Poly (∊-caprolactone), (PCL) or simply polycaprolactone as it is usually referred to, is a synthetic biodegradable aliphatic polyester which has attracted considerable attention in recent years, notably in the biomedical areas of controlled-release drug delivery systems, absorbable surgical sutures, nerve guides, and three-dimensional (3-D) scaffolds, for use in tissue engineering. Various polymeric devices like microspheres, microcapsules, nanoparticles, pellets, implants, and films have been fabricated using this polymer. It can be transformed by spinning into filaments for subsequent fabrication of desirable textile structures. Spinning may be accomplished by various approaches. The fibers may be fabricated into various forms and can be used for implants and other surgical applications such as sutures. Although numerous studies have investigated different properties and applications of PCL, there is no comprehensive study investigating different fabrication methods of PCL fibers and their biomedical applications. The present article presents a review on the production of PCL fiber via various methods, along with correlations between structure and properties of the fibers. The applications of these fibers in biomedical domains are also discussed.

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An index Xh21 with numerator calculated solely from solubility parameters and denominator measured by on-line viscosity of the fiber precursor in coagulation medium was defined as an indicator of the fiber structure and tensile properties. The Xh 21 values of wet-spun and wound polyacrylonitrile fibers from their dimethylformamide solutions with different polymer concentrations (series A) or nonsolvent concentrations in 10 vol % polymer solutions (series B) into water with draw ratio of one were determined and compared with the corresponding fiber structure and tensile properties. The Xh 21 value of about 0.8 3 10 6 s 21 led to finger-like structure with overall fiber porosity of 82 vol %. By reducing Xh 21 through dope polymer concentration enhancement to 20 vol %, overall fiber porosity decreased to 62 vol % via substitution of some micrometer voids with dense polymer ligament. Accordingly, strong fiber modulus and elongation at break enhancement were observed due to structural defect reduction and cohesive energy density increment. On the other hand, dope nonsolvent concentration increment from 0 to 5 vol % at 10 vol % polymer concentration showed minute overall fiber porosity decrement via Xh 21 increment through micrometer void substitution with nanometer ones (nuclei). Therefore, mild fiber modulus and elongation at break improvements were detected due to defect size reduction which magnifies mechanical properties improvements. Curve fitting of the Wang's second order modulus-porosity correlation to the as-spun fibers modulusporosity data verified the solid-liquid phase separation through nuclei growth-resistance as the main governing morphological evolution mechanism.

Co-polymers of lactide and glycolide, referred to as PLGA, have generated tremendous interest because of their excellent biocompatibility, biodegradability and mechanical strength. Various polymeric devices like microspheres, microcapsules, nanoparticles, pellets, implants, and films have been fabricated using these polymers. They can be transformed by spinning into filaments for subsequent fabrication of desirable textile structures. Spinning may be accomplished by various routes. The fibers may be fabricated into various forms and may be used for implants and other surgical applications such as sutures. They are also easy to formulate into various delivery systems for carrying a variety of drug classes. The present article presents a review on the production of PLGA fiber by various methods, along with correlations between structure and properties of the fibers. The applications of these fibers in biomedical domains are also discussed.