Grafting, hydrophobic enhancing functional

Figure 7 Mesoporous silica grafting for catalysis enhanced activity towards glycerol esterification is obtained when a hydrophobic methyl chain is cografted with the sulfonate function, providing favorable interactions with fatty acid reagents...

The surface properties of particles are very important with respect to their end use. Many particles are used for fillers and to impart properties that enhance a materials function. In order to do so, the particles need to be compatible with the environment into which they are placed. Often this is in a polymer matrix such as a film. To enhance particle compatibility of the surface of 2-5 pm silica particles and silica glass beads, surface modification of these particles was carried out. Surface modifications were accomplished by surface polymerization, surface polymer grafting, by surface dendrimerization and by developing organo-silicone particles. The surfaces obtained can have a wide variety of properties, fi om highly hydrophilic to highly hydrophobic, from anionic and cationic to nonionic, as well as being environmentally responsive. 

Recently, several studies have immobilized bioactive species, such as enzymes, peptides and proteins, directly onto the polymer surface. The polymer siuface is fimctionalized with one of the above techniques to introduce the desired functional groups to subsequently react with the bioactive molecule. Thus, the functional group or the grafted polymer chains act as a spacer molecule between the material sm-face and bioactive compound. This helps in reducing the steric hindrance and shields the biomolecule from the hydrophobic surface preventing protein denaturation and enhancing bioactivity. The intermediary molecular chemistry can influence the bioactive compound behavior on the material surface. This approach has been used for PDMS used as biosensors [37]. 

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