolyte gels in relation to the progressive substitution of monovalent counterions by divalent counterions as the gels are equilibrated in solvents of diff...

INTRODUCTION At present, the polymer gel dosimeter is considered to be the best possible dosimeter for measuring 3-dimesional radiation dose distribution in radiotherapy. These gels are normally toxic; therefore, manufacturing, handling and discarding them require special attention. In order to find less toxic recipe, N-isopropyle acrylamide polymer gel (NIPAM) was introduced. In this study, th...