Thermoinduced aggegation of chitosan systems in perikinetic and orthokinetic regimes

Influence of Glycerophosphate Salt Solubility on the Gelation Mechanism of Colloidal Chitosan Systems

“…The rate of sol-gel phase transition of colloidal chitosan systems induced by stochastic Brownian motion was determined using turbidimetric techniques by measuring the values of transmittance T [%] and backscatter BS [%] signals in the entire sample volume [ 21 ]. Examples of experimental curves obtained in subsequent time intervals for a colloidal solution of chitosan acetate with the addition of disodium glycerophosphate are shown in Figure 4 a.…”

“…In order to take into account the total changes observed during the formation of the spatial structure, the Turbiscan Stability Index (TSI) parameter was determined, defining the total destabilization of the system, the changes of which can be successfully used to compare the course of the gelation process with the results obtained during rheometric measurements [ 21 ]. Based on the final TSI values ( Figure 7 a), it can be concluded that the greatest changes were observed in the case of the use of magnesium glycerophosphate, and the smallest in the case of the addition of calcium salt.…”

“…The nuclei formed in this stage undergo further rapid aggregation in the second stage, the so-called fast gelation region. The differences in the course of the curves visible in the first stage result from the process regime, perikinetic or orthokinetic [ 21 ].…”

“…Applying the theoretical approach of colloid engineering [ 20 , 21 ], the authors in their previous research showed that the process of forming a spatial polymer network (gel) from a colloidal chitosan solution in the presence of GP salt proceeds in two stages. Since the amino groups present in the chitosan chain form non-covalent bonds with anionic phosphate groups, it was found that the aggregation rate of particles is not limited only by the phenomenon of their diffusion (diffusion-limited cluster aggregation (DLCA) mechanism [ 22 , 23 , 24 , 25 ]), but will also depend on the resulting interactions between the amino groups and anionic phosphate groups, so-called reaction-limited cluster aggregation (reaction-limited cluster aggregation (RLCA) mechanism [ 22 , 23 , 24 , 25 ]).…”

Influence of Injection Application on the Sol–Gel Phase Transition Conditions of Polysaccharide-Based Hydrogels

“…200 to over 43,000 s −1 (depending on the needle diameter) or even 55,000 s −1 taking into account the strongly shear-thinned nature of polymer systems. As a consequence, high shear stresses are generated which may affect the spatial conformation of the polymer molecules including their arrangement along the streamlines The previous authors' research [32] has shown that the spatial conformation of biopolymer molecules will strongly depend on the applied shear field, its direction and magnitude.…”