Preparation And Hydrophobic Properties Of Dodecylamine-Bridged POSS Materials

Bridged polysilsesquioxanes are a class of organic-inorganic hybrid materials withexcellent mechanical properties. The organic and inorganic parts of the material arecovalently attached to achieve a composite of nanoscale proportions. This paper focuseson the preparation conditions and optimization of surface hydrophobicity in a newdodecylamine-bridged polysilsesquioxane.The bridged monomer used in this study was prepared by reaction of twoequivalents of glycidyloxypropyltrimethoxysilane with one equivalent of dodecylamine.We affirm the best experimental condition finally, the temperature and time respectivelywere60℃and36hours. The result of FTIR and epoxy value analysis indicates that theconnections between DA and GPMS are successful.The orthogonal experiment was designed to get the best ratio of raw materialsduring preparation of using formic acid. The best ratio of raw materials were: Si:formicacid=60:1，Si:H2O=1:4，THF:40g. Bridged POSS materials with formic acid gavematerials with a Lamellar structure. This effect is attributed to the intrinsic self-assembly properties of the organic component, which involve hydrophobic interactionsbetween adjacent dodecyl chains. The atomic force microscope (AFM)3D scanning canclearly see this structure. The interlayer spacing is2.31nm by profile analysis. Thecontact angles of materials and films respectively were82.82°and70.96°. To improvethe contact angle, we used post-treatment technology. The results shows that the filmaging in the ethanol and then extracting with hexane can get largest contact angle ashigh as73.1°. After that, we added TEOS in the synthesis process, The highest contactangles(74.02°) were achieved with the addition of TEOS (15wt%).Finally, In order to improve the contact angle effectively, we used acid-basecatalyzing polymerization reaction of the bridged monomer. By using a two steppolymerization the contact angles increased to113.40°, both the surface and the internalmaterials were hydrophobic. The highest contact angles(140.57°) were achieved withthe addition of TEOS (15wt%). SEM analysis of the polymerizations shows a roughaggregate morphology at micron scale, which is conducive to enhancing hydrophobicitythrough a lotus effect. The results of TG and DTA indicates that the materials havegood thermal stability with the decomposition temperature as high as260℃.