Dear Colleagues,

The global mass production of plastics started in the 1950s, with an estimated total number of 8.3 to 9.1 million metric tons (Mt) already manufactured up to the current day. From this, only 9% has been recycled and 12% incinerated, whereas the remaining 79% has now accumulated in landfills or in the environment. Their high stability and nondegradability cause serious environmental issues to living organisms with a problem called today “microplastics”. Research efforts have focused on producing environmentally friendly materials that could “disappear” after their use without leaving fragments or harmful products behind. Biodegradability is directly dependent on the chemical structure of polymers, with polysaccharides, peptides and aliphatic polyesters having hydrolysable bonds. Most of them can be found in biomass, a cheap energy and functional material source.

Biomass is produced in abundance from plants every year through photosynthesis, using only CO2 and water (approximately 954 Mt/year in EU countries). However, the chemical energy stored in biomass (4.500 EJ) in the form of glucose or sugars is lost during the annual cycle of seasons (animals–microorganisms). In recent years, apart from biofuels and energy, the production of biobased platform chemicals, monomers and polymers from biomass has received great attention. In this direction, there has been a high demand to valorise agricultural and forest residues, animal waste from farms, municipal solid waste and waste from industry and households. Different pretreatments (hydrothermal, steam explosion, mild acid/base hydrothermal, organosolv, enzymatic hydrolysis, pyrolysis, liquefaction, gasification, etc.) can be applied to convert lignocellulosic or other relevant biomass and isolate primary fractions (i.e., extractives, cellulose, hemicellulose, lignin, etc.), bio-oils, as well as sugars and phenolic compounds, to serve as platform chemicals and raw materials for further upgrading and utilization.

Based on all of the above, the worldwide demand for a sustainability and green economy has led research interest in the field of biorefining and polymer technology in three different directions:

• To effectively valorise biomass using green processes to extract or synthesize functional nanoadditives and building blocks (biobased monomers, nanocellulose, nanolignin, biochar, etc.);
• To produce novel, eco-friendly, compostable or mainly biodegradable polymers and composites based on these additives and monomers;
• To replace the use of fossil-derived polymers and composites in various applications, for example, in the fields of food packaging, agriculture and construction, with eco-friendly biomaterials.

Developments in biobased nanomaterials are coupled with biotechnologies applied to biomass, converting renewable resources into high-added-value polymers. Although a lot of research has been conducted in this area in the last two decades, only a very limited number of products have been commercialized, reaching market end users. The major challenge in the area lays in the fact that novel product concepts are restricted from entering the market because end user applications remain at small lab-scale tests, therefore, having limited exploitation capacity for industrial deployment. This is the ‘valley of death’ which BIOMAC intends to overcome (https://www.biomac-oitb.eu). To accelerate the market entrance of nanoenabled biobased materials (NBMs), BIOMAC aims to establish an open innovation test bed (OITB) dedicated to upscaling processes incorporating major developments in this area based on two pillars: to generate knowledge and to capture business value. Starting from the utilization of biomass sources, followed by the production of biobased nanoparticles and different building blocks, the ecosystem community is currently developing biopolymers for the strategic sectors of food packaging, agriculture, construction, automotive and printed electronics, making up a large market share.

This Special Issue of the international open access journal Polymers aims to collect cutting-edge, state-of-the-art and original full-length research articles and critical or tutorial reviews on the topic of “nanoenabled biobased materials”, including, but not limited to:

• Green techniques for biomass (pre)treatment and valorisation;
• Ecofriendly processes to recover biobased additives and monomers from biomass;
• Biomass (pre)treatment to produce biobased monomers and building blocks, such as lactic acid, succinic acid, adipic acid, azelaic acid, aminodecanoic acid, terephthalic acid, furan dicarboxylic acid, diol-like ethylene, propylene and butane diol and polyols, isosorbide, acetic acid, formic acid, diamines, etc., originating from the chemo/bio/electro/photocatalytic processing of biomass primary sugars and phenolics.
• Production of nanocellulose, nanolignin, biochar and respective modified materials to serve as the functional nanoadditives of biobased polymers;
• Synthesis and characterization of biobased and biodegradable macromolecules such as poly(lactic acid, poly(butylene succinate), polyhydroxyalkanoates, polycaprolactone, etc., with desired mechanical and biodegradable properties;
• Synthesis of biobased copolymers using biomass precursors with enhanced performance and biodegradability;
• Development of biobased composites and nanocomposites with enhanced properties;
• Assessment and demonstration of specific advantages of biobased and/or biodegradable polymers and composites compared with fossil-derived polymers;
• Properties of biomacromolecules and composites and their applications in relevant fields;
• Production and study of biodegradable blends;
• Biobased polymer recycling methods and depolymerization techniques.

This Special Issue is supported by BIOMAC, funded by the European Union’s Horizon 2020 Research and Innovation Programme under grant agreement no. 952941.

Prof. Dr. Dimitrios Bikiaris
Prof. Dr. Konstantinos S. Triantafyllidis
Dr. Zoi Terzopoulou
Prof. Dr. Gianmarco Griffini
Guest Editors

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• biomass pretreatment
• biomass fractionation
• biobased platform chemicals
• biobased monomers
• biobased additives
• nanocellulose
• nanolignin
• biochar
• biomacromolecules
• biobased polymers
• biodegradable polymers
• natural biobased polymers
• synthetic biobased polymers
• nanocomposites
• enzymatically hydrolysable polymers
• biodegradability
• compostability
• environmentally friendly polymers
• biopolymer and composite applications