Monomer compatibility

Even in polymer chemistry these species may be of interest since more and more attention is devoted to polymerization in confined volumes, such as micelles, whereby the graft copolymer could first help in the emulsion polymerization of a monomer compatible with the backbone and subsequently act as a surface modifier of the polymer formed (wetting agent, pigment binder, coating binder, antistatic compound, adhesion factor, etc.). 

Another peculiar feature of the grafting of acrylic acid is the break observed in the conversion curves particularly at low dose rates. The interpretation of this effect proposed above does not account for the fact that no break is observed with other monomers except at much higher grafting ratios (2, 4). These striking differences in kinetics for systems which in principle should exhibit comparable behavior are presumably related to differences in diffusion rates and polymer-polymer and polymer-monomer compatibilities. Little is known at present on the factors which govern these effects and on their influence on the kinetics. 

Homopolymers and copolymers containing carbosiloxane and carbosilane units have been produced that bear latent reactive sites along the chain [184]. Reactive carbosiloxane and unreactive carbosilane homopolymers were first prepared in order to ensure catalyst monomer compatibility and to set end points for copolymer properties. Carbosiloxane homo- and copolymers were synthesized with latent reactivity dispersed throughout the polymer chain in the form of methyl silyl ethers (Scheme 21). It is well known that Si-OMe bonds, although inert during metathesis, can react with atmospheric moisture creating stable Si-O-Si bonds and methanol [185]. 

The list of monomers compatible with anionic polymerization overlaps the radical list (Figure 13.16) considerably, but the unique features of anionic polymerization mean that the same polymer can be a different material. For example, one important feature of anionic polymerizations is that they show a tendency to produce stereoregular polymers, in contrast to radical polymerizations. As such, polystyrene produced by anionic polymerization is more crystalline than polystyrene produced by radical polymerization. This is just another example of how one polymer— polystyrene—can represent several different materials. Note also that because carbanions generally do not abstract protons from C-H bonds, chain transfer (and branching) is typically not a problem in anionic polymerizations. 

One approach to compatibilize non-compatible polymers is to include in the blend a block copolymer which contains one chain segment derived from monomers compatible with one blend polymer and another chain segment derived from monomers compatible with the other blend polymer (2). 

The formation of copolymers involves the reaction of (at least) two kinds of monomers. This means that each must be capable of undergoing the same propagation reaction, but is is apparent that quite a range of reactivities is compatible with this broad requirement. We shall examine such things as the polarity of monomers, the degree of resonance stabilization they possess and the steric... 

The third generation are latices made with independentiy prepared surfactant to mimic the in situ prepared functional monomer surfactant. These emulsifiers are often A—B block polymers where A is compatible with the polymer and B with the aqueous phase. In this way surface adsorption of the surfactant is more likely. These emulsions are known to exhibit excellent properties. 

In these mbber-modified polystyrene polymers, the mbbers should have low T, large particle sizes (0.5—5 J.m), graftable and cross-linkable sites, and should be compatible with styrene monomer (93). Polybutadiene, with a T of —SS C, meets all of these requirements and is used most frequently. These mbber-modified systems exhibit excellent low temperature impact strength, a required attribute for use in refrigerators. 

Polyacrjiates (3), where R = H, CH n < 100, 000 and Y = OH, OCH, O, etc, or copolymers with compatible monomers, are probably the most flexible dispersant products, because they are produced in a variety of molecular weights and degrees of anionic charge. Moreover, reaction of acryflc acid with other monomers confers additional properties that make them more adaptable for niche appHcations. 

Polymaleates (4), where n < 100, 000 and Y = OH, 0 , or copolymers with compatible monomers such as styrene, acryflc acid, etc, generally show... 

The anomalous effect of the last two rubbers in the table with their low solubility parameters is possibly explained by specific interaction of PVC with carbonyl and carboxyl groups present respectively in the ketone- and fumarate-containing rubbers to give a more than expected measure of compatibility. It is important to note that variation of the monomer ratios in the copolymers and terpolymers by causing changes in the solubility parameter and eompatibility will result in variation in their effect on impact strength. 

Because of its low price, compatibility, low viscosity and ease of use styrene is the preferred reactive diluent in general purpose resins. Methyl methacrylate is sometimes used, but as it does not copolymerise alone with most unsaturated polyesters, usually in conjunction with styrene in resins for translucent sheeting. Vinyl toluene and diallyl phthalate are also occasionally employed. The use of many other monomers is described in the literature. 

