Trimethylene carbonates

Poly(glycolide-co trimethylene carbonate). Another successful approach to obtaining an absorbable polymer capable of producing flexible monofilaments has involved finding a new type of monomer for copolymerization with glycoHde (42). Trimethylene carbonate polymerized with glycoHde is shown below ... 

In order to achieve the desired fiber properties, the two monomers were copolymerized so the final product was a block copolymer of the ABA type, where A was pure polyglycoHde and B, a random copolymer of mostly poly (trimethylene carbonate). The selected composition was about 30—40% poly (trimethylene carbonate). This suture reportedly has exceUent flexibiHty and superior in vivo tensile strength retention compared to polyglycoHde. It has been absorbed without adverse reaction ia about seven months (43). MetaboHsm studies show that the route of excretion for the trimethylene carbonate moiety is somewhat different from the glycolate moiety. Most of the glycolate is excreted by urine whereas most of the carbonate is excreted by expired CO2 and uriae. 

Polyglyconate (5) is made by the bulk copolymerisation of a mixture of 67% glycoHde and 33% trimethylene carbonate. The suture is distributed under the trade names Maxon and Maxon CV. It is claimed to retain approximately 50% of its strength four weeks after implantation, 25% at six weeks, and to be essentially completely absorbed ia six months. 

Glycomer-631 (6) is a terpolymer produced by the bulk polymerisation of a mixture of 60% glycoHde, 14% 2,5- -dioxanone, and 26% trimethylene carbonate. The suture is distributed under the trade name Biosyn. It is claimed to retain approximately 40% of its strength three weeks after implantation and to be absorbed completely in 90 to 110 days. 

Poly(1,3-Trimethylene Carbonate) and Their Copolymers with D,L-Eactic Acid Ande-Caprolactone.230... 

POLYd, 3-TRIMETHYLENE CARBONATE) AND THEIR COPOLYMERS WITH d,l-LACTIC acid ANDE-CAPROLACTONE... 

SCHEME 8.7 Synthesis of statistical poly(trimethylene carbonate-co-caprolactone). 

Pego AP, Poot AA, Grijpma DW, and Feijen J. Copolymers of trimethylene carbonate and epsilon-caprolactone for porous nerve guides Synthesis and properties. J Biomater Sci Polym Ed, 2001, 12(1), 35-53. 

Pego AP, Siebum SB, Luyn MJAV, et al. Preparation of degradable porous structures based on 1,3-trimethylene carbonate and D,L-lactide(co)polymers for heart tissue engineering. Tissue Eng, 2003, 9, 981 994. 

Pego AP, Luyn MJAV, Brouwer LA, et al. In vivo behaviour of poly (1,3-trimethylene carbonate) and copolymers of 1,3-trimethylene carbonate with D,L-lactide or e-caprolactone Degradation and tissue response. J Biomed Mater Res, 2003, 67A, 1044—1054. 

Storey RF and Hickey TP. Degradable polyurethane networks based on D,L-lacdde, glycohde, e-caprolactone, and trimethylene carbonate homopolyester and copolyester triols. Polymer, 1994, 35, 830-838. 

Table 2 Ring-opening polymerization of lactones initiated by lanthanide complexes (CL = e-caprolactone LA = lactide TMC = trimethylene carbonate). 

These representative aliphatic polyesters are often used in copolymerized form in various combinations, for example, poly(lactide-co-glycolide) (PLGA) [66-68] and poly(lactide-co-caprolactone) [69-73], to improve degradation rates, mechanical properties, processability, and solubility by reducing crystallinity. Other monomers such as 1,4-dioxepan-5-one (DXO) [74—76], 1,4-dioxane-2-one [77], and trimethylene carbonate (TMC) [28] (Fig. 2) have also been used as comonomers to improve the hydrophobicity of the aliphatic polyesters as well as their degradability and mechanical properties. 

Fig. 3 Examples of monomer units having reactive side-chain groups, which can be copolymerized with polyesters (a) a-malic acid, (b) [S-malic acid, (c) a-carboxyl- -caprolactone, (d) carboxy lactic acid, (e) trimethylene carbonate derivative, and (1) depsipeptide...

Meanwhile Ethicon (and others) developed alternative absorbable surgical sutures, based, for example, on copolymers of polyglycolide with poly-L-lactide or poly(trimethylene carbonate), and on polydioxanone, and on poly(e-oxycaproate), and also on copolymers of these with polyglycolide or with each other. These different structures made it possible to provide fibres with different rates of absorption, with different degrees of stiffness or flexibility, and for use in monofilaments, braided multifilaments, and other yam structures, as required for different surgical operations. 

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... 

Kricheldorf FIR, Ahrensdorf K, Rost S (2004) Star-shaped homo- and copolyesters derived from e-caprolactone, L,L-lactide and trimethylene carbonate. Macromol Chem Phys 205 1602-1610... 

Scheme 6.39 Ring-opening poiymerization of trimethylene carbonate and 5-vaieroiactone, respectiveiy, catalyzed by a thiourea derivative 40 in the presence of a base.

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