Agriculture is undergoing a major transformation as researchers and industries search for sustainable alternatives to conventional plastic-based materials. Within the PHAntastic project, one promising approach is the development of biodegradable delivery systems based on polyhydroxyalkanoates (PHAs), a family of biobased and biodegradable polymers produced by microorganisms. These materials have the potential to replace persistent petroleum-based plastics while offering advanced functionalities for agricultural applications.
At Chalmers University of Technology, our work focuses on developing PHA-based capsules and foams capable of delivering active compounds such as biostimulants, nutrients, probiotics or elicitors directly to crops and soils in a controlled and environmentally friendly way. Beyond simply replacing plastic, the goal is to create materials with carefully engineered structures that can influence how active compounds are released over time.
Why delivery systems matter in agriculture
Modern agriculture relies heavily on fertilizers, pesticides, and growth-promoting agents. However, many of these compounds are applied inefficiently, resulting in losses to the environment through leaching, volatilization, or degradation before plants can fully benefit from them.
Delivery systems can help address these challenges. By encapsulating active ingredients inside biodegradable matrices, it becomes possible to protect sensitive compounds and regulate their release depending on environmental conditions such as humidity, temperature, or microbial activity.
PHA materials are especially attractive because they combine biodegradability, biocompatibility, and tunable material properties. Unlike conventional plastics, PHAs can naturally degrade in soil environments, reducing long-term accumulation and environmental pollution.
Developing biodegradable capsules and foams
One of the key challenges in this work is designing processes capable of transforming PHA into structures suitable for agricultural applications. (Link to our recent review paper.) Depending on the desired function, the material can be processed into compact capsules or lightweight porous foams.
The development process involves optimizing several parameters, including polymer formulation, temperature, mixing conditions, and processing techniques. Small modifications during manufacturing can strongly influence the final morphology and performance of the material.
For capsule production, we investigate methods that allow active ingredients to be efficiently encapsulated while maintaining structural integrity during handling and storage and preserving the functionality of the compounds.
Flexible foam. Photo: Chalmers University
Foam production presents a different challenge. Agricultural foams require highly porous structures that can retain water, protect active compounds, and provide a large surface area for interaction with the environment. Achieving this balance requires careful control of pore formation and material expansion during processing.
An important aspect of our research is incorporating sustainable additives and biobased components to further improve functionality while maintaining biodegradability.
Looking closer: the importance of microscopic structures
While these materials may appear simple to the naked eye, their internal structures are highly complex. Microscopy techniques play a crucial role in understanding how processing conditions affect material architecture and performance.
By using scanning electron microscopy (SEM) and optical microscopy, researchers can observe features such as pore size distribution, wall thickness, surface roughness, and capsule morphology (see picture below). These microscopic characteristics directly influence properties including mechanical resistance, water absorption, degradation rate, and controlled release behavior.
PHAntastic capsules
For example, highly interconnected porous structures in foams may enhance water retention and accelerate biodegradation, while denser capsule walls may provide slower and more controlled release of encapsulated compounds. Microscopic analysis also helps identify structural defects that could compromise material performance. Air bubbles, collapsed pores, or uneven dispersion of additives can all affect the final functionality of the delivery system.
Understanding these structure–property relationships is essential for scaling up production and tailoring materials for different agricultural applications.
Towards sustainable agriculture
The development of biodegradable PHA delivery systems represents an important step toward more circular and sustainable agricultural practices. By combining renewable materials, advanced processing technologies, and detailed structural characterization, the PHAntastic project aims to create next-generation agricultural materials that reduce environmental impact while improving efficiency. As research progresses, these materials could contribute to reducing plastic waste in agriculture and supporting smarter delivery of bioactive compounds in the field.
In future studies, the team will continue optimizing formulations and processing methods while investigating how these materials behave under real agricultural conditions. Understanding how microscopic structures influence large-scale performance will remain a key part of this journey toward sustainable agricultural innovation.
Written by: Chalmers University
