Lactide—dioxanone copolymer

Figure 2.12 Copolymerization reaction steps of lactide-dioxanone copolymer (Bezwada, 1995).

Absorbable suture materials are catgut (collagen derived from sheep intestinal submucosa), reconstituted collagen, polyglycolide (e.g., Dexon , Dexon II , Dexon S ), poly(glycolide/lactide) random copolymer (e.g.. Vicryl ), antimicrobial-coated Vicryl (Vicryl Plus ), poly-/ -dioxanone (e.g., PDS , PDSII PDS Plus), poly(glycolide/trimethylene carbonate) block copolymer (e.g., Maxon ), poly(glycolide/e-caprolactone) (e.g., Monocryl ,... 

Figure 6 Poly(p-dioxanone-co-(L-) lactide) segmented copolymers.

Poly(p-dioxanone-co-lactide) segmented copolymers m p, and the poly(p-dioxanone) portion 70-98 wt %... 

Bezwada, R.S., Cooper, K., 1997. High strength, melt processable, lactide-rich, poly(lactide-co-p-dioxanone) copolymers. U.S. Patent 5 639 851, U.S. Patent Office. 

Poly-p-dioxanone and copolymers Poly-p-dioxanone (PDS) Copolymers of PDS and 1-lactide Copolymers of PDS and glycolide Poly-p-dioxanone-co-morpholine-2,5 dione Copolymers of p-dioxanone and polyethlyene-p-phenylene diglycolate Copolymers of polytrimethylene malonate and p-dioxanone A, B, F, G A, B, G A, B, G A, B, G A, B, G, J A, B, G, H... 

Some of these pol miers and copolymers do not possess the mechanical properties that are required for certain applications. For example, as implants for soft tissue poly(lactide)s, poly(glycolide)s, PCL, poly(dioxanone) and their copolymers may require increased flexibiUty and a modulus of elasticity that is closer to soft tissue. 

Monocryl Plus), and poly(gycolide/p-dioxanone/trimethylene carbonate) triblock copolymer (e.g., Biosyn ), poly(glycolide/ -caprolactone/trimeth-ylene carbonate) triblock copolymer (Monosyn ), poly(glycolide/L-lactide/ -caprolactone/trimethylene carbonate) teriblock copolymer (Caprosyn ), and 100% poly-L-lactide (Orthodek ) (Chu et al., 1997). 

Like poly(p-dioxanone) homopolymer, copolymers of PDO and lactide can be prepared by several conventional polymerization means. The most commercially viable method relies upon melt polymerization. Since a thermodynamic equilibrium between the monomer (p-dioxanone) and the polymer [poly (p-dioxanone) ], results during polymerization (Bezwada et al, 1987, 1990) in conversions ranging from... 

Thus, to a dry, round bottom, two neck flask, 95 grams of p-dioxanone, 0.197 ml of 1-dodecanol, and 0.0975 ml of stannous octoate (0.33 molar in toluene) are added. The stirred reaction mixture is heated under nitrogen for 6 hours at 100 C. Five grams of L(-) lactide are added to the reaction mixture, and the temperature is raised to 140°C and maintained there for 2 hours. The copolymer is isolated, ground, and vacuum dried for 48 hours at 80°C. 

Extrusion of the poly (p-dioxanone-co-L(-) lactide) segmented and random copolymers was performed in a similar fashion as that of poly (p-dioxanone). The tensile properties were determined with an INSTRON tensile tester. The breaking strength retention (BSR) in vivo of the fibers was determined by implanting two strands of the fiber in the dorsal subcutis of each of a number of Long-Evans rats. 

Segmented copolymers of p-dioxanone/glycolide (Bezwada, Shalaby and Newman, 1987) can be prepared by a similar method as segmented copohnners of p-dioxanone/L(-)lactide. Firstly, p-dioxanone (PDO) monomer is melt pohnner-ized to produce a mixture of poly(p-dioxanone) homopolymer and pedioxanone monomer. 

Molecular weights and viscosities can be controlled by the type of initiator and by the ratio of initiator to monomer. Handling properties of the coating copolymers can be controlled by changing the mole ratios of p-dioxanone, lactide and glycolide. 

The resulting poly(p-dioxanone-co-lactide) copolymer was cooled to room temperature under a stream of nitrogen, isolated, and dried for 96 hours at 80°C under vacuum (0.1 mm Hg) to remove any unreacted monomers. The copolymer had an inherent viscosity of 0.11 dL/g. 

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