Synthesis and characterization of UV-curable ladder-like polysilsesquioxane (original) (raw)
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The present study explores the exploitation of ladder-like polysilsesquioxanes (PSQs) bearing reactive functional groups in conjunction with SiO2 nanoparticles (NPs) to produce UV-curable nanocomposite coatings with increased hydrophobicity and good thermal resistance. In detail, a medium degree regular ladder-like structured poly (methacryloxypropyl) silsesquioxane (LPMASQ) and silica NPs, either naked or functionalized with a methacrylsilane (SiO2@TMMS), were blended and then irradiated in the form of a film. Material characterization evidenced significant modifications of the structural organization of the LPMASQ backbone and, in particular, a rearrangement of the silsesquioxane chains at the interface upon introduction of the functionalized silica NPs. This leads to remarkable thermal resistance and enhanced hydrophobic features in the final nanocomposite. The results suggest that the adopted strategy, in comparison with mostly difficult and expensive surface modification and st...
Journal of Polymer Science Part A: Polymer Chemistry, 2004
Two ladder-like polysilsesquioxanes (LPS) containing side-chain maleimide groups have been synthesized successfully by reacting N-(4-hydroxyphenyl)maleimide (HPM) with LPS containing 100 mol % of chloropropyl groups (Ladder A) and 50 mol % of each methyl and chloropropyl group (Ladder B). HPM was synthesized by reacting maleic anhydride with 4-aminophenol, and the resulting amic acid was imidized using p-toluenesulfonic acid as a catalyst (Scheme 1). The LPSs were characterized by Fourier transform infrared (FTIR), 1 H nuclear magnetic resonance (NMR), proton-decoupled 13 C NMR, 29 Si NMR, wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Characterization indicated that these polymers had ordered ladder-like structures with possible defects. These polymers were soluble in common solvents at ambient temperature, which suggested that they were not crosslinked. Both the polymers and the HPM were cured, and their kinetics were followed by dynamic DSC. The Ozawa and Kissinger methods were used to calculate activation energies for curing. Curing increased the temperature at which both 5% weight loss and maximum rate of weight loss were observed.
Chemistry of Materials, 2008
A high-molecular-weight and well-defined ladder polyphenylsilsesquioxane (Ph-LPSQ) was synthesized via a new three-step approach: monomer self-organization in solution, lyophilization, and surface-confined polycondensation. A ladder superstructure, which served as a template to direct the polycondensation, was self-assembled from the 1,3-diphenyl-tetrahydroxy-disiloxane monomer (M) in acetonitrile solution. Following that, it was lyophilized to form a thin layer on the inner surface of a flask. Subsequently, polycondensation of the ordered monomeric thin layer was performed under a triethylamine (TEA) atmosphere. This strategy increased the ladder regularity of the Ph-LPSQ by preventing common complications faced in solution polycondensation of silanol-containing monomers, such as cyclization and gelation side reactions. 29 Si NMR analysis showed a very narrow peak (peak width at half-height, w 1/2) 2.5 ppm) at δ)-78.5 (corresponding to a Ph-SiO 3/2 unit), indicating a high degree of regularity of the polymer structure.
New polysilsesquioxane materials of ladder-like structure
Journal of Molecular Structure, 2009
Alkoxy derivatives of linear oligomethylsiloxanes were applied as substrates for preparation of novel type, ladder-like polymeric silsesquioxane-siloxane materials. A systematic study of the effect of diverging the structure of a polysiloxane chain (distribution of alkoxysilyl groups along the polymer chain) on the properties of silsesquioxane materials obtained by condensation of ethoxy groups, has been undertaken. A series of polysiloxane materials cross-linked with-SiOSi-bonds, forming ladder-like linkages between main siloxane chains was prepared. There were used siloxanes of a regular structure with formula [M(D 2 D OR) 10 D 2 M] and [M(D 2 D OR 2) 10 D 2 M] ] as well as siloxane oligomers of random distribution of MeSi-OR (D OR) units along the main siloxane chain [MD (1Àx) D OR x M (x = 0.3, 0.5, 1.0)]. Alkoxy-functionalized oligosiloxane precursors were cross-linked under hydrolytic condensation conditions catalyzed by HCl/ NH 4 OH system or nucleophilic catalysts (TBAF and TBAH). The relationship between the structure of siloxane chain (the amount of Si-OR units and their distribution along the polymer backbone) and the properties of obtained preceramic materials was studied with FTIR (as a main method) and NMR, XRD, DTA. The surface area and pores distributions of the studied samples were measured using nitrogen adsorption methods (BET).
