Cyclo-copolymerization

In this section wc consider systems where the radical formed by propagation can eyclizc to yield a new propagating radical. Certain 1,4-dicncs undergo cyclocopolymerization with suitable olefins. For example, divinyl ether and MAH are proposed to undergo alternating copolymerization as illustrated in Scheme 4.19.167 These cyclo-copolymerizations can he quantitative only for the case of a strictly alternating copolymer. This can be achieved with certain electron donor-electron acceptor pairs, for example divinyl ether-maleic anhydride. 

Interestingly, the vinyl as well as the allyl double bonds are both sluggish to polymerize separately in ethene- and allylsulfonates, but in the cyclo-copolymerization, when both moieties are present in the same molecule, they react rather rapidly. 

The cyclo-copolymerization of diallyl compounds with SO2 has also been reported [61i], For example, 4-substituted 1,6-heptadiene derivatives with SO2 of the following structure were also studied [61j] ... 

Doiuchi T., Yamaguchi H., Minoura Y, Cyclo-copolymerization of o-Umonene with maleic-anhydride, Eur. Polym. J., 17(9), 1981,961-968. 

Polymer-supported TADDOL-Ti catalyst 79 prepared by chemical modification was poorly active in the Diels-Alder reaction of 3-crotonoyloxazolidinone with cyclo-pentadiene (Eq. 24) whereas polymeric TADDOL-Ti 81 prepared by copolymerization of TADDOL monomer 80 with styrene and divinylbenzene had high activity similar to that of the soluble catalyst. In the presence of 0.2 equiv. 81 (R = H, Aryl = 2-naphthyl) the Diels-Alder adduct was obtained in 92 % yield with an endolexo ratio of 87 13. The enantioseleetivity of the endo product was 56 % ee. The stability and recyclability of the catalyst were tested in a batch system. The degree of conversion, the endolexo selectivity, and the enantioseleetivity hardly changed even after nine runs. Similar polymer-supported Ti-TADDOLate 82 was prepared by the chemical modification method [99]. Although this polymer efficiently catalyzed the same reaction to give the (2R,2S) adduct as a main product, asymmetric induction was less than that obtained by use of a with similar homogeneous species. 

In an attempt to prepare polycyclopentadiene which would be stable in toluene solution, the polymer was hydrogenated over a platinum oxide catalyst in a Parr bomb immediately after the completion of the polymerization reaction. Infrared analysis indicated the presence of residual unsaturation and the polymer became insolubilized on standing. An attempted copolymerization of cyclo-pentadiene with propylene gave a product whose infrared spectrum indicated the presence of C-methyl groups but which was still insoluble in toluene. No attempt was made to determine whether copolymerization had occurred. 

Substituted 1,2-dienes such as cyclohexylallene, (3-phenylpropyl)allene, 1,1 -dimethylallene, 1 -methyl-1 -phenylallene, 4-(terf-butyl)phenoxyallene, and (4-allenyloxy)azobenzene undergo alternating copolymerization with CO in the presence of the Rh complex to produce unsaturated polyketones -CO-C(=CRR/)-CH2- n (R, R =H, cyclo-C6Hn H, (CH2)3Ph Me, Me Me, Ph H, OC6H4-f-Bu-4 H,OC6H4-N=N-C6H5) (Eq. 53) [179]. 

The aforementioned l,4-bis(2-hydroxyhexafluoroisopropyl)cyclohexane has been combined with the 2-trifluorometylacrylic structure [290,305,307]. The fluorodiol was half-protected with an ethoxymethyl group and reacted with 2-trifluoromethylacryloyl chloride in the presence of triethylamine to afford 2-[4-(2,2,2-trifluoro-l-ethoxymethoxy-l-trifluoromethylethyl)cyclo-hexane]hexafluoroisopropyl 2-trifluoromethylacrylate. This heavily fluorinated acrylate was copolymerized with 2-methyladamanty 2-trifluoromethylacrylate by anionic initiation with potassium acetate/18-crown-6 [307] as described in the literature [303] (Fig. 90). The copolymer (made from a 1 1 feed) was unexpectedly transparent with OD157 of 1.6/pm. However, imaging of the copolymer resists was sluggish perhaps due to their low Tg. Radical copolymerization was also performed with norbornene derivatives [290,305]. 

