Cleantech For Dirty Problems: The Quest For Biodegradable Diapers

How are innovators are now rethinking one of the most widely used yet environmentally damaging products – nappies. 

Written by José Manuel Salvador López

EDITED by ARIYANA RAYATT

04 November 2025

What is dirtier than a dirty diaper? A landfill full of dirty diapers.  Innovators are now rethinking one of the most widely used yet environmentally damaging products – nappies. 

From production to disposal, nappies have a huge toll on the environment, being considered one of the largest culprits for plastic waste, with over 300,000 disposable nappies being disposed of each minute. Where is the destination for this waste? It is either landfills or oceans. This waste will disrupt ecosystems and pose risks to human health by contaminating waterways or by releasing toxic chemicals. In short, the nappy economy is unsustainable, using non-renewable source material, and producing non-recyclable waste.
This industry has no sign of stagnating, with the disposable nappy market valued at over $60 billion, and the ageing population is signalling a growing market for adult protective briefs. Some people advocate for returning to reusable nappies, but these come with different problems, such as the associated environmental impact of cleaning. In a fast-paced world, it is clear that convenience is a huge selling point for disposable nappies, with 95% of families in developed countries opting for disposable nappies.

The development of a circular economy for nappies offers an alternative for a future with the convenience of disposable nappies without the waste. Amaury van Trappen, CEO & co-founder of A&B Smart Materials Limited, is working to make this future a reality.

The Issue With Modern Nappies

The first disposable nappies were composed of an external waterproof layer and an internal water-absorbent layer, and they aimed to be more efficient than their predecessors. The different layers used in nappies have evolved into what we can see today in modern nappies, where several layers of different materials are woven together.

Every layer has a purpose. The outer shell is soft to the touch for caregivers, while just beneath it, a waterproof barrier keeps leaks and messes contained. Deeper inside, absorbent layers pull moisture away from the baby’s skin, locking it in place so they stay dry and comfortable. The innermost layer strikes a delicate balance: it lets urine pass through but holds onto a touch of natural moisture, protecting the skin from irritation.

The biggest leap in nappy technology came with the invention of super-absorbent materials like sodium polyacrylate, which can soak up many times its weight in liquid without releasing it under pressure. This innovation transformed nappies into the efficient, leak-proof products we rely on today. But it came at a cost: the petroleum-based plastics that make modern nappies possible also tie the industry to the massive oil consumption – an estimated 248 million barrels of crude oil every year.

 

Since current options for disposable nappies are petroleum-based and non-biodegradable, some people advocate for the use of reusable nappies. However, these come with their own baggage, with their reuse being associated with high energy and water consumption.

An alternative to current products is the development of biodegradable and compostable nappies that can be easily disposed of in an environmentally friendly manner. This is where Amaury believed A&B Smart Materials can step in. With their biobased Super Absorbent Polymer (SAPs), A&B Smart Materials are developing an absorbent material that is just as effective as those currently on the market, whilst also being biodegradable. 

Super Absorbent Polymers

The “super absorbent” part of SAP’s name is clear – these materials can absorb large amounts of water, making them perfect for nappies. and adjacent fields. The “polymer” portion of the term gives a clue as to how they work. Polymers are large molecules composed of smaller molecules chained together. The chemical composition, but also the structure of these chains, plays an important role in the absorbent properties of the material.

Until the 1920s, water-absorbing materials were fibre-based products, such as tissue paper, cotton, sponge, and fluff pulp. Fibres are essentially an ordered molecular structure, with the polymer chains oriented in the same direction. Fibre-based absorbent materials absorb less water, and release it more easily under pressure, like a wet sponge when it’s squeezed. However, unlike SAPs, the sponge has a lower absorbent capacity, and will easily release the absorbed water when pressure is applied. 

Beads of SAP material, which will swell when absorbing water. Renato Lombardero, CC BY 2.0 , via Wikimedia Commons

 

SAPs are characterised by a chaotic molecular structure. The chaos is possible because of cross-linker molecules that bind different polymer molecules in different positions. This is the case with sodium polyacrylate and the other plastic-like materials that can be used as SAPs. Cross-linking gives SAPs their water retention power, which is critical to preventing leaks and reducing skin irritation. 

These chaotic chemical structures can be made with natural materials with a few chemical modifications. Natural compounds such as cellulose, starch, chitosan, and proteins have been used to generate SAPs. A&B Smart Materials are following nature’s lead and are using widely available natural compounds to improve their water absorption and retention properties. Amaury, went on to tell us, “We are using a source material and changing it, enhancing their properties from a chemistry angle to arrive at high performances at the price parity of synthetic alternatives.”

Developing Sustainable SAPs

In A&B Smart Materials, they are busy researching new ways to improve their SAPs further to meet the needs of their application in nappies. With both performance and environmental impact at the forefront of mind, A&B Smart Materials are testing factors that might affect biodegradability as well as absorbent capacity.

Image of SAPs being developed by A&B Smart Materials, showing their increase in volume after absorbing water.

 

While the absorbent capacity of their product is already very close to industrial standards, Amaury explains that “When you add salt to water, it is more difficult for the material to absorb, but that’s what diaper manufacturers are looking for [because urine is saline]. And they are also looking for absorption under centrifuge and also under pressure because when you sit on a diaper, you want to make sure the water stays in it.”

Expanding The Horizon Of Sustainable SAPs

A&B Smart Materials is not the only company looking at SAPs, with companies like Zymochem and Ecovia also developing SAPs with polyglutamic acid (PGA)–based materials, which require large-scale fermentation, while other start-ups pursue utilising waste-stream for agricultural use.

The impressive soaking ability of SAPs is not only used in nappies, menstrual pads, and other hygienic products, but SAPs are also used across a variety of industries. For example, SAPs can be mixed with concrete to promote self-healing of building structures. They can also be used to generate microcapsules to liberate drugs inside the body in a controlled manner. Another important application is in agriculture, where they can be used in arid soils to soak up water during rainy seasons and release it slowly over drought periods, promoting plant growth. From 2028, European legislation will require the SAPs used in agriculture to meet standard biodegradability criteria. 

 

Besides improving their biobased and biodegradable SAPs, A&B Smart Materials are busy raising investment, planning scale-up trials, and securing their IP. Amaury is very positive about the future of sustainable SAPs across other toiletries products, such as menstrual pads, agriculture and beyond and is very motivated about having a positive impact on the development of a more sustainable future, one where dirty nappies are less of a problem.

We are [...] enhancing their properties from a chemistry angle to arrive at high performances at the price parity of synthetic alternatives.”
Amaury van Trappen

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