General Description

4-Acryloylmorpholine is a critical compound in adhesive formulations, particularly for UV-curable adhesives used in products like smartwatch protectors. While it enhances adhesion and durability, it is also a significant allergen, posing health risks such as allergic contact dermatitis. Reports of adverse reactions underscore the need for careful consumer protection measures, including alternative formulations and improved labeling. Additionally, poly(4-acryloylmorpholine), derived from this compound, significantly boosts the activity of lipase A from *Bacillus subtilis* in ionic liquids, highlighting its versatility in enhancing biocatalysis while addressing enzyme compatibility issues in these environments.

Figure 1. 4-Acryloylmorpholine

Benefits and Risks in Adhesives

Introduction to 4-Acryloylmorpholine

4-Acryloylmorpholine is a chemical compound that has recently gained considerable interest due to its applications in various products, particularly in adhesives. This compound plays a critical role in the formulation of UV-curable adhesives, which are widely used in the manufacturing of personal care items, including those that attach protective cases to smartwatches. However, it is important to note that 4-Acryloylmorpholine is identified as a significant allergen, capable of triggering allergic reactions in some individuals. Awareness surrounding 4-Acryloylmorpholine is essential, especially in consumer products like smartwatch screen protectors, where prolonged skin contact can lead to adverse health outcomes.

Application in Adhesives

In the context of adhesive formulations, 4-Acryloylmorpholine is indispensable due to its properties that enhance adhesion and durability. This compound is integral to the development of strong bonding materials that securely attach protective cases to smartwatches, ensuring both functionality and aesthetics. However, despite its advantages, concerns surrounding the safety of products containing 4-Acryloylmorpholine have emerged. Recent studies have revealed instances of allergic contact dermatitis linked to the presence of this compound in adhesives. These findings illustrate that while 4-Acryloylmorpholine contributes to effective adhesion, it poses a risk to individuals who are sensitive to it, thereby necessitating a careful approach in its utilization.

Health Implications

The detection of 4-Acryloylmorpholine in adhesives associated with smartwatch protectors raises significant health concerns. Reports have documented cases where consumers have experienced allergic contact dermatitis, presenting symptoms such as vesicular inflammatory plaques. A notable case series featuring three women who developed dermatitis after using smartwatches with cases bonded by adhesives containing 4-Acryloylmorpholine emphasizes the urgency of addressing these risks. To protect consumers while still harnessing the benefits of 4-Acryloylmorpholine in adhesive applications, it is crucial to explore alternative formulations or enhance labeling practices to inform users. Such measures can help mitigate allergic reactions and improve overall product safety, ensuring that the advantages of 4-Acryloylmorpholine do not come at the expense of consumer health. ¹

Role of its Polymers in Ionic Liquids

Enhancement of Lipase Activity Using 4-Acryloylmorpholine-Based Polymers

4-Acryloylmorpholine, a versatile polymer, has been shown to significantly enhance the activity of lipase A from *Bacillus subtilis* in anhydrous ionic liquids. By covalently attaching the polymer, named poly(4-acryloylmorpholine), to the enzyme, the solubility of lipase in the ionic liquid 1-butyl-3-methyl imidazolium hexafluorophosphate is improved. This modification led to up to a 19-fold increase in the enzyme's transesterification activity. The improvement is directly linked to the increase in solubility of lipase in the ionic liquid and the number of 4-acryloylmorpholine repeat units attached to the enzyme. The polymer effectively mitigates enzyme aggregation in the aqueous buffer, which is crucial for optimizing activity in the ionic liquid environment. ²

Molecular Interaction and Biocatalysis Optimization

The favorable interactions between poly(4-acryloylmorpholine) and the ionic liquid enhance the dissolution of lipase, addressing the typically poor enzyme-ionic liquid compatibility. This approach, confirmed by static light scattering and the Flory-Huggins interaction parameter, shows that the polymer-ionic liquid interactions help to counteract the enzyme-ionic liquid incompatibilities. As a result, the polymer modification of lipase facilitates better enzyme performance by reducing diffusional limitations. This method of utilizing 4-acryloylmorpholine-based polymers can be extended to improve other enzyme-ionic liquid systems, offering a broad scope for enhancing biocatalysis in similar environments. ²

Reference

1. Gatica-Ortega ME, Mowitz M, Navarro-Trivi?o FJ, et al. Nonoccupational Allergic Contact Dermatitis to 4-Acryloylmorpholine in Smartwatch Screen Protectors Glue. Dermatitis. 2022; 33(6): 429-434.

2. Chado GR, Holland EN, Tice AK, Stoykovich MP, Kaar JL. Modification of Lipase with Poly(4-acryloylmorpholine) Enhances Solubility and Transesterification Activity in Anhydrous Ionic Liquids. Biomacromolecules. 2018; 19(4): 1324-1332.