LACTONE POLYMER

Koleske, J. V., and Lundberg, R. D., Lactone polymers. II. Hydrodynamic properties and unperturbed dimensions of poly-e-caprolactone, J. Polym. Sci., Part A-2. 7, 897-907, 1969. 

Davis, P. A. Nicolais, L., Ambrosio, L., and Huang, S. J., Synthesis and characterization of semi-interpenetrating polymer networks of poly(2-hydroxyethyl methacrylate) and poly(capro-lactone), Polym. Mater. Sci. Eng., 56, 536-540, 1987. 

Theee two reaotiona ( and C) oait be compared to the formation of cyclic anhydro caib< ates or sulfites from a-hydmxy acids these cydic derivatives deoompoee to give a-lactone polymers ... 

Is a remarkably easy anionic, ring-opening reaction that takes place rapidly and completely In organic media at mild temperatures. Since It appears to be similar to other 3-lactones In Its polymerization and the properties of Its polymers have been more widely studied than those of other 3-lactone polymers, the formation and properties of polyplvalolactone will be emphasized In this discussion. 

Low molecular weight head-to-tail poly (y-crotonolactone), VIII, was prepared for comparison with the lactone polymers prepared in this study. The IR spectrum of the anionically prepared material (VIII), with strong absorptions in the region 1760 and... 

A compilation of the unsubstituted lactone polymers, the enzymes used, and the corresponding citation(s) is given in Table 4.2. 

Lactones. Polymer supports have been tested as media for cyclizations of a>-hydroxy-alkanoic acids to lactones (Equation 30). Lactones larger tlum 7-membeied are difti-cult to prepare because of a large decrease in entropy. There is also an unfavorable enthalpy of cyclization to the strained 8-12 membered rings. The side reactions that conqrlete with unimolecular cydization are bimolecular formation of cyclic and acyclic dimers and higher oligomers (Equations 30 and 31). 

Around 110 megatons (Mt) of CO2 are annually used in commercial synthesis processes, to produce urea, salicylic acid, cyclic carbonates, and polycarbonates. The largest use is for urea production, which reached around 90 Mt/yr in 1997. In addition to these applications, there are a number of promising reactions currently under study in various laboratories, reactions that differ in the extent to which CO2 is reduced during the chemical transformation. They include the synthesis of commodities and intermediates (acetic acid, methanol, carbonates, cyclic carbonates, and lactones), polymers (polyurethanes, polypyrones) and a variety of functionalized carboxylic acids (propenic acid, 3-hexen-l,6-dioic acid). A more detailed description can be found in the cited review. ... 

Koleske J V, Lundberg R D (1969), Lactone polymers. I. Glass transition temperature of poly-e-caprolactone by means on compatible polymer mixtures , J Polym Sci, Part A-2, 7, 795-807. 

When weak bases or ammonium carboxylates are used as initiators, a similar mechanism has been observed which involves the carboxylate anions responsible for propagation. Subsequently, it was confirmed that, in the case of a,a -dialkyl-P-propiolactone, no chain transfer could occur as a-proton abstraction could no longer take place [29]. Interestingly, a similar result was recently highlighted by Guerin et al. who showed that, compared to poly(malolactonate) (as obtained from a,a, P-trisubstituted P-lactones), polymers prepared by the ROP of P-lactones without substitution in the a-position were characterized by major discrepancies between the experimental molecular weights and the theoretical values expected for a controUed/ Uving polymerization (see below) [30]. 

S, (2002) lipase-catalyzed ring-opening polymerization of substituted lactones. Polymer Journal, 34(11), 835-40,... 

---