A NOVEL SUPRAMOLECULAR CLATHRATE OF RODLIKE p-BUTOXYBENZYLIDENE-p′-DODECOXYANILINE TRAPPED WITHIN POLYORGANOSILOXANE PORE

A novel supramolecular polysiloxane clathrate, POS/C, has been preparedby in-situ encapsulating rodlike p-butoxybenzylidene-p ' - dodecoxyaniline (BBDA ) , one kindof Schiff base liquid crystal molecule, within the pore of polyorganosiloxane (POS) whichis prepared by hydrosilylation coupling reaction of polyvinylsilsesquioxane (Vi- T ) withtetramethyldisiloxane (H-MM). Investigation by polarized light microscopy (PLM), differ-ential scanning calorimetry (DSC), infrared spectroscopy (IR), atomic force microscopy(AFM) and molecular simulation gives a preliminary support to the existence of the titlesupramolecular clathrate.

SYNTHESIS AND CHARACTERIZATION OF NOVEL REACTIVE POLYORGANOSILOXANE CONTAINING NITRO GROUPS

A novel reactive polyorganosiloxane containing nitro groups was first prepared by acid-catalyzed equilibration polymerization. The monomer, 3-(4-nitrophenoxy)propylmethyldichlorosilane (NPPMS), was synthesized by hydrosilylation reaction with dicyciopentadienylplatinum(II) chloride (Cp2PtCl2) catalyst in high yield. The synthesized polynitroorganosiloxane, which has potential application as a precursor for synthesizing advanced functional polymers, was characterized by FTIR, H-1-NMR, C-13-NMR, Si-29-NMR, vapor pressure osmometry (VPO) and gel permeation chromatography(GPC).

SYNTHESIS AND CHARACTERIZATION OF A NOVEL ALCOHOL-SOLUBLE POLYORGANOSILOXANE CONTAINING AMINO SIDE GROUPS

A novel alcohol-soluble polyorganosiroxane containing amino side groups, poly[3-(4-aminophenoxy)-aminophenoxy) propylmethylsiloxane] (2), was first prepared by the reduction of nitro groups on 4-nitrophenoxypropyl side chains of poly[3-(4-nitrophenoxy)propylmethylsiloxane] (1). The reaction proceeded easily with nearly 100% conversion. The synthesized alcohol-soluble polymer 2, which has potential application as a precursor for preparing advanced functional polymers, was characterized by FTIR, H-1-NMR, C-13-NMR, Si-29-NMR, VPO and GPC, respectively.

STRUCTURAL INVESTIGATION OF A NEW POLYORGANOSILOXANE CONTAINING NANOTUBULAR CAVITIES USING ORGANIC FLUORESCENT PROBES

Fluorescent molecules - p-dimethylaminobenzonitrile (DMABN) and trans-stilbene (TSB ) - were used as probes to investigate the inner structure of the nanotubular cavities contained in a new polyorganosiloxane (POS) which was prepared by the hydrosilylation coupling reaction of cis-isotactic ladderlike polyvinylsilsesquioxane (Vi-T) with 1,1,3,3-tetramethyldisiloxane (H-MM) as coupling agent in the presence of catalyst dicyclopentadienyldichloroplatinum (Cp2PtCl2). The results from FTIR spectra and fluorescence spectra in combination with molecular simulation reveal that the cross-section of the nanotubular cavity is nearly rectangular in shape, and is about 0.62 nm in width and about 0.38 nm in height. This work gains in-depth knowledge into the inner structure of the nanotubular cavities of POS and furthermore provides a guide to the selection of proper guest molecules in constructing functional supramolecular clathrate based upon POS.

Effect of Surface-modified Clay on the Thermal Stability and Insulation of Polyorganosiloxane Foam

Polyorganosiloxane foam（SIF） nanocomposites reinforced with vinyl-modified montmorillonite（Mt-V） and hydroxyl-modified montmorillonite（Mt-OH） were prepared through cross-linking and foaming. The effects of modified Mt on the density, pore morphology, and thermal and compressive properties of the prepared polyorganosiloxane foams were investigated. The structure of the polyorganosiloxane foam was studied by solid-state nuclear magnetic resonance analysis. Clay dispersion in polyorganosiloxane nanocomposites and pore morphology were in- vestigated by X-ray diffraction and scanning electron microscopy analyses. The thermal and mechanical properties of the prepared materials were also evaluated by differential scanning calorimeter, thermogravimetric analysis, thermal diffusivity and compressive strength. The results show that Mt-V exhibits improved cell structure, thermal insulation, and crush compressive than Mr-OH. The addition of modified Mt reduces the density, cell size, and thermal conduc- tivity but increases the high-temperature resistance and compressive strength of the nanocomposite. The amount of the residues of SIF/Mt-OH nanocomposites increases by 9% compared with that of the pure SIF. Furthermore, SIF/Mt-V decreases the thermal conductivity to 0.014 W/mK and the cell size to 98μm. Those properties give the material potential application value in the aerospace and construction industry.

