Enhancing the physical and structural properties of poly(glycolide-co-trimethylene carbonate-co-ε-caprolactone) copolymer fibers

Nowadays, due to the methodological needs in the application of internal surgery new methods evolving novel design for surgical suture are recommended. In this work, the effect of cold drawing process and the thermal annealing process on the different optical and structural properties of surgical suture fibers were studied. For the thermal annealing process, samples of Monosyn monofilaments suture fibers were thermally annealed at temperatures ranging from 50 to 100 ° C $$ {}^{\circ}\mathrm{C} $$ for annealing time = 120 min. The thermal treatment was carried out under free end condition. For the cold drawing process, an Instron was used to mechanically draw and measures the tensile stress strain curve of Monosyn samples. Using differential scanning calorimetry, X-ray diffraction techniques, and optical polarizing microscope the different properties of the tested sutures, such as the crystallinity, sample radius, birefringence, molecular orientation, and tensile properties were measured. From the resulting data, there was a marked increase in the physical and structural properties during the thermal annealing and cold drawing processes. This means that a new reorientation of Monosyn suture molecular chains were performed and approved by calculating the different orientations f(θ) and f_c . This is an important improvement for these biodegradable materials to widen their medical use and improve their clinical results.

A Strategy for Control of "Random" Copolymerization of Lactide and Glycolide: Application to Synthesis of PEG-b-PLGA Block Polymers Having Narrow Dispersity

Poly(lactic-co-glycolic acid) (PLGA) is a biodegradable copolymer that is also acceptable for use in a variety of biomedical applications. Typically, a random PLGA polymer is synthesized in a bulk batch polymerization using a tin-based catalyst at high temperatures. This methodology results in relatively broad polydispersity indexes (PDIs) due to transesterification, and the polymer product is often discolored. We report here the use of 1,8-diazabicyclo[5.4.0]-undec-7-ene (DBU), a known, effective, and convenient organocatalyst for the ring-opening polymerization of cyclic esters, to synthesize random copolymers of lactide and glycolide. The polymerization kinetics of the homo- and copolymerizations of lactide and glycolide were explored via NMR spectroscopy. A novel strategy that employs a controlled addition of the more reactive glycolide monomer to a solution containing the lactide monomer, the poly(ethylene glycol) (PEG) macroinitiator, and DBU catalyst was developed. Using this tactic (semi-batch polymerization), we synthesized a series of block copolymers that exhibited excellent correlation of the expected and observed molecular weights and possessed narrow PDIs. We also measured the thermal properties of these block copolymers and observed trends based on the composition of the block copolymer. We also explored the need for experimental rigor in several aspects of the preparations and have identified a set of convenient reaction conditions that provide polymer products that retain the aforementioned desirable characteristics. These polymerizations proceed rapidly at room temperature and without the need for tin-based catalysts to provide PEG-b-PLGAs suitable for use in biomedical investigations.