Catalina Natalia Cheaburu

Poly(vinyl alcohol)/chitosan/montmorillonite nanocomposites for food packaging applications Influence of montmorillonite content

Poly(vinyl alcohol) (PVA)/chitosan (CS)/montmorillonite (C30B) materials for food packaging applications were prepared by using a noninvasive and low-cost freeze/thawing method. Cloisite 30B nanoclay content in PVA/CS gels was varied in order to establish optimum amount to obtain improved properties. The structural, morphological, rheological aspects, thermal stability, and antimicrobial activity were investigated using various techniques as Fourier transform infrared, scanning electron microscopy, rheology, thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical thermal analysis, and antibacterial tests. It was noticed that the obtained materials show an intercalated structure with specific interactions between components and nanoclay incorporation led to an increased thermal stability, mechanical properties, and excellent antimicrobial activity against Escherichia coli, Listeria monocytogenes, and Salmonella typhimurium due to synergistic action of CS and nanoclay.

Characterisation of the Chitosan/layered silicate nanocomposites

Characterization of chitosan / layered silicate nanocomposites obtained by solution-mixing technique, having different compositions including treated and untreated montmorilonite (MMT) has been performed. The optimum amount of MMT and also the effect of nanoparticles type on nanocomposite properties by DSC, X-ray diffraction and TG measurements have been established. The chitosan chains were inserted into silicate layers to form the intercalated nanocomposites. The interlayer distance of the silicates in the nanocomposites enlarged as their amount increased. The stiffness and thermal stability enhanced.

Nanocomposites Based On Montmorillonite/Acrylic Copolymer for Aqueous Coating of Soft Surfaces

Nanocomposites based on layered silicate organically modified montmorillonite (Cloisite 20A) and acrylic comonomers (butyl acrylate and methyl methacrylate) were prepared by simple “in situ” batch emulsion polymerization method. The particle size and zeta potential of the emulsions were analyzed. The structural characterizations of the nanocomposites were performed by FTIR, thermal behaviors of the films were investigated by DSC, mechanical properties of the films were tested by DMA and intercalation success was viewed by XRD. The mechanical properties of the nanocomposites were improved significantly especially at the temperatures above Tg. The ultrasonication process was found to be useful for increasing the homogeneity of the emulsions and intercalation success. The obtained nanocomposite emulsions were applied on garment leathers in a finishing formulation as aqueous binders sharing good film forming ability and elasticity.

Evaluation of crosslinked chitosan hydrogels as carriers for prolonged delivery of some novel nitric oxide donor compounds based on theophylline and paracetamol

Abstract The hydrogels of crosslinked chitosan with different glutaraldehyde amounts have been “in vitro” tested as carriers for prolonged release of some drugs for inflammatory and bronchopulomonary diseases. These hydrogels have been loaded with two novel nitric oxide donors, derivatives of 7-[2-nitroxyacethyloxy- 3-(4-acethyl-amino-phenoxy)-propyl]-8-R-1,3-dimethyl-xanthine compounds (R=H, NO2 for 65 and respectively 77 compounds) designed as multitarget drugs and parent compounds as paracetamol, theophylline, two xanthine derivatives 7-[2- hydroxy-3-(4-acethyl-amino-phenoxy)-propyl]-8-R-1,3-dimethyl-xanthine derivatives with (R=H, NO2 for D1 and respectively D2) and their release was evaluated in an acidic solution (pH=2.2) simulating the gastric fluid. Results have been correlated with the swelling behaviour which was also followed in acidic media with pH=2.2. The relationships between the release profiles and kinetics and matrix characteristics and/or drug properties have been established.