Synthesis of Renewable Poly(limonene): A Kinetic Modeling Study to Improve the Polymerization

Abstract

Despite its potential in the production of polymers from renewable sources, D-limonene faces difficulties in its polymerization, resulting in low monomer conversion and molar mass. In order to investigate the non-ideality inherent kinetics, this work explores different modeling strategies for D-limonene radical polymerization, using benzoyl peroxide as initiator. The starting model considered the classical approach for conventional radical polymerization. This model was then corrected by including reaction orders different from the unit. After an analysis and choice of the best model, computer simulations were compared with experimental results from literature, validating the chosen approach. It was found that the process is drastically influenced by chain transfer reactions, presenting a non-ideal behavior. Finally, an analysis of distinct reaction conditions provided information on monomer conversion, molar mass and polymer dispersity, which could guide future research in the synthesis optimization. Higher molar mass poly(limonene) were obtained by simultaneously reducing the monomer and initiator concentrations.

Recent Advances in Antioxidant Polymers: From Sustainable and Natural Monomers to Synthesis and Applications

“…Commercial applications of limonene and polylimonene include food preservation, enhancing the flavor and aroma of foods [93]. A fundamental constraint in the development of polymeric products globally is the recyclability of the precursor and the ecological effects; this remains a priority concern in polylimonene synthesis, considering that most precursors are sourced from fossil fuels [94]. In light of this challenge, the synthesis of non-toxic and renewable plastics is a priority for manufacturers.…”

“…Beyond the ubiquity of the precursors, terpenes (D-limonene in particular) are ideal based on their chemical structure and the presence of isoprene units; these units are key enablers for addition-based polymerization processes. The choice of D-limonene as a precursor in the current case is supported by the worldwide production capacity [94] and compatibility with microbial mediated synthesis processes, including PMD, Codon optimized MVK, and PMK (see Table 10).…”

“…The biotechnology-based production of limonene from microorganisms does not address production-related constraints, including the molar mass loss/lack of sufficient molar mass, selection of an acceptable monomer for conversion. Most of the precursors for terpenes have practical drawbacks and limitations-a factor influencing the choice of orange peel-based precursors-a precursor proven useful in the synthesis of polylimonene through recycling polymerization [94]. Other sources of terpenes include tea, thyme, cannabis, Spanish sage, and citrus fruits (lemon, orange, mandarin) [91].…”

“…Under standard conditions, Coelho and Vieira synthesized polylimonene by placing D-limonene in a solution containing Ziegler-Natta catalysts and Lewis acids in the first stage. The molar mass of the mixed species was below 1000 g/mol [94]. The second stage entailed the initiation of free-radical polymerization using benzoyl peroxide.…”

An Experimental and Computational Approach on Controlled Radical Photopolymerization of Limonene

“…[ 6,13,14 ] For example, the radical polymerization of limonene using benzoyl peroxide as initiator at 85 °C provided low monomer conversions. [ 15,16 ] The increased proportion of limonene in copolymerization with n‐butyl acrylate and 2‐ethylhexyl acrylate caused a reduction in molar mass and polymerization rate. [ 17,18 ] Nevertheless, some improvements in monomer conversions in its (homo) and copolymerization were recently reported using ionic approach.…”