Introduction

Abstract

The properties of plastic material do not depend merely on the fossil or non-fossil origin but on the molecular structure of the chain. The term bioplastic is commonly used for all polymeric materials having a certain bio-character, either from the origin or from the properties. Thus, polyethylene obtained from the polymerization of ethylene produced by the fermentation of natural ethanol is called bio-polyethylene, while polyethylene indicates the same polymer prepared by polymerization of ethylene from oil. Clearly, the two monomers are chemically identical and the derived polyethylenes produced with the same polymerization procedure have the same properties and in particular are both non-biodegradable. The world of the so-called bio-related plastics is quite complex as many aspects are involved. Indeed, one can identify:

• 1. Biopolymers produced by nature such as cellulose, starch, proteins and polyhydroxyalkanoates.

• 2. Polymers or bio-monomers derived from natural products as, for example, poly(lactic acid ) and nylon 11.

• 3. Polymers of non-natural monomers prepared starting from renewable sources: polyethylene obtained by polymerization of ethylene from fermentation products.

• 4. Biodegradable polymers of monomers from fossil origin as linear aliphatic polyesters and poly(vinyl alcohol).

• 5. Mixed polymers such as polyurethanes prepared by combining diols from renewable sources and diisocyanates from fossil oil or blends of biopolymers with polymers of fossil origin.

• 6. Any polymer from fossil or natural sources for biomedical application.

The very complex situation does not allow an univocal classification, and rather, it shows that the use of renewable materials may reduce consumption of the available resources, while on the other side can provide additional elements to extend the versatility of plastic materials , thanks to the basic new structures. The main consideration is therefore that the future increasing the needs of highly specialized applications of the human society can conveniently profit from the availability of differentiated plastic materials .

Appendix

IUPAC Definitions and Statements about Bio-derived Polymers Selection of terms common to all domains and related notes that can be of interest for the book purposes (definitions extracted from Vert et al. (2012)).

Artificial Polymer

Man-made polymer that is not a biopolymer . Note 1: Artificial polymer should also be used in the case of chemically modified biopolymers . Note 2: Biochemists are now capable of synthesizing copies of biopolymers that should be named synthetic biopolymers to make a distinction with true biopolymers . Note 3: Genetic engineering is now capable of generating non-natural analogues of biopolymers that should be referred to as artificial biopolymers , e.g. artificial protein , artificial polynucleotide, etc.

Bio-based

Composed or derived in whole or in part of biological products issued from the biomass (including plant, animal and marine or forestry materials). Note: A bio-based polymer or polymeric device is not necessarily environmentally friendly nor biocompatible nor biodegradable, especially if it is similar to a petrol-based (oil-based) polymer.

Biocompatibility

Ability to be in contact with a living system without producing an adverse effect.

Biodegradable

Qualifier for a substance or device that undergoes biodegradation .

Biodegradation

Degradation caused by enzymatic process resulting from the action of cells.

Biodegradation (bio-related polymer)

Degradation of a polymeric item due to cell-mediated phenomena. Note 1: [omissis]. Note 2: In vivo, degradation resulting solely from hydrolysis by the water present in tissues and organs is not biodegradation ; it must be referred to as hydrolysis or hydrolytic degradation . Note 3: Ultimate biodegradation is often used to indicate the complete transformation of organic compounds to either fully oxidized or reduced simple molecules (such as carbon dioxide/methane, nitrate/ammonium and water). It should be noted that, in case of partial biodegradation , residual products can be more harmful than the initial substance. Note 4: When biodegradation is combined with another degrading phenomenon, a term combining prefixes can be used, such as oxo-biodegradation , provided that both contributions are demonstrated. Note 5: Biodegradation should only be used when the mechanism is proved; otherwise, degradation is pertinent. Note 6: Enzymatic degradation processed abiotically in vitro is not biodegradation . Note 7: Cell-mediated chemical modification without main chain scission is not biodegradation .

Biodisintegration

Disintegration resulting from the action of cells.

Biofilm

The aggregate of microorganisms in which cells that are frequently embedded within a self-produced matrix of extracellular polymeric substance (EPS) adhere to each other and/or to a surface. Note 1: A biofilm is a fixed system that can be adapted internally to environmental conditions by its inhabitants. Note 2: The self-produced matrix of EPS, which is also referred to as slime, is a polymeric conglomeration generally composed of extracellular biopolymers in various structural forms.

Biomacromolecule

Macromolecule (including proteins , nucleic acids and polysaccharides ) formed by living organisms. Note: Not to be confused with biopolymer , although this term is often used as a synonym.

Biomaterial

Material exploited in contact with living tissues, organisms or microorganisms. Note 1: The notion of exploitation includes utility for applications and for fundamental research to understand reciprocal perturbations as well. Note 2: [omissis]. Note 3: This general term should not be confused with the terms biopolymer or biomacromolecule. The use of ‘polymeric biomaterial’ is recommended when one deals with polymer or polymer device of therapeutic or biological interest.

Biopolymer

A substance composed of one type of biomacromolecules .

Bio-related

Qualifier for actions or substances that are connected to living systems.

Degradation

The progressive loss of the performance or of the characteristics of a substance or a device. Note: The process of degradation may be specified by a prefix or an adjective preceding the term ‘degradation ’. For example, degradation caused by the action of water is termed ‘hydrodegradation’ or hydrolysis; by visible or ultraviolet light is termed ‘photodegradation ’; by the action of oxygen or by the combined action of light and oxygen is termed ‘oxidative degradation ’ or ‘photooxidative degradation ’, respectively; by the action of heat or by the combined effect of chemical agents and heat is termed ‘thermal degradation ’ or ‘thermochemical degradation ’, respectively; by the combined action of heat and oxygen is termed ‘thermooxidative degradation ’.

Degradation (bio-related polymer)

Degradation that results in desired changes in the values of in-use properties of the material because of macromolecule cleavage and molar mass decrease.