Polymers Containing Silicon

The thermal and thermo-oxidative degradation of dimethyl siloxane-phenol-phthalein terephthalate block copolymers has also been studied. In inert atmosphere cross-linking occurred in the polyester blocks and changes in the infrared spectrum suggested the invoivement of the Fries rearrangement. In air, degradation was preferentially in the siloxane block.  

All the papers reported here relate to polymers in which carbaborane units had been incorporated into the main chain. These included polyamides, polyesters, and polysiloxanes. The polyamides possessed structures (7)—(9). 

ADMET polymerization has been used to integrate silicon into linear and network hydrocarbon polymers in an attempt to produce novel materials with enhanced thermal and mechanical stability. While ADMET has been used to produce copolymeric architectures unattainable through conventional methods, application of this polymerization to synthesis is feasible only if the silicon-based functionality does not inhibit metathesis. This research, initiated in the early 1990s by Wagener and colleagues, has shown that the silane and siloxane 

The ability of the complementary Py-GC-MS technique to differentiate between linear and branched polysiloxanes has been investigated. Erzin and co-workers [56] investigated the ability of Py-GC-MS to detect trace levels of silicone polymer in recycled paper, and to differentiate between linear and branched polysiloxanes. The mass spectrometer had a mass range of 100-700 m/z and was operated by single ion monitoring and by selected ion data collection to enhance resolution and detection. A pyrolysis temperature of 750 °C was used. Silicone polymer scraped from the backing sheet was used for calibration. Thermal desorption GC-MS at 225 °C was used for the analysis of volatile components. It was concluded that concentrations of parts per million, and possibly as low as parts per billion could be measured. 

Fujimoto and co-workers [40] studied the pyrolysis products of polysiloxane including their stereo and structural isomers. Separation was achieved by gas chromatography on a fused silica capillary column. Mass fragmentation data was obtained on pyrolysis products formed at 600 °C. 

Chu and co-workers [41] carried out pyrolysis of the refractory polymer polyborosilazane under nitrogen at temperatures between 1250 and 1800 °C. The boron content of the pyrolysis product increased with increased thermal exposure 

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SYNTHETIC METHODS SILICON-CONTAINING POLYMERS, FUNCTIONALIZED POLYOLEFINS, AND TELECHELICS... 

Polycarbosilanes are an interesting class of polymers from a materials standpoint however, they do not occur naturally. A variety of synthetic methods can be employed to produce such polymers, but this part of the chapter will focus on using ADMET as a viable route to synthesize polycarbosilanes, siloxanes, and other silicon-containing polymers. 

The first type of polycarbosilane synthesized by using ADMET methodology was a poly[carbo(dimethyl)silane].14c Linear poly(carbosilanes) are an important class of silicon-containing polymers due to their thermal, electronic, and optical properties.41 They are also ceramic precursors to silicon carbide after pyrolysis. ADMET opens up a new route to synthesize poly(carbosilanes), one that avoids many of the limitations found in earlier synthetic methods.41... 

Another class of silicon-containing polymers that have great potential to be extremely useful precursor materials are poly(chlorocarbosilanes).14f 46 Poly (chlorocarbosilanes) are not useful without modification because of the rapid hydrolysis of Si—Cl bonds, forming HC1 and an insoluble crosslinked polymer network. However, nucleophilic substitution of these Si—Cl bonds with various reagents produces materials widi a broad range of properties that are determined by the nature of the nucleophile used.47 Poly(chlorocarbosilanes) can be easily synthesized by ADMET (Fig. 8.18) without any detrimental side reactions, since the Si—Cl bond is inert to both catalysts 12 and 14. Early studies produced a polymer with Mn = 3000.14f... 

Silicon alkoxide groups, 455 Silicon-containing polymers, 450-460 Silicon-methoxy bonds, hydrolysis of,... 

Jones RG (1995) Silicon-containing polymers. The Royal Chemical Society, Cambridge... 

A. Sivakumar and M. Ramesh. Demulsification of oily waste waters using silicon containing polymers. Patent US 5560832, 1996. 

For a review and books of optically active dialkylpolysilanes and diarylpolysilanes, (a) Fujiki, M. Macromol. Rapid Commun. 2001, 22, 539. (b) Fujiki, M. Koe, J. R. In Silicon-Containing Polymers The Science and Technology of Their Synthesis and Applications. Kluwer, Dordrecht, 2000, Chapter 24. (c) Koe, J. R. Fujiki, M. Nakashima, H. Moton-aga, M. In Synthetic Macromolecules with Higher Structural Order. Khan, I. (Ed.). ACS Symposium Series 812. American Chemical Society, Washington, DC, 2002. 

Fujiki, M. Koe, J. R. Optically Active Silicon-containing Polymers. In Silicon-based Polymers The Sdence and Technology of their Synthesis and Application Jones, R. G., Ando, W., Chojnowski, J., Eds. Kluwer Dordrecht, 2000 pp 643-662. 

Parsonage, J. R. Kendrick, D. A. Silicate Sources of Polyorganosiloxane Materials A Brief Review. In Silicon-Containing Polymers-, Jones, R. G., Ed. Special Publication 166 - Royal Society of Chemistry Cambridge, 1995 pp 98-106. 

There are several problems encountered with silicon containing polymers that affect their lithographic properties. First, a decrease in Tg often accompanies silicon incorporation into a polymer. This may lead to dimensional instability of features during processing. Also, the hydrophobic nature of most useful silicon substituents may hinder the aqueous development of these resists. Careful selection of the polymer components can alleviate and/or eliminate these problems. 

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