Chitosan-g-oligolactide copolymers with relatively long oligolactide grafted chains of various stereochemical compositions have been synthetized via a solvent-free mechanochemical technique and tailored to fabricate three-dimensional hydrogels using two-photon induced microstereolithography. An effect of the characteristics of chitosan and oligolactide used for the synthesis on the grafting yield and copolymer’s behavior were evaluated using fractional analysis, FTIR-spectroscopy, dynamic light scattering, and UV-spectrophotometry. The lowest copolymer yield was found for the system based on chitosan with higher molecular weight, while the samples consisting of low-molecular weight chitosan showed higher grafting degrees, which were comparable in both the cases of l,l- or l,d-oligolactide grafting. The copolymer processability in the course of two-photon stereolithography was evaluated as a function of the copolymer’s characteristics and stereolithography conditions. The structure and mechanical properties of the model film samples and fabricated 3D hydrogels were studied using optical and scanning electron microscopy, as well as by using tensile and nanoindenter devices. The application of copolymer with oligo(l,d-lactide) side chains led to higher processability during two-photon stereolithography in terms of the response to the laser beam, reproduction of the digital model, and the mechanical properties of the fabricated hydrogels.
The aim of the present study was to investigate an ability of chitin nanocrystals to be used as stabilizing components for fabrication of poly(L,L-lactide) microparticles via the Pickering oil/water emulsion solvent evaporation technique. The anisometric chitin nanocrystals were extracted from two different samples of crab shell chitin via acetic hydrolysis and analyzed using atomic force microscopy, dynamic light scattering, and FTIR spectroscopy. The extracted nanocrystals showed no difference in the chemical structure but possessed different morphology and aspect ratios as a function of raw chitin used. The effect of chitin nanocrystals characteristics and concentration in the aqueous phase on the total yield, size distribution, and shape and surface morphology of the prepared polylactide microparticles was evaluated.
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