Synthesis of Soybean Oil Biomass Main Chain Poly(Acrylic Acid)-Poly(ε-Caprolactone) Based Heterograft Copolymer by Simultaneous Photo-Induced Metal-Free ATRP and Ring-Opening Polymerizations

A photo-induced and completely metal catalyst-free synthetic pathway is proposed for the preparation of bio-based heterograft copolymer based on poly(acrylicacid) (PAA) and poly(epsilon-caprolactone) (PCL) pendant groups on the soybean oil (SBO) backbone (PAA-SBO-PCL). For this purpose, the SBO possessing primary hydroxyland bromide functionalities (Br-SBO-OH) is prepared from epoxidized soybean oil(ESBO) by ring-opening reaction catalyzed by hydrochloric acid. The photo-inducedmetal-free atom transfer radical and ring-opening photopolymerizations (PIMF-ATRP and PIMF-ROP) of tertiary butylacrylate (t-BA) and epsilon-CL monomers are concurrently performed on the Br-SBO-OH bifunctional macro photo-initiator without affecting each other, using perylene as an organic photo-catalyst (lambda= 400-500 nm). The t-BA groups of resulting bio-based PtBA-SBO-PCL is hydrolyzed into acrylic acid moieties via acidolysisto achieve the ultimate PAA-SBO-PCL. Spectroscopic, chromatographic,wettability and thermal investigations such as FT-IR, H-1-NMR, GPC,WCA, TGA and DSC analyses indicate that both the required intermediates and thetargeted polymers are successfully synthesized, as well as the conversion of t-BA groups to acrylic acid units. Thus,this efficient and most importantly green and sustainable process that can beenabled to production of a variety of SBO-based heterograft copolymers could greatly expand the potential applications of widely used polymers as advanced materials.

Automated summary

A photo-induced and completely metal catalyst-free synthetic pathway has been proposed for the preparation of a bio-based heterograft copolymer. The copolymer consisting of poly(acrylic acid) and poly(epsilon-caprolactone) pendant groups is synthesized on the soybean oil backbone. The successful synthesis of both the required intermediates and the targeted polymers has been confirmed through spectroscopic, chromatographic, wettability, and thermal investigations.