Direct copolymerization

A number of patents cl aim THF copolymers by direct copolymerization of THF and other cycHc ethers (168,256—259). Although samples of THF copolyethers are available occasionally, none had any industrial importance as of 1996. 

With some limitations. Single-stage soapless emulsion polymerization can be used for the direct copolymerization of a relatively apolar monomer with a polar... 

The relative proportions of triads is determined by the synthetic conditions chosen as described above for acrylic acid copolymers of acrylamide derived by either direct copolymerization or by hydrolysis. Also, the polymerization pH has a considerable effect on the reactivity in acrylamide/acrylic acid copolymerization. 

One of the promising synthetic strategies of conformation-dependent sequence design is based on direct copolymerization under unusual conditions. 

SuPAES). In common with the previously mentioned PEMs, initial SuPAES materials (see Section 3.3.2.1 for later work on block copolymer derivatives of SuPAES) had a statistical distribution of sulfonic acid groups along the polymer backbone. However, instead of using postsulfonation techniques, sulfonic acid groups were introduced via direction copolymerization that is, suitable sulfonic acid precursor groups were introduced into one of the monomers (13). The advantages of this method are threefold ... 

Direct copolymerization techniques have also been employed in the s)m-thesis of sulfonated poly(aryl ether ketones),i i polyimides, i 5 and poly(benzoimidazoles). The synthesis of random disulfonated biphenol poly(arylene ether sulfone) copolymers (BPSH x where x represents the percentage of disulfonated diphenylsulfone moieties in the polymer versus unsulfonated diphenylsulfone moities) (14) is shown in Scheme 3.5. 

Xing, P., Robertson, G. R, Guiver, M. D., Mikhailenko, S. D. and Kaliaguine, S. 2004. Sulfonated poly(aryl ether ketone)s containing the hexafluoroisopro-pylidene diphenyl moiety prepared by direct copolymerization, as proton exchange membranes for fuel cell application. Macromolecules 37 7960-7967. 

Direct Copolymerization of Sulfonated Monomers To Afford Random (Statistical) Copolymers... 

Figure 13. Placement of the sulfonic acid group in postsulfonation (activated ring) versus direct copolymerization (deactivated ring).

Figure 15. Synthesis of directly copolymerized wholly aromatic sulfonated poly(arylene ether sulfone), BPSH-ax, where XX is the ratio of sulfonated/unsulfonated activated halide.

Directly copolymerized sulfonated poly(arylene ether ketone) PEMs are also possible by employing a sulfonated dihalide ketone monomer (sodium 5,5 -carbonylbis(2-fluorobenzenesulfonate)), as first reported by Wang. ° The sulfonated monomer chemical structure is shown in Figure 20. 

Direct copolymerization of sulfonated monomers has been used to synthesize sulfonated poly (benzimidazoles), poly(benzoxazole)s, and poly(benzothia-zole)s. As an example, Kim et al. synthesized poly-(benzthiazole)s from 2,5-diamino-1,4-benzenedithiol dihydrochloride and either 2-sulfoterethphthalic acid sodium salt, 5-sulfoisophthalic acid sodium salt, or 2,4-disulfoisophthalic acid potassium salt in poly-phosphoric acid (PPA), as shown in Figure 34. Similar sulfonated poly(benzimidazole) and sulfonated poly(benzoxazole) ° structures have also been synthesized. A general synthetic scheme for each is shown in Figure 35. The stability of these polymers in aqueous acidic environments appears... 

Postsulfonation of polymers to form PEMs can lead to undesirable side reactions and may be hard to control on a repeatable basis. Synthesis of sulfonated macromolecules for use in PEMs by the direct reaction of sulfonated comonomers has gained attention as a rigorous method of controlling the chemical structure, acid content, and even molecular weight of these materials. While more challenging synthetically than postsulfonation, the control of the chemical nature of the polymer afforded by direct copolymerization of sulfonated monomers and the repeatability of the reactions allows researchers to gain a more systematic understanding of these materials properties. Sulfonated poly(arylene ether)s, sulfonated poly-(imide)s, and sulfonated poly(styrene) derivatives have been the most prevalent of the directly copolymerized materials. 

CALB-catalyzed copolymerization of CL with 11-mercaptoundecanoic acid (1IMU) leads to the formation of poly(ester-c6>-thioester)s having a Mn of 13.7 kDa (PDI 1.6) after precipitation [30] (Fig. 11). The amount of incorporated IIMU (8.7mol%) was slightly less than the feed ratio (10mol%). Similar results were obtained when using 3-mercaptopropionic acid (3MP) as a comonomer (Mn 14.3 kDa, PDI 1.4). CALB-catalyzed transesterification of pCL with either 1 IMU or 3MP resulted in similar H-NMR and C-NMR spectra as the direct copolymerization of the two monomers, showing that continuous transesterification plays an important role in the microstructure of the polymer [30]. 

This observation is corroborated with what has been found in Figures 8-10. There is more of an inversion phenomenon occurance at 20°C. However, the difference between 30°C and 40°C is small and apparently similar, within experimental error. Nevertheless, the new established reactivity ratios of butadiene and isoprene at all three temperatures differ by a smaller factor than what were reported by the work of Korotkov (8) (e.g. rj - 3.38 and 2 = 0.47). Moreover, butadiene is more reactive and initial copolymer contains a larger proportion of butadiene randomly placed along with some incorporation of isoprene units. The randomness of the copolymer via direct copolymerization has been confirmed by the comparison with pure diblock copolymer produced by sequential monomer addition. Both copolymers have similar chemical composition (50/50) and molecular weight. Their... 

