Interfacial polymerization for preparation of capsaicin microcapsules: Achieving sustained release in UV-curable coatings on plastic substrates

Abstract

In this study, we incorporate capsaicin microcapsules into UV-curable coatings applied on PVC substrates to achieve sustained capsaicin release coatings. The microcapsules are synthesized using interfacial polycondensation, overcoming self-limitation nature of interfacial polycondensation through solvent evaporation and swelling effects, resulting in microcapsules with well-defined thick shells that can encapsulate capsaicin successfully. These capsaicin microcapsules exhibit enhanced thermal stability compared to pure capsaicin as revealed by thermogravimetry. When embedded into UV-curable coatings, the capsaicin microcapsules contribute to increased hardness, abrasion resistance, tensile strength with uncompromised adhesion strength. Cumulative releases in accelerated tests demonstrate that these coatings have the lowest release of 40% while pure capsaicin can reach cumulative release of 90% in the investigated time scale, indicating a coordinated regulation of capsaicin release by microcapsule shell. Importantly, these UV-curable coatings embedded with sustained release capsaicin microcapsules offer a promising solution for rodent repellency, particularly applicable to power cable surfaces in the power and telecommunication industries.