Functionalized vegetable oils as precursors for polymers by thiol-ene reaction Mihail Ionescu a , Dragana Radojc ˇic ´ a , Xianmei Wan a , Zoran S. Petrovic ´ a,⇑ , Thomas A. Upshaw b a Kansas Polymer Research Center, Pittsburg State University, Pittsburg, KS 66762, United States b Chevron Phillips Chemical Company LP, Bartlesville Technology Center, Bartlesville, OK 74003-6670, United States article info Article history: Received 8 September 2014 Received in revised form 17 December 2014 Accepted 19 December 2014 Available online 5 January 2015 Keywords: Thiol-ene Monomers Polymers Vegetable oils abstract A range of vegetable oil derivatives with hydroxyl, amine, isocyanate, isothiocyanate, epoxy and silane terminal groups, useful for making new bio-based polymers, were synthe- sized from mercaptanized oils and different allyl organic compounds by thiol-ene reaction. All products were low viscosity liquids of light yellow color except amine containing oil, which was a low melting solid. Novel functionalized oils had 3–6 functional groups per mole and were suitable for rigid and flexible polymer products. Ó 2015 Elsevier Ltd. All rights reserved. 1. Introduction Vegetable oils are excellent raw materials for a range of polymers but they must contain functional groups to serve as reactants. Functional oils were prepared by introducing hydroxyl, epoxy, amine, isocyanate or vinyl groups using multistep processes. Polyols were prepared by epoxida- tion/ring opening with alcohols, organic and inorganic acids or water, or by hydrogenation [1], hydroformyla- tion/hydrogenation [2] or glycerolysis/glycolysis [3]. Amine derivatives of vegetable oils can be obtained by hydroformylation followed by reductive amination. Oils with isocyanates were prepared by bromination of triglyc- erides at the allylic positions by a reaction with N-bromo- succinimide and treatment with AgNCO to convert them to isocyanate-containing oils [4]. In a similar fashion isothio- cyanate derivatives of soybean oil (SBO) triglycerides were prepared. All these reactions are complex, generating side products or wide molecular weight distributions, with often limited yield. Direct conversion of vegetable oils to functionalized oils in one step is always desirable from an economic point of view. In this paper we describe the utilization of ‘‘click’’ thiol-ene reactions of allyl organic compounds with merc- aptanized soybean oil to obtain bio-based precursors for polymers having different functional groups. Thiols or mercaptans are sulfur analogues of alcohols where oxygen is replaced with sulfur. They have some advantages over alcohols since they can be directly added to double bonds of organic compounds in so called thiol-ene reactions [5– 21]. Thiol-ene reactions belong to ‘‘click’’ chemistry, char- acterized by high yield, high reaction rates and the absence of by-products when run at an equimolar ratio of thiol groups to double bonds. The general thiol-ene reaction is presented in Scheme 1. The addition of thiol groups to double bonds can be ini- tiated photochemically by ultraviolet light and photoiniti- ators, or by thermal splitting of radical initiators (azo derivatives, peroxides). The thiol-ene reaction is a chain reaction and proceeds through the four steps: (1) thermal or photochemical generation of free radicals; (2) transfer http://dx.doi.org/10.1016/j.eurpolymj.2014.12.037 0014-3057/Ó 2015 Elsevier Ltd. All rights reserved. ⇑ Corresponding author at: Pittsburg State University, Kansas Polymer Research Center, 1701 S. Broadway, Pittsburg, KS 66762, United States. Tel.: +1 620 235 4928. E-mail address: zpetrovic@pittstate.edu (Z.S. Petrovic ´). European Polymer Journal 67 (2015) 439–448 Contents lists available at ScienceDirect European Polymer Journal journal homepage: www.elsevier.com/locate/europolj