Study on the crystallization of segmented GL-b-[GL-co-TMC-co-CL]-b-GL copolymer with application as monofilar suture

Abstract

The present study reports the kinetics of both, isothermal and non-isothermal crystallization, of a biodegradable monofilar suture commercialized as MonosynTM. This polymer is constituted by hard blocks of polyglycolide and soft segments derived from glycolide, ε- caprolactone and trimethylene carbonate. Specifically, the segmented nature in copolymers improves their properties and allows their use in biomedical area as a surgical suture. First of all, the polymer was characterized by using different techniques as Gel Permeation Cromatography (GPC), Nuclear Magnetic Resonance (1H-NMR), Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC). The crystallization analyses were followed by DSC and Optical Microscopy (OM) equipped with temperature control system. The sample was crystallized from melt and glass state giving rise to spherulites which included the non crystallizable soft segment and showed different morphology depending on the crystallization temperature. Avrami analysis indicated a heterogeneous nucleation and a three dimensional growth, despite it tended to be bidimensional when isothermal crystallizations were performed under a low supercooling. The Lauritzen and Hoffman treatment was applied to determine the crystallization regimes showing high secondary nucleation constants due to the significant role of hampering from soft segment. The particular morphology of spherulites, flower-like appearance or fibrillar texture, was analyzed in detail with Atomic Force (AF) and Transmission Electron (TE) Microscopies. The present study reports the kinetics of both, isothermal and non-isothermal crystallization, of a biodegradable monofilar suture commercialized as MonosynTM. This polymer is constituted by hard blocks of polyglycolide and soft segments derived from glycolide, ε- caprolactone and trimethylene carbonate. Specifically, the segmented nature in copolymers improves their properties and allows their use in biomedical area as a surgical suture. First of all, the polymer was characterized by using different techniques as Gel Permeation Cromatography (GPC), Nuclear Magnetic Resonance (1H-NMR), Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC). The crystallization analyses were followed by DSC and Optical Microscopy (OM) equipped with temperature control system. The sample was crystallized from melt and glass state giving rise to spherulites which included the non crystallizable soft segment and showed different morphology depending on the crystallization temperature. Avrami analysis indicated a heterogeneous nucleation and a three dimensional growth, despite it tended to be bidimensional when isothermal crystallizations were performed under a low supercooling. The Lauritzen and Hoffman treatment was applied to determine the crystallization regimes showing high secondary nucleation constants due to the significant role of hampering from soft segment. The particular morphology of spherulites, flower-like appearance or fibrillar texture, was analyzed in detail with Atomic Force (AF) and Transmission Electron (TE) Microscopies. Flat-on crystals of spherulites were observed at high temperature in contrast to microcrystals with acicular form obtained at low temperatures. These observations were confirmed with electron diffraction patterns.