Cyclolinear polymer

An alternative, and more recent, approach is shown in reaction (42).9091 Here, a cyclophosphazene is synthesized with two non-geminal alkoxy chains that bear terminal olefinic groups. Treatment of these compounds with an organometallic ADMET catalyst causes loss of ethylene and formation of a cyclolinear polymer. The chain lengths achieved by this method are generally longer than those produced by the dehydrohalo-genation technique. 

The molecular architecture of a polyphosphazene has a profound influence on properties. For example, linear and tri-star trifluoroethoxy-substituted polymers with the same molecular weight (1.2 x 104 or higher) have strikingly different properties.138 The linear polymers are white, fibrous materials that readily form films and fibers, whereas the tri-arm star polymers are viscous gums. One is crystalline and the other is amorphous. Cyclolinear polymers are usually soluble and flexible. Cyclomatrix polymers are insoluble and rigid. Linear polymers can be crystalline, but graft or comb polymers are usually amorphous. 

When di- and trifunctional organochlorosilanes cocondense in an acid medium, there are favourable conditions for the interaction (according to the scheme of intermolecular condensation) of structure I cyclic compounds, formed as a result of intermolecular dehydratation of alkyl- and aryltrihydroxysilanes, with linear products of the hydrolytic condensation of diorganodichlorosilanes. As a result, as the products polycondense further, we find structure II cyclolinear polymers ... 

Such type of Tiso dependence on MM of cyclolinear polymers is quite different from the analogous dependence for PDES [42] and PDPS [41], in which (as mentioned above) the ability to form the mesophase is observed at polymerization degrees as follows P>200 for PDPS and P>500for PDES. 

Cyclolinear polymers were synthesized by hydrosilylation reaction of dihydride-containing organo-cyclotetrasiloxanes with divinyl containing organocyclotetrasiloxanes [80] ... 

Table 12. Some physical and chemical parameters of cyclolinear polymers with ethylene bridges bonding rings...

Data on MMD (Table 14) indicate that cyclolinear polymers with the most homogeneous structure and composition are formed on the reduced catalyst. The more so, every particular case displays its own optimal type of the reduced form, i.e. catalytic system for synthesizing cyclolinear polymers should be selected with regard to activity of dihydrorganocyclosiloxane in polyaddition reaction. It should be noted that as yellow colloid is applied as the catalyst, the reaction temperature has no ef-fect on the shape of MMD curves for ethyl-substituted polymers with tetra- and hexasiloxane cyclic fragments. 

In the Mark-Kuhn-Hauvink equation, parameter a for copolymer 6 solution in toluene at 25°C equ-als 0.30, which is typical of branched macromolecules. For cyclolinear polymer 3 under the same conditions, this parameter equals 0.62 (Figure 7). Molecular masses vary within the range from 4xl03 to 565xl03. 

Structures of volatile degradation products show that all these molecules were detached from the cyclolinear polymer by the mechanism first suggested for poly(dimethylsiloxane) by Thomas [4], In this mechanism, degradation starts with formation of an intermediate fourcentered structure, and then two siloxane bonds involved are rearranged. 

Figure 1 Different types of polyphosphazenes including linear classical macromolecules (1), star structures (2), block copolymers (3), cyclolinear polymers (4), and comb or graft copolymers (5) and (6). Not shown are cyclomatrix materials in which cyclic trim eric rings are connected in three dimensions ...

The thermal behaviour of copolymers (113) with pendant phosphazene groups, prepared by copolymerization of [NP(OPh)2]NP(OPh)[OC6H3(OH)2-3,5], C6H4(0H)2-1,3 and OCN(CH2)6NCO, have been investigated. An enhancement of the char yield has been observed with increasing phosphazene content. The related cyclolinear polymer will be discussed in Section 4. 

Cyclolinear polymers with cyclotriphosphazene, pyrimidine and triazine units have been applied to enhance the durability of fabrics. The use of polyphos-phazene membranes for the separation of dyes from waste streams has been patented. ... 

The results of the thermal decomposition of branched chain methylsiloxane polymers and polycyclics indicate that the decomposition is similar to that observed with PDMS. The structures of the degradation products from (T2D6) and (T2D9) show that they originate from the cyclolinear polymers through the loop mechanism. Indeed, considering the bicyclic compounds of series I in Table 13 they can only be formed via a concerted intramolecular mechanism. Products in series II could result from three consecutive rearrangement steps which would explain the presence of the three-mem-bered cyclic siloxane... 

