Formation of effective concentration of film forming superhydrophobic coatings based on silicon dioxide

The object of research is the hydrophobization of a coating based on styrene-acrylic copolymer and cellulose acetate butyrate with pyrogenic silicon dioxide. The hydrophobicity or hydrophilicity of a surface depends mainly on the chemical structure of the surface and its roughness. A relief hydrophilic surface will be wetted much more easily than a flat surface of the same material, and vice versa – an increase in the roughness of a hydrophobe is accompanied by a more pronounced repulsion of water. The size and number of irregularities significantly affect the wetting characteristics of the investigated surface. The combination of low surface energy and relief structure forms a superhydrophobic surface. Such surfaces have found application in self-cleaning, frost-resistant, antifriction, electrically conductive and oil-sorbing coatings. In this work, styrene-acrylic copolymer and cellulose acetate butyrate were used as a film former. Pyrogenic silicon dioxide Aerosil R 972, which was hydrophobized with dimethyldichlorosilane, was used as a nanofiller. In this work, the compositions were applied to laboratory glasses by dip coating. The determination of surface energy was carried out using glycerin and diiodomethane. The hydrophobic properties of the coatings were evaluated by measuring the contact angles with water using a goniometer. The analysis of the morphological structure of the coating surface with photographs of a scanning electron microscope has been carried out. The energy state of the surface of the created superhydrophobic coatings has been determined and their surface energies have been calculated using the technique based on the Owens-Wendt model. The process of hydrophobization of polymer-based coatings is investigated, which occurs both due to chemical modification with the introduction of silicon dioxide and due to the creation of nanoroughness of the surface layer of the coatings. The dependences of this process on materials are investigated using an electron microscope and the determination of their surface energy depending on the SiO2 filling. The values of the critical concentration of the modifier for the transition of polymers to the superhydrophobic state have been determined. As a result, the influence of polymer crystallinity on hydrophobization was determined by comparing changes in the surface energy of materials during their modification.

Biobased intelligent packaging application

Changes in consumer preferences in order to reach safe food have led to innovations in packaging technologies. Intelligent and active packaging is a constantly developed packaging technology that plans to offer safer and higher quality products. Active packaging refers to the inclusion of additives in the package in order to maintain and / or extend shelf life and product quality. Intelligent systems, on the other hand, are systems that monitor the status of packaged food during this entire period to provide information about the quality of the packaged during storage and transportation. The aim of this study is to produce a completely natural intelligent packaging material using rosehip extract and biopolymer, which is a substance that naturally changes color with pH. In this study, cellulose acetate butyrate biobased films containing different rates (1, 2.5, 5, 10 wt%) of rosehip extract were produced by solvent casting method. The chemical structure the rosehip containing biobased film and blank biobased film were characterized by ATR-FTIR. The transparency of prepared five different films were determined by UV spectroscopy. The color characteristic of blank and rosehip containing films measured with spectrophotometer. Surface energy of all films and contact angles were determined with goniometer. Biobased films were printed and printability parameters such as color, gloss, contact angle, surface tension were examined. It is concluded that blank biobased film is colorless, transparent and all biobased films have good printability. It was determined that the amount of rosehip extract increased the color change visibly. The biobased films obtained are pink in acidic medium and yellow-green in alkaline medium. The results prove that biobased film produced with rosehip extract and cellulose acetate butyrate can be used in intelligent packaging applications.