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Contents:
  1. About this book
  2. Silicon dioxide - Wikipedia
  3. LIQUID CRYSTAL POLYMERS AND DENDRITIC LIQUID CRYSTALS

The volatiles were removed using a rotary evaporator and hexane 20 mL was added. Pyridine 4. The solution was stirred at RT for 2 hrs and transferred to a separation funnel. The water layer was washed with hexane three times. All hexane washings were combined and evaporated to give a viscous oil. The mixture was re-dissolved in hexane 20 mL and washed three times with water.

Sodium sulfate was used to dry the moisture in hexanes solution and was filtered out. The hexane phase yielded 0. The hexane phase yielded 1. The formulations were cast by wire-wound lab rods of wire size 12 Paul N. Dardner Company onto glass slides, and then covered immediately and pressed tightly together with a second glass slide. All the formulations firmly adhered to glass slides. Heptane 0.

A transparent and robust material was obtained. HBP and linear components were mixed. In cases where polysilphenylene siloxane linear polymer was used, a few drops of THF were added to hexane to achieve solubility. The scratch hardness of cured materials was determined using a Paul-Gardner Scratch Tester Model Measurements were made on Qioptiq CMG AR cover glass substrates where transmission cut off at nm, and are summarized in Table 2 below. Measurements were made on quartz coupons where transmission cut-off at nm.

For the PDMS control and for adhesive formulations of the present invention with no phenyl content, the transmission cut-off was comparable with that of quartz, but as phenyl content increased, cut-off occurred at higher wavelengths see FIGS. Transmittance from nm to nm was measured before and after exposure. The formulation shows no discernible change in transmittance before and after UV exposure across the entire wavelength range see FIG. PDMS control samples were damaged by proton and electron radiation, but the following are examples of formulations that were undamaged by proton and electron radiation.

Transmittance from to nm was measured before and after exposure. These results are shown in Table 3 below. The refractive index measurements made for various hyperbranched polymers are summarized in Table 4 below. For the polysiloxane series, RI increases from 1. The homogenous solution was kept at RT and observed at regular intervals to determine if cure had taken place. Formulation mixtures were prepared in the presence of catalyst, but in the absence of solvent, in order to determine how long they could stand at RT before cure occurred.

It was found that shelf life could be controlled by varying the catalyst. The masses of the samples before and after vacuum exposure were recorded, and percent mass loss was calculated using the mass of material lost and the initial sample mass. Duplicate experiments were carried out for each formulation, and the mean percent mass loss for a given formulation was quoted in Table 5 below.

The solution was stirred for 10 mins under nitrogen. Octasilane POSS 2. Although the invention has been described with reference to its preferred embodiments, those of ordinary skill in the art may, upon reading and understanding this disclosure, appreciate changes and modifications which may be made which do not depart from the scope and spirit of the invention as described above or claimed hereafter. Effective date : Year of fee payment : 4.

Shape and Functional Elements of the Bulk Silicon Microtechnique A Manual of Wet Etched Silicon Stru

The HBP Free-POSS compounds of Formula I are superior to prior HB polymers and linear polymers in space and electronic applications because they have better resistance to electrons, protons and atomic oxygen, have superior out-gassing performance, and are transparent. They are used as coatings, films, adhesives, sealants and elastomers. Field of the Invention This invention generally relates to hyperbranched polymers containing POSS as a branching monomer or backbone monomer component.

Description of Related Art The hyperbranched polymers described in U. SEC means size exclusion chromatography THF means tetrahydrofuran General Discussion The use of HB POSS phenyl-containing polymers of Formula I gives an unexpected combination of proton resistance from POSS and phenyls , electron resistance particularly at low wavelengths of importance in multijunction photovoltaics , atomic oxygen resistance from POSS , transparency from nano-POSS domains , ability to crosslink to form cured coatings, adhesives, sealants or films , low viscosity from HB architecture , low glass transition temperature from FIB architecture , good adhesion and no cracking over wide temperature range from hyperbranched and POSS architecture , and low out-gassing owing to hyperbranched rather than linear architecture, and no tendency to generate low mass volatiles.

What is claimed is: 1. B y is a POSS entity including closed-caged T8, T10, or T12 or an open-cage T8, T10, or T12, or another non-POSS monomer, having y number of B-type functional groups that are chosen to react with the A-type functional groups and are selected from vinyl, hydridosilyl Si—H , alkoxysilyl or hydroxyl, with all functionality being the same for a given monomer;. The compound of claim 1 wherein x is an integer from 2 to The compound of claim 1 wherein y is 3 to The compound of claim 1 wherein the POSS is substituted with one or more of carbosiloxane, siloxane, ether or alkyl groups.

The compound of claim 1 where B is a difunctional, trifunctional or tetrafunctional organosil icon compound. The compound of claim 1 wherein R is methyl or phenyl. A method for using a compound of Formula I as defined in claim 1 comprising reacting the polymer with curable end-groups having SiOR or SiOH, where R is defined as in claim 1 , and curing the polymer by condensation reaction, with or without a catalyst.

The method of claim 9 wherein the functionalized polymer is tested for transmission of light or UV radiation after coating a glass plate or forming a film on a glass plate with functionalized polymer, or tested by forming an adhesive having the functionalized polymer in a layer sandwiched between at least 2 glass plates, or tested after proton and electron radiation of the functionalized polymer sandwiched between at least 2 glass plates, or tested for its elastomeric properties having the functionalized polymer, or tested for refractive index of transmission through the functionalized polymer, or tested under vacuum for mass loss of out-gassing of the functionalized polymer.

