Ring-Opening Polymerization Routes

Block copolymer systems have aroused interest with reviews of the synthesis of nylon elastomers, thermoplastic polyether-polyamide elastomers, and thermoplastic cross-linked polyamides of 3,3 -bis(hydroxymelhyl) glutaric add. Block copolymers were also reported from poly(/n-phenylene isophthalamidc) and poly(ethylene oxide) or poly(dimethylsiloxane). The polycondensation of oco -dicarboxylic-poly(amide 11) and x -dihydroxy-polyoxyethylene has also been studied and rate constants and activation energies evaluated for the process. The polycondensation of axo -diacid and e9o -diester-poly(amide 11) oligomers with cuco -dihydroxy-polyether oligomers has similarly been reported. Lactam Rli -opening Polymerization Routes.—The effects of ring size, substitution and the presence of heteroatoms on the polymerizability of lactams has been the subject of reviews. - In the field of lactam polymerization, two systems have evoked major interest, namely caprolactam and 2-pyrrolidone. Studies on caprolactam have reported the effect of water on the mechanism of polymerization and polymerization rate, where it was found that the process was 

Nagata, Kyoto Furitsu Daigaku Gakujutsu Hakdku Rigaku. Seikatsu Kagaku, 1976, 27, 65 iChem. Abs., 1977,86, 107 706). 

Bondarowski, L. Geltz, K. Kelar, and J. Gzarnecki, Polim. Twori. Wielk., 1977, 22, 316. 

Polymerization efficiencies for the initiator systems hexamethylene di-isocyanate and 7V-acetyl caprolactam have been evaluated and the di-isocyanate found to be the more active. Studies on -caprolactam in closed systems have been made and the main polymerization processes for the system, caprolactam, water, and a viscosity stabilizer (acetic acid or butylamine), were evaluated. These are ring-opening polymerizations by hydrolysis, polycondensation of amine and carboxyl ends, and polyaddition of caprolactam to amino end-groups. Apparent activation energies were determined for these main reactions and it was suggested that addition occurred in preference to polycondensation. Post-polymerization of E-caprolactam under reduced pressure in the presence of water vapour and phosphoric acid has been kinetically analysed and the rate of increase of the degree of polymerization was derived theoretically as a function of reaction variables. 

The catalytic activity of aqueous acid solutions for e-caprolactam has been investigated and related to the nucleophilicity of the anion formed on dissociation.  

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The scheme for the polycondensations of dimethylphosphite with diols to form poly(alkylene phoshonate)s is shown in Figure 4. This route is complementary to the ring-opening polymerization route because... 

The common ring opening polymerization route to linear polyphos-phazenes is limited by some difficulty in forming copolymers. However, it is posible to functionalise end groups by a phosphoraminime conden-sation route. 

The ring-opening polymerization of ketene acetals (45, X=0) provides a novel route to polyesters and many examples have now been reported (Scheme 4.27). " "7 A disadvantage of these systems is the marked acid sensitivity of the monomers which makes them relatively difficult to handle and complicates characterization. This area is covered by a series of reviews by Bailey ct a/.177 228 ... 

Poly(tetramethylene oxide) polyols (see Scheme 4.4) are a special class of polyethers syndiesized via acid-catalyzed ring-opening polymerization of tetrahy-drofuran. Although less susceptible to side reactions, the synthesis of these C4 ethers is less flexible in terms of product composition and structure. Thus, because of diis syndietic route, only two-functional glycols are available and copolymers are not readily available. Molecular weights of commercial C4 glycols range up to about 3000 g/m. 

In connection with studies on the ring-opening polymerization of cyclic acetals, we have undertaken investigations on the polymerization of bicyclic acetals, bicyclic oxalactone, and bicyclic oxalactam, which yield polysaccharide analogs, macrocyclic oligoesters, and a hydrophilic polyamide, respectively, some of which can be expected to be useful as novel speciality polymers. The monomers employed in the studies were prepared via synthetic routes presented in Scheme 1, starting from 3,4-dihydro-2H-pyran-2-carbaldehyde (acrolein dimer) I. 

Ring-opening polymerization of 2-methylene-l,3-dioxepane (Fig. 6) represents the single example of a free radical polymerization route to PCL (51). Initiation with AIBN at SO C afforded PCL with a of 42,000 in 59% yield. While this monomer is not commercially available, the advantage of this method is that it may be used to obtain otherwise inaccessible copolymers. As an example, copolymerization with vinyl monomers has afforded copolymers of e-caprolactone with styrene, 4-vinylanisole, methyl methacrylate, and vinyl acetate. 

