Cyclic alternating copolymerization copolymers

Maleic anhydride and vinyl ether undergo a radical-catalyzed cyclic alternating copolymerization in a 2 1 ratio. This copolymer, frequently designated in the literature as DIVEMA or as pyran copolymer, has shown unusual and exciting biological activity, and has therefore undergone intensive investigation. 

Via metal catalysis, cyclic monomers such as TV-substituted maleimides M-40, M-41, and M-42 do not homopolymerize but can copolymerize with vinyl monomers, among which alternating copolymers can be obtained with styrene via a radical mechanism. The 1-13 (X = Br)/CuBr/L-l system induced alternating copolymerizations with styrene to give controlled molecular weights and narrow MWDs (Mw/Mn =1.1 — 1.4) in the bulk or anisole at 80—110 °C.219-222... 

Configuration of atoms C2/C3 in the ring of E—N copolymers can be either 5// or R/S, so two subsequent norbomene units can be either erythro di-isotactic (meso) or erythro di-syndiotactic (racemic). The possible stereochemical environments of norbomene in alternating sequences, diads, and triads are illustrated in Fig. 4. Erythro di-isotactic and erythro di-syndiotactic microstmctures of ENENE and ENNE segments can be obtained, depending on the catalyst stracture (for a recent review on catalysts for cyclic olefin copolymerization see [42]). The microstmcture of the copolymer can be controlled by the appropriate choice of reaction conditions and catalyst stmcture. 

Some copolymerizations have been studied where one of the reactants is a compound not usually considered as a monomer. These include copolymerizations of epoxides and higher cyclic ethers with carbon dioxide, episulhdes with carbon dioxide and carbon disulhde, and epoxides with sulfur dioxide [Aida et al., 1986 Baran et al., 1984 Chisholm et al., 2002 Inoue and Aida, 1989 Soga et al., 1977]. The copolymers are reported to be either 1 1 alternating copolymers or contain 1 1 alternating sequences together with blocks of the cyclic monomer. 

TPPAIOR (1b) was effective for the copolymerization of epoxide with C02 (8-9) or with cyclic acid anhydride emd produced copolysiers with ester and ether linkages. These copolymers have a narrow moleculeir weight distribution, but do not yield alternating structures. 

In order to enhance the reactivity of aluminum porphyrins (J ) especially towards C02 in the copolymerization with epoxide (Equation 4), the effect of addition of an amine or phosphine as a possible sixth ligand to the aluminum porphyrin was examined. The enhancement in reactivity by the addition of a tertiary amine such as N-methyl-imldazole was actually observed for the epoxlde-C02 reaction. The product, however, was a cyclic carbonate (JO), not a linear copolymer. On the other hand, J he addition of trlphenylphosphlne was very effective in the formation of an alternating copolymer from epoxide and... 

The principle of cyclopolymerization has been applied to the synthesis of macrocyclic ether-containing polymers which may simulate the properties of crown ethers. l,2-Bis(ethenyloxy)benzene (a 1,7-diene) and l,2-bis(2-ethenyloxyethoxy)benzene (a 1,13-diene) are typical of the monomers synthesized. Homopolymerization of the 1,7-diene via radical and cationic initiation led to cyclopolymers of different ring sizes homopolymerization of the 1,13-diene led to cyclic polymer only via cationic initiation. Both monomer types were copolymerized with maleic anhydride to yield predominantly alternating copolymers having macro-cyclic ether-containing rings in the polymer backbone. 

Random copolymerization of different oxazolines is described in Section 15.1,2.2. The reactivity ratios increase as expected with monomer basicity 18). Statistical copolymers of cyclic imino ethers with other groups of monomers are not known, although oxazolines and oxazines form readily alternating copolymers with a number of electrophilic monomers by spontaneous zwitterionic polymerization. The mechanism and examples of this process are discussed in Section 15.2.1. 

Under the same conditions, the reactivity of three-membered cyclic ethers in anionic copolymerization with cychc anhydrides is higher than that of four-membered ethers Higher membered cyclic ethers can polymerize or copolymerize with anhydrides only by a cationic mechanism whereby not only alternating copolymer but also a great number of polyether sequences are formed. This difference in reactivity is evidently associated with the basicity of cychc ethers, three-membered ethers having the lowest basicity The lower basicity causes a lower reactivity of the epoxide (cychc ether) in competitive reactions or in copolymerization with other cychc monomers compared with the expected reactivity which follows from the strain in the ring. The strain energy, taken as the difference between the experimental and calculated heats of formation was found to be 54.4kJ/mol for ethylene oxide... 

The high oxophilicity of early transition metal catalysts (titanium, zirconium, or chromium) causes them to be poisoned by most functionalized olefins, particularly the commercially available polar comonomers. However, there are examples of copolymerizations with special substrates or with very high levels of a Lewis acid incorporated into the polymerization system to protect the polar functionality through complexation. " Alternative routes to polar copolymers involving metathesis of cyclic olefins and functionalization of the resulting unsaturated polymer or metathesis of polar cycloolefins followed by hydrogenation to remove the resulting unsaturation have been published.The cost of these multistep... 

Alternating copolymers are obtained from the free radical copolymerization of tetrafluoroethylene with trifluoronitrosomethane, CF3NO. At higher temperatures, however, a cyclic oxazetidine is obtained ... 

An alternative way to mne the polymer properties and insert desired functionalities is copolymerization with different monomers. Cyclic carbonates have been copolymerized with various other cyclic monomers, such as lactones or lactides. For example, TMC was copolymerized with 5-methyl-5-benzyloxycar-bonyl-l,3-dioxan-2-one (MBC) using lipase from Pseudomonas flourescens (PF) resulting in a highly amorphous random copolymers (Fig. 8) [74]. In another smdy, 5-benzyloxy-trimethylene carbonate (BTMC) was copolymerized with 5,5-dimethyl-trimethylene carbonate (DTC) using an immobilized hpase on silica particles [79]. In the copolymerization of TMC with a lactone, m-pentadecalactone (PDL), employing Novozyme 435, highly erystalline TMC-PDL eopolymers were obtained, and as opposed to chemical catalysts, enzyme eatalyst (Novozyme 435) polymerized PDL more rapidly than TMC [80]. 

Copolymerization of a slx-membered cyclic phosphite 51 with 46 also occurred without added catalyst (23). However, the product copolymer did not possess the 1 1 alternating structure as expressed by 52 (Eq 11). 

Both linear and cyclic acetals with vinyl residues copolymerize in an alternating fashion with MA. Two good examples are the copolymers prepared from the O-vinyl acetals of formaldehyde or acetaldehyde and 2-vinyl-l,3-dioxalane. The monomer 4-methylene-2-(trichloromethyl)-l,3-dioxolane also copolymerizes in a 1 1 fashion with MA, regardless of the initial monomer feed ratio in the reaction mixture, duration of reaction time, and monomer conversion. l,3-Dioxep-5-enes are also cyclic acetals. The copolymerization of these monomers with was discussed in... 

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