Organic surface modification

Fairbrother, FI. CAREER Exploring the Mechanisms of Organic Surface Modification Processes. 2000 (NSF CHE 9985372). 

Moreland J (1979) The first decade of inorganic and organic surface modification. In Society of the plastics industry, reinforced plastics/composites industries, proceedings of the 34th annual conference. Society of Plastics Industry, New York, Section 14-A, 30 Jan-2 Feb 1979... 

Rao, AV, Kalesh, R R (2004) Organic surface modification of TEOS based silica aerogels synthesized by co-precursor and derivatization methods. J Sol-Gel Sci Technol 30(3) 141-147. 

Depending on the average pore size, the modulus of compression, and the type of aerogel under investigation, the compression of the sample can be in part or totally irreversible. In particular, sUica-based aerogels without organic surface modification are irreversibly deformed. 

As an example, the role and the effect of alkylammonium ions in the montmorillonite interlayer in relation to the interaction (but also cleavage) energy between the components were investigated by MD simulation. It was confirmed that the organic surface modification of montmorillonites increases the likelihood of exfoliation of high-aspect ratio aluminosilicate layers in polymer matrices. The molecular interpretation on the basis of the simulation is supported by various experimental observations, such as cleavage energies and surface tensions [26,27, 36]. 

The first section of the book deals with the thermal stability of layered silicates and polymer nanocomposites. Chapter 1 provides an overview of layered silicates as fillers, organic surface modification of such layered silicates, and thermal stability considerations in relation to the surface modification molecules ionically exchanged on the filler surface. Chapter 2 provides in-depth information on the mechanisms of thermal degradation of layered silicates modified with ammonium and other thermally stable filler surface modifications. Chapter 3 provides the example of generating thermally stable polystyrene... 

Improvements in the impact resistance of hybrid sol-gel silica coatings have been obtained after modifying the surface of silica nanoparticles obtained by the Stober method [74] with 3-methacryloxypropyltrimethoxysilane (3-MPS). The reaction of the —OH groups with —O—CH3 groups leads to organic surface modification (Figure 39.4). 

Surface Modification. Plasma surface modification can include surface cleaning, surface activation, heat treatments, and plasma polymerization. Surface cleaning and surface activation are usually performed for enhanced joining of materials (see Metal SURFACE TREATMENTS). Plasma heat treatments are not, however, limited to high temperature equiUbrium plasmas on metals. Heat treatments of organic materials are also possible. Plasma polymerization crosses the boundaries between surface modification and materials production by producing materials often not available by any other method. In many cases these new materials can be appHed directly to a substrate, thus modifying the substrate in a novel way. 

Patterns of ordered molecular islands surrounded by disordered molecules are common in Langmuir layers, where even in zero surface pressure molecules self-organize at the air—water interface. The difference between the two systems is that in SAMs of trichlorosilanes the island is comprised of polymerized surfactants, and therefore the mobihty of individual molecules is restricted. This lack of mobihty is probably the principal reason why SAMs of alkyltrichlorosilanes are less ordered than, for example, fatty acids on AgO, or thiols on gold. The coupling of polymerization and surface anchoring is a primary source of the reproducibihty problems. Small differences in water content and in surface Si—OH group concentration may result in a significant difference in monolayer quahty. Alkyl silanes remain, however, ideal materials for surface modification and functionalization apphcations, eg, as adhesion promoters (166—168) and boundary lubricants (169—171). 

Organic titanates perform three important functions for a variety of iadustrial appHcations. These are (/) catalysis, especially polyesterification and olefin polymerization (2) polymer cross-linking to enhance performance properties and (J) Surface modification for adhesion, lubricity, or pigment dispersion. 

UV irradiation on a polymer surface produces chemical modification as well as wettability and bondability improvement. It causes chain scission and oxidation on polymer surfaces. -iven in the presence of an inert gas [45]. Carbonyls are found to be introduced onto polyethylenes on UV irradiation. Sivram et al. [46] have used photochemical treatments for surface modification of polymers. They have generated surfaces of vaying surface energies by simple organic reactions. 

The improvement of its activity and stability has been approach by the use of GE tools (see Refs. [398] and [399], respectively). A process drawback is the fact that the oxidation of hydrophobic compounds in an organic solvent becomes limited by substrate partition between the active site of the enzyme and the bulk solvent [398], To provide the biocatalyst soluble with a hydrophobic active site access, keeping its solubility in organic solvents, a double chemical modification on horse heart cytochrome c has been performed [400,401], First, to increase the active-site hydrophobicity, a methyl esterification on the heme propionates was performed. Then, polyethylene glycol (PEG) was used for a surface modification of the protein, yielding a protein-polymer conjugates that are soluble in organic solvents. 

Zhang Y., Hanayama K., and Tsubaki N. 2006. The surface modification effects of silica support by organic solvents for Fischer-Tropsch synthesis catalysts. Catal. Commun. 7 251-54. 

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