The Chemistry Behind Water-Soluble Films: How They Dissolve and Decompose

March 27, 2024

1. Introduction to Water Soluble Films

Dissolvable films, sometimes referred to as water-soluble films or pods , manufactured by Water soluble film manufacturer are becoming more and more common in home and personal care products. Convenience and waste reduction are achieved by these films, which encapsulate concentrated cleaning agents and dissolve rapidly in water. However, what precisely makes these movies function, and how do they fall short? Let's examine the chemistry of films that are soluble in water.

2. Key Ingredients: Polyvinyl Alcohol (PVOH)

A minimum of one polyvinyl alcohol, partially hydrolyzed polyvinyl acetate, polyvinyl pyrrolidone, alkyl celluloses like methyl, ethyl, and propyl-cellulose, as well as their derivatives like ethers and esters, and acrylic polymers like water-soluble polyacrylates, polyacrylamides, and acrylic maleic anhydride copolymers are examples of typical water-soluble polymers.

At the heart of water-soluble films manufactured by Water soluble film manufacturers lies a polymer called polyvinyl alcohol (PVA). PVA is a versatile material that provides the necessary properties for these films:

Solubility: PVA dissolves rapidly and completely in water, even in cold water. Detergent pod films with 85–90% hydrolyzed PVA are fully soluble in cold water1.

Strength: The film needs to hold chemically active liquids and solids without breaking apart prematurely.

Environmental Safety: PVA manufactured by Water soluble film manufacturers is biodegradable and poses minimal risk to the environment.

Polyvinyl acetate is usually saponified, or hydrolyzed, to create PVOH, a synthetic resin. Upon converting every acetate group to an alcohol group, PVOH is said to be "fully hydrolyzed." Conversely, "partially hydrolyzed" PVOH is the outcome if a specific percentage of acetate groups are permitted to stay (Figure 1). Even though vinyl acetate and vinyl alcohol are actually copolymers, PVOH is still a common term for the latter.

3. Water Solubility of PVOH

Water solubility of PVOH is basically determined by its degree of hydrolysis (DH) while its degree of polymerization playing a secondary role. It is decided primarily by opposing effects of the hydrogen bonds. On one hand, due to presence of a number of hydrogen bonds it has intense solubility while on the other hands the hydrogen bonds existing in intra and inter molecules cause hinderance and reduce its solubility. Partially hydrolyzed PVOH is less crystalline, more weekly hydrogen bonded and generally soluble in cold water (<100 C).  While completely hydrolyzed PVOH is more crystalline and is thus soluble in hot water (>600 C).

4. Biodegradation of PVOH

One of the rare vinyl polymers that is soluble in water and capable of ultimate biodegradation in the presence of appropriately acclimated microorganisms is PVOH manufactured by Water soluble film manufacturers. The environment that PVOH eventually finds itself in greatly influences its biological destiny.

similar to most polymers, such as polyolefins, polystyrene, and polyacrylates, PVOH is composed of a single carbon bond. However, PVOH is distinct from other synthetic polymers. It is because of its a 1,3-diol structure, which is frequently found in natural materials like carbohydrates. It will be of no surprise that the biodegradation of PVOH generally begins with an enzymatic attack on these 1,3-diol repeating units outside of the cells. A combination of hydroxy and acetoxy-hydroxy fatty acids is produced as a result. These can be further metabolized via the Krebs cycle and the classical β-oxidation pathway after intracellular enzymatic de-acetylation. All microorganisms that degrade PVOH share this mechanism Various species belonging to the genera Pseudomonas and Sphingomonas are among the degrading strains.

Figure 4 Simple Biodegradation Process of PVOH

5. Environmental Effect and Biodegradability

The degradation mechanism of water-soluble films, such as polyvinyl alcohol (PVOH) manufactured by Water soluble film manufacturers can vary depending on environmental conditions. Generally, exposure to moisture, heat, and light can initiate degradation. Moisture can cause hydrolysis, breaking down the polymer chains into smaller fragments. Heat can accelerate this process, while light exposure can induce photo-oxidation, leading to further degradation. In harsh environments, microbial activity may also contribute to degradation. Overall, these factors can result in the disintegration of the film into water-soluble components over time.

6. Conclusion

In conclusion, water-soluble films, driven by the chemistry of polyvinyl alcohol (PVOH), offer convenience and environmental benefits in home and personal care products. With variations like hot and cold water-soluble films, their versatility caters to different applications. PVOH's solubility, strength, and biodegradability make it a standout material, although its degradation can vary based on environmental factors. Understanding the science behind these films is crucial for maximizing their efficiency while minimizing environmental impact.




1. What are water-soluble films, and how do they work?

Water-soluble films, also known as dissolvable films or pods, encapsulate concentrated cleaning agents and dissolve rapidly in water. They work by utilizing polymers like polyvinyl alcohol (PVOH), which dissolves completely in water, releasing the encapsulated contents.

2. What are the differences between hot and cold water-soluble films?

Hot water-soluble films dissolve at higher temperatures and are suitable for uses in hot water environments, such as with dishwasher detergents. Cold water-soluble films dissolve readily in cold water and are ideal for applications like laundry bags or single-use packaging.

3. What is the key ingredient in water-soluble films, and why is it important?

The key ingredient in water-soluble films is polyvinyl alcohol (PVOH). It provides essential properties such as solubility, strength, and environmental safety. PVOH is biodegradable and dissolves rapidly and completely in water, making it an ideal choice for these films.

4. How does the degree of hydrolysis affect the water solubility of PVOH?

The degree of hydrolysis (DH) of PVOH primarily determines its water solubility. Partially hydrolyzed PVOH is less crystalline and more soluble in cold water, while completely hydrolyzed PVOH is more crystalline and soluble in hot water.

5. What factors contribute to the degradation of water-soluble films?

Exposure to moisture, heat, light, and microbial activity can contribute to the degradation of water-soluble films. Moisture can cause hydrolysis, heat can accelerate degradation, light exposure can induce photo-oxidation, and microbial activity can further break down the polymer chains over time.



1. Biodegradability of Polyvinyl Alcohol Based Film Used for Liquid Detergent Capsules

2. Translating our Science: About Water-Soluble Film

3. What makes dissolving detergent pods hold together, and are they safe for the environment?

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