Polymers which are produced naturally or genetically from microorganisms, have a great potential in many fields of material science. One of them are coatings and films which can also be used in packaging materials (papers, boards, cardboards). Polymers like bacterial cellulose, Xanthan, Curdlan and Pullulan are polymers, produced from different bacteria, with specific properties. This group of polymers consists mainly from polyhydroxyalkanoates. Hyaluronic Acid, Poly (gamma-glutamic acid), Cyanophycin and Microbial Exopolysaccharides are well known polymers, but not commonly used in packaging field. Their applications are promising but still under research and implementation. One of the main drivers and the goal for the development of bio based coatings from different bio based polymers, is the production of materials which are fully biodegradable, made from the renewable raw materials. Fermentation of agricultural products produced by bacterial microorganisms causes the production of polymers as substrates. The applications of this products could lead to new possibilities for improving base materials, substrates such as papers, boards and cardboards. The applicability into the coating industry is still related with performance, processing and costs of such polymers. The review paper introduces new possibilities of polymers made from microorganisms, which have a potential in a coating industry.

Producers of bio-based materials are keen on replacing oil-based packaging materials with green, sustainable materials which also have improved mechanical, antimicrobial, barrier properties. One of the most nontoxic and widely used polymers are polysaccharides, chitosan being one of them. This research shows the preparation, characterisation of the chitosan and rice starch films. The aim of the research was to improve the mechanical, moisture and optical properties of chitosan, rice starch and composite chitosan-rice starch film using ultrasonic treatment. Our research was focused on the effect of ultrasonic treatment on the solutions for the preparation of the mentioned films. The results showed that an ultrasonic treatment improved elasticity, moisture resistance and that films were more transparent. Elongation at break and tensile strength increased, especially at blend films. Moreover, moisture content showed a decrease proportional to an increase in thickness with decreasing film solubility at all treated samples. The surface at untreated blend film was more uneven compared to chitosan and rice starch films, which improved after the treatment. However, preparing film solutions with ultrasound is an improved procedure to increase many properties of biodegradable films and in this form could be used as packaging materials.

Our research focused on the sorption properties of enzymatically treated viscose/chitosan and viscose fibers treated with enzymes and chitosan. To improve sorption properties of viscose fibers and to obtain the characteristics similar to viscose/chitosan fibers, we performed two different treatments. First, we treated both fibers with enzyme cellulase for 60 min and afterwards treated viscose fibers with the chitosan in an ultrasonic bath. In our research, structural characteristics and the accessibility of free adsorption places were investigated. We noted a noticeable change in the structure (degree of polymerization, crystallinity, and molecular orientation) of treated viscose and viscose/chitosan fibers. Changes that occurred in the morphology and in the structural properties of both types of tested fibers were also reflected in their physical and chemical properties. Research showed that the sorption properties of enzymatic treated fibers were improved.

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In this study, a biodegradable chitosan coating was applied to paper made from invasive alien plant species Fallopia japonica. The aim of the study was to investigate the influence of different concentrations of chitosan in the coating solution (5 wt% and 10 wt%) on the physical and mechanical properties of the paper substrate. Scanning electron microscopy was used to evaluate the influence of the coating on the microstructures and porosity of the paper. The results showed the compatibility of chitosan and paper substrate. The water and moisture resistance of coated paper substrates decreased. The tensile properties of the coated paper showed promising results at lower concentrations (5%) of chitosan. Tensile strength and elongation at break increased, mainly due to the combination of chitosan matrix and polymer chain interactions. Thermogravimetric analysis revealed thermal stability and weight changes in coated paper. A high weight loss of 20%, between 300 °C and 400 °C, was found for 5% to 10% chitosan-coated paper due to the degradation of the chitosan main chains. The coated papers had better thermal, mechanical and water resistant properties. Considering the bio-based nature of the coating and the paper substrate used, the process can offer an environmentally friendly and sustainable solution.