Sorption and desorption of PVA-pyrene chains in and out of agarose Gel.

In situ steady-state fluorescence (SSF) measurement technique was applied to investigation of pyrene labeled Poly(vinyl alcohol) (PVA-Py) molecules diffusion in and out of agarose gels. Gel samples with four different concentration of agarose were prepared. PVA-Py was synthesized by "click" chemistry method and dissolved in water to use in diffusion experiments.

Thermal phase transitions of agarose in various compositions: a fluorescence study.

The effect of agarose content on thermal phase transitions of the agarose gels was investigated by using Steady State Fluorescence (SSF) method. Scattered light, I(sc) and fluorescence intensity, I(fl) were monitored against temperature during heating and cooling processes to investigate phase transitions. Two regions were observed during the heating and cooling processes.

Electrical and optical percolations of polystyrene latex-multiwalled carbon nanotube composites.

Electrical conductivity and optical transmittance properties of polystyrene (PS)-multiwalled carbon nanotube (MWCNT) composite films were investigated. Composite films were prepared by mixing of various mass fractions of MWCNT in PS-water dispersions. After water evaporates, powder composite films were annealed at 175 degrees C above the glass transition of PS for 20 min.

Vapor-induced film formation from low-Tg particles for different solvent compositions.

The photon transmission method was used to study latex film formation from poly(vinyl acetate) (PVAc) particles induced by two different solvents. Films with the same latex content were prepared from PVAc particles and exposed to vapor of ethanol-water and acetone-water mixtures in various compositions. Transmitted photon intensities, Itr, from these films increased with increasing vapor exposure time.

Cation effect on thermal transition of iota-carrageenan: a photon transmission study.

Coil-to-double helix (c-h) and double helix-to-dimer (h-d) phase transitions of iota-carrageenan in various cation (CaCl2) solutions upon heating and cooling were studied using the photon transmission technique. Photon transmission intensity, Itr, was monitored against temperature to determine the (c-h) and (h-d) transition temperatures (Tch and Thd) and activation energies (DeltaEch and DeltaEhd). An extra dimer-to-dimer (d-d) transition was observed during cooling at low temperature region.

Photon transmission study on conformational ordering of iota-carrageenan in CaCl2 solution.

Coil-to-double helix (c-h) and double helix-to-dimer (h-d) phase transitions of iota-carrageenan in CaCl(2) solution upon cooling were studied using photon transmission technique. Photon transmission intensity, I(tr) was monitored against temperature to determine the (c-h) and (h-d) transition temperatures (T(ch) and T(hd)) and activation energies (DeltaE(ch) and DeltaE(hd)). An extra dimer-to-dimer (d-d) transition was also observed during cooling at low temperature region.

Photon transmission study on swelling of kappa-carrageenan gels prepared in various concentrations.

kappa-Carrageenan gels prepared with various carrageenan concentrations in pure water were completely dried and then swelled in pure water. Photon transmission measurements were performed using a UV-Vis (UVV) spectrometer during the swelling of kappa-carrageenan gels. Transmitted photon intensity, I(tr), increased exponentially as swelling time is increased for all gel samples.

Cation effects on swelling of kappa-carrageenan: a photon transmission study.

Swelling behavior of kappa-carrageenan gels in water and KCl solutions was investigated by photon transmission experiments following the preparation of gels in the presence and absence of externally added K+ ion as a gel promoting agent. Transmitted photon intensity, Itr, increased continuously during swelling depending on the carrageenan and ion content in the gel. This increase in Itr was modeled using the Li-Tanaka equation.

Cation effects on sol-gel and gel-sol phase transitions of kappa-carrageenan-water system.

Sol-gel and gel-sol phase transitions of kappa-carrageenan in pure water and in KCl solution were studied using photon transmission technique. Photon transmission intensity, I(tr), was monitored against temperature to determine the sol-gel and gel-sol temperatures (T(sg) and T(gs)) and activation energies (deltaH(sg) and deltaH(gs)). It was observed that T(gs) was notably higher than T(sg) due to the hysteresis on the phase transition loops.