Selection Principles of Organic Silane Coupling Agents

The selection of organic silane coupling agents is generally based on empirical summarization of test data for organic silane coupling agents, and it is very difficult to accurately predict the organic silane coupling agents. The increased bond strength after using organic silane coupling agents is a comprehensive series of complex factors, such as wetting, surface energy, adsorption of the boundary layer, polar adsorption, acid-base interaction, etc.

Rules for the Pre-selection of Organic Silane Coupling Agents

Unsaturated polyester can use vinyl, epoxy, and methacryloxy-type organic silane coupling agents; epoxy resin should use epoxy or amino-type organic silane coupling agents; phenolic resin should use amino or methacryloxy-type organic silane coupling agents; polyolefins should use vinyl-type organic silane coupling agents ; sulfur-vulcanized rubber should use mercapto-type organic silane coupling agents, etc.

General Principles for Choosing Teos Silane Coupling Agents

The hydrolysis rate of teos silane coupling agents depends on the silicon functional group, while the reaction activity with organic polymers depends on the carbon functional group. Therefore, it is crucial to choose the appropriate teos silane coupling agent for different substrates or treatment objects. The selected method mainly relies on experiments, pre-selection, and should be based on the existing experience or rules. Since the adhesive strength between different materials is affected by a series of factors, such as wetting, surface energy, interfacial layer, polar adsorption, acid-base effects, interpenetrating network, and covalent bond reactions. Therefore, pre-selection by experiment alone is sometimes not accurate enough, and the composition of materials and their sensitivity to the reaction of teos silane coupling agents must be comprehensively considered. In order to improve hydrolytic stability and reduce modification costs, trialkoxy silane can be added to the tmds silane coupling agent; for difficult-to-adhere materials, the crosslinked polymer of the silane coupling agent can be shared.

When teos silane coupling agents are used as thickening agents, they mainly achieve it through the formation of chemical bonds and hydrogen bonds with polymers, wetting and surface energy effects, improvement of polymer crystallinity, acid-base reactions, and the formation of interpenetrating polymer networks. Thickening mainly revolves around three systems: inorganic materials to organic materials; inorganic materials to inorganic materials; organic materials to organic materials. For the first type of adhesion, it usually requires that the inorganic material be bonded to the polymer, so it is necessary to prioritize the reaction activity of Y in the tmds silane coupling agent with the functional groups contained in the polymer. The latter two belong to adhesion between materials of the same type, so the tmds silane coupling agent's hydrophobic polymer and inorganic materials require the silane coupling agent used for thickening.