Lignin-Inspired Polymers with High Glass Transition Temperature and Solvent Resistance from 4-Hydroxybenzonitrile, Vanillonitrile, and Syringonitrile Methacrylates

Olivier Bonjour,Lauri Vares,Hannes Nederstedt,Siim Laanesoo,Monica V. Arcos-Hernandez,Patric Jannasch

doi:10.1021/acssuschemeng.1c07048

Olivier Bonjour, Lauri Vares + Show 4 more

Open Access

https://doi.org/10.1021/acssuschemeng.1c07048

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Abstract

We here report on the synthesis and polymerization of nitrile-containing methacrylate monomers, prepared via straightforward nitrilation of the corresponding lignin-inspired aldehyde. The polymethacrylates reached exceptionally high glass transition temperatures (Tg values), i.e., 150, 164, and 238 °C for the 4-hydroxybenzonitrile, vanillonitrile, and syringonitrile derivatives, respectively, and were thermally stable up to above 300 °C. Copolymerizations of the nitrile monomers with styrene and methyl methacrylate, respectively, gave potentially melt processable materials with tunable Tg values and enhanced solvent resistance. The use of lignin-derived nitrile-containing monomers represents an efficient strategy toward well-defined biobased high Tg polymer materials.

Highlights

The development of new biobased thermoplastic polymers from sustainable feedstocks is essential when addressing the issues caused by fossil-based plastics.[1−6] In order to compete with and replace fossil-based conventional plastics, biobased polymers must be produced from inexpensive and sustainable natural sources, have suitable thermal and mechanical properties, and be readily processable.[7]. This is perhaps especially difficult to achieve when it comes to amorphous thermoplastic polymers with high glass transition temperatures (Tg > 100 °C) because of the great challenge to produce this kind of material from biobased feedstocks.[8]
Lignins are biopolymers consisting of hydroxyphenyl, guaiacyl, and syringyl units, whose relative amounts depend on the natural source..[19−21] The depolymerization and purification of lignin remains a challenge,[19,22] only vanillin can nowadays be isolated from lignin in large scale.[23]
These monomers are based on lignin-inspired building blocks, namely, 4-hydroxybenzaldehyde 1a, vanillin 1b, and syringaldehyde 1c, which correspond to hydroxyphenyl, guaiacyl, and syringyl lignin units, respectively.[20] (Scheme 1)

Summary

■ INTRODUCTION

The development of new biobased thermoplastic polymers from sustainable feedstocks is essential when addressing the issues caused by fossil-based plastics.[1−6] In order to compete with and replace fossil-based conventional plastics, biobased polymers must be produced from inexpensive and sustainable natural sources, have suitable thermal and mechanical properties, and be readily processable.[7]. Poly(styrene-co-acrylonitrile) (SAN) has a Tg above 100 °C, depending on the acrylonitrile content.[29] benzonitrile methacrylate polymers have recently been predicted by artificial neural network to possess high Tg.[30] From an industrial point of view, nitrilation is readily achieved by ammoxidation, using ammonia, oxygen, and a vanadium or molybdenum oxide catalyst.[31,32] With the aim to develop biobased high-performance polymethacrylates with high Tg values resulting from both high macromolecular chain rigidity and polarity, we have in the present work prepared three different nitrile-containing methacrylate monomers These monomers are based on lignin-inspired building blocks, namely, 4-hydroxybenzaldehyde 1a, vanillin 1b, and syringaldehyde 1c, which correspond to hydroxyphenyl, guaiacyl, and syringyl lignin units, respectively.[20] (Scheme 1). The thermal stability and melt processability of the copolymers were subsequently investigated by rheology measurements

■ RESULTS AND DISCUSSION

■ CONCLUSION

■ ACKNOWLEDGMENTS

■ REFERENCES