Cyclic unsaturated polyesters

When the cyclic anhydride is maleic anhydride, the product understandably becomes an unsaturated polyether ester somewhat similar to traditional unsaturated polyester resins (UPRs). 

Maleic anhydride is a cyclic anhydride with one double bond in the ring and two double-bonded oxygens hanging off the ring. The resulting reactivity leads to maleics use in making polymers, unsaturated polyesters, alkyd resins, plasticizers, and dicarboxylic acids. 

Polymers are normally classified into four main architectural types linear (which includes rigid rod, flexible coil, cyclic, and polyrotaxane structures) branched (including random, regular comb-like, and star shaped) cross-linked (which includes the interpenetrating networks (IPNs)) and fairly recently the dendritic or hyperbranched polymers. I shall cover in some detail the first three types, but as we went to press very little DM work has been performed yet on the hyperbranched ones, which show some interesting properties. (Compared to linear polymers, solutions show a much lower viscosity and appear to be Newtonian rather than shear thinning [134].) Johansson [135] compares DM properties of some hyperbranched acrylates, alkyds. and unsaturated polyesters and notes that the properties of his cured resins so far are rather similar to conventional polyester systems. 

Trimethylcyclohe.xanone [873-94-9] (TMC-one, 3,3,5-trimethylcyclohexanone) is a saturated cyclic ketone. It is a colorless high boiler with an aromatic odor reminiscent of menthol. Trimethylcyclohexanone is only moderately miscible with water, but is miscible in all proportions with all organic solvents. It is chemically closely related to isophorone. Trimethylcyclohexanone dissolves cellulose nitrate, low molecular mass PVC grades, poly(vinyl acetate), vinyl chloride-vinylacetate copolymers, chlorinated rubber, alkyd resins, unsaturated polyester resins, epoxy resins, acrylic resins, etc. 

Isophorone [14.268], [14.269] is an unsaturated cyclic ketone. It consists of a-isophorone [78-59-1] (3,5,5-trimethyl-2-cyclohexen-l-one), which contains about 1-3% of the isomer P-isophorone [471-01-2] (3,5,5-trimethyl-3-cyclohexen-l-one). Isophorone is a stable, water-white liquid with a mild odor that is miscible in all proportions with organic solvents. It dissolves many natural and synthetic resins and polymers, such as poly(vinyl chloride) and vinyl chloride copolymers, poly(vinyI acetate), polyacrylates, polymethacrylates, polystyrene, chlorinated rubber, alkyd resins, saturated and unsaturated polyesters, epoxy resins, cellulose nitrate, cellulose ethers and esters, damar resin (dewaxed), kauri, waxes, fats, oils, phenol-, melamine-, and urea-formaldehyde resins, as well as plant protection agents. However, isophorone does not dissolve polyethylene, polypropylene, polyamides. 

A series of poly(alkylene phthalate)s and some unsaturated polyesters were also investigated by Py-GC. The major pyrolysis products for these polyesters were the associated diols and anhydrides, such as phthaUc anhydride and maleic anhydride, as well as the products formed through the six-membered cyclic transition state. Moreover, various kinds of cyclic ethers and cyclic esters were also observed in considerable quantities. The general scheme of the degradation of poly(alkylene phthalatejs is shown in Figure 5.3. ... 

Cyclic structures form on polymer backbones through 1,3-dipolar additions to caibon-to-caibon or carbon-to-nitrogen double bonds. Because many 1,3-dipoles are heteroatoms, such additions can lead to formations of five-membered heterocyclic rings. An example is addition of nitrilimine to an unsaturated polyesters ... 

An unsaturated polyester possessing exclusively cis structure was synthesized by lipase CA-catalyzed polymerization of dimethyl maleate and 1,6-hexanediol in toluene (127). During the polymerization, formation of cyclic oligomers was observed. The cycles were semicrystalline, whereas the linear polymer was amorphous. In the lipase CA-catalyzed copolymerization of dimethyl maleate and dimethyl fumarate with 1,6-hexanediol, the content of the cycliza-tion was found to mainly depend on the configuration and concentration of the monomers (128). 

The compression, impact, and fracture properties of many cured unsaturated polyester resin formulations have been studied and reviewed.The compressive strengths of the rigid cured polyesters are of the order 15,000-30,000 psi. Cyclic glycols and specialty fumarate resins tend to raise this value, while aliphatic saturated acids lower the compressive strength. For aliphatic acids, the impact strength is proportional to the acid chain length. 

The resistance of cured unsaturated polyesters to chemical attack, i.e., corrosion resistance, has been the subject of many studiesand the subject of several reviews.In general, polyester resins containing cyclic hydroxy compounds, such as hydrogenated bisphenol-A and 1,3- or 1,4-cyclohexanediol or 1,4-cyclohexanedimethanol, have improved chemical resistance.Chemical resistance may also be obtained by employing neopentyl glycol, isophthalic acid trimethyl pentanediol, and propoxylated... 

The purpose of this review is to report on the recent developments in the macromolecular engineering of aliphatic polyesters. First, the possibilities offered by the living (co)polymerization of (di)lactones will be reviewed. The second part is devoted to the synthesis of block and graft copolymers, combining the living coordination ROP of (di)lactones with other living/controlled polymerization mechanisms of other cyclic and unsaturated comonomers. Finally, several examples of novel types of materials prepared by this macromolecular engineering will be presented. 

MDI is derived from the breakage reaction of the urethane linkage drawn in Scheme 12.1c, the polyester product are formed by intramolecular rearrangement of ether bonds, eliminating cyclic oligomers, and by radical breakage of the polyester chain to partly unsaturated linear oligoethers. 

Ambrettolide is an unsaturated cyclic lactone, which readily undergoes ROMP to an unsaturated linear polyester (A/ — 95 000) in the presence of WCl6/Me4Sn (Ast 1976b, 1977a). 

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