Other natural product-based resins also became widely used, such as the light colored Lewis acid oligomerized products of terpenes such as a-pinene, p-pinene, and limonene. These natural product resins are relatively expensive, however, and formulators now often use the newer, less expensive synthetic resins in present day natural rubber PSAs. These are termed the aliphatic or C-5 resins and are Lewis acid oligomerized streams of predominately C-5 unsaturated monomers like cis- and /rawi-piperylene and 2-methyl-2-butenc [37]. These resins are generally low color products with compatibility and softening points similar to the natural product resins. Representative products in the marketplace would be Escorez 1304 and Wingtack 95. In most natural rubber PSA formulations, rubber constitutes about 100 parts and the tackifier about 75-150 parts. 

The other class of acrylic compatible tackifiers includes those based on ter-penes. Terpenes are monomers obtained by wood extraction or directly from pine tree sap. To make the polyterpene tackifiers, the monomers have to be polymerized under cationic conditions, typically with Lewis acid catalysis. To adjust properties such as solubility parameter and softening point, other materials such as styrene, phenol, limonene (derived from citrus peels), and others may be copolymerized with the terpenes. 

Some applications, such as incise drapes require loading of the PSA matrix with anti-bacterial agents. Proper selection of the monomers allows the PSA to be compatible with compounds like iodine, while maintaining the adhesion to the skin. 

Acyclic C5. The C5 petroleum feed stream consists mainly of isoprene which is used to produce rubber. In a separate stream the linear C5 diolefin, piperylene (trans and cis), is isolated. Piperylene is the primary monomer in what are commonly termed simply C5 resins. Small amounts of other monomers such as isoprene and methyl-2-butene are also present. The latter serves as a chain terminator added to control molecular weight. Polymerization is cationic using Friedel-Crafts chemistry. Because most of the monomers are diolefins, residual backbone unsaturation is present, which can lead to some crosslinking and cyclization. Primarily, however, these are linear acyclic materials. Acyclic C5 resins are sometimes referred to as synthetic polyterpenes , because of their similar polarity. However, the cyclic structures within polyterpenes provide them with better solvency power and thus a broader range of compatibility than acyclic C5s. 

Monomer Reactive material that is compatible with the basic resin. 

These concepts are tested in Fig. 7(a,b) where one can see that both in the non-adsorbed case (Fig. 7(a)) and in the adsorbed case (Fig. 7(b)) the data is compatible with normal diffusion of the parallel (longitudinal) component, g2/(t) = 4Djyt. For e = —1.5, the chains are freely diffusing in the 3d bulk, far away from the adsorbing wall, g / = For e = —3 most monomers... 

Table 7.3-1 Compatibility of the ionic liquids [EMIMJjBFJ and [BPJjBFJ with monomers and...

An effective method of NVF chemical modification is graft copolymerization [34,35]. This reaction is initiated by free radicals of the cellulose molecule. The cellulose is treated with an aqueous solution with selected ions and is exposed to a high-energy radiation. Then, the cellulose molecule cracks and radicals are formed. Afterwards, the radical sites of the cellulose are treated with a suitable solution (compatible with the polymer matrix), for example vinyl monomer [35] acrylonitrile [34], methyl methacrylate [47], polystyrene [41]. The resulting copolymer possesses properties characteristic of both fibrous cellulose and grafted polymer. 

Polymerizations of methacrylic monomers in the presence of methacrylic macromonomers under monomer-starved conditions display many of the characteristics of living polymerization (Scheme 9.36). These systems involve RAFT (Section 9.5.2). However, RAFT with appropriate thiocarbonylthio compounds is the most well known process of this class (Section 9.5.3). It is also the most versatile having been shown to be compatible with most monomer types and a very wide range of reaction conditions.382... 

The reaction scheme for RAFT copolymerization is relatively complex (Scheme 9.49) when considered alongside that for NMP or ATRP (Scheme 9.48). A summary of RAF T copolymerizations is provided in fable 9.22. An advantage of RAFT over other methods is its greater compatibility with monomers containing protic functionality though as yet few have taken advantage of this in the synthesis of functional copolymers. 

I he method of polymerization needs to be chosen for compatibility with functionality in the cores and the monomers to be used. Star block copolymers have also been reported. Mulli(bromo-compounds) may be used directly as ATRP initiators or they can be converted to RAFT agents. One of the most common... 

The monomer can be readily decompd by concns as low as 1% NaOH. Compatible with NC from 20—80% compd/80—20% NC and with rubber from 50—80% compd/50—20% rubber The monomer has a Qc of 2999cal/g at 25°... 

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