A Versatile Equilibrium Method for the Synthesis of High-Strength, Ladder-like Polyphenylsilsesquioxanes with Finely Tunable Molecular Parameters

A versatile equilibrium method for synthesizing ladder-like polyphenylsilsesquioxanes (L-PPSQs) with various molecular weights (from 4 to 500 kDa) in liquid ammonia was developed. The effect of diverse parameters, such as temperature, monomer concentration, reaction time, addition or removal of water from the reaction medium, on the polycondensation process was determined. The molecular weight characteristics and structure of the L-PPSQ elements obtained were determined by GPC, 1H, 29Si NMR, IR spectroscopy, viscometry, and PXRD methods. The physicochemical properties of L-PPSQs were determined by TGA and mechanical analyses.

Effect of Electrolytic Manganese Residue in Fly Ash-Based Cementitious Material: Hydration Behavior and Microstructure

Electrolytic manganese residue (EMR) is a solid waste with a main mineralogical composition of gypsum. It is generated in the production of metal manganese by the electrolysis process. In this research, EMR, fly ash, and clinker were blended to make fly ash-based cementitious material (FAC) to investigate the effect of EMR on strength properties, hydration behavior, microstructure, and environmental performance of FAC. XRD, TG, and SEM studied the hydration behavior of FAC. The pore structure and [SiO4] polymerization degree were characterized by MIP and 29Si NMR, respectively. The experimental results indicate that FAC shows excellent mechanical properties when the EMR dosage is 10%. Moderate content of sulfate provided by EMR can promote hydration reaction of FAC, and it shows a denser pore structure and higher [SiO4] polymerization degree in this case. Heavy metal ions derived from EMR can be adsorbed in the hydration products of FAC to obtain better environmental properties. This paper presents an AFt covering model for the case of excessive EMR in FAC, and it importantly provides theoretical support for the recycling of EMR in cementitious materials.

Synthetic Approaches to the Incorporation of Gallium and Germanium into Inorganic Polymer Structures

<p>New sol-gel and solid-state synthesis methods and combinations of these were developed for the preparation of several new inorganic polymers related to aluminosilicate inorganic polymers, attempting to substitute gallium and germanium for aluminium and silicon. Gallium could successfully substitute for aluminium, but germanium could not be substituted for silicon by these methods. Gallium silicate and gallium aluminosilicate inorganic polymers were synthesised from mixtures of KGaO2, KAlO2, KOH solutions with finely divided SiO2 (silica fume) using a combination of sol-gel and solid-state techniques. The products of these reactions were studied by X-ray powder diffraction (XRD), solid-state 27Al, 29Si, 71Ga and 39K nuclear magnetic resonance with magic-angle spinning (MAS NMR) and scanning electron microscopy (SEM). For the synthesis of these mixed gallium-aluminium silicate inorganic polymers, the optimal SiO2:(Ga2O3+Al2O3) ratio was found to be 7 and the Ga:Al ratio could range from 100% Ga to 100% Al, with all intermediate ratios yielding inorganic polymers. The products showed all the characteristics of a true inorganic polymer, being X-ray amorphous and containing gallium and/or aluminium in tetrahedral coordination states. 29Si MAS NMR showed the occurrence of Si(3Ga) and Si(2Ga) sites when gallium was present, and Si(3Al) and Si(2Al) sites when aluminium was present. Unreacted silica was also detected in these compounds by 29Si NMR and spherical silica particles were observed by SEM. Heat treatment of gallium silicate, gallium aluminosilicate and aluminosilicate inorganic polymers synthesised by variations of the sol-gel method was monitored by thermal analysis methods (DSC-TGA) which revealed a water loss at 75 [degrees]C and 160 [degrees]C followed by a phase transition at 950 [degrees]C. At this temperature the inorganic polymers crystallised to KGaSi2O6 and KAlSi2O6. The thermal behaviour of these samples was found to be different at 1200 [degrees]C; the high-temperature products derived from the gallium silicate inorganic polymers remained as crystalline KGaSi2O6 and retained their shape, while gallium aluminosilicate and aluminosilicate inorganic polymers melted and slumped, losing their shape and becoming X-ray amorphous. Attempts to substitute germanium for silicon in the inorganic polymer structure were unsuccessful. A sol-gel approach using GeO2 produced crystalline K6Ga6(GeO4)6(H2O)7. In an alternative solid-state approach, potassium germanate was synthesised and subsequently reacted with KGaO2 in a solidstate reaction to form partially amorphous hydraulic precursors; however, these did not set on the addition of water. A solid-state reaction of potassium germanate with KGa5O8 formed a partially amorphous precursor powder that set with the addition of water. However, the cured product was not amorphous, but proved to be crystalline K6Ga6(GeO4)6(H2O)7. In another approach, a sol-gel reaction of NaAlO2 solution and GeO2 with KOH solution set to an X-ray amorphous but brittle product. 27Al MAS NMR showed this to contain aluminium in both tetrahedral and octahedral coordination states. When KAlO2 was used instead of NaAlO2, the products were crystalline. The study of the structure of these germanium compounds is hindered by the inaccessibility of the germanium nuclide to MAS NMR. Nevertheless, the ability to synthesise a new category of materials by these new methods opens up the possibility of their potential applications as fluorescent materials and as components of optoelectronic devices.</p>

