Chemical copolymers

Homopolymers possess only one type of repeat unit in the chain structure. Thus, except for the chain ends, the composition is constant throughout the chain. It is also possible to prepare chemical copolymers, in which two chemically different repeat units are distributed along the chain backbone. In terpolymers, there are three different types of repeat units. A chemically copolymeric polyphosphazene is shown in Figure 2.17. Thus, copolymers involve a composition variable since, for example, an AB copolymer... [Pg.23]

If the chain backbone contains atoms that are unsymmetrically substituted, then stereochemical variability becomes possible. Stereochemical copolymers have repeat units that are chemically identical but stereochemically different, and in a sense these parallel the chemical copolymers already described. If substituted skeletal atoms in adjacent repeat units have the same atomic configuration, then the placement is said to... [Pg.24]

Cyclization studies have also been carried out on the chemical copolymers poly (ethylene, dimethylsiloxane), and poly(styrene, dimethylsiloxane).68,69 99 Numerous intramolecular interactions need to be taken into account in a chemical copolymer and,... [Pg.164]

CLASS Chemical copolymers ethylene copolymers STRUCTURE -(CH2-CH2) -[CH2-C(CH3)(Co2Na+)] -... [Pg.34]

CLASS Chemical copolymers polyolefin copolymer ter-pol5mier elastomer... [Pg.103]

CLASS Chemical copolymers unsaturated thermoplastic elastomers... [Pg.158]

CLASS Chemical copolymers STRUaURE [-CH2-CHCI-CHCI-CH2-]... [Pg.935]

CLASS Chemical copolymers EPDM rubber derivatives... [Pg.990]

CLASS Chemical copolymers fluoroelastomers CAS REGISTRY NUMBER [9011-17-0]... [Pg.998]

CLASS Chemical copolymers STRUCTURE [ CHj-CHCl-CHCl-CHz-... [Pg.935]

Another interesting feature of the table pertains to the melting points for polymers having m = 6-9. The side chains are now long enough to crystallize. Such side-chain crystallization has also been seen in polysilane homopolymers and chemical copolymers of polyethylene,(so-called linear low-density polyethylene). In any case, such crystallization presumably could interfere with the mesophases that might otherwise form. ... [Pg.38]

Cyclization studies have also been carried out on the chemical copolymers poly(ethylene, dimethylsiloxane) and poly(styrene, dimethylsilox-ane). Numerous intramolecular interactions need to be taken into account in a chemical copolymer. Consequently, the results on the copolymers have been given only a preliminary interpretation in terms of rotational isomeric state theory. Cyclization calculations have also been carried out for poly(dihydrogensiloxane) [-SiH O-], but at present there are no experimental data available for comparison with theory. [Pg.85]

Similar results have been obtained on PDMS elastomers. Examples are tetraethoxysilane-cured hydroxyl-terminated PDMS, methylhydrogensi-loxane-cured vinyl-terminated PDMS, and methylhydrogensiloxane-cured vinyl-terminated poly(dimethylsiloxane-co-diphenylsiloxane) chemical copolymer. Restructuring has also been observed in un-cross-linked copolymers, for example PDMS-co-polyst)u ene, using sum frequency generation vibrational spectroscopy. [Pg.127]

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