Other Organofunctional Silanes

Organofunctional silanes with hydroxy-, epoxy-, acryl-, ester- and carboxy-functions are produced industrially. They are in particular utilized as additives for modification of polymers and for functionalizing silicones for different application sectors. Most of these compounds are manufactured by the addition of appropriately functionalized alkenyl-compounds. 

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Silanes with organohalo-groups are utilized as precursors in the production of other organofunctional silanes and as a component of different reactive silane products. Manufacture of the most important representative from this product group, chloropropyltrichlorosilane, is carried out continuously by reacting trichlorosilane with chloropropene ( allylchloride ) in the presence of platinum catalysts. Alkoxysilanes, which are produced from the chlorosilanes, are often used in practice. 

Electron beam irradiation is one of the methods of cross-linking in fhis process. The other methods use peroxide, multifunctional azide, or an organofunctional silane. Polyethylene resins respond to electron beam irradiation well since the rate of cross-linking exceeds significanfly fhe chain scission. Polypropylene (PP) is prone to P-cleavage, which makes if difficult to cross-link by a free radical process. For fhaf reason, PP resins... 

Chemisorption. A key step in the development of a successful membrane modified FET is the adherence and longevity of the membrane and the success of the encapsulation procedure. Sudholter et al (35) have proposed a method for the attachment of the ion selective membrane to a silylated SiC>2 gate oxide. An organofunctional silane, for example methacryloxypropyl trimethoxysilane, forms a bond between the surface and a photocrosslinkable polymer (eg polybutadiene). The ionophore would be directly bound to the polymer backbone, thus eliminating the need for plasticiser. Without any further modification with ionophore the membrane is sensitive to pH and shows a long life time (some months). Similar approaches have also been proposed by other workers, eg (36)... 

Other thixotroping agents include Bentones and Tixogels, of which a number of grades are available, and China clay or kaolin, usually added as a filler, but which imparts thixotropy to the formulated product. Organofunctional silanes are extremely effective... 

Some specific organofunctional silanes can be analyzed via colorimetry with suitable reagents. Examples include epoxysilane with bromothymol blue/thiosulfate solution methacryloxy andvinylsUanes with permanganate salts amino/diamino silanes with ninhydrine [33]. The results are semiquantitative within the same system of mineral and silane in all other cases, they are only of qualitative nature. 

The interaction between the surface of particulate and fibrous fillers and a polymer matrix plays a key role in deterrnining the processability and properties of filled composites. Unmodified filler surfaces often give poor interactions and this has led to the growth of an industry based on the use of additives to modify filler surfaces and improve their interactions with polymers. Several types of additives have been evolved for this purpose. Two of these, organofunctional silanes and titanates, have been described in Chapters 4 and 5. This chapter covers other approaches that have been studied, although only a few of these, notably fatty and unsaturated carboxylic acids and functionalized polymers, have achieved much commercial importance. 

Researchers discovered that antimicrobial organofunctional silanes could be chemically bound to receptive substrates by what were believed to be Si-0 linkages. The method was described as orienting the organofunctional silane in such a way that hydrolyzable groups on the silicon atom were hydrolyzed to the silanols and formed chemical bonds with each other and to the substrate. The resultant surface modification, when an antimicrobial moiety such as a quaternary nitrogen was included, provided for the antimicrobial group to be oriented away from the surface. ... 

The use of organofunctional silanes as adhesion promoters is well documented [90], and much is now known about their mode of operation [91], Surface analysis has played, and continues to play, an important role in the understanding of the action of these complex materials, which have been. studied on glass, and on steel and other metals. There is now general agreement that the... 

IETS is well suited for investigating the adsorption of organofunctional-alkoxy silanes on alumina. Surface sensitivity at the sub-monolayer level, and orientational selectivity makes this technique particularly attractive, especially when used in conjunction with other techniques such as FT-IR, and SER spectroscopies. 

Adsorption of alkoxysilanes onto cellulose fibers also holds promise for modification of the cellulose surface. The basic formula of the silane-coupling agents used has an organofunctional group on one side of the chain and an alkoxy group on the other. Abdelmouleh studied the adsorption of several prehydrolyzed alkox-... 

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