Journal of Sol-Gel Science and Technology, 2023
Ladder-like polysilsesquioxanes (LPSQs) are characterized by a double-stranded siloxane backbone, whose chemical and structural properties depend on both the synthesis parameters and the nature of the organic side-chains. In the case of ladderlike (methacryloxypropyl) polysilsesquioxanes (LPMASQ), polymer matrices can be produced by exploiting the presence of photocurable methacrylate groups. Consequently, they can be used to prepare functional nanocomposites (NCs), either by blending with organic polymers such as polybutadiene or exploiting the inorganic fillers' dispersion. Since the properties of LPMASQ-based NCs are strongly related to their structure, the structural changes of polymerized LPMASQ were investigated upon addition of low loadings of TiO 2 nanoparticles (up to 3 wt%) by solid state nuclear magnetic resonance and X-ray diffraction. The filler addition leads to the reduction of the polymerization capacity of the LPMASQ organic sidechains. Moreover, a different organization of ladder chains has been highlighted, ascribable to the increase in fully condensed linear ladder units at the expenses of folded chains and defective structures. The methodological approach here adopted can be extended to other composite systems and may help to describe the properties at the filler-matrix interface, offering valuable hints for a better design of these materials.
Preparation and characterization of aryl-substituted polysilsesquioxanes
1998
Polymerizations of aryltrialkoxysilanes generally afford soluble oligomeric or polymeric arylsubstituted silsesquioxanes. This is in spite of being based on trifunctional precursors capable of forming highly crosslinked and insoluble network polymers. In this study, soluble phenyl, benzyl, and phenethyl-substituted silsesquioxane oligomers and polymers were prepared by hydrolyzing their respective triethoxysilyl precursor with water or aqueous acid. Additional samples of the polymers were prepared by heating the materials at 100 "C or 200 "C under vacuum in order to drive the condensation chemistry. One sample of polybenzylsilsesquioxane was heated at 200 "C with catalytic NaOH. The resulting materials were characterized using solution 'H, I3C, and 29Si NMR spectroscopy, gel permeation chromatography, and differential scanning calorimetry. Of particular interest was the effect of the aryl substituent, and processing conditions on the molecular weight and glass transition temperatures of the polysilsesquioxanes. DISCLAIMER This report was prepared as an account of work sponsored by an agency of the
Polymer, 2010
Linear polysiloxanes having different amounts of polyhedral oligomeric silsequioxane (POSS) side groups were prepared from the hydrosilylation reaction of poly(ethylhydrosiloxane) with different amount of POSS and 1-octene using platinum(0)-divinyl tetramethyldisiloxane as a catayst. 1-Octene and platinum(0)-divinyl tetramethyldisiloxane were found to be very important for the preparation of the linear polymer without any cross-linked structures. The linear polysiloxanes with POSS side groups are soluble in various organic solvents. When the content of POSS-containing monomeric unit is larger than 10 mol%, free standing films can be prepared from a routine solution casting method, although this polysiloxane is not cross-linked.
Journal of materials chemistry A, 2019
Polysilsesquioxanes (RSiO 1.5) n are organic-inorganic hybrid materials that have an array of properties and synergistic features and are considered to be robust materials in the family of siliceous compounds. Their careful tailoring at the nano and micro scale has been investigated worldwide, as their architecture dictates the final properties. Non-porous nano and micro organosilica hybrid particles that have been designed using careful optimization of the effective parameters, for example the amount of monomer, reaction time, concentration of the catalyst, temperature, and stirring speed, are detailed in this article. Different sized particles comprising bridged, ladder-like, cage shape and other geometries modified by organically functionalized reagents are discussed. This review presents a summary of the recently reported nano and micro-sized polysilsesquioxanes with different functional materials and their geometries, describing their preparation methods and further applications in science and technology, especially those reported in the last half decade.