Biobased, Biodegradable and Bio-Insect Repellent Polymers as an alternative to conventional chemical pesticides – BIO_III

Every year, crops are attacked by dangerous pest species, resulting in significant economic losses and risks. Aphids, for example, are among the most damaging taxa. Their control is challenging because of their specific feeding behaviour and unusual reproductive biology. Current control strategies, based on extensive use of chemicals, are considered unsustainable for sustainable agriculture due to the negative impacts on the environment and human health. Moreover, this approach has led to increasing insect resistance to pesticides. Therefore, there is a need for new solutions for pest control. The French national "EcoPhyto" plans and the "Farm to Fork" strategy of the European Greendeal have the common goal of reducing and replacing pesticides and promoting new solutions for sustainable agriculture.
In recent years, alternatives to reduce the use of chemicals and pesticides have been developed through the development of physical barriers, such as the use of insect nets, which are mainly made of high-density polyethylene. However, this is a palliative measure that involves the disposal of such waste materials. Since such polymeric materials are often placed on plants and sometimes buried in the ground, it is troublesome to collect them separately from plant debris and soil. They must then be stored for at least three years, until the amount of chemicals and pesticides has decreased, before they can be recycled at low cost. Currently, European countries are encouraging the industry to rethink its production methods to reduce the use of fossil resources and minimise the environmental impact of products throughout their life cycle. For these reasons, new French and European regulations, as well as environmental issues such as plastic pollution, pose a real challenge to the development of new bio-based and/or compostable materials for different market segments. As a result, bio-based materials are on the rise, mainly based on plant components, i.e. from annually renewable sources (sugar cane, corn, oils, etc.). However, these bio-based materials do not have suitable properties to be easily processed and suitable for applications that require combined performances such as specific mechanical properties and additional functions such as insect repellency. Biobased textile fibres today are mostly based on polylactic acid (PLA) due to its rheological and melting properties. Natureworks' Ingeo® fibre, for example, is well known for apparel (socks), furniture (bedding) and technical applications (roofing and geotextiles). However, the mechanical properties of PLA fibres drastically limit their potential for use in technical textiles compared to fossil-based polyethylene fibres, which can achieve high strength values.
Therefore, the challenge of the BIO_III project is to overcome these limitations by developing biodegradable and bio-based textile fibres that exhibit multifunctionality, i.e., high strength and insect repellency. Due to their bio-based and biodegradable nature, PLA and then polybutylene succinate adipate are being considered as they are certified as "OK compost" and "OK compost HOME" respectively. In this way, polyester-based fibres are going to be processed into knitted fabrics that have an excellent surface-to-volume ratio and allow the release of natural molecules. To address these two challenges, a new generation of bio-based and biodegradable polymers is being developed that contain bio-insect repellents derived from the fraction of sweet potato aerials parts containing caffeic acid compounds.