Ethylene glycol based polyurethane shell microcapsules for textile applications releasing medicinal lavender and responding to mechanical stimuli

Abstract

Interfacial polymerization has been used to encapsulate essential oils (EOs). Nevertheless, interfacial polymerization to form polymeric interface of EOs with the environment has been poorly studied. The objective of this study was to develop a kind of polyurethane (PU) based shell microencapsulated EOs to induce controlled delivery. In this study, ethylene glycol based PU microcapsules were prepared to release medicinal lavender oil from some textiles with controlled delivery mechanism and mechanical stimuli. Various diisocyanates and ethylene glycol (EG) are used to synthesize the PU based shell microcapsules for optimization and reveal structure property relationship of shell structure in controlled release issue. The sensing mechanical stimuli of the polymer capsules is achieved by using a short molecule, EG. The original lavender fragrance was encapsulated in PU shells by the interfacial interaction of toluene diisocyanate, isophorone diisocyanate, or methylene bisphenol diisocyanate with EG at the interface of oil and water phases. The fragrance capsules were characterized by Fourier Transform Infrared (FT-IR) spectroscopy, particle size distribution (PSD) analysis, polarized optical microscopy (POM) and scanning electron microscopy (SEM) investigations. The release behavior of the fragrance capsules was determined by periodic weight checks over 30 days. According to the release analysis, the efficient EOs encapsulation ratio of the particles were 34.90%, 39.84% and 48.70% for particles produced using toluene diisocyanate, isophorone diisocyanate, and methylene bisphenol diisocyanate respectively. The average particle size was determined in a range of 10–30 µm for the particles produced used any diisocyanate, which meant they were at commonly used sizes for textile applications. The -NH, -CO, -C-O-C, and -C-N peaks in the structure of the PU were determined by FT-IR to demonstrate successful synthesis. SEM images revealed that microparticles with medicinal lavender oil were fragile to increase the release rate when needed.