This publication is important result of slovenian research project Z1-4219. Syntheses of various N-Heterocyclic carbenes (NHC) and their precursors is presented. NHC could be used as powerful catalysts for the preparation of various polyhedral silsesquioxanes. NHCs also catalyze a rearrangement of existing cages and a scrambling between two different cages. For this purpose either free isolable carbenes or their cryptoforms could be used. Polyhedral silsesquioxanes could be prepared from hydrolyzates of trifunctional silanes, silsesquioxane resins or existing silsesquioxane cages in process where these precursors are exposed to organocatalytic action of carbenes in organic solvent at appropriate temperature. Carbenes are excellently soluble in reaction media so they are active at a concentrations as low as 1 mol%.
COBISS.SI-ID: 5241626
In this chapter possibilities for tuning of surface properties of thickness insensitive spectrally selective paint coating is discussed. POSS nano-composites were used as low surface energy additives for rough TISS coatings, where considerable improvements of contact angles for water In same manner anti-wetting properties of coatings with smooth surfaces for use as protective lacquers for polymeric glazing were studied in relation to the concentration of POSS compound in prepared coatings.
COBISS.SI-ID: 5112858
This chapter consists of two parts. In the first one a brief historical overview of the development of solar paint coatings is given together with the basic principles that make paint coatings spectrally selective. Distinctive properties of Thickness Sensitive Spectrally Selective (TSSS) and Thickness Insensitive Spectrally Selective (TISS) are outlined and the useof the latter paint coatings as cool paints is proposed and demonstrated. Materials' aspects of the colored cool TISS paint coatings are given by the description of cool pigments, metallic and metallized flake pigments and polymeric resin binders which are used for the production of solar paint coatings. Second part contains information about the chemistries of the paintproduction showing how to achieve with the help of dispersant molecules uniform distribution of the finely ground pigment particles in the polymeric resin binder. Intentionally, we focused on organo (silicon) i.e. silane dispersants because they enable the stabilization of many different nanoparticle systems and also commercial pigments. Basics of the sol-gel chemistry of silanes are given and the preparation of polyhedral oligomeric silsesquioxane (POSS) molecules is described and the dispersive effect of thelatter on pigments demonstrated. The importance of the POSS molecules representing a new multifunctional nanocomposite materials is revealed by describing paints and lacquers with hydrophobic and oleophobic properties and the possibility to attain anti-soiling properties of cool paints is also discussed.
COBISS.SI-ID: 5198618
In this chapter possibilities for tuning of surface properties of thickness insensitive spectrally selective paint coating is discussed. POSS nano-composites were used as low surface energy additives for rough TISS coatings, where considerable improvements of contact angles for water In same manner anti-wetting properties of coatings with smooth surfaces for use as protective lacquers for polymeric glazing were studied in relation to the concentration of POSS compound in prepared coatings.
COBISS.SI-ID: 5112602
The influence of the addition of a mixture of POSS compounds substituted equally by 3-aminopropyl and isobutyl groups (AP4IB4 POSS) on sol-gel coatings prepared from (3-glycidoxypropyl)trimethoxysilane (GPTMS) was evaluated from the point of view of their anticorrosion properties. AP4IB4 POSS belong to a group of polyhedral oligomeric silsesquioxanes and their functionalisation with amino groups enables cross-linking with the epoxy groups of GPTMS. Additionally, GPTMS molecules react among themselves through hydrolysis and condensation processes of trimethoxysilane groups when catalysed by 0.1 M KF. The results of the Raman and IR measurements revealed that a molar ratio of GPTMS:H2O = 1:3 is more beneficial than a molar ratio of 1:1.5 for the preparation of sol-gel coatings. The anticorrosion properties of the mixed GPTMS/POSS coatings deposited on AA 2024 aluminium alloy were tested using potentiodynamic electrochemical measurements and a salt-spray chamber test. It was found that the mixed GPTMS/POSS coatings showed improved corrosion protective properties vs. either pure GPTMS or POSS coatings.
COBISS.SI-ID: 4764698