Miscibility and Isothermal Crystallization Behavior of Poly-(L-Lactide-Co-Glycolide)/ Poly(ρ-Dioxanone) Blends

Abstract

We prepared a series of blends from solution co-precipitation of poly-(L-lactide-co-glycolide) (PLGA) and poly (ρ-dioxanone) (PPDO) at various mass ratios. Using a scanning electron microscopy (SEM), PLGA and PPDO were revealed to be immiscible. The crystallization behavior of PLGA/PPDO blends was investigated by differential scanning calorimetry (DSC) under isothermal conditions. Through comparing the crystallization exothermic peak location and the PLGA/PPDO blends' shape, the crystallization rate was determined to slow as the temperature increased. We applied the Avrami equation to analyze the primary stage of the isothermal crystallization and obtained relevant crystallization kinetic parameters. The data revealed that the PPDO component acted as nucleation sites in blends and accelerated the PLGA crystallization rate by increasing the crystallization rate constant k and decreasing the half-crystallization time (t1/2). The Arrhenius equation was used to analyze the crystallization's activation energy. Our analysis confirmed that blending with PPDO accelerates PLGA crystallization. Our micrograph imaging of the spherulites via a polarizing optical microscopy (POM) revealed that the PLGA/PPDO blends' crystals were smaller in size but greater in number than that of pure PLGA. This finding indicated that PPDO is a good nucleation agent for PLGA. All these results suggest that it is possible to control the PLGA crystallization rate by adding a PPDO component.

Fabrication of Porous Crystalline PLGA-PEG Induced by Swelling during the Recrystallization Annealing Process

“…However, there are a few ways to prepare porous materials from crystalline PLGA. The traditional way to obtain PLGA crystals is isothermal annealing, but the crystallinity of PLGA crystals is generally low. , In the crystallization of PLA, the stereocomplexation between PLLA and PDLA − and the addition of a nucleating agent are the most effective ways to improve the crystallization rate and the crystallinity of PLLA. , The nucleating agent of PLA includes talc, − montorillonite, N , N ′-ethylenebis­(12-hydroxystearamide), poly­(butylene succinate), and so forth. Apart from these, multibranched short-chain PLLA is reported to be an effective nucleating agent in PLA crystallization.…”