Internally Plasticized Cellulose Derivatives: New and Innovative Materials obtained from Sustainable Resources, Chemistry and Processes. – PLACELMAT

Currently, cellulose derivatives can be melt-processed only with a significant amount of external plasticizers, whose major drawback is their exudation from the polymer over time. This phenomenon can lead to dramatic environmental consequences due to migration in the ecosystem and to the deterioration of the material properties, narrowing the application fields of these renewable polymers. To overcome this problem, the PLACELMAT project aims at designing and developing internally plasticized cellulose-based polymers. This new class of biopolymers will be easily processed from the melt and will exhibit mechanical and optical properties that can exceed the performance of polymers derived from fossil resources, thus opening a perspective of new application domains and markets.
The difficulty in processing cellulose comes from the inherent rigidity of the chain and the strong inter-molecular interaction due to the compact packing. To achieve internal plasticization, we will follow an innovative strategy based on both the increase of the flexibility of the cellulosic backbone and the addition of free volume, through controlled chemical modification of the sugar residues. Firstly the use of specific oxidation reactions will allow us to cleave the sugar rings and induce a major release of molecular motions within the chains. Secondly, the grafting of bulky side groups using controlled reactions will further increase the free volume and increase the inter-chain mobility, finally leading to internal plasticization.
This ambitious joint academic/industrial program will first be based on collaborative transversal actions intended for a proof of concept. Modeling techniques at different scales will provide theoretical structure-properties relationships that will be verified by experiments on model systems at laboratory scale. Based on the results the relevant parameters and the best structures to target will be identified.
Secondly, innovative ‘green’ chemical reactions and processes compatible with an industrial development will be implemented to propose synthesis tools to achieve the controlled oxidation of cellulose and the subsequent grafting of bulky side groups. These actions will benefit from the recent development of eco-compatible polysaccharides oxidation methods using bio-inspired catalysts and green oxidants. The grafting will be based on strategies inspired from the world of polyamides or polyesters. Both actions will strongly benefit from a characterization toolbox that will be provided in the proof of concept phase.
Finally, the processability of the polymers will be examined; first at the lab scale using the ‘proof of concepts’ samples developed in the transversal tasks and later on at a greater scale with the products prepared from the synthetic routes developed in the two synthesis operational steps. As the final targeted properties will be tested at this stage, this task will provide feedback and will be used to dynamically validate the full procedure.
The PLACELMAT project will take advantage of the synergistic expertise of the partners as well as their recent fruitful collaborations in a rich technical environment. Through this upstream research topic of ‘internal plasticization of biopolymers’, our project clearly follows a logic of giving a structural functionality to a bulk biopolymer such as cellulose that will not only provide mid-term solutions to an environmental problem, but will also be applied and/or adapted to a wider class of polysaccharides. This will allow the industry to a) propose new polymers with very low CO2 footprints and virtuous life cycles and b) enhance, through appropriate grafting groups, its offer in the class of ‘green’ polymers going from the thermoplastic derivatives to the family of hydrosoluble or hydrodispersible derivatives, covering various applications such as ‘plastic grade’ applications, detergency, home and personal care, etc.