Polymer polyaxial

Unextruded annealed polyaxial polymer exhibits a lower melting (T j) and heat of fusion (AHf) as compared to its linear counterpart. 

Crystalline copolyesters made by end-grating crystallizable segments onto amorphous polyaxial initiators exhibit a lower overall degree of crystallinity but higher tendency to crystallize from the melt into smaller crystallites as compared to their linear coimterparts. The polyaxial polymers are more suitable than linear ones for developing high-impact, more compliant biomedical devices as compared with their linear counterparts. 

However, until recently, the use of a combination of controlled branching (polyaxial chain geometry) and chain segmentation or block formation of the individual branches to produce absorbable polymers with tailored properties has been overlooked. Accordingly, for addressing this area, the synthesis and available properties of this new family of copolyesters and monofilament sutures therefrom are discussed in this chapter. 

Conceptual Designs of the Polyaxial Chain and General Examples of Polymers and Their Applications... 

In a study by Carpenter and co-workers, two types of copolyesters were made to determine the effect of a basic central group on the properties of the polymer.il Accordingly, triethanolamine (TEA) and trimethylolpropane (TMP) were used to prepare the polyaxial initiator with central amine and carbon atoms, respectively, using trimethylene carbonate (TMC) and capro-lactone (CL) as comonomers. 

Successful development of crystalline, polyaxial, absorbable polyesters with modulated compliance and unique thermal properties and microtexture are expected to lead to new applications and more effective uses of absorbable polymers as biomaterial devices, which calls for highly compliant, resilient, and/or microporous forms of textile constructs, films, and foams. 

An absorbable polymeric modifier that is compatible with the chosen cyanoacrylate to achieve a moderate-to-high preuse viscosity for ease of application, and to increase the absorption rate and compliance of tile cured adhesive for minimizing residence time at the application site and maximizing mechanical biocompatibility — for this, highly absorbable liquid oxalate polymers, such as poly(triox-yethylene oxalate) (PTOEO) and amorphous or low-melting absorbable copolyesters such as those described in Chapter 3 — polyaxial copolyesters and other copolymers based on cyclic monomers — were selected. 

As noted in Section 12.5.1, a family of polyaxial copolyesters described in Chapter 2 can be used to prepare two or more of the critical components of a femoral sealing device. Other compliant members of this family of polymers, which can be converted to compliant, stretchable membranes and strong, stretchable monofilament fibers, can be used to construct a mantle or cover for metallic endovascular stents. Thus, a composite of thin film, reinforced with a monofilament in cross-coiled configuration, can be assembled into a highly compliant, expandable, tubular mantle or sleeve. This can be placed tightly as a cover outside an expandable metallic or polymeric stent so that under concentric irreversible expansion at the desired site of... 

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