The modification of the gel-like copolymers, because of the slow reaction rate and restricted reagent diffusion, produced copolymers with only very modest surface areas.
Similarly, the stirring rate has no effect on the dissolution rates, because being a chemical control, the reagent diffusion process is quicker compared to the chemical reaction, even if at low [H3O+], diffusion plays an important role.
Research on surface properties of whey protein aerated gels can be important because the surface shape, roughness and porosity are essential for such processes such as enzymes hydrolysis, reactivity of the surface in contact with chemical reagents, adhesion and diffusion of the active ingredients, deposition of micro-organisms on the surface of the product.
Fig. 22 a Illustration of microreactor used for the slow diffusion of reagents, channels are filled with oil through which each reagent slowly diffuses, b image of reactor plate with seven parallel reactors, c microscopy images of crystals of silver phenylacetylide formed by common laboratory methods (top) and using the microfluidic diffusion chip (bottom) Reprinted with permission from Ref. [45].
Figure 7 Schematic of the reagent and by-product diffusion paths and diagram of the Au/Si Schottky contact.
With gas filled polydimethylsiloxane (PDMS) membranes, isolated cells can be created, capturing the two reagent streams and enabling diffusion of specific volumes of solution.
The mesoporosity of the oxide support favors the diffusion of reagents towards the catalytic centers.
However, using solution photochemistry for acid-labile deprotection requires the reaction sites being isolated from each other to prevent diffusion of reagents during a photolytic reaction.
As a dense polymer, they can actively interfere in the reaction by modulating sorption and diffusion of reagents and products, leading to significantly enhanced catalytic activities.
This well-tailored concept of the PBCNT-GO functional carbon support provides various features, including a two-dimensional (2D) structure, dimensional stability, versatile solubility (from toluene to water), enhanced diffusion of reagents, and recyclability.
In the unreacted shrinking core model for spherical particles with formation of solid products, two stages can be slow: the chemical reaction in the interface between the unreacted core and the ash halo, and the diffusion of reagents and products through the ash halo [48].
