Stereoregular Polymerization of Acyclic Terpenes

Abstract

The growing environmental pollution and the expected depleting of fossil resources have sparked interest in recent years for polymers obtained from monomers originating from renewable sources. Furthermore, nature can provide a variety of building blocks with special structural features (e. g. side groups or stereo-elements) that cannot be obtained so easily via fossilbased pathways. In this context, terpenes are widespread natural compounds coming from non-food crops, present in a large variety of structures, and ready to use as monomers with or without further modifications. The present review aims to provide an overview of how chemists can stereospecifically polymerize terpenes, particularly the acyclic ones like myrcene, ocimene, and farnesene, using different metal catalyst systems in coordination-insertion polymerization. Attention is also paid to their copolymers, which have recently been disclosed, and to the possible applications of these bio-based materials in various industrial sectors such as in the field of elastomers.

(+)‐Limonene‐Lactam: Synthesis of a Sustainable Monomer for Ring‐Opening Polymerization to Novel, Biobased Polyamides

“…[ 10,11 ] Most of them are abundant and derived from non‐edible parts of plants, therefore generally considered as “green” and “sustainable.” There are over 80 000 terpenoid structures, of which many have the desired stereocenters or functional groups, making this class of natural compounds to be a “gold mine” for polymer and materials chemistry. [ 12,13,14 ] A classification can be made into acyclic, monocyclic, bicyclic and polycyclic terpenes, as well as into the number of isoprene (C5) structural units. [ 15 ] Accordingly, many different terpene‐based polymers have already been described, e.g., different polyolefin/hydrocarbon polymers [ 16 ] and polyesters.…”

Polymerization of Bio‐Derived Conjugated Dienes with Rare‐Earth‐Metal Complexes

“…Sustainable polymers can be derived from natural sources or synthesized from renewable resources. Especially, the synthesized sustainable polymers could be precisely constructed at a molecular level in a way similar to their analogues derived from petroleum chemicals, and has been an active topic in both industry and academia [12–16] …”

“…The objective of this study is to offer a comprehensive overview of the available literatures on various homogenous rare‐earth metal catalysts used for polymerization of numerous bio‐derived conjugated dienes, especially terpenes and its derivates. As we known, natural terpenes comprise one type of secondary metabolite derived from five‐carbon isoprene (IP) units, which are assembled in thousands of combinations with cycloaliphatic structures [15,16] . The terpenes are merely hydrocarbons, and their structures follow the so‐called isoprene rule (C5 rule), which is based on the number and organization of carbon atoms in the molecule [19] .…”

“…On the other hand, the reader is referred to other literatures about the polymerization of bio‐based monomers by the means of cationic or radical polymerization [20–21] . Other metals centers and conventional heterogeneous catalysts are beyond the scope of this discussion [16,22] …”

Biobased Elastomer from Renewable Biomass β-Farnesene: Synthesis, Characterization, and Properties

“…Alternatively, β-farnesene can also be derived by dehydration of farnesol, a compound present in rose oil . A growing variety of monomers based on monoterpenes (C 10 ) and sesquiterpenes (C 15 ) already exist in the literature and have already gained significant attention as monomers in elastomer science and technology. − β-myrcene, − β-pinene, , and limonene have been exploited to synthesize a vast range of polymeric materials. In contrast, the extensive use of β-farnesene, a sesquiterpene, as a monomer has been hardly exploited, and there have been only a few reports on the polymerization of β-farnesene to date. − Indeed, polyfarnesene has been synthesized through anionic and, more recently, living/controlled radical polymerization. , Yoo et al fabricated farnesene-based polymers via anionic polymerization pathways claiming a highly branched “bottlebrush” structure and unique thermal and rheological polymer properties .…”