Stephane Bruzaud

Biopolymers: General overview and focus on the polyhydroxyalkanoates

Stéphane Bruzaud is Full Professor at the University of South Brittany (UBS) located in Lorient (France). His current research activity concerns the development of biobased and/or biodegradable polymers, from their production to their end of life. He leads a research group working on biopolymer engineering. This concerns the implementation of virtuous approaches for the elaboration (through biotechnological processes using of wastes derived from local agro-industrial by-products, for instance) and the formulation (blending with other biopolymers and/or incorporation of natural fillers) of bioplastics as well as the study of the polymer degradation. He has conducted many studies on the polymers’ recycling and on the ageing and the (bio)degradation of polymers in various environments (photo-oxidation, gamma irradiation, soil, distilled water and seawater). For several years, Stéphane Bruzaud also develops research about the evaluation of plastic contamination in the environment, with the objective to establish innovative protocols and methodologies for the sampling and the analysis of microplastic fragments collected in sediments and seawater. He is scientific partner of TARA Expedition and MED Expedition which are French non-profit organizations fighting against the plastic pollution and searching for solutions to protect the marine environment. These studies illustrate and confirm the interest of developing materials that are more environmentally friendly, which can constitute a virtuous and realistic alternative to the plastics usually used.

Stéphane Bruzaud is involved in many academic and industrial collaborations and some collaborative contracts funded by Europe, the French Minister of Environment, CNRS, ADEME, Brittany region, TASSILI and some industrial partners. He has also supervised 20 Ph.D. students and is the author of about 80 papers in peer-reviewed journals and 04 book chapters.

Currently, he provides courses for graduate and under-graduate students in the Faculty of Sciences and Engineering Sciences at UBS, on organic chemistry, polymer synthesis, biopolymers, nanocomposites and chemical degradation.

After managing the French Polymer Group in the West region of France (2001-2007), he is elected member of the executive board of the French Polymer Group since 2016.

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The conference will begin with the presentation of some background elements to define biobased and biodegradable polymers and to illustrate the interest of developing such polymers for certain industrial sectors. Different materials that are more respectful of the environment will be developed that can constitute a virtuous and realistic alternative to the polymers/plastics usually used.

Then, the conference will specially focus on polyhydroxyalkanoates (PHA), which are bacterial polyesters and constitute a very promising family of polymers both from the point of view of their use properties and that of their environmental impact. The production of PHA is particularly relevant since it breaks away from traditional chemical processes, using some of the most energy-efficient industrial biotechnology processes. For a large number of marine and terrestrial bacteria, PHA are an ideal carbon and energy storage material, due to their low solubility and high molar mass. The chemical composition (nature of the monomer units constituting the PHA and proportion of these in the chain) and therefore the physico-chemical PHA properties depend closely on the producing bacterial strain and on the carbon sources available in its environment. Different examples of PHA production will present in order to show how the choice of substrates integrated at the beginning of the biosynthesis process makes it possible to influence the chemical structure and the morphology of the PHA produced and thus to adjust the physico-chemical properties. Finally, results recently obtained by different approaches will illustrate the capacity of these polymers to rapidly biodegrade in the marine environment. Significant differences in the PHA behaviour are observed with regard to the composition and morphology of PHA. The main factors intrinsic to PHA (chemical structure, molar mass, free volume, glass transition, mobility, crystallinity, solubility, hydrophilic / hydrophobic balance, etc.) will be explained and it will be shown to what extent they can influence the behaviour of polymers with respect to biodegradation, in particular in the marine environment.

The results already obtained and those to come are aimed at developing models to help in the design of tailor-made biodegradable polymers whose (bio)degradation could be controlled by playing on the physical and chemical factors previously identified and intrinsic to PHA.