Epoxidized natural rubber grafted polyacrylamide and their polypyrrole composites for functional application

Abstract

Fabrication of containing renewable material epoxidized natural rubber (ENR) graft polyacrylamide (PAM) functional composites are promising exploration for the treatment of organic dye and heavy metal. This research developed a hydrogel consisting of epoxidized natural rubber (ENR) and acrylamide (AM) via a one-pot free radical polymerization that can be exploited as an absorbent for organic dye removal. The ungrafted ENR in the ENR grafted polyacrylamide (ENR-g-PAM) hydrogel system through physical chain entanglement can form a secondary network, which is beneficial to improvements of the comprehensive properties of the hydrogel. The resultant hydrogel shows better mechanical properties due to the entanglement structure that is crucial for stress transfer and dissipation. The mass ratio of ENR and AM was varied and explored to ensure a superior ratio. Methylene blue (MB), a cationic dye, is often utilized to determine adsorption behaviors. The ENR/AM weight ratio at 3:2 hydrogel (60ENR) has a better swelling ratio (up to 336%). More importantly, 60ENR exhibited a better adsorption value of 766.4 mg/g for MB. The experimental data can be also better depicted by the pseudo-second-order kinetic and the Freundlich models, revealing adsorption processes were governed by chemical and multilayer mechanisms. In addition, 7% polypyrrole@ENR-g-PAM (7% PPy@ENR-g-PAM) hydrogel fabricated by a simple mixture method can effectively adsorbed Cr (VI) with a high adsorption value of 284.4 mg/g when pH=2 and be also exploited as a pressure sensor with better durability. Based on the above study results, the ENR-g-PAM hydrogel was expected to play a key role in fields such as dye treatment, heavy metal ion adsorption, and pressure sensor.