Surface covalent grafting

Sebe, G. and Brook, M. (2001). Hydrophobization of wood surfaces covalent grafting of silicone polymers. Wood Science and Technology, 35(3), 269-282. 

Irregularly hyperbranched grafts provide a useful way to modify surfaces. A variety of chemistry can be used and a wide variety of grafts can be prepared. The hyperbranched grafts can serve as supported membranes, as catalyst supports or as substrates for further covalent graft chemistry. Functional groups within these interfaces can be readily modified by solution-state chemistry. The interfaces themselves can be used as media for further chemistry within the interface or as substrates in molecular recognition and self assembly of other macromolecules. 

Azobenzene has also been added to the internal surface of mesoporous films and powders through postsynthesis grafting.58,60-62 The effect of oligomer size on azobenzene isomerization kinetics was studied for branched oligomer-modified azobenzene derivatives in solution and covalently grafted to nanoporous silica 61 the size of the dendrimer had little effect on the thermal cis to trans isomerization rate in solution... 

The grafting to method was used to anchor polymer chains onto the surface of silica particles and silicon wafers (Scheme 1). The synthetic procedure starts with covalent grafting of GPS to the surface. A self-assembled monolayer of GPS on silicon wafer surfaces was prepared according to the procedure suggested by Luzinov [32], For this, Si wafers were immersed in a 1% GPS toluene solution for 15 h under dry Ar atmosphere (< 1 ppm H2O). After treatment, GPS modified wafers were washed 3 times in dry toluene under dry Ar atmosphere to avoid polymerisation of non-grafted GPS and precipitation of particles. Afterwards, the silanized wafers were washed 2 times with ethanol in ultrasonic bath for 5 min followed by drying with nitrogen flux. The thickness of the GPS layer was determined by null ellipsometiy. 

In this work, the synthesis of high surface densities of chlororopropyl groups covalently grafted on mesoporous micelle templated aluminosilicates (Al-MTS) of various initial pore diameters is presented. The hybrid chiral materials resulting from halogen substitution are applied in the enantioselective addition of diethylzinc to benzaldehyde. 

A wide variety of polymer microspheres can be made by dispersion polymerization. A key component in all of these systems is the stabilizer (dispersant) both during particle formation and for the stability of the resulting colloidal particles. Functionality can be introduced into colloidal particles in various ways by copolymerization of functional monomers (like HEMA), or incorporation of functional dispersants, initiators, chain transfer agents, or macromonomers. Many different types of macromonomer are prepared and used to prepare functional microspheres. Amphiphilic macromonomers provide a particularly versatile component in these systems, being the source of both stabilizer and functional residue. They act as stabilizer because they are covalently grafted onto the particles surface by copolymerization with main monomers, and form tightly bound hairy shells on the particles surface. 

POMs have potential for forming hybrid materials due to nucleophilic surface oxygen atoms at the vacant site of them, which allow the covalent grafting of electrophilic group... 

Thus, mesoporous structures, because of their pores, make it possible to incorporate large catalytically active transition metal complexes. Covalently grafting these complexes in the hydrophobic patches provides better dispersion of the catalyst, as well as resistance to leaching. Improvement in catalytic performance is to be expected when materials with even larger pore diameters are studied. It will also be necessary to passivate the silanol groups responsible for promoting adsorption on the catalytic surface. 

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