Castor oil: a suitable green source of capping agent for nanoparticle syntheses and facile surface functionalization

Abstract

Castor oil (CO) is an inedible vegetable oil (VO) that has been employed extensively as a bioresource material for the synthesis of biodegradable polymers, cosmetics, lubricants, biofuels, coatings and adhesives. It is used in medicine, pharmaceuticals and biorefineries, due to its versatile chemistry. However, there has been less focus on CO as an alternative to toxic and expensive solvents, and capping/stabilizing agents routinely used in nanoparticle syntheses. It provides a richer chemistry than edible VOs as a solvent for green syntheses of nanoparticles. CO, being the only rich source of ricinoleic acid (RA), has been used as a solvent, co-solvent, stabilizing agent and polyol for the formation of polymer–nanoparticle composites. RA is a suitable alternative to oleic acid used as a capping and/or stabilizing agent. Unlike oleic acid, it provides a facile route to the functionalization of surfaces of nanoparticles and the coating of nanoparticles with polymers. For applications requiring more polar organic solvents, RA is more preferred than oleic acid. In this review, we discuss the production, chemical and physical properties, triglyceride and fatty acid (FA) compositions and applications of CO, focusing on the use of CO and RA as well as other VOs and FAs in syntheses of nanoparticles and surface functionalization.

Development of castor oil–based polymers: A review

“…Castor oil is obtained from the seeds of the plant known as Ricinus communis L., and it is believed to have its origin in various areas including Africa, Asia, India, and China . It has been used for medical purposes as a purgative.…”

Ricin and Ricinus communis in pharmacology and toxicology-from ancient use and “Papyrus Ebers” to modern perspectives and “poisonous plant of the year 2018”

“…The castor seeds contain 40-50% oil. Between 2009 and 2013, the average annual world production of castor oil seed was approximately 1.99 × 10 6 tons (Mensah et al 2018) and represents~0.15% of the total vegetable oil produced worldwide (Severino et al 2012).…”

“…5). These include, for example, the high proportion of the fatty acid ricinoleic acid as well as the presence of a number of functional groups useful for performing a variety of chemical reactions (including halogenation, dehydration, alkoxylation, esterification, sulfation;Ogunniyi 2006;Patel et al 2016;Mensah et al 2018). For a more detailed description and critical appraisal of the potential of castor oil in the context of biotechnology and industrial uses, including renewable fuels, the reader is referred to the literature (e.g., Mutlu and Meier 2010;Severino et al 2012;Mensah et al 2018).…”

“…Furthermore, castor oil has been used as a solvent, co-solvent, stabilizing agent, and polyol for the formation of polymer-nanoparticle composites. It provides a facile route of nanoparticle surface functionalization and nanoparticle coating with polymers (Mensah et al 2018).…”

Future manufacturing and remanufacturing of polymeric materials

“…Likewise, nanocellulose can be used as a rheology modifier or a nanoreinforcing agent in composites. Castor oil has been used as the polyol in biodegradable polymers, especially polyurethanes . There are technologies for conversion of carbon dioxide (from fossil‐fuel power plants) to methanol to olefins for the production of PE and PP .…”