Effect of environmental factors on the nanostructure of bioplastics

A biologist from RUDN University studied the aggressive effect of environmental factors, such as ozone, salts and water, on Ultrafine nanofibers of biopolymers.

The RUDN University biologist studied the aggressive impact of environmental factors (water, salts and ozone) on ultrafine nanofibers of biopolymers. The results will help to choose the appropriate bioplastic depending on the use; for example, for medical implants, biodegradable packaging or filters for cleaning water. Image credit: RUDN University.

These results will help to select an appropriate bioplastic depending on the application, for example filters for cleaning water, biodegradable packaging and medical implants. The results of the study were published in the Polymers newspaper.

Bioplastics are a suitable substitute for ordinary plastics. Bioplastics come from both plant waste and the food industry. Due to the safe composition of bioplastics, they are used as medical implants, as “sponges” to clean reservoirs, and as filters for liquids and gases.

Depending on the area of ​​application, bioplastics are exposed to many different environmental factors, such as water, light, physiological environment and temperature. However, the effects of the external environment on the nanostructure of bioplastic products are not yet clear. A biologist from RUDN University has just identified the impact of the environment on the nanofibers of two plastics of organic origin: polyhydroxybutyrate and polylactide.

We obtained the electrospun ultrafine fibers based on thermoelastic biopolyesters. Both produced from naturally abundant renewable resources, namely polylactide and polyhydroxybutyrate. But our main objective was not to obtain the fibers themselves, but to determine whether their properties are preserved under the impact of aggressive environmental factors..

Alexandre Vetcher, PhD, Deputy Director of the Scientific and Educational Center “Nanotechnologies”, RUDN University

Using the electrospinning method, the researchers obtained six types of fibers from polylactide granules and polyhydroxybutyrate powder. The polymer solution was placed in a high voltage electrostatic field, “pulling” the solution in thin jets. After cooling, they turned into fibers. Six forms of finished fibers were obtained and these fibers differed depending on the content of polymers in the composition, from pure polyhydroxybutyrate and polylactide to their mixtures in varying proportions.

Biologists at RUDN University studied the effect of ozone, water, and the physiological environment (internal environment of the body) on the resulting nanofibers. They discovered that the absorption of water vapor depends on the structure of the polymer. A higher proportion of polylactide causes the fibers to absorb more water, i.e. up to 1% of the weight of the sample.

To mimic the internal environment of a living organism, scientists used a phosphate buffer. Polylactide fibers lost more than 50% of their mass in solution over a 21 day period, while samples high in polyhydroxybutyrate lost less than 15%.

Polymers containing a higher polylactide content also absorbed ozone molecules faster when treated with this gas stream and the polymers were destroyed due to the intense oxidation. Ozone seeped into the fibers with a 50:50 ratio of the two fastest polymers.

We have demonstrated that biodegradable nanofibers, characterized by a crystalline structure, are more resistant to decomposition by water and ozone. It is now necessary to test the resistance of these materials to UV light and to microorganisms in order to determine the optimal applications for each type of fiber..

Alexandre Vetcher, PhD, Deputy Director of the Scientific and Educational Center “Nanotechnologies”, RUDN University

Journal reference:

Olkhov, AA, et al. (2021) Aggressive impacts affecting biodegradable ultrafine fibers based on poly (3-hydroxybutyrate), polylactide and their mixtures: water sorption, hydrolysis and ozonolysis. Polymers. doi.org/10.3390/polym13060941.

Source: https://eng.rudn.ru/