Ring opening polymerization of oxetanes

The chemistry of polymerization of the oxetanes is much the same as for THE polymerization. The ring-opening polymerization of oxetanes is primarily accompHshed by cationic polymerization methods (283,313—318), but because of the added ring strain, other polymerization techniques, eg, iasertion polymerization (319), anionic polymerization (320), and free-radical ring-opening polymerization (321), have been successful with certain special oxetanes. 

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

Lewis Acid Driven Anionic Polymerization of a Monomer with High Cationic PolymerizabiHty Ring-Opening Polymerization of Oxetane with Aluminum Porphyrin in the Presence of a... 

Fig. 9.U Scheme of the cationic ring-opening polymerization of oxetanes.

Scheme 8.16 Living cationic ring-opening polymerization of oxetane using tetrahydropyran as solvent to control polymerization.

RUD 11] Rudati P.S., The preparation of insoluble hole-transport layer via cationic induced ring-opening polymerization of oxetan-derivatized materials by poly(3,4-ethlenedioxythiophene) . Journal Material dan Energi Indonesia, vol. 01, no. 03, pp. 148-153,2011. 

The ring-opening polymerizations of oxetanes (1,3-epoxides) with Lewis acids such as boron trifluoride etherate and aluminum alkyls are well documented. Hall and coworkers reported the ring-opening polymerization of 7-oxabicyclo[2.2.Ijheptane (50) with Lewis acids such as boron trifluoride etherate to give poly(cyclohexene oxide) (51). Ogata reported that the polymerization of... 

Scheme 6.4 Living cationic ring-opening polymerization of oxetane using 1,4-dioxane to control the nudeophilicity of the living chain-end to prevent the occurrence of chain-transfer reactions. Hexafluoroantimonate counterions are omitted for clarity.

The cationic ring-opening polymerization of epichlorohydrin in conjunction with a glycol or water as a modifier produced hydroxyl-terminated epichlorohydrin (HTE) liquid polymers (1-2). Hydroxyl-terminated polyethers of other alkylene oxides (3 4), oxetane and its derivatives (5 6), and copolymers of tetrahydrofuran (7-15) have also been reported. These hydroxyl-terminated polyethers are theoretically difunctional and used as reactive prepolymers. 

Kinetic measurements of the ring-opening polymerization of trimethylene carbonate (TMC) versus the enchainment of oxetane and CO2 to provide poly (TMC) reveal that these processes in the presence of (salen)CrCl and an ammonium salt have similar free energies of activation (AG ) at 110°C. This similarity in reactivity coupled with the observation that in situ infrared studies of the copolymerization of oxetane and CO2 showed the presence of TMC during the early stages of the reaction has led to the overall mechanism for copolymer production shown in... 

The ring-opening polymerization of cyclic ethers having 3-, 4-, and 5-membered rings (e.g., epoxides, oxetanes, THF) yields polymeric ethers. Six-membered rings (1,4-dioxane) are not capable of polymerization. 

Uryu and coworkers also reported the first synthesis of a nonhydro-lyzable polysaccharide by cationic, ring-opening polymerization of an oxetane ring. The monomer was 3,5-anhydro-l,2-0-isopropylidene-a-D-xylofuranose, and it formed a polymer of molecular weight of 10,000-11,000. Spectral and optical data indicated regular polymerization to a (3— 5)-linked polymer of 1,2-O-isopropylidene-a-D-xylofuranose.14... 

Figure 8.16 Reaction coordinate diagram with activation parameters for the copolymerization of oxetane and C02 and for the ring-opening polymerization of TMC.

A series of water-dispersible, surface-active poly(fluorinated oxetane)s was prept sd by ring-opening polymerization of fluorinated oxetane monomers using Lewis acid catalysis <02L5993>. 

Aluminum porphyrins are versatile initiators which are applicable to controlled ring-opening polymerization of various heterocyclic monomers (Table 1) such as epoxides (11)," oxetanes (12) lactones with four-, six-, and seven-membered rings (13-15), lactide (16), six-membered cyclic carbonates (17) and cyclic siloxanes (19).-" They are also excellent initiators for the controlled addition polymerization of unsaturated monomers such as acrylates (20), methacrylates (21)-- and methacrylonitrile (22).- - ... 

Anionic polymerization of 2-hydroxymethyloxetane is imsuccessfiil (34). The failure of such a reaction is most likely due to the fact that oxetanes are not known to ring-open imder basic conditions. The successful cationic ring-opening polymerization of 3-ethyl-3-(hydroxymethyl)oxetane gave hydroxy-functional hyperbranched polyethers (45,46) (Fig. 7). The cationic polymerization can proceed according to two different mechanisms, activated chain end (ACE) or activated monomer mechanism (AMM) (45) (Fig. 8). 

Several papers describe the synthesis of copolyoxetanes and the evaluation of relative reactivity of differently substituted aliphatic oxetanes [28-31]. Adapting previous work [26, 32], BF3(Et20) catalyst and 1,4-butanediol cocatalyst were used for cationic ring-opening polymerization of A and B oxetanes (Equation 10.4). 

S,S-Dialkyl-S-(hydroxyphenyl)sulfonium salts are active photoinitiators for the cationic ring-opening polymerizations of a wide variety of heterocyclic monomers, including tetrahy-drofuran, s-caprolactone, epoxides, oxetanes, thiiranes, and 1,3,5-trioxane. It has been suggested that ring-opening... 

Magnusson H, Malmstrom E, Hult A (1999) Synthesis of hyptabranched aliphatic polyethers via cationic ring-opening polymerization of 3-ethyl-3-(hydroxymethyl)oxetane. Macromol Rapid Commun 20 453 57... 

A few hyperbranched polymers are known in this category. Ring-opening polymerization of 2-hydroxy methyl oxetane under basic conditions gave only low molecular weight polymer [55]. Most of the work in this category of polymers has been concentrated in polybenzyl ether or polyphenylene ethers. 

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