Abstract
Composite materials of various compositions based on chitosan and polylactide were obtained in the form of films or porous bulk samples. Preliminarily, poly-d,l-lactide was synthesized by ring-opening polymerization of lactide in the presence of Ti(OiPr)4. Polylactide obtained at components molar ratio [lactide]:[Ti(OiPr)4] = 3:1 had the best molecular weight characteristics at a high product yield. Film composition with the weight ratio chitosan-polylactide 50:50 wt. % was characterized by high mechanical properties. The value of the tensile strength of the film was 72 MPa with a deformation of 10% and an elastic modulus of 40 GPa, which is higher than the tensile strength of native chitosan by ~three times. The observed effect is a consequence of the fact that the chitosan-polylactide composite has an amorphous structure in contrast to the native chitosan, which is proved by X-ray phase analysis. An increase in the elastic modulus of the composite in the range of 20–60 °C in contrast to polylactide was found by dynamic mechanical analysis. The observed effect is apparently caused by the formation of hydrogen bonds between functional groups of chitosan and polylactide which is possible through an increase in polylactide segments mobility when its glass transition temperature is reached. The composite material is biocompatible and characterized by high cellular adhesion of fibroblasts (line hTERT BJ-5ta). Their growth on the composite surface was 2.4 times more active than on native chitosan. Bulk porous samples of the composition with the weight ratio chitosan-polylactide 50:50 wt. % were synthesized by original method in ammonium bicarbonate presence. Samples were characterized by a porosity of 82.4% and an average pore size of 100 microns. The biodegradability of such material and absence of inflammatory processes were proven in vivo by the blood parameters of experimental animals. Thus, materials with the weight ratio chitosan-polylactide 50:50 wt. % are promising for potential use in regenerative medicine.
Highlights
Mixtures of polymers are an attractive alternative for the production of new polymeric materials with desired properties, without the need to synthesize completely new materials.Other advantages of obtaining mixed compositions are versatility, simplicity, and low cost of their production
The production of polylactide with a high molecular weight and ununder conditions excluding the use of toxic catalysts is relevant for use in biomedicine
A technique was developed that ensures the production of polylactide this regard, a technique was developed that ensures the production of polylactide using using titanium isopropoxide as a catalyst [39]
Summary
Mixtures of polymers are an attractive alternative for the production of new polymeric materials with desired properties, without the need to synthesize completely new materials. Other advantages of obtaining mixed compositions are versatility, simplicity, and low cost of their production. Composites and copolymers of polysaccharides with polyhydroxyalkanoates, such as chitosan and polylactide, are of great practical and theoretical interest for biomedicine [1,2]. Chitosan is a deacetylated form of the natural biopolymer of chitin [3] and consists mainly of 2-amino-2-deoxy-β-D-glucopyranose (D-glucosamine) units. Chitosan is considered the most promising polysaccharide for biomedical applications [4]. The unique structure and properties of this natural cationic polymer make it a valuable starting material for the synthesis of graft copolymers. Chitosan and its derivatives show excellent biocompatibility, biodegradability, absence of allergic reactions, and inflammatory processes [5,6]
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