High-performance resins and thermoplastics from syringaldehyde

Polymers from renewable sources

Materials Environmental

Syringaldehyde can be isolated from many common wood species including beetle-killed spruce

Phenolic compounds constitute platform chemicals to manufacture everyday-life items. As polymers, phenols offer rigidity, water resistance, and resistance against fire. Bisphenol compounds such as bisphenol A (BPA) are widely used as building blocks for a variety of commercial and industrial products. Specifically, bisphenols are the building blocks for polycarbonate plastics, epoxy resins, polyester resins, cyanate ester resins, and other polymers or resins. Commercially available bisphenol compounds, especially polyaromatic bisphenols, are currently derived from petroleum.  Approximate 5.4 million tons of BPA was produced in 2015.

In an effort to create more sustainable bisphenol building blocks, Navy researchers have developed a series of polyaromatic bisphenol compounds derived from syringaldehyde. Syringaldehyde can be isolated from natural feedstocks that include lignin via an enzymatic reaction and with the Navy’s novel method, can be efficiently converted into polyphenols. The ability to either homocouple (react two identical molecules to form a different one) or cross-couple syringaldehyde with various renewable aldehydes allows for the synthesis of a variety of multifunctional bisphenols that can be converted to resins with exceptional glass transition temperatures (Tg). The Tg is one of the most important properties of any epoxy and is the temperature region where the polymer transitions from a hard, glassy material to a soft, rubbery material. The utilization of renewable polyphenols as precursors to epoxies, polycarbonates, and high temperature thermosets including cyanate esters, provides an opportunity to develop full-performance resins while reducing the use of petroleum-based feedstocks.

Parties interested in this patent may also wish to review US patent 8,853,343 – Thermoset compositions from plant polyphenols

Continuations-in-part related to this US patent 8,993,688 listed below (US patent number; patent title; description):

8,921,614 –Selective deoxygenation of hydroxybenzaldehydes.  The effective utilization of multifunctional benzaldehydes requires selective deoxygenation methods. This invention teaches how to remove the hydroxyl groups of syringaldehyde and vanillin to give 3,5-dimethoxybenzaldehyde or 3-methoxybenzaldehyde, respectively. The latter is useful as a starting material for the manufacture of many other products including resveratrol, a natural product that has potential as an anticancer compound.

Three benefits of the process:

  • The process starts from a cheap and renewable phenol (syringaldehyde) that can be isolated from various biomass sources, and obtained as a byproduct of paper production or conversion of lignocellulosic feedstocks to biofuels
  • The process is selective for the trans-isomer
  • The decarboxylation does not require a copper catalyst

8,993,689 – Polyphenols and high-performance resins from syringaldehyde.  The patent focuses on making resins from syringaldehydes comprising: reductively coupling syringaldehyde with an additional molecule of syringaldehyde or at least one aromatic aldehyde having a hydroxy group, or methoxy group.  Derived polyphenols are reacted with a base to yield cyanogen halides or pseudohalides to produce cyanate ester resins.

9,018,314 – Polyphenols and high performance resins from syringaldehyde.  This patent starts with the method from ‘689 but reacts the polyphenols with a reagent such as phosgene, triphosgene, carbonates, sulfones or aldehydes to produce thermoplastics such as polysulfones, polyesters, polyester-styrene, polycarbonates, and others.

9,051,414 – Polyphenols and high performance resins from syringaldehyde.  This patent starts with the method from ‘689 but converts the polyphenols to thermosetting resins such as epoxy, benzoxazine, phenolic bismaleimide, polyphenylene, phthalonitrile endcapped, phenylethynyl, and other resins.

9,127,115 – Polyphenols and high performance resins from syringaldehyde.  This patent starts with the method from the ‘688 patent but converts the polyphenols to thermosetting resins selected from the group consisting of epoxy, benzoxazine, phenolic, bismaleimide and polyphenylene resins as well as phthalonitrile endcapped, phenylethynyl endcapped, and other endcapped resins.

9,187,591 – Polyphenols and high performance resins from syringaldehyde.  This patent starts with the method from the ‘688 patent but converts the polyphenols by reaction with reagents selected from the group consisting of phosgene, triphosgene, diphenylcarbonate, other carbonates, bis(4-chlorophenyl)sulfone, other functionalized sulfones, diacid chlorides, phthalic acids, formaldehyde, other aldehydes, and epichlorohydrin to produce thermoplastics selected from the group consisting of polysulfones, polyesters, polyester-styrene polymers, polyarylates, polycarbonates, and any combination thereof.

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