Cyclolinear copolymers

Table 6. Some physical and chemical parameters of carbosiloxane cyclolinear copolymers with tricyclodecasiloxane fragments in the backbone...

Contrary to previous considerations [25], dimethylsiloxane backbone length increase ( =21) does not cause formation of two-phase systems in cyclolinear copolymers with rigid decaphenyltricyclodecasiloxane fragments and flexible dimethylsiloxane units (n = 25). 

Mukbaniani N.O., Synthesis and Investigation of Properties of Carbosiloxane Cyclolinear Copolymers, Candidate s Dissertation on Chemistry, 2001, Tbilisi State University, Tbilisi, Georgia. 

Reviewed in this paper is synthesis of cyclolinear copolymers with regular disposition of mono-cyclic fragments in dimethylsiloxane backbone using HFC and hydride polyaddition reaction as the methods for synthesis of polymers. 

Siloxane Cyclolinear Copolymers with Organocyclotetra(Penta, Hexa)-Siloxane Fragments in Dimethylsiloxane Backbone... 

HFC reaction of difunctional organocyclosiloxanes with a,0— dichloro(dihydroxy, dimethylamino)-dimethylsiloxanes of different length (n) proceeding with formation of cyclolinear copolymers pos-sessing regular disposition of cyclic fragments in dimethylsiloxane chain is discussed in the current Section. 

Thus basing on data obtained in the study of HFC reaction between dichloro(dihydroxy)-organo-cyclotetrasiloxanes with a, -dihydroxy(dichloro)dimethylsiloxanes, it has been shown [14] that the reaction is both intermolecular forming cyclolinear copolymer and intramolecular giving bicyclic structures (at low values of n). As a consequence, the current reaction proceeds in accordance with the following scheme ... 

Spectral data of H NMR analysis have indicated the regular structure of cyclolinear copolymers, which correlates well with the data from the literature [22]. Some physical and chemical parameters of copolymers with cyclotetrasiloxane fragments in the backbone are shown in Tables 1-2. 

Table 2. Some physical-chemical parameters and yield of cyclolinear copolymers of the structure III...

Thermogravimetric studies of cyclolinear copolymers indicate that 1,3-and 1,5-dispositions of hexa-phenylcyclotetrasiloxane fragment cause no difference in mass losses of copolymers. 

As a result, by HFC reaction of l,5-dihydroxy-l,5-bistrimethylsiloxytetraphenyl-cyclotetrasiloxane with a, -dichloromethylsiloxanes in the presence of pyridine and in 60% anhydrous toluene so-lution at 20 - 25°C cyclolinear copolymers with regular disposition of 1,5-bistrimethylsiloxy-tetraphenylcyclotetrasiloxane in the dimethylsiloxane backbone, completely dissoluble in organic solvents, were synthesized [29], The reaction proceeds in accordance with the general scheme as follows ... 

For the purpose of synthesizing cyclolinear copolymers with regular disposition of organocyclotetra- organocyclopenta- and organocyclohexasiloxane fragments in linear the dimethylsiloxane backbone, HFC reaction of 1,5-dihydroxy-1,5-... 

Figure 9. CH4, C6II6, D3 and D4 liberation curves for cyclolinear copolymers 2 and 4 (structure I, Table 3.1 ). -C0H0, 0-CH4, x- D3andD4 (<1.5%). Here - is corresponded to copolymer 2 and — to copolymer 4.

X-ray diffraction studies were carried out for cyclolinear copolymers and it was shown, that they are amorphous systems. Independently of the length of single-unit dimethylsiloxane chain, diffraction patterns display two amorphous halos. It is known that the first amorphous halo, d, characterizes the average interchain distance in amorphous polymer [52], whereas d2 is more complicated and corresponds to both intrachain and interchain or interatomic distances. 

Thermogravimetric studies of cyclolinear copolymers have displayed their sufficiently high thermal oxidative stability. For short lengths of dimethylsiloxane unit, initial mass loss is observed at 260 - 280°C and 5% loss at 300°C. Above 750°C no mass loss variation is observed, which is apparently associated with formation of secondary structures. Thermal oxidative stability of copolymers with carbocyclosiloxane fragments in the backbone is similar to that of their pure siloxane analogues. Moreover, thermal oxidative stability of copolymers is decreased with increase of the volume of cyclic carbosiloxane fragment. 

Cyclolinear Copolymers Derived by Polymerization of Organobicyclo-and Organotricyclosiloxanes... 

The main reason for the investigation was to create convenient methods for the synthesis of organosiloxane copolymers with monocyclosiloxane fragments in the side chain. To establish the influence of the cyclic fragment on the properties of copolymers the initial difunctional organodichlorosiloxyorganocyclosiloxanes and a new class of cyclolinear copolymers, with monocyclic fragments in the side chain were synthesised. 

Consequently it is possible to conclude that hydride addition of methyldichlorosilane to 1-vinyl-l-methyltetraphenyl-cyclotrisiloxane proceeds with formation of a P-adduct. The synthesised difunctional compounds are interesting products for the production of cyclolinear copolymers with cyclic fragments in the side chain. 

Activity of A,A-diallyl-A -acetylhydrazine in reactions of radical homo- and copolymerization has been studied. It was determined, that A,A-diallyl-A -acetylhydrazine does not homopolymerize aceording to fi"ee-radical mechanism, but copolymerize with N-vinylpyrrolidone, acrylamide, methaerylic and maleic acids resulting in formation of water-soluble copolymers with a random distribution of the comonomer units in a maeromoleeule. A,A-diallyl-A -acetylhydrazine is less active if compared with vinyl monomers. A,A-diallyl-A -acetylhydrazine exhibits high activity at copolymerization with sulphur dioxide. The reaction results in alternating of copolymers of equimolar eomposition irrespeetive of reaetion conditions. NMR and electron spectroscopy data proved A,A-diallyl-A -aeetylhydrazine to copolymerize (both double bonds are involved) with formation of pyrrolidine struetures. Cyclolinear copolymers obtained are soluble owing to intramoleeular eyelization of N,N-diallyl-A -acetylhydrazine when formation of the polymer ehain and to the absenee of intermolecular crosslinks. Kinetic regularities of the proeess, stmeture and some properties of copolymers have been studied. 

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