Functionalization Of The Organosilane And Its Application On Surface Treatment And Property

In this dissertation, some functionalizing modifications were performed on organosililane by isocyanation, fluoride alkylation and haloamination, respectively. The functionalizing products were then applied on the material surface treatment, the self-assembled monolayers(SAMs) and N-halamine antimicrobial cotton fabrics were finally prepared. During this stage, the reaction mechanism of silane functionalization process was studied in depth, the microscopic structures of the surface treatment films were investigated as well, and the relationship between the structure and properties of the functionalizing silanes was well analyzed. Main discussions were as followings:(1) 1,3,5,7-tetra(trimethylsiloxysilicatecarboxypropyl)-1,3,5,7-tetramethylcyclotetrasiloxane(2) was synthesized by esterification and hydrosilylation reaction using acrylic acid and 1,3,5,7-tetramethylcyclotetrasiloxane(D4H) as raw materials.(2) was hydrolyzed to obtain 1,3,5,7-tetracarboxypropyl-1,3,5,7-tetramethylcyclotetrasiloxane(3), followed by staudinger reaction and curtius rearrangement reaction to give the target product 1,3,5,7-tetraisocyanatoethyl-1,3,5,7-tetramethylcyclotetrasiloxane(4), the isocyanate groups were then introduced into cyclotetrasiloxane. The structures of the target product together with intermediate products were characterized by 1H NMR, MS and FTIR techniques.(2) 3-isocyanatepropyl triethoxysilane(IPTS) was synthesized using one-pot reaction with 3-aminopropyl triethoxysilane(APTES) and triphosgene as the raw materials. IPTS was then reacted with three kind of perfluoroalkyl alcohol to obtain 3-(1H,1H,2H,2H-perfluoroalkoxyamidepropyl)-triethoxysilane with different kind of fluoroalkyl chain length. Three kind of self-assembled monolayers were then obtained with different fluorine contents; the results of ATR-IR indicated that a combination of possible bonding forms was the likely result of the silanization reaction. The hydrophobic and oleophobic properties of the self-assembled monolayers were investigated, and the thermodynamic property of the fluoroalkylsilane was discussed. XPS and AFM were used to characterize the element contents and the changes of chemical structures of the SAMs surface, results showed that the fluoroalkyl tended to migrate from the internal of the monolayers to the outermost surface in the heat, and fluorine was then riched in the surface. The results of contact angles showed that the water- and oil- repellency increased with the growth of fluorine contents. Heat-treatment would result in the microphase separation of the SAMs surfaces, then the decline of surface free energy, and finally the increase of liquid repellency.(3) N-(3-triethoxysilylpropyl)-carboxypropyl formamide(TSCF) was synthesized through the reaction between APTES and succinic anhydride, then TSCF was reacted with N,N-carbonyldiimidazole(CDI), followed by reacting with three kind of perfluoroalkyl alcohol to synthesize 3-(1H,1H,2H,2H-perfluoroalkoxycarbonyl)-propionamide-propyl-triethoxysilane(PFHPT, PFOPT, PFDPT) with different kind of fluoroalkyl chain length under very miled conditions. The introduction of CDI could prevent the generation of water during the synthesis of target compounds, which would finally avoid the hydrolysis of ethoxy groups; this method was particularly suitable for the derivatized of the easily hydrolyzed alkoxysilane substrates. The fluoroalkylsilanes were then self-assembled on the Silicon wafers to obtain SAMs with different fluorine contents. The hydrophobic property and surface free energy of the self-assembled monolayers were investigated in depth, and the contact angles, adhesive force and surface free energy were measured as well. Relations between the assembling property and the fluorine alkyl chain length as well as the carbon chain length were discussed. Results showed that the longer fluoroalkyl chain length of perfluoroalkyl silane would result in a poor compatibility between the perfluoroalkyl silane and the hydroxyl-terminated surface, which finally resulted in the poorer self-assembled performance. The results of AFM and EDS showed that PFOPT could assemble on the silicon substrate uniformly.(4) N-(3-triethoxysilylpropyl)-N′-(N″′-heptylcarbamido-N″-ethyl)-butanediamide and three kind of N-(3-triethoxysilylpropyl)-N′-alkyl-butanediamide were synthesized using CDI as activating reagent. The functional silanes were then attached onto cotton fibers through hydrolysis of oxyethyl groups to form silyl ether linkages with cotton fibers, followed by immersing the cotton fabrics into sodium hypochlorite solution to endow it with antibacterial property. Controlled release of the oxidative chlorine and the endurance of antimicrobial treatment were investigated, and results showed that the washing fastness and storage stability of the antimicrobial cotton fabrics were considerable good, while the UVA stability was fairly poor. The relationships between the silane finishing agents with different sterically hindered amines structures and the antimicrobial property together with durability were investigated, and results showed that the antibacterial efficacy of the cotton fabrics treated with the N-halamine precursor with aromatic steric hindrance amine was superior to the aliphatic ones. In addition, the antibacterial efficacy increased with the growth of N-Cl groups. The results of bacteriostatic rate test showed that the chlorinated coated cotton fabrics provided excellent antibacterial property against E. coli O157:H7 and S. aureus. Among which, the antibacterial efficacies against E. coli were somewhat inferior compared to that against S. aureus for these antibacterial materials. The results of TGA and breaking strength indicated that both the decomposition of N-Cl groups, heat treatment on cotton fibers and the oxidation or corrosion of the cellulose fibers caused by sodium hypochlorite solution made a contribution to accelerate the decomposition of cotton fibers, which resulted in the decrease of breaking strength.