Preparation and temperature-responsive behavior of crosslinked polymers between poly(N-isopropylacrylamide) and natural rubber

Abstract

Stimuli-responsive polymers are considered as smart materials as they can respond to subtle changes in external stimuli, such as pH, temperature, light, magnetic field, etc. Natural rubber (NR) is one of the most important renewable resources, offering excellent flexibility and fatigue resistance. In this work, temperature responsiveness was introduced to NR via a crosslinking reaction with poly(N-isopropylacrylamide) (PNIPAM) using benzoyl peroxide as a free radical crosslinker. PNIPAM was chosen because it is a well-known temperature-responsive polymer with a lower critical solution temperature near the human body temperature, enabling applications in biomedical fields. The crosslinked materials between PNIPAM and NR were characterized using Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, and X-ray photoelectron spectroscopy. The effects of polymer and crosslinker concentration, reaction temperature, and reaction time on the gel content were studied. The temperature responsiveness of the crosslinked polymers was investigated and the lower critical solution temperature was found to be in the range 30-34 °C. Based on these results, we demonstrated a straightforward strategy for preparing crosslinked polymers between PNIPAM and NR. The introduction of temperature responsiveness into NR will lead to new responsive rubber-based materials and expand the range of potential applications. Open image in new window