Anionic Ring-Opening Copolymerization of Farnesyl Glycidyl Ether: Fast Access to Terpenoid-Derived Amphiphilic Polyether Architectures

Abstract

Motivated by increasing attention to biobased and potentially sustainable polymers from renewable sources, this work describes the synthesis and anionic ring-opening polymerization (AROP) of the terpenoid-derived farnesyl glycidyl ether (FarGE) as a hydrophobic epoxide building block for the synthesis of biobased, amphiphilic polyethers that represent novel, nonionic surfactants. In combination with ethylene oxide (EO), the synthetic strategies employed provide access to both amphiphilic diblock (mPEG 114 -b-PFarGE m ) and statistical copolymers (PEG nco-PFarGE m ), featuring facile tunability of their amphiphilic and surfactant properties. The versatile application of FarGE for different polyether architectures is demonstrated by the wellcontrolled molecular weights in the range of 5040−11170 g mol −1 and narrow molecular weight distributions (Đ = 1.04−1.11), both for block and statistical architectures. Owing to the unexpected, nearly ideally random microstructure of the statistical EO/FarGE copolyethers, determined by in situ kinetics (r EO = 1.18 and r FarGE = 0.85), the branched alkenyl side chain impedes the crystallization of polyethylene glycol (PEG) with increasing FarGE incorporation, allowing for fine-tuning of polymer properties. Observing a low glass transition temperature (T g ) of around −70 °C for the PFarGE homopolymer, the thermal analysis also unveils farnesyl side-chain control of the T g even at low FarGE content (7.6 mol %). Detailed investigations of aqueous polymer solutions reveal self-assembly of the amphiphilic copolymers into micelles and aggregates, characterized by very low critical micelle concentrations (CMC, 10−53 mg L −1 ), as well as larger clusters (R H,micelle = 17−35 nm and R H,cluster = 59−107 nm). The results demonstrate the enormous potential of terpenes and terpenoids for partially biobased surfactant alternatives.

A New Semicrystalline Polymer from Renewable Source: Poly-1,4-(3-methylene-cyclopentene) as an Example of Three-Dimensional Topotactic Transition Triggered by Temperature

“…In the realm of natural products, terpenes represent a particularly interesting class of molecules for polymer chemists due to the presence of conjugated double bonds that offer both the opportunity to further functionalization or to directly polymerize these molecules in analogy to 1,3-alkadienes such as butadiene or isoprene. − As a matter of fact, the stereoregular polymerization of acyclic terpenes has been investigated by using many catalytic systems, giving macromolecules various microstructural features and in some cases physical properties analogous to those of elastomers based on nonrenewable monomers. − It is worth noting that, with a few exceptions, due to the long alkyl chain of the starting monomers such as myrcene, ocimene, and farnesene, even the highly stereoregular polymers do not show any crystallinity, limiting the possible application of polymers derived from terpenes.…”