Crowther has reported the copolymerization of ethylene and norbornene using asymmetric cyclo-pentadienyl—amido complexes (132, 133) to yield alternated polymers that melt at 250 °C (Scheme... 

Belokon and co-workers (50,51) attributed their template effects (see "Distance Accuracy of Two Functional Groups") to the existence of cyclopolymerization, since polymers of low crosslinking also showed a good selectivity. What takes place is an intrachain reaction rather than an interchain one. Only in one case have we observed a similar behavior (23,49,52). In our case a cyclo-polymerization was proved by copolymerization of 3.4-0-isopropylidene-D-mannitol 1, 2,5,6-bis-O-[(4-vinylphenyl)... 

Lipase CA catalyzed the polymerization of cyclic dicarbonates, cyclo-bis(hexamethylene carbonate) and cyclobis(diethylene glycol carbonate), to give the corresponding polycarbonates (214). The enzymatic copolymerization of cy-clobis(diethylene glycol carbonate) with DDL produced a random ester-carbonate copolymer. Enzymatic synthesis of poly(ester-carbonate) was also achieved by the copolymerization of l,3-dioxan-2-one and lactide (215). The PPL-catalyzed copolymerization at 100°C produced the copolymer with My, higher than 2x 10. ... 

Thermal and UV-initiated cyclo-polymerizations of mixed allyl-butenedioate monomers with both donor and acceptor unsaturations such as methyl allyl fumarate or maleate were recently described. Hyperbranched macromolecules were obtained by free radical alternating copolymerization of bifunctional monomers containing two polymerizable double bonds of allyl and vinylene type with styrene or maleic anhydride. Thanks to their original structure, this new class of liquid blends exhibit improved mechanical and physical properties useful for a wide range of coating applications. ... 

The reactivity ratio and Q,e values for were obtained in styrene (M2) copolymerizations using mol percents of in the feed between 3.2 and 90.9. The values of rj = 0.16 (0.13-0.18) and T2 1.55 (1.41-1,71) exhibited a rather large 95% joint confidence limit, but it is again quite clear that the vinyl group is very electron-rich (e = -1.98). We therefore see a remarkable similarity in the value of e" to the values obtained with every other n -cyclo-pentadienyl monomer studied to date. Also, in agreement with other such monomers, a large value of Q (1.66) was found. 

The monomers 4-vinylcyclohexene and 1,5,9-cyclododecantriene have also been copolymerized with MA. Copolymerization in both cases were run in benzene at 60°C with AIBN, using various molar ratios of the two different monomer pairs. In the case of 4-vinylcyclohexene, the low-molecular-weight copolymers for each run was essentially a 2 3 molar composition of vinyl-cyclohexene to MA. Copolymerization of 1,5,9-cyclo-dodecatriene with MA produced insoluble material. Copolymer composition studies showed these materials tended to be alternating. 

Copolymerizations under identical conditions show that ethylidenebi-cyclo[2.2.1]-2-heptene 61B has a greater reaction rate, by perhaps a factor... 

Metallocene catalysts have a unique feature of polymerizing cyclo-olefin monomers (i.e., cyclopentene, norbornene) selectively without ring opening, and also enable copolymerization with ethylene [47, 48]. Application of metallocene catalysts to cyclo-olefin copolymer (COC) will be discussed in Section IV. 

The literature describes several cases of the copolymerization of ethylene with cyclopentene [31b], cyclo-heptene [31b], norbornene [31c], 2-methylnorbornene [31c], dicyclopentadiene [31d], dimethanooctahydro-naphthalene [31a,e], and 2-methyldimethanooctahy-dronaphthalene [31a]. When chiral catalysts were employed (e.g., ethylenebis(indenyl)zirconium dichloride associated with methylaluminoxane), the activity was much higher than that of the achiral catalyst. In addition, the ehiral catalyst increased the polymer stereoselectivity and the amount of the cycloolefin incorporated into the copolymer. Materials having exeellent transpareney, thermal stability, and ehemical resistance—properties that are useful for optical disks—may be produced efficiently by this method. 

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