Equation 1 illustrates a synthetic scheme which we have used in the preparation of polyolefin graft copolymers. Borane group containing polyolefin copolymers (I) were obtained by direct copolymerization [9,10] of a-olefin/borane containing a-olefin and a... 

Copolymerizations of benzvalene with norbornene have been used to prepare block copolymers that are more stable and more soluble than the polybenzvalene (32). Upon conversion to (CH), some phase separation of nonconverted polynorbomene occurs. Other copolymerizations of acetylene with a variety of monomers and carrier polymers have been employed in the preparation of soluble polyacetylenes. Direct copolymerization of acetylene with other monomers (33—39), and various techniques for grafting p oly acetylene side chains onto solubilized carrier polymers (40—43), have been studied. In most cases, the resulting copolymers exhibit poorer electrical properties as solubility increases. 

In a copolymerization system in which the product rxrz would exceed unity, the copolymer would contain sequences of like units in greater abundance than in a random copolymer of the same composition, and this tendency should be greater the larger the product rxrz (79). However to our knowledge no example of this case is known therefore the synthesis of copolymers with long uninterrupted stretches of a same monomer must be carried out by other methods than by direct copolymerization. In feet such copolymers have been synthesized their properties are more similar to those of a mechanical mixture of both homopolymers and differ markedly from those of a random copolymer. 

A variety of copolymers have been synthesized by the direct copolymerization of S8 with other comonomers.56 For example, S8 undergoes an equilibrium copolymerization with Se8, as shown in reaction (8) ... 

So far, theoretically, there have been two possible approaches for the synthesis of functional polyolefins, namely, (a) direct copolymerization of olefins with functional monomers using polymerization and catalyst technologies, and (b) post-polymerization reaction with polyolefins. 

The first approach has found limited applications. Concerning the direct copolymerization of olefins with functional monomers, studies of copolymerization of olefins by metallocene catalysts have been reported with functional... 

Figure 11 Schematic representation of techniques used for solubilized and immobilized affinity ligands in polyacrylamide gels. (A) Solubilized ligand method the ligand can move freely in the gel-buffer system. (B) Macroligand method the solution of acrylamide contains the macroligand that becomes entrapped within the gel matrix after polymerization. (C) Chemically bound ligand direct copolymerization of polyacrylamide gel with the copolymerizable derivative of the ligand. (Reproduced with permission from Ref. 13.)...

Direct copolymerization of VFA can be carried out either with BVU, in the presence of silica particles, or with VTS, which must be pre-grafted onto silica surfaces. Both reactions can be used to immobilize large amounts of PVFA-co-PVAm on silica surfaces. The second described direct co-polymer-ization procedure is exhibited by the covalently bonded polyelectrolyte layer on the inorganic substrate. The swelling capacity of the PVFA/silica hydrogels can be controlled by the degree of hydrolysis of the PVFA. 

In contrast to Group IV-based polymerization catalysts, late transition metal complexes can carry out a number of useful transformations above and beyond the polyinsertion reaction. These include isomerization reactions and the incorporation of polar monomers, which have allowed the synthesis of branched polymer chains from ethylene alone, and of functional polyolefins via direct copolymerization. The rational design of metallocene catalysts allowed, for the first time, a precise correlation between the structure of the single site catalyst and the mi-crostructure of the olefin homo- or copolymer chain. A similar relationship does not yet exist for late transition metal complexes. This goal, however, and the enormous opportunities that may result from new monomer combinations, provide the direction and the vision for future developments. 

Typically, carboxylate ionomers are prepared by direct copolymerization of acrylic or methacrylic acid with ethylene, styrene or similar comonomers by free radical copolymerization (65). More recently, a number of copolymerizations involving sulfonated monomers have been described. For example, Weiss et al. (66-69) prepared ionomers by a free-radical, emulsion copolymerization of sodium sulfonated styrene with butadiene or styrene. Similarly, Allen et al. (70) copolymerized n-butyl acrylate with salts of sulfonated styrene. The ionomers prepared by this route, however, were reported to be "blocky" with regard to the incorporation of the sulfonated styrene monomer. Salamone et al. (71-76) prepared ionomers based on the copolymerization of a neutral monomer, such as styrene, methyl methacrylate, or n-butyl acrylate, with a cationic-anionic monomer pair, 3-methacrylamidopropyl-trimethylammonium 2-acrylamlde-2-methylpropane sulfonate. 

Dispersancy Incorporating dispersancy into OCP VI improvers is considerably more difficult than the case with free-radical solution chemistry, as described for PMAs. Direct copolymerization of the preferred N- or O-containing monomers is not practical since these Lewis bases will complex, and thus poison, the acidic Ziegler-Natta catalysts. The only option identified so far is to use an amount of catalyst in excess of that complexed by the polar monomer, as described for N-vinylimidazole [24] or V-vinyl succinimide [25]. 

Ionomers of practical interest have been prepared by two synthetic routes (a) copolymerization of a low level of functionalized monomer with an olefinically unsaturated monomer or (b) direct functionalization of a preformed polymer. Typically, carboxyl containing ionomers are obtained by direct copolymerization of acrylic or methacrylic acid with ethylene, styrene and similar comonomers by free radical copoly-merization. Rees (22) has described the preparation of a number of such copolymers. The resulting copolymer is generally available as the free acid which can be neutralized to the degree desired with metal hydroxides, acetates and similar salts. Recently, Weiss et al.(23-26) have described the preparation of sulfonated ionomers by copolymerization of sodium styrene sulfonate with butadiene or styrene. 

As in the case of S/MMA copolymers prepared by direct copolymerization, the methoxy proton resonances of the derived S/MMA copolymers occurred in three general areas (A - 6 = 3.2-3.8 ppm,... 

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