A biopolymer ( Greek: bios βίος, ' poly with Greek πολύ much ' life and μέρος meros, part ' ) is a polymer that is synthesized in the cell of a living being. In the form for example of polysaccharides, proteins, nucleic acids, etc. biopolymers serve as energy stores ( glycogen, starch), have structural functions for the cell or the whole organism (fibers, lipid membranes) act in metabolism ( uptake, transport, enzyme, excretion), recognize states ( sensors), cause changes ( muscle, Color Swap ), resist harmful influences from active (toxins, immunology ), store or convey information ( genetic, hormonal, CNS).
Frequently, the term biopolymer is also used for distinguishing between materials. Here is also spoken by the technical biopolymers or Biopolymerwerkstoffen to distinguish them from non-usable as a material biopolymers. A uniform definition for technical biopolymers has not yet been established. So including materials are summarized, for example, composed of biogenic raw materials ( renewable raw materials ) and / or are biodegradable ( biogenic and biodegradable polymers). Thus, this includes bio-based biopolymers that are biodegradable or not biodegradable, as well as petroleum-based polymers, which are biodegradable. This results in a definition of the conventional, petroleum-based materials and plastics which are not biodegradable, such as polyethylene (PE), polypropylene (PP ) and polyvinyl chloride (PVC).
For other definitions petroleum products are not counted among the biopolymers ( biogenic polymers). In contrast, both native polymers (eg, cellulose and cellulose derivatives) as well as bio-based plastics, which were prepared by extensive chemical alteration of biogenic raw materials (eg, polylactides (PLA ) with the help of white biotechnology produced lactic acid ) will count.
A related term is bioplastic, which is also used inconsistently, and partially or strongly overlaps with the term biopolymer. Again, the prefix is understood as biogenic or biodegradable organic, depending on the definition.
The following table shows important, naturally occurring ( biogenic ) biopolymers with the respective monomer, the nature of chemical bonding and examples are given to their occurrence:
Technical biopolymers ( Biomaterials ) can be, according to the definition of Endres and Siebert -Rath, divided into the three discussed in the following paragraphs categories. This definition coincides with the definition of bioplastics, but has no general validity used by the European Bioplastics.
Become biopolymers contrast is defined as biodegradable polymers, not all are dazuzuzählen examples listed below with Natural Polymers and Bio-based polymers.
Plastics are usually not homogeneous products, but require different auxiliaries and additives, which are often petroleum- based. Only partly a replacement is possible through bio-based components.
In nature or in biomass occurring polymers such as cellulose and starch may be used without or with only small changes, or may be used with retention of the basic structure for the production of biopolymers:
- Cellulose and certain cellulose derivatives Regenerated fibers such as viscose and cellophane
- Thermoplastic starch
Organic compounds such as starch or sucrose, may be extensively modified to form bio-based polymers:
- Polylactide (PLA ) polymer of lactic acid, the monomer may, for example, by fermentation with bacteria ( white biotechnology ) of organic compounds, such as glucose, are prepared
- Polyhydroxybutyrate (PHB ) in nature as storage substance in bacteria occurring polymer, produced by fermentation of bacteria from other organic compounds
- Thermoplastics lignin
- Epoxy acrylates based on oil ( currently mainly linseed and palm oil)
Degradable, petroleum-based polymers
Certain petroleum- based plastics are biodegradable and are therefore sometimes referred to as biopolymers ( or bioplastics ) referred to:
- Certain polyesters
- Polyvinyl alcohol
- Polybutylene terephthalate ( PBAT )
- Polybutylene succinate (PBS)
- Polycaprolactone (PCL)
- Polyglycolide (PGA)
The biodegradability is particularly relevant for the subsequent disposal of the material. From an environmental and sustainability aspects are degradable plastics are of increasing interest and of increasing economic importance.
It should be remembered that polymers of natural or biologically based raw materials are often biodegradable, but also products can be produced that are resistant. Similarly, polymers from fossil raw materials is often of high resistance, but also degradable products can be generated (see paragraph Degradable, petroleum-based polymers).
Depending on the application raw unmodified biopolymers are mixed with other raw biopolymers ( blended ), to achieve the desired properties. Manufacturer of such blends are eg Nova Mont, Biotec, FKuR and Limagrain.