P&G R&D Leverages Advanced Analytical Techniques to Differentiate Water-Soluble Polymers

Polyethylene Glycol (PEG) and water soluble grades of Polyvinyl Alcohol (PVA) are examples of water-soluble polymers widely used in various detergent applications, including Ariel and Tide PODS, Lenor Perfume Beads, and Cascade and Fairy dishwashing capsules. Our analytical team collaborated with external scientists from the European Synchrotron Radiation Facility (ESRF, Grenoble), applying advanced analytical techniques to visibly distinguish at the nanoscale, water-soluble polymers from microplastics and nanoplastics for the first time, which adds further evidence to the differences found through traditional approaches.

In this article, P&G R&D analytical expert Vincenzo Agostiniano answers some key questions.

Why did you want to understand the solubility behavior of water-soluble polymers and microplastics?

Microplastics are an important topic to P&G, regulatory bodies and our consumers. Therefore, it is important for us to define methods that can help guide our R&D experts in the materials we use. In general, water soluble polymers are excluded from the definition of microplastics. The aim of this study was to understand if we can differentiate water-soluble polymers from microplastics and nanoplastics after dissolution down to molecular or the nano-meter scale. We know that the types of PVA and PEG used by P&G, and other “water soluble” polymers are not microplastics from many external studies using industry recognized techniques. In this research, we wanted to push the analytical boundaries and challenge ourselves to see at the molecular scale how these water-soluble polymers appear in water, compared to micro- or nanoplastics.

In addition, some studies have implied that polymers and particularly water-soluble film PVA could accumulate in the environment as microplastics. These opinions were refuted by authoritative regulatory agencies ⁽¹⁾ and our study continues to support the existing solubility data of such polymers. Importantly, it provides an even stronger scientific basis to show that water-soluble polymers have distinctively different behaviors compared to microplastics at the molecular level. Therefore, water soluble polymers like soluble film PVA do not meet the definitions of microplastics, either the European regulatory definition ^{(2, 3)}, or other definitions ⁽⁴⁾ which state or imply such microplastic chemistries as “particles”, and/or have a hard or solid interface with water in solution.

What methods did you use to demonstrate water-soluble polymers behave differently than microplastics?

P&G researchers are providing leadership to advance the science of analytical methods with best in class capabilities from the public and private sectors. We employed Dynamic Light Scattering (DLS) and Small Angle X-ray Scattering (SAXS) to measure the conformation and size of the polymers in water. Additionally, Atomic Force Microscopy (AFM) was used to visually confirm the behavior of these materials in solution.

Can you explain how these analytical methods work?

Dynamic Light Scattering (DLS) and Small Angle X-ray Scattering (SAXS) work by shining visible light or X-rays through the solutions to analyze; by examining how the patterns of photons are modified, scientists can reveal the shape and size of tiny particles or molecules, down to the size of one millionth of a millimeter. Atomic Force Microscopy (AFM) uses a tiny needle (with a tip size close to the dimensions of a molecule) to sense atomic forces on a surface, creating a detailed map of the particles’ shapes and sizes.

Have these studies been done before?

This is ground-breaking work. We are fortunate as P&G to have access to world-class analytical facilities—we used the Synchrotron in Grenoble ⁽⁵⁾ to demonstrate the single molecule behavior. The AFM capability was developed by P&G several years ago, yet this is the first time it has been used to visualize the difference between a water-soluble polymer and a microplastic.

What is the difference you found between water-soluble polymers and microplastics?

We found that water-soluble polymers dissolve completely in water, forming single molecules with random coil structures and showing no signs of aggregation. In contrast, microplastics (for example, Polystyrene beads) retain their rigid, round shapes—the millions of polymer chains are tightly bound together into a solid structure. Hence, the tightly wound coils do not dissolve, maintaining a defined hard interface with the surrounding water.

We examined PVA, PEG, and Polystyrene beads in this study but the same techniques can be applied to other materials to distinguish soluble materials (that are not microplastics) from non-soluble microplastics.

Some studies claim to have found particles made of PVA, how is this possible if it is water soluble?

Polymers can be modified in many different ways and as a result within the same “family” of polymers there can be a high variety of properties. PVA is such a versatile material and is approved for use in many different applications. The soluble grades of PVA can be used in eyedrops, food, and detergents-films whereas the more durable and insoluble grades are designed for other applications like construction or textile applications. So, it is possible that insoluble PVA is found but it is incorrect to conclude those are similar to the soluble grades of PVA used to encapsulate detergents.

