Polymerizable silane

This open tubular approach was improved by Tan and Remcho [21] who generated molecularly imprinted polymer films attached to walls of 25 pm ID capillaries. They injected as well a mixture of porogen, template, functional monomers, crosslinker, and initiator into a capillary activated with a polymerizable silane and performed the polymerization at elevated temperatures. A capillary with a total length of 100 cm and a separation length of 85 cm, respectively, coated with a polymer imprinted with dansyl-L-phenylalanine was applied for a separation of the racemate of dansyl-phenylalanine. Using acetonitrile/lOmmol (pH 7.0) phosphate buffer (10 1, v/v), a baseline separation of the two enantiomers could be achieved (Fig. 9). 

The main advantage of using Laponite instead of MontmoriUonite is the dimension of the crystals (e.g., 1 nm thick and 40 nm long), which is of the same order of magnitude as the diameters of the polymer latexes. In the first paper of their series, these authors demonstrated that nanocomposite coUoids based on Laponite could be readily obtained by grafting of a polymerizable silane on the clay surface [137]. 

Another class of extenders used widely in coating applications is calcium carbonate (CaCOj). Yu et al. recently reported the preparation of CaCOj/polystyrene composite particles using a polymerizable silane derivative previously attached onto the mineral surface [143]. The pretreated CaCOj particles were shown to act as comonomers during the emulsion polymerization process in similar manner as discussed previously for the case of silica. 

Modification of the surfaces of coUoidal silica spheres with silane coupling agents enables transfer of the particles to nonpolar solvents. With 3-methacryloxypropyltri-methoxysilane bonded to the surface, the particles have been transferred from water to the polymerizable monomer, methyl acrylate. Electrostatic repulsion due to a low level of residual charge on the particle surfaces cause the dilute dispersions of particles to form a non-close packed colloidal crystalline array (CCA). Polymerization of the methyl acrylate with 200 nm diameter silica spheres in a CC fixes the positions of the spheres in a plastic film by the reactions shown in Figure 11.14. The difriaction... 

Presently, many organic additives fall into the category of polymerizable monomers. A non-exhaustive list includes esters (including carboxylic esters/carbonates and other inorganic esters such as phosphates, sulfates, and silicates) that are derived from vinyl and allyl alcohols [2,54,71], vinyl pyridine [63], acrylic acid nitrile [110], maleic acid derivatives [125, 131], vinyl sulfones [128], vinyl silanes [113], and isocyanates [65, 171] (Fig. 2). The synergistic effect of different unsaturated compounds used in various combinations has also been reported [1]. 

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