U Minn researchers develop bio-based elastomers from recoverable methyl valerolactone; tires, gaskets, seals, etc.
Researchers at the University of Minnesota have developed and demonstrated at laboratory scale a novel process to synthesize low-cost, polymeric valerolactones with tunable mechanical properties and low glass transition temperatures.
The glass transition temperature is the temperature region in which a polymer transitions from a hard, glassy material to a soft, rubbery material. In other words, when the polymer is cooled below the glass transition temperature, it becomes hard and brittle. The low glass transition temperature allows these polymers to be used at lower temperatures than other biodegradable polymers; applications could include tires, gaskets, seals adhesive, sealant and damping products.
Described in a paper in the ACS journal Industrial & Engineering Chemistry Research, the process creates chemically crosslinked poly(β-methyl-δ-valerolactone) (PMVL) elastomers from high molar mass PMVL homopolymers that can be chemically converted back to recover the monomer in high purity. The crosslinked PMVL materials are highly tunable and exhibit lower glass transition temperature values (near −50°C).
Cross-linked polymers (CPs) encompass almost a third of the synthetic polymer industry and are vital in a wide variety of products including tires, contact lenses, elastomers, adhesives, and foams. While cross-linking confers a number of advantages, including high thermal stability and solvent resistance, this structure also prevents these materials from being reprocessed. Postconsumer CPs are consequentially disposed of in landfills or by incineration, leading to significant loss of value. Additionally, the vast majority of synthetic polymers—including CPs—are petroleum-derived and non- degradable. Their production and disposal is therefore unsustainable in the long term. In recent years, considerable effort has been devoted to the development of CPs that are recyclable, some of which are also renewable.—Brutman et al.
Currently available bioderived and/or elastomers based on recoverable monomers are not easily tunable, exhibit poor mechanical properties, and exhibit glass transition temperature values above −40°C, greatly limiting their applications. Commercial petroleum-derived polyurethanes are highly resistant to degradation and are environmentally unfriendly. Using recoverable aliphatic polyesters to produce thermoplastic elastomers requires rigorous reaction conditions and yields materials with poor solvent resistance, low thermal stability, and significant stress softening (Mullins effect).
The University of Minnesota method overcomes these obstacles by combining a MVL monomer and crosslinking methods.
The University is seeking to license the technology.
Jacob P. Brutman, Guilhem X. De Hoe, Deborah K. Schneiderman, Truyen N. Le and Marc A. Hillmyer (2016) “Renewable, Degradable, and Chemically Recyclable Cross-Linked Elastomers” Industrial & Engineering Chemistry Research Vol. 55: Issue. 42: Pages. 11097-11106 doi: 10.1021/acs.iecr.6b02931