Co-polymerisation

Fig. 24.2. A two-phase polymer alloy, mode by co-polymerising styrene and butadiene in polystyrene. The precipitates ore a polystyrene-butadiene copolymer.

A mixture under confinement in a glass pressure bottle at 20°C polymerised explosively, the polymerisation probably being initiated by access of fight through the clear glass container. Such alkene-sulfur dioxide co-polymerisations will not occur above a ceiling temperature, different for each alkene. 

The binders vary quite widely—the most common being starch, soy protein and latexes in conjunction with other soluble polymers. Styrene-butadiene latexes have been the most popular but ethylene-vinyl acetate binders are also used. The method of polymer synthesis provides a way of modifying the properties of the latex. For example, adjustment of the ratio of styrene butadiene in the co-polymer gives rise to different degrees of softness or hardness. This property has a profound influence on the quality of the coating. It is also possible to co-polymerise monomers so as to introduce, for example, carboxy groups on to the surface of the latex particle which in turn assist in... 

The oligomerisation of isobutene, with and without isomerisation or fragmentation, and its polymerisation and co-polymerisation are industrial processes of considerable... 

There are many papers which purport to record the effect of counter-ion on such factors as transfer constants, co-polymerisation ratios, etc. It is significant that in most of these studies relatively high initiator concentrations have been used, so that counter-ion effects are more likely but before accepting that the observed effects are indeed due to change of counter-ion (derived from different catalysts or co-catalysts) it must be ascertained that these polymerisations are in fact cationic and not pseudo-cationic - in which case the effects would stem from the different reactivities of different esters (see Section 5). 

However, for a variety of reasons it seems extremely unlikely that the same mechanism is applicable to the polymerisation of cyclic formals and acetals. One reason is that these compounds cannot be co-polymerised with cyclic ethers another is that the polymers are predominantly cyclic, with the number of end-groups far smaller than the number of growing chains. One mechanism which has been proposed and which accounts for most of the observations involves formation of an oxonium ion (X) from the initiator and the monomer, and a subsequent propagation by a ring-expansion reaction (see 13). 

IPVE in benzene (Deffieux et al., 1983a). The results below rac are rather irregular, but a calculation similar to that for EVE gives kp+ = (10 5) x 105 EmoH S"1. In order to understand why both kp and kpf are so much greater for IPVE than for EVE we would need more information, such as activation energies and their co-polymerisation ratios in dilute solution and in bulk. 

Other arguments in favour of the reality of pseudocationic polymerisation, based on activation energies, co-polymerisation ratios, electric field effects, etc., have been given [6] and will be elaborated elsewhere. 

Aliphatic Aldehydes > Aromatic Aldehydes > Ketones Aldehydes are generally suitable, excepting highly reactive examples such as formaldehyde which may undergo co-polymerisation with the arylbiguanide in preference to dihydrotriazine-formation. 

In principle, aqueous ATRP offers the tantalising possibility of the direct synthesis of reasonably well-defined zwitterionic block copolymers in water without recourse to protecting group chemistry. However, ATRP in acidic media is generally unprofitable, hence the (co)polymerisation of acidic monomers such as methacrylic acid or 4-vinylbenzoic acid must be carried out in weakly alkaline solution, i.e. the monomer should be in its anionic carboxylate... 

Poly-isobutylene (PIB) is a very useful rubber because of its very low gas permeability. Co-polymerised with small amounts of isoprene (to enable vulcanisation with sulphur) to butyl rubber (HR), it is the ideal rubber for inner tubes. If PIB would crystallise, it could not be used as a technical rubber The same holds for the rubbers BR and IR. 

We have found that the ratios of silanes used can be varied within wide limits, and more than two silanes can be used. For example, TEOS, y-aminopropyl trimethoxysilane (AMP-silane) and phenyl trimethoxysilane can be co-polymerised to give a material containing both amino groups and phenyl groups. Some representative examples of materials synthesised by this procedure are detailed in Tables 1 and 2... 