Roll-to-roll fabrication of large-scale polyorgansiloxane thin film with high flexibility and ultra-efficient atomic oxygen resistance

One of the most widely used and well-established atomic oxygen(AO)protection solutions for low Earth orbit(LEO)satellites is the deposition of protective coatings on polymeric materials.However,manufacturing extensive expanses of these coating materials with good transparency,flexibility,smoothness,ultra-thinness,and exceptional AO resistance remains a critical issue.Herein,we successfully deposited a 400 nm thick polyorgansiloxane(SiO_(x)C_(y)H_(z))coating with high optical transparency and uniform good adherence on to a 1.2 m wide polyimide surface,by optimizing the distribution of hexamethyldisiloxane and oxygen as precursors in the roll-to-roll compatible plasmaenhanced chemical vapor deposition process.After AO irradiation with the fluence of 7.9×10^(20)atoms·cm^(–2),the erosion yield of the SiO_(x)C_(y)H_(z)-coated Kapton was less than 2.30×10^(–26)cm^3·atom^(–1),which was less than 0.77%of that of the Kapton.It indicates that the SiO_(x)C_(y)H_(z)coating can well prevent the erosion of Kapton by AO.In addition,it was also clarified that a SiO_(2) passivation layer was formed on the surface of the SiO_(x)C_(y)H_(z)coating during AO irradiation,which exhibited a‘self-reinforcing’defense mechanism.The entire preparation process of the SiO_(x)C_(y)H_(z)coating was highly efficient and low-cost,and it has shown great potential for applications in LEO.

THE HYDROSILATION REACTION OF LADDERLIKE POLYALLYLSILSESQUIOXANE(ALLYL-T)AND POLYHYDROSILSESQUIOXANE(H-T)

The one plus one (1 + 1) mode of hydrosilation reaction of ladderlike cis-isotatic polyallylsilsesquioxane (Allyl-T) and polyhydrosilsesquioxane (H-T) using dicyclopentadienylplatinumdichloride (Cp2PtCl2) as the catalyst leads to the formation of a new polyorganosiloxane (POS). The presence of nanoscale tubular structure in the product POS was preliminarily proved by IR, H-1-NMR, differential scanning calorimetry (DSC), X-ray diffraction (XRD), gel permeation chromatography (GPC), atomic force microscopy (AFM) and molecular simulation.

THE HYDROSILYLATION REACTION OF LADDERLIKE POLYVINYLSILSESQUIOXANE WITH 1, 1, 3, 3-TETRAMETHYLDISILOXANE

The hydrosilylation reaction of ladderlike polyvinylsilsesquioxane (Vi-T) with 1, 1, 3, 3-tetramethyldisiloxane (H-MM) catalyzed by dicyclopentadienyl-dichloroplatinium (Cp2PtCl2) was carried out well in tetrahydrofuran (THF) to produce a soluble white solid. This product was characterized by IR, H-1-NMR, C-13-NMR, Si-29-NMR, DSC, X-ray diffraction method, gel permeation chromatography (GPC), vapour pressure osmometry (VPO), atomic force microscopy (AFM) and molecular simulation. These results prove that the product contains nanoscale tubular structure.

Progress in the Supramolecular Architecture-directed Synthesis of Perfect Ladder Polysiloxanes

1 Introduction Ladder polysiloxanes (LPSs) including organo-bridged ladder polyorganosiloxanes (R-OLPSs, R is side group) and ladder polyorganosilsesquioxanes (R-LPSQs) have intrigued polymer chemists for about 50 years due to their excellent resistance to all kinds of degradations. However, their synthesis has been a great challenge to polymer chemists. Here, we describe a new approach based on supramolecular concerted interactions as follows.2 Results2.1 Synthesis of Perfect R-OLPSsA series of real ...