Why does it matter that water-soluble polymers like polyvinyl alcohol dissolve into single molecules and are not microplastics?

When polymeric materials dissolve into single molecules, this means they cannot form persistent microplastics. Said simply, a single molecule is not a plastic because the molecular chains have been completely separated. Several literature references refer to the benefits of polymers dissolving to individual molecules ^{(6, 7)} to reduce their environmental impact. This behavior enhances their environmental degradability and prevents their ability to act as a carrier for any contaminants which could otherwise adsorb onto a solid surface.

In addition, there are many validated techniques to investigate the environmental fate and effect of single molecules, including biodegradability in wastewater and aquatic toxicity. Such studies were used by the EPA ⁽¹⁾ to assess the environmental safety of water soluble PVA. Therefore, dissolution into single molecules helps to confirm a robust assessment of the safety of materials such as the polymers we studied, PEG and water soluble PVA, as well as other water soluble polymers that are commonly used in the down the drain applications.

Does this mean polymers that are not water-soluble cannot biodegrade?

No, solubility and biodegradability are two different material properties. There are insoluble polymers that can biodegrade and vice versa. However, breaking down polymers or particles into single molecules enhances their bioavailability to biodegrading microorganisms and can therefore speed up the degradation processes. This also reduces to zero the possibility of forming microplastics. That’s why solubility in general and the lack of a solid particle surface is cited as a key difference between materials considered as non-plastics and materials seen as micro-or nanoplastics.

So, does this help explain that laundry- and auto-dishwashing detergent films do not contribute to plastic pollution?

Indeed, the study shows the water-soluble films used for our laundry detergents are not made from durable plastic materials associated with plastic or microplastic pollution. Our study shows these films are based on soluble grades of PVA. While the films share some of the favorable characteristics with plastics when dry, it is proven their environmental behavior is distinctly different when dissolved in water. Unlike durable plastics, during their intended use by consumers, the films fully dissolve into single molecules in water and degrade, with none of the components contributing to microplastic pollution.

How will you use these results?

This study was important in multiple ways. First, we learned that these techniques provide a robust scientific basis to differentiate soluble polymers from microplastics based on their behavior in solution. With that, such methods can be considered for future screening of ingredients by my R&D colleagues. We are lucky to have access to such sophisticated techniques. These insights can also help regulators to better assess the differences between soluble polymers and microplastics. We have also published our work ⁽⁸⁾ to share our observations and recommendations with other experts, which can lead to other ideas to study. Finally, the findings can be used to inform our stakeholders about the properties of polyvinyl alcohol and PEG and show these soluble polymers do not form microplastics after dissolution.

1. EPA ruling, April 2023 on petition for PVA review: https://www.federalregister.gov/documents/2023/04/27/2023-08864/polyvinyl-alcohol-pva-tsca-section-21-petition-for-rulemaking-reasons-for-agency-response-denial-of

2. Commission Regulation (EU) 2023/2055 of 25 September 2023. https://eur-lex.europa.eu/eli/reg/2023/2055/oj

3. RAC/SEAC (2022). Opinion on an Annex XV dossier proposing restrictions on intentionally added microplastics, p78. https://echa.europa.eu/documents/10162/a513b793-dd84-d83a-9c06-e7a11580f366

4. Hartmann et al, Are we Speaking the Same Language? Recommendations for a Definition and Categorisation Framework for Plastic Debris; Environ. Sci. Technol, 53, (2019) 1039-1047

5. European Synchrotron Radiation Facility (ESRF). (2025). https://www.esrf.fr/

6. Chinaglia et al, Biodegradation rate of biodegradable plastics at molecular level, Polymer Degradation and Stability 147 (2018), 237-244

7. An et al, Surface Chemistry in Environmental Degradation of Polymeric Solids, Langmuir (2024), 40, 9336-9344

8. Agostiniano et al, “Advanced Analytical Techniques Characterising Polymer Conformation in Water: A valid approach to differentiate water soluble polymers from nanoplastics at the Molecular Level” SOFW Journal, Verlag fur chemische Industrie (2025), 1/2, 8-15.