Cyclolinear polymers are macromolecules formed by the linkage of intact ring systems, as depicted in IX, whereas cyclomatrix polymers (X) are formed by the three-dimensional crosslinkage of ring systems. 

Linear, branched and cyclolinear polymers are usually soluble. Lightly crosslinked polymers (VII) are swelled by, but are insoluble in liquids. Highly crosslinked or cyclomatrix polymers are insoluble in all media. Oligomers dissolve in liquids to give non-viscous solutions. High polymers dissolve to give highly viscous solutions. 

N3P3(OPh)50B3NjMe5. Heating of [NP(NH2)2Jn mixtures with urea gives cyclolinear polymers bridged by NH and NHC(0)NH units . Expoxy resins can be cured with a variety of phosphazenes i.e. 

Cyclolinear polymers have been evolved with the aim of combining the thermal stability of the phosphazene ring with the flexibility or elastic properties of the chain which Unks them. On the other hand, cyclomatrix polymers contain fully cross-linked rings which are rigid, insoluble, highermelting-point resins of a thermosetting nature. 

Cyclolinear polymers can be made by condensation reactions with diols involving geminal (12.244) or non-geminal groups (12.245) [93,94]. 

Polymer 2 (Fig. 4.1) is an example of a condensation polymer where a difionctional cyclophosphazene can react with an organic or an inorganic difiinctional reagent to afford a linear polymer. These polymers contain the cyclophosphazene ring as a repeat motif in the polymer backbone. These polymers have also been termed cyclolinear polymers. In this type of polymers also, the scope for variation is considerable, although in practice this has not been realized. Polymers of the type 3 (Fig. 4.1) are examples of in-termolecularly crosslinked cyclophosphazenes. These are reminiscent of thermoset polymers such as phenol-formaldehyde or melamine-formaldehyde resins. The presence of the cyclophosphazene units in the crosslinked matrix is expected to impart special properties. However, this family of polymers also has not yet fulfilled the promise that they seem to hold. 

Cyclolinear polymers contain cyclophosphazenes as a repeat unit of a polymer chain. Cyclomatrix polymers contain crosslinked cyclophosphazene units. These polymers have not been studied as well as the other members of the phosphazene polymer family. Some of the strategies that have been employed for the preparation of these types of polymers are discussed in this section. The preparation of cyclolinear polymers depends on the design of cyclophosphazene monomers that retain two reactive sites. A few strategies for achieving the synthesis of such monomers are shown in Fig. 4.21 [17],... 

The task of preparing appropriate cyclophosphazene monomers for cyclolinear polymers consists of the following. N3P3CI6 consists of six reactive P-Cl units. Clearly this compound as such would not be a suitable monomer for preparing soluble cyclolinear polymers. Recall that condensation polymers involving organic monomers relied on difunctional monomers such as diols, diacids, diamines etc. Replacing four chlorine at-... 

Fig. 22. Dependence of the glass transition temperature T, melting point and isotropization temperature T, on the number of phenyl groups n in cycles of cyclolinear polymer Horizontal solid lines indicate the corresponding transitions for PDPhSandPDMS...

We studied a behavior of 5-trimethylsilyl-2-norbomene under the conditions of addition polymerization initiated by some Ni- and Pd-containing catalytic systems. The catalysts of this type have already demonstrated high activity in addition polymerization of norbomene and its alkyl derivatives [25,26]. The known Pd-containing catalytic systems (Ti -allyl)Pd(SbF6) [27] and a,7t-bicyclic complex [NB(OMe)PdCl]2 [28] turned out to be practically inactive in polymerization of 5-trimethylsilyl-2-norbomene. On the contrary, Ni-based complexes displayed a real activity in respect to this monomer. As a result saturated cyclolinear polymers were formed according to Scheme 6 of addition polymerization. The absence of any unsaturation in these polymers was confirmed by both infrared (IR) (no bands in 1620-1680 cm region) and H NMR spectroscopy (no signals at 5-6 ppm). 

Analysis of presented copolymer spectra shows DAAH to copolymerize with VM and SO2, both double bonds participating, with formation of cis-, trans-stereoisomeric pyrrolidine structures in cyclolinear polymer chain in the proportion 4 1. 

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