The method of claim 11 wherein the crosslinked polymer is tested for transmission of light or UV radiation after coating a glass plate or forming a film on a glass plate with the crosslinked polymer, or tested by forming an, adhesive having the crosslinked polymer in a layer sandwiched between at least 2 glass plates, or tested after proton and electron radiation of the crosslinked polymer sandwiched between at least 2 glass plates, or tested for its elastomeric properties having the crosslinked polymer.

A process for preparing a hyperbranched polymer comprising reacting: a difunctional or polyfunctional monomer A x a POSS entity including closed-caged T8, T10, or T12 or an open-cage T8, T10, or T12 or another non-POSS monomer, having x number of A-type functional groups, where the A-type functional groups are hydridosilyl Si—H , vinyl, hydroxyl, chlorosilyl, or alkoxysilyl, with all functionality being the same for a given monomer, and x is an integer of 2 or more with.

About this book

This small shift indicates that the polysilyne 2 unit cell increased due to Li adsorption in the network Fig. After Li de-insertion at 3. In the case of 4 , the sharp peaks observed in the XRD pattern of the starting sample disappear after Li insertion and do not reappear following de-insertion Fig. This result indicates that the Si—Si bonds of 4 were attacked by the Li ions and then collapsed, which agrees well with the reversibility behaviour observed in the electrochemical tests Fig.

Thus, for polysilyne 2 , the Si—Si network was mainly retained during electrochemical cycling, whereas for polysilane 4 , the Si—Si chain structure was broken during Li insertion.


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It was thus concluded that the redox centres in the Si—Si bonds of the polysilynes were partially replaced with Si—Li bonds after Li insertion. It should be noted that the three-dimensional networks of polysilynes 1 and 2 are important in the electrochemical performance, the Si—Li bonds in reduced polysilyne 1 and 2 can be changed into Si—Si bonds.

On the other hand, the chain structures of polysilanes 3 and 4 collapsed after formation of the Si—Li bonds. As a result, the Si—Si bonds in 3 and 4 could not be reformed. Therefore, the chain structures of these polysilanes could not be reconstructed because of the very long distance between the Si atoms. In addition, the cycle stabilities of polysilynes 1 and 2 were nearly the same, which indicates that the organic capping moieties did not affect their electrochemical stabilities.


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  4. And also, we previously reported that Si—phenyl bond of phenyl capped lithiosilane was stable, in which the two lithium atoms are associated with the two phenyl groups Based on all of the present results and previous report, it was thus concluded that the stabilities of polysilynes 1 and 2 were enhanced due to the introduction of the capping groups. As mentioned above, it was demonstrated that Li ions were electrochemically inserted into the polysilynes.

    After milling, the Li fragments completely disappeared, and the yellow powdered polysilyne changed into a black powder. To investigate the changes in the electronic band structure, solid-state diffuse reflectance UV-vis spectra were recorded. After milling 2 with 0.

    In addition, in the XRD patterns shown in Fig.


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    7. These results agree well with those obtained from the electrochemical Li insertion reaction analysis, for which values of 0. In other words, the quantity of Li that could be inserted increased when the polysilyne included an organic substituent that expanded the cage size. Furthermore, these results indicate the formation of new electron band levels following lithiation of the polysilynes. This property renders the polysilynes suitable for use as anode materials, because their conductivities increase during the Li insertion process. Diffuse reflectance UV-vis spectra of a poly methylsilyne 1 and b poly phenylsilyne 2.

      Corresponding photos for each sample are also shown insets. Colour change with lithiation was observed.

      Silicon dioxide - Wikipedia

      XRD patterns of c poly methylsilyne 1 and d poly phenylsilyne 2. Finally, to assess the low-temperature performances of these new anode materials, cells were prepared in which i commercial graphite Fig. These cells were subjected to deep Li insertion to 0. The situation was very different with polysilyne 1. Due to the polymeric silicon structure of polysilyne 1 , the electrolyte wetted both the outside and inside surfaces of the anode, which had a highly lipophilic character. Thus, it is thought that the mobility of the Li ions in the polysilyne anode was higher than that in the graphite anode.

      In addition, the potential for Li insertion is very close to that of Li metal formation for the graphite anode, and therefore, Li compounds readily formed on the electrode surface. The stability of the anode material surface is known to be important for battery cycling and safety. Thus, the present results suggest that polysilyne is a suitable anode material for LIBs operated at low temperatures or high rates due to its stability.

      Initial surface of anodes based on a graphite and d poly methylsilyne 1.

      LIQUID CRYSTAL POLYMERS AND DENDRITIC LIQUID CRYSTALS

      Polysilynes were proposed as anode materials that can successfully address the safety concerns associated with the anode materials currently used in LIBs. The results obtained for the polysilynes may lead to the development of new types of anode materials containing Si frameworks that can safely be applied in the next generation of EV batteries.

      Future studies are planned to further develop the design of the Si framework and to optimize the organic substituents in order to increase their performances. The excess sodium was quenched with MeI, and the resulting mixture was washed with water, hexane and toluene to remove salts and excess monomers.