Plastics are woven into nearly every part of modern life, from packaging and clothing to buildings and cars. Made from petroleum, they persist as waste for centuries, fragmenting into pieces now found in crop fields, deep-sea fish, and even human blood. Yet their low cost, durability, and versatility make them difficult to replace. Scientists are now turning to eco-friendly plastic alternatives made from naturally-sourced materials, called bioplastics. However, these bioplastics are typically weak, temperature-sensitive, and difficult to manufacture on a large scale.
Researchers at Northeast Forestry University in China are exploring a new type of bioplastic made from bamboo that retains its distinctive strength and flexibility. Their low-energy production process creates fully recyclable bioplastics that could replace conventional plastics, ranging from simple household items to demanding industrial uses.
The team began by extracting the long, bundled chains of a plant molecule called cellulose that are tightly bound to other plant tissues within the bamboo chips. They washed away the binding using peroxyformic acid, then they neutralized it immediately to prevent chemical damage to the cellulose bundles. This washing step also removed plant cells attached to the bundles, which can disrupt the structure and weaken the resulting bioplastic.
Once the cellulose bundles were broken apart, the researchers treated them with a special mixture of formic acid, zinc chloride, and water, known as a deep eutectic solvent or DES. Here, zinc chloride acts like a molecular unzipper, breaking the hydrogen bonds that entangle cellulose chains. Formic acid plays a supporting role by stabilizing these loosened fibers and temporarily preventing the bonds from reforming, allowing the cellulose chains to rearrange more uniformly.
They then added calcium chloride as a new zipper slider, reforming the hydrogen bonds between the reorganized chains. At the same time, this also created additional physical bridges within the structure, forming a reinforced 3D network called a hydrogel. Together, the DES and calcium chloride functioned as a two-way molecular zipper, gently disentangling and then rebuilding the cellulose network. This process improved the structure’s uniformity without the high temperatures, pressures, and harsh chemicals that industries typically use to process cellulose.
The researchers then immersed the hydrogel in ethanol to stimulate the gel, causing the cellulose chains to tighten and set as the ethanol pulled water out of it. This final step transforms the flexible hydrogel into a denser, rigid bioplastic. With its structure fixed, the team then evaluated how this transformation affected the bioplastic’s mechanical performance.
Their tests showed that converting the hydrogel into a bioplastic dramatically improved its mechanical performance. They observed that the bioplastic was 5 times harder and could withstand over 11 and 1,150 times more stretching and bending forces before it failed. Unlike a soft gel that deforms easily, the bioplastic also resisted changes in shape by over 1,290 and 3,330 times under the same forces.
To explore its potential range of applications, the researchers next exposed the bioplastic to different environmental conditions. They kept separate samples for 7 days at either a low temperature of -30°C (-22°F) or a high temperature of 100°C (212°F). In both cases, the bioplastic didn’t melt or become brittle. It was able to twist and bend even at temperatures above 250°C (482°F), exceeding the maximum working range of most conventional plastics. The bioplastic also maintained its shape and structural integrity after spending 30 days in a high-humidity environment and after 7 days of exposure to harsh acids and solvents.
Beyond performance, the researchers demonstrated that they can mold and cast their bioplastic using methods similar to those used for conventional plastics, without the need for high temperatures and pressures. The scraps from the fabrication process are highly recyclable, as both the bioplastic fragments and the DES can be recovered and reused. When the team produced new bioplastics from recycled components, the material had comparable mechanical properties to those made from fresh components.
Taking it a step further, they also buried the bioplastics in soil to examine what happens upon disposal. Unlike petroleum-based plastics that persist for centuries and other bioplastics that only partially degrade, the bamboo-based bioplastic completely decomposed in soil within 50 days.
The team concluded that bamboo can be transformed into recyclable bioplastics through a scalable, sustainable synthesis process. With its exceptional mechanical performance and environmental stability, the bamboo-based bioplastic is a potential alternative to commercially available plastics that can outperform them in industrial and household uses while reducing pollution and dependence on petroleum.
