Vinyl polymers are generally considered resistant to biodegradation, with some exceptions. Their biodegradation requires an oxidation process, and most biodegradable vinyl polymers contain readily oxidizable functional groups. However, polyvinyl alcohol (PVA) is an exception and can undergo biodegradation relatively easily.
Studies have shown that PVA biodegradation occurs under the influence of the soil bacterium Pseudomonas. The first step in the biodegradation process is the oxidation of the secondary alcohol groups to ketone groups. Subsequent hydrolysis of these ketone groups leads to cleavage of the polymer chain.
Moreover, PVA can form complexes with many components and is used as a detoxifying agent in organisms. It is commonly applied in low-molecular-weight form (below 15,000) and excreted from the organism through the kidney. Additionally, PVA is used as a polymer carrier for plant protection, such as herbicides and pesticides.
In contrast to PVA, other vinyl polymers are not readily biodegradable. Therefore, the focus has been on developing biodegradable alternatives to these polymers. One such alternative is polyhydroxyalkanoates (PHAs), which are a group of naturally occurring polyesters synthesized by microorganisms. PHAs have similar properties to traditional plastics but are biodegradable under natural conditions. They can be produced by bacterial fermentation and have shown potential for use in packaging, agriculture, and medical applications.
Another alternative to non-biodegradable vinyl polymers is polycaprolactone (PCL), a polyester that has been thoroughly examined as a biodegradable medium and matrix for controlled drug-release systems. Studies have shown that PCL can be broken down enzymatically. Due to its biodegradability and low toxicity, PCL has potential applications in medical and environmental fields.
In conclusion, while most vinyl polymers are resistant to biodegradation, some exceptions such as PVA exist. To overcome the environmental impact of non-biodegradable vinyl polymers, alternative biodegradable polymers such as PHAs and PCL have been developed and studied for potential applications in various fields.