The battle for the “green” polymer. Different approaches for biopolymer synthesis: bioadvantaged vs. bioreplacement

Abstract

Biopolymers have been used throughout history; however, in the last two centuries they have seen a decrease in their utilization as the proliferation of inexpensive and mass-produced materials from petrochemical feedstocks quickly became better-suited to meeting society's needs. In recent years, high petroleum prices and the concern of society to adopt greener and cleaner products has led to an increased interest in biorenewable polymers and the use of sustainable technologies to produce them. Industrial and academic researchers alike have targeted several routes for producing these renewable materials. In this perspective, we compare and contrast two distinct approaches to the economical realization of these materials. One mentality that has emerged we term "bioreplacement", in which the fields of synthetic biology and catalysis collaborate to coax petrochemical monomers from sugars and lignocellulosic feedstocks that can subsequently be used in precisely the same ways to produce precisely the same polymers as we know today. For example, the metabolic engineering of bacteria is currently being explored as a viable route to common monomers such as butadiene, isoprene, styrene, acrylic acid, and sebacic acid, amongst others. Another motif that has recently gained traction may be referred to as the "bioadvantage" strategy, where the multifunctional "monomers" given to us by nature are combined in novel ways using novel chemistries to yield new polymers with new properties; for these materials to compete with their petroleum-based counterparts, they must add some advantage, for example less cost. For instance, acrylated epoxidized soybean oil readily undergoes polymerization to thermosets and recently, thermoplastic rubbers. Additionally, many plants produce pre-polymeric or polymeric materials that require little or no post modification to extract and make use of these compounds.

Effect of Microwave Cure on the Thermo-Mechanical Properties of Tung Oil-Based/Carbon Nanotube Composites

“…The soluble material recovered after Soxhlet extraction from each sample was analyzed by 1 H NMR spectroscopy ( Figure 10) and the results reveal that the extracts correspond to partially reacted tung oil and/or tung oil oligomers. Figure 10C shows a standard 1 H NMR spectrum of a conjugated triglyceride with peaks at 4.00-4.40 ppm, corresponding to the glycerol methylenes, and the series of multiplets at 5.20-6.50 ppm, corresponding to the protons of conjugated sp 2 hybridized carbons.…”

“…Natural starting materials, such as vegetable oils, are readily available in large quantities, low cost, and have the potential to offer properties not currently available in commercial petroleum-based products. These promising characteristics, and the increasing attention bio-renewable chemicals have been receiving in both industrial, and academic settings is expected to lead to significant progress towards environmental sustainability in the near future [1,2].…”

Thermoplastic Elastomers from Vegetable Oils via Reversible Addition-Fragmentation Chain Transfer Polymerization

“…This result is surprising since each polytriglyceride repeat unit has the potential to crosslink with at least one other polytriglyceride. When approximately a fraction of 1/N of such units have crosslinked (N denotes the average degree of polymerization), the polymers are said to be at their "gel point" at which an infinite polymer network has formed (27). Moreover, due to the multiple reaction sites of AESO, polymerizations tend to have larger polydispersity due to the different polymer chains growing at same time, see Figure 7.…”

“…Due to controllled/living free radical polymerization (CFRP), high molecular weight hyperbranched polymers can be obtained without gelation (27). CFRP techniques such as atom transfer radical polymerization (ATRP) (21) and RAFT (24) have been recently used in the creation of styrene-based thermoplastic elastomers from vegetable oils.…”

Bipyrrolidine salan alkoxide complexes of lanthanides: synthesis, characterisation, activity in the polymerisation of lactide and mechanistic investigation by DOSY NMR

“…1 Supported by public opinion, this has triggered a concerted research effort between academia and industry towards the development of sustainable alternatives from renewable resources. [2][3][4][5] Polylactide (PLA), a thermoplastic aliphatic polyester derived from lactic acid, is arguably one of the most widely studied degradable and renewable polymers. PLA is commercially available for packaging and fibre applications, 6 and prepared through a solvent-free ring-opening polymerisation (ROP) of lactide (LA).…”