The properties of mPE can be changed over a wide range by incorporation of co-monomers. The effect of a co-monomer was proved in the co-polymerisation with 1-hexene. By the addition of 60 mol.% 1-hexene to the feed, Mn could be reduced to nearly half the value for homopolyethylene. Also, the density and melting point are reduced steeply by the incorporation of 1-hexene, whereas the polydispersity is not influenced. 

Because most industrial production of VDF is generated from F141b (C12CFCH3) or F142b (C1CF2CH3) for which the process is not ready to stop, it can be imagined that (co)telomerisation and (co)polymerisation of such an olefin still keep a prosperous future. 

This problem was overcome by anchoring the recognition unit - zinc cyclene - onto a polymer. [2] Cyclene bearing a vinylbenzyl group was co-polymerised with an ethylene glycol dimethacrylate cross-linker, yielding a solid material (Scheme 2). 

Stoichiometric complexes of the zinc(II)-cyclene monomer with tetraacetylriboflavin and creatinine were prepared and co-polymerised with ethylene glycol dimethyl acrylate. After exhaustive extraction of the material which removed impurities and the templates, a functional polymer was formed. Control polymers without template and with cobalt(II) instead of zinc(II) were also prepared. 

It is difficult to introduce phosphorus into a linear polymer by conventional polymerisation or co-polymerisation of phosphorus containing monomers. The polymers containing... 

Coordination polymerisation via re complexes comprises polymerisation and copolymerisation processes with transition metal-based catalysts of unsaturated hydrocarbon monomers such as olefins [11-19], vinylaromatic monomers such as styrene [13, 20, 21], conjugated dienes [22-29], cycloolefins [30-39] and alkynes [39-45]. The coordination polymerisation of olefins concerns mostly ethylene, propylene and higher a-olefins [46], although polymerisation of cumulated diolefins (allenes) [47, 48], isomerisation 2, co-polymerisation of a-olefins [49], isomerisation 1,2-polymerisation of /i-olcfins [50, 51] and cyclopolymerisation of non-conjugated a, eo-diolefins [52, 53] are also included among coordination polymerisations involving re complex formation. 

Nickel(II) complexes obtained from nickel(0) or nickel(II) compounds and the (Me3Si)2NP(=NSiMe3)2 phosphorane component, which promote the isomerisation 2, co-polymerisation of a-olefins, are referred to as nickel migratory catalysts. It must be emphasised that this is a peculiarity of the (Me3Si)2NP(=NSiMe3)2 phosphorane other phosphoranes of this type in which only one silicon atom is substituted by a carbon atom give an inactive catalyst [183],... 

Considering the necessity of the presence of at least one hydrogen atom at every carbon atom in the a-olefin molecule for the 2,co-polymerisation, the... 

It may be interesting that the activation energy for 2,co-polymerisation decreases with the length of the a-olefin used. This is interpreted in terms of an increase in the number of exergonic migration (isomerisation) steps with the length of the a-olefin (the insertion step is endergonic) [183]. 

One problem of 2,co-polymerisation is that the molecular weight of the product, poly[2,co-(a-olefin)], is always very low (Mw k6x 103), whereas the molecular weight distribution is small (Mw/Mn ss 1.6). It is possible, however, to increase the molecular weight of the polymer, e.g. the molecular weight of poly[2,6-(l-hexene)], to Mw 90 x 103 by increasing the reaction pressure to 1400 MPa. The reason for this is the possible kinetic pressure effect in the case of 1-hexene in which the insertion but not the isomerisation is the rate determining step for 2,co-polymerisation [183]. 

First study of co-polymerisation by Wagner-Jauregg Early theories of rubber-elasticity (Mark, Meyer, Guth, Kuhn and others) Carothers famous work proves by means of organic synthesis that polymers are giant, stable molecules. He first proves it by the discovery of neoprene (polychloro-butadiene), then by the condensation polymerisation of amino acids and esters. As a consequence the first fully synthetic textile fibre, nylon, is developed. In Carothers group Flory elucidates the mechanisms of radical and condensation polymerisation... 

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