Autoxidized Oleic Acid Bifunctional Macro Peroxide Initiators for Free Radical and Condensation Polymerization. Synthesis and Characterization of Multiblock Copolymers

Authors: HAZER, BAKI - Bülent Ecevit University; AYYILDIZ, ELIF - Bülent Ecevit University; EREN, MELIKE - Bülent Ecevit University; CANBAY, HALE - Mehmet Akif Ersoy University; Ashby, Richard - Rick

Submitted to: Journal of Polymers and the Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/15/2019
Publication Date: 10/13/2019
Citation: Hazer, B., Ayyildiz, E., Eren, M., Canbay, H., Ashby, R.D. 2019. Autoxidized oleic acid bifunctional macro peroxide initiators for free radical and condensation polymerization. Synthesis and characterization of multiblock copolymers. Journal of Polymers and the Environment. 27(11):2562-2576. https://doi.org/10.1007/s10924-019-01536-6.
DOI: https://doi.org/10.1007/s10924-019-01536-6

Interpretive Summary: Environmental concerns persist especially in areas such as widespread plastic use. In fact, the plastic conundrum is especially prevalent with the existing worldwide state of (or lack of) efficient plastic disposal (recycling) protocols. Experts estimate that under current practices, by the year 2050 there will be as much plastic in the oceans (by weight) as there are fish. This is a sobering thought. As such, different means of producing more environmentally-benign plastics have been explored that can alleviate some of the present concerns over end-of-life outcomes. In this paper, oxygen from the air was utilized along with a common fatty acid (oleic acid; a renewable component of vegetable oils and animal fats) to produce reactive intermediate molecules. These molecules were demonstrated under appropriate reaction conditions to catalyze the formation of unique plastics using polystyrene and polyethylene glycol (both well-known petroleum-based materials) that are more ecofriendly than many of the currently used materials and yet demonstrate properties that can be useful in drug delivery systems and tissue engineering. While polystyrene is known to be slow to degrade in nature and may not appear to be an advantageous starting material, by intercalating the readily degradable oleic acid into these new plastic molecules, they can be more easily broken down into smaller pieces which can improve degradation over time relative to the currently-used polystyrene.

Technical Abstract: Autoxidation of unsaturated fatty acids gives fatty acid macroperoxide initiators containing two functionalities which can lead to free radical and condensation polymerizations in a single pot. The oleic acid macroperoxide initiator obtained by ecofriendly autoxidation (Pole4m) was used in both the free radical polymerization of styrene and the condensation polymerization with amine-terminated polyethylene glycol (PEGNH2) to obtain triblock branched graft copolymers. The narrow molar masses of the poly oleic acid-g-styrene (PoleS) and poly oleic acid-g-styrene-g-PEG (PoSG) graft copolymers were successfully obtained. The overall rate constant for the free radical polymerization of styrene initiated by Pole4m was 0.39 x 10-4 and compared to well-known peroxide initiators such as benzoyl peroxide and soybean oil macroperoxide. The inclusion of oleic acid decreased the glass transition temperature of the polystyrene segment because of the plasticizing effect of oleic acid. In addition, mechanical properties of the copolymer was improved when compared with the pure PS. Structural characterization, morphology of the fracture surface, micelle formation, thermal analysis and molar masses of the obtained products were also evaluated.