Synthetic Approaches to the Incorporation of Gallium and Germanium into Inorganic Polymer Structures

<p>New sol-gel and solid-state synthesis methods and combinations of these were developed for the preparation of several new inorganic polymers related to aluminosilicate inorganic polymers, attempting to substitute gallium and germanium for aluminium and silicon. Gallium could successfully substitute for aluminium, but germanium could not be substituted for silicon by these methods. Gallium silicate and gallium aluminosilicate inorganic polymers were synthesised from mixtures of KGaO2, KAlO2, KOH solutions with finely divided SiO2 (silica fume) using a combination of sol-gel and solid-state techniques. The products of these reactions were studied by X-ray powder diffraction (XRD), solid-state 27Al, 29Si, 71Ga and 39K nuclear magnetic resonance with magic-angle spinning (MAS NMR) and scanning electron microscopy (SEM). For the synthesis of these mixed gallium-aluminium silicate inorganic polymers, the optimal SiO2:(Ga2O3+Al2O3) ratio was found to be 7 and the Ga:Al ratio could range from 100% Ga to 100% Al, with all intermediate ratios yielding inorganic polymers. The products showed all the characteristics of a true inorganic polymer, being X-ray amorphous and containing gallium and/or aluminium in tetrahedral coordination states. 29Si MAS NMR showed the occurrence of Si(3Ga) and Si(2Ga) sites when gallium was present, and Si(3Al) and Si(2Al) sites when aluminium was present. Unreacted silica was also detected in these compounds by 29Si NMR and spherical silica particles were observed by SEM. Heat treatment of gallium silicate, gallium aluminosilicate and aluminosilicate inorganic polymers synthesised by variations of the sol-gel method was monitored by thermal analysis methods (DSC-TGA) which revealed a water loss at 75 [degrees]C and 160 [degrees]C followed by a phase transition at 950 [degrees]C. At this temperature the inorganic polymers crystallised to KGaSi2O6 and KAlSi2O6. The thermal behaviour of these samples was found to be different at 1200 [degrees]C; the high-temperature products derived from the gallium silicate inorganic polymers remained as crystalline KGaSi2O6 and retained their shape, while gallium aluminosilicate and aluminosilicate inorganic polymers melted and slumped, losing their shape and becoming X-ray amorphous. Attempts to substitute germanium for silicon in the inorganic polymer structure were unsuccessful. A sol-gel approach using GeO2 produced crystalline K6Ga6(GeO4)6(H2O)7. In an alternative solid-state approach, potassium germanate was synthesised and subsequently reacted with KGaO2 in a solidstate reaction to form partially amorphous hydraulic precursors; however, these did not set on the addition of water. A solid-state reaction of potassium germanate with KGa5O8 formed a partially amorphous precursor powder that set with the addition of water. However, the cured product was not amorphous, but proved to be crystalline K6Ga6(GeO4)6(H2O)7. In another approach, a sol-gel reaction of NaAlO2 solution and GeO2 with KOH solution set to an X-ray amorphous but brittle product. 27Al MAS NMR showed this to contain aluminium in both tetrahedral and octahedral coordination states. When KAlO2 was used instead of NaAlO2, the products were crystalline. The study of the structure of these germanium compounds is hindered by the inaccessibility of the germanium nuclide to MAS NMR. Nevertheless, the ability to synthesise a new category of materials by these new methods opens up the possibility of their potential applications as fluorescent materials and as components of optoelectronic devices.</p>

Solid State NMR Analysis for Hide Powder Tanned by Aluminum, Silicon and Phosphorus Tanning Agents before and after Hydrothermal Denaturation

In order to investigate the change of chemical bonds between tanning agents and collagen molecules directly, hide powder tanned by aluminum, silicon and phosphorus tanning agents were prepared. The chemical shifts of Al, Si and P in tanned hide powder were analyzed by solid-state 27Al NMR, 29Si NMR and 31P NMR. The results showed that, the chemical shift of Al in aluminum tanned hide powder which interacted with collagen molecules through coordination bond could be regarded as unchanging after hydrothermal denaturation (only slightly moved to high field area). The chemical shift of Si in silicon tanned hide powder which interacted with collagen molecules through hydrogen bond did not change after hydrothermal denaturation. The chemical shift of P in phosphorus tanned hide powder, which interacted with collagen molecules through covalent bond, was obviously shifted to the high field area after hydrothermal denaturation.

Novel Silsesquioxane-Derived Boronate Esters—Synthesis and Thermal Properties

The functionalization of mono- and octahydrospherosilicate with vinylboranes and allylboranes via hydrosilylation reaction in the presence of a Karstedt’s platinum (0) catalyst is presented. This is the catalytic route to obtain a new class of silsesquioxanes containing boron atoms in their structure in high yields (>90%) and with satisfactory selectivity. The obtained compounds were fully characterized by spectroscopic (1H, 13C, 29Si NMR) and spectrometric methods (MALDI-TOF-MS), as well as thermal analysis (TGA). The obtained compounds were subjected to thermal tests, characterizing the processes of melting, thermal evaporation, sublimation and thermal decomposition.