Fraunhofer Flagship Project SUBI²MA – Sustainable Bio-based and Biohybrid Materials

Objectives and solution approaches

SUBI²MA materials provide the plastics and chemical industries or downstream markets such as construction chemicals, automotive, textile chemicals and health with an answer to the challenges of national and global sustainability strategies. Digital twins of the innovation principles created also enable the company to respond quickly and flexibly to future challenges in the transformation of plastics technology and other markets in the context of sustainability.

Three key topics/objectives are addressed in the project:

1. Provision and demonstration of new bio-based materials through development of synthesis routes, processing technologies, characterization and evaluation
2. Provision and demonstration of new biohybrid materials through optimization of properties, functionalization, characterization and evaluation
3. Development and establishment of sustainable fast-track developments through digitalization, simulation and holistic ecological assessment

New bio-based materials

Objective 1 New bio-based materials is to be achieved by developing a new bio-based high-performance polyamide, our caramide, to market maturity. This new bio-based polyamide was synthesized for the first time by the Straubing branch of Fraunhofer IGB. As part of the project, it will be further developed and its application demonstrated, both in terms of synthesis and processing methods, so that it can be used as a competitive alternative to fossil polyamides. 

New biohybrid materials

Objective 2 New biohybrid materials is fulfilled by integrating biological building blocks into plastics, which give them additional functions and thus expand the range of applications. The pre- and post-moulding of PET and cellulose, as mass-produced polymers, plays a decisive role here. The desired functionalities are the control of hydrophilicity, bio-based additives for flame retardancy, accelerated degradation and antimicrobial effectiveness.

Fast-track developments

Objective 3 Fast-track developments comprises the conceptualization of a digital value chain in order to significantly accelerate material substitutions in the future, as well as sustainability considerations in material development. The digital value chain includes digitalization and simulation from the molecular level of synthesis to the modelling of processes such as fiber spinning, as well as the development of digital demonstrators. 

Research activities at the Straubing branch of Fraunhofer IGB focused on objectives 1 and 2. 

Further development of Caramide

The main task of objective 1 is to further develop caramide by optimizing its synthesis and processing. Caramide is obtained from the natural substance 3-carene after chemical modification. 3-carene, a monoterpene, is produced in large quantities during the production of cellulose in the Kraft process as a sidestream that has hardly been utilized to date. Two different monomer building blocks can be obtained from 3-carene: 3S-caranlactam and 3R-caranlactam.

In objective 1, Fraunhofer IGB is focusing on optimizing the reaction conditions for the synthesis of the two monomers 3S- and 3R-caranlactam, as well as their provision in sufficient quantities. By commissioning a contract manufacturer, it was possible to provide pilot plant quantities of 3R-caranlactam. Purification took place at Fraunhofer CBP.

The purified 3R-caranlactam monomer and smaller quantities of the 3S-caranlactam synthesized in smaller batches at Fraunhofer IGB were handed over to Fraunhofer IAP.

Polymerization into cast polyamide was carried out at Fraunhofer IGB, hydrolytic polymerization was developed at Fraunhofer IAP, as was processing into sustainable monofilaments for textiles. At Fraunhofer ICT, caramide is foamed into bio-based polyamide foams, e.g. for lightweight construction.

Hydrophobic treatment of cellulosic fibers and finishing of cellulosic-based membranes

Within the framework of objective 2, the focus at Fraunhofer IGB is on the hydrophobization of cellulose fibers for textile applications and on the exemplary finishing of cellulose-based membranes using the example of receptors of the innate immune system, the toll-like receptors (TLR) as a simple analysis tool for microbial contamination.

The hydrophobization of cellulose was carried out using fusion proteins consisting of a cellulose binding domain and a hydrophobin on a gram-scale. By varying both domains, different fusion proteins were produced recombinantly and analyzed. Depending on the type and concentration of the construct, successful hydrophobization of the cellulose was demonstrated in drop tests.

Current work is investigating the influence of hydrophobized cellulose on the production of cellulose fiber-reinforced PLA. To this end, PLA compounds with hydrophobized and untreated cellulose are being produced and compared in terms of their material properties (including tensile testing).

TLRs recognize microbial residues, isolated chemical structures, cell wall components or complete microorganisms. In contrast to antibodies, which are limited to the detection of very specific antigens, TLRs can detect broad classes of microorganisms such as Gram-negative or Gram-positive bacteria. This makes TLR particularly suitable for narrowing down unknown analytes in the sense of a sum analysis or for selecting class-specific samples. This is the strength of TLRs as analytical tools, as the individual TLRs or TLR complexes can be used to very quickly narrow down the sources of contamination (Gram-positive or Gram-negative bacteria, viruses, yeast, fungi). This knowledge significantly reduces the analysis effort, offers a time advantage and thus saves costs. The fermentative production of TLRs in mammalian expression systems and the directed functionalization of selected materials with TLRs have already been carried out. The aim is to produce exemplary structured functionalized cellulose membranes with immobilized TLR and to use them to create the first test strips for the detection of Gram-positive bacteria and their residues as a demonstrator.