The conventional route to prepare I generally involves a high temperature melt polymerization of hexachlorocyclotriphosphazene, or trimer (IV). Recent studies have demonstrated the effectiveness of various acids and organometalllcs as catalysts for the polymerization of IV (8). Alternate routes for the preparation of chloro-polymer which do not involve the ring opening polymerization of trimer have been reported in the patent literature (9. 10). These routes involve a condensation polymerization process and may prove to be of technological importance for the preparation of low to moderate molecular weight polyphosphazenes. 

In addition to solvent uses, esters of lactic acid can be used to recover pure lactic acid via hydrolysis, which in-tum is used to make optically active dilactide and subsequently polylactic acid used for drag delivery system.5 This method of recovery for certain lactic acid applications is critical in synthesis of medicinal grade polymer because only optically active polymers with low Tg are useful for drug delivery systems. Lactic acid esters themselves can also be directly converted into polymers, (Figure 1), although the commercial route proceeds via ring-opening polymerization of dilactide. 

Manners, Ian, Ring-Opening Polymerization ofMetallocenophanes A New Route... 

Ring-opening polymerization of cyclic monomers, usually by anionic or cationic catalysts, is another route to elastomers. These include the polymerization of octamethylcyclotetrasiloxane... 

Fig. 7 Synthesis of heterobifunctional PEG. (a) Nagasaki et al. developed a method for the polymerization of EO using an initiator containing defined functionalities [16, 17]. (b) Akiyama et al. further developed a synthetic route to prepare a series of heterobifunctional PEGs [18-21]. After the ring-opening polymerization of ethylene oxide, a second functional group was introduced at the co-end of PEG...

Figure 8.3 Two mechanisms have been proposed for the cationic ring-opening polymerization of oxetanes, the ACE route and the AMM [16]...

Becer CR, Paulus RM, Hoppener S et al. (2008) Synthesis of poly(2-ethyl-2-oxazoline)-h-poly(styrene) copolymers via a dual initiator route combining cationic ring opening polymerization and atom transfer radical polymerization. Macromolecules 41 5210-5215... 

Feng Y, Klee D, Keul H, Hdcker H (2000) Lipase-catalyzed ring-opening polymerization of morpholine-2,5-dione derivatives a novel route to the synthesis of poly(ester amide)s. Macromol Chem Phys 201 2670-2675... 

Detrembleur C, Mazza M, Halleux O, Lecomte P, Mecerreyes D, Hedrick JL, Jerome R (2000) Ring-opening polymerization of y-Bromo-E-caprolactone a novel route to functionalized aliphatic polyesters. Macromolecules 33 14-18... 

El Habnouni HS, Darcos V, Coudane J (2009) Synthesis and ring-opening polymerization of a new functional lactone, a-iodo- -caprolactone a novel route to functionalized aliphatic polyesters. Macromol Rapid Commun 30 165-169... 

Tian D, Dubois P, Grandfils C, Jerome R (1997) Ring-opening polymerization of l,4,8-trioxaspiro[4.6]-9-undecanone A new route to aliphatic polyesters bearing functional pendent groups. Macromolecules 30 406 09... 

The synthesis of polyamides follows a different route from that of polyesters. Although several different polymerization reactions are possible, polyamides are usually produced either by direct amidation of a diacid with a diamine or the self-amidation of an amino acid. The polymerization of amino acids is not as useful because of a greater tendency toward cycliza-tion (Sec. 2-5b). Ring-opening polymerization of lactams is also employed to synthesize polyamides (Chap. 7). Poly(hexamethylene adipamde) [IUPAC poly(iminohexanedioylimi-nohexane-l,6-diyl) or poly(iminoadipoyliminohexane-l,6-diyl)], also referred to as nylon 6/6, is synthesized from hexamethylene diamine and adipic acid [Zimmerman, 1988 Zimmerman and Kohan, 2001]. A stoichiometric balance of amine and carboxyl groups is readily obtained by the preliminary formation of a 1 1 ammonium salt (XU ) in aqueous solution at a concentration of 50%. The salt is often referred to as a nylon salt. Stoichiometric... 

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