– Although the pattern formation on polymer gels has been considered as a result of the mechanical instability due to the volume phase transition, we found a macroscopic surface pattern formation not caused by the mechanical instability. It develops on gelation surfaces, and we consider the reaction-diffusion dynamics mainly induces a surface instability during polymerization. Random and straig...

Microencapsulation has become a common technique in the production of controlled release dosage forms. Many results have been reported, concerning the use of alginate beads as controlled release drug formulations. Alginate has a unique gel-forming property in the presence of multivalent cations, in an aqueous medium. Ibuprofen is an excellent analgesic and antipyretic, non-steroidal anti-inflam...

We study a chemical gelation model in two dimensions which includes both monomer aggregations and bond fluctuations. Our numerical simulation shows that a sol-gel transition occurs when an initial monomer concentration is above a critical concentration. Fractal aggregates grow until the sol-gel transition occurs. After the gelation, however, bond fluctuations break the fractal structure and an ...

A random mixture of bifunctional and tetrafunctional units is placed on a simple cubic lattice. Permanent bonds between these units are then formed by the random motion of active centres (radicals) resulting in a model for the gelation of polyacrylamide and similar processes. The largest of the clusters formed by this kinetic percolation process is identified with the gel fraction, the ‘mean cl...

The aim of this work was to study the structure formation of yogurt made with cultures containing ropy Lactobacillus delbrueckii ssp. bulgaricus (R), capsule-forming nonropy Streptococcus thermophilus (CNR), and noncapsule-forming nonropy cultures (NCNR). Similar gelation profiles were shown for milk fermented by ropy and nonropy lactic cultures. The gelation point occurred at lower pH values i...

The gelation of water suspension of a synthetic clay (Laponite) has been studied by dynamic light scattering in a wide range of clay weight concentration (C(w)=0.003-0.031). At variance with previous determination, indicating a stable liquid phase for C(w)<C(*)(w) approximately 0.015-0.018, we find that gelation actually takes place in the whole examined C(w) range. We find also that C(*)(w) ma...

The present work investigated the preparation of biodegradable beads with alginate polymer by ionotropic gelation method to improve the control release properties of the antibiotic rifampicin. Ionotropic gelation method was applied to prepare beads using calcium chloride (CaCl2) as cationic component and alginate as an anionic component. In this method, adding 0.5% w/v polyvinyl alcohol (PVA) t...

We investigated the temperature-responsive gelation of collagen/genipin solutions using pepsin-solubilized collagen (PSC) and acid-solubilized collagen (ASC) as substrates. Gelation occurred in the PSC/genipin solutions at genipin concentrations 0-2 mM under moderate change in temperature from 25 to 37°C. The PSC/genipin solutions exhibited fluidity at room temperature for at least 30 min, wher...

An organogelator was produced and identified from a dynamic imine system, resolved and amplified by selective gelation. The formation of the organogel was monitored in situ by (1)H NMR, showing the existence of multiple reversible reactions operating simultaneously, and the redistribution of the involved species during gelation. The formed organogelator proved effective with a range of organic ...