Blending polysaccharides with biodegradable polymers. I. Properties of chitosan/polycaprolactone blends

Abstract

Blends of polycaprolactone (PCL) and chitosan (CHT) were prepared by casting from a solution. CHT and PCL were dissolved by using acetic acid/water mixtures. Both solutions were slowly mixed to cast blend films containing 10%, 20%, 30%, and 40% by weight of CHT. PCL and CHT form phase separated blends. The phase morphology is in large extent controlled by the casting procedure. Even if casting of the film starts from a clear solution, the solvent composition determines the form in which phase separation takes place and consequently the morphology of the resulting blend after solvent evaporation. The blend containing 20% CHT presents cocontinuous phases. The sample presents a high elastic modulus even at temperatures above melting of PCL. Blends with higher CHT contents consist of disperse PCL domains in a CHT matrix and the contrary occurs in the blend containing 10% CHT in which disperse CHT domains with a network morphology appear inside the spherulites of PCL. In all the blends, the nucleation effect of CHT accelerates the crystallization of PCL from the melt, although in the blends with high CHT contents a part of the PCL mass included in large domains might not be affected by the presence of CHT. The sample containing 20% CHT has a peculiar behavior with respect to the crystallization of PCL, only a small part of PCL crystallizes in isothermal treatments although this fraction crystallizes faster than in the rest of the blends.

Endothelial and smooth muscle cells derived from human cardiac explants demonstrate angiogenic potential and suitable for design of cell-containing vascular grafts

“…This problem drew researchers’ attention to biodegradable materials, among which chitosan and polycaprolactone (PCL) found wide medical application [60]. Using a mixture of natural (chitosan) and synthetic (PCL) polymers made it possible to combine positive features of both materials [91]. Furthermore, this approach increases feasibility and reduces expense compared to standard PCL-monomer synthesis followed by polymerization.…”

Blending polysaccharides with biodegradable polymers. II. Structure and biological response of chitosan/polycaprolactone blends

“…Blending CHT with PCL allows one to obtain a system in which water sorption ability can be modulated by controlling the fraction of CHT in the system. The procedure to prepare the blends in this work was the same than in our previous work,25 although the molecular weight of PCL in this work is higher. PCL and CHT were solved in suitable solvents, aliquots of both solutions were mixed with strong stirring and the polymer blend cast from this homogenized solution.…”

“…In Ref. 25 it was shown that the crystallinity of PCL drops sharply in the blend containing 20 wt% CHT, when a PCL and CHT phase becomes cocontinuous. The size of PCL spherulites also changes suddenly around this composition as shown in SEM microphotographies of Figure 1.…”

“…CHT and PCL were blended in three different mass ratios and processed into films as described in our previous work 25. In brief, different aliquots of CHT solutions (2wt% in acetic acid at 1% v/v) were slowly added to 20 mL of PCL solutions (1.8 wt% in glacial acetic acid) to obtain 10, 20, and 30 wt%, in the PCL/CHT blend.…”

“…In our previous work,25 processing conditions to form CHT/PCL blends from high concentrations solutions of both polymers in acetic acid and water mixtures were performed and the crystallization kinetics of PCL in the CHT/PCL blends was studied by DSC showing that it strongly depends on the distribution of CHT domains. The results showed that CHT component hinder the crystallization of PCL, resulting in decreasing crystallinity of this component in the blends and the mechanical properties of the blends are improved with the addition of CHT.…”