On the universal nature of the behavior of polymers

Translations: FR

A theory is an economy of thought (read E. Mach , P. Duhem , A. Einstein ). We make a representation of reality by establishing unlikely links between things or phenomena that are a priori very different. In the 1970s, P.G. de Gennes achieves a major advance of this type by noting that polymers were critical objects whose self-similarity makes it possible to establish universal laws of behavior (called scaling laws) for observable macroscopic quantities such as osmotic pressure, viscosity or elasticity when expressed as a function of carefully chosen variables (called reduced variables). This was followed in France (particularly at Saclay) for about twenty years by an abundant experimental activity which had a lasting impact on the physics of soft matter.

I started my career at the very end of this period, but working alongside colleagues at Saclay who had been major players (Jacques des Cloizeaux, Gérard Jannink, Mohamed Daoud, Mireille Adam, Jean-Pierre Cotton) and who made me want to tackle these questions. Even though almost everything had been done in this area I found some niches where scaling laws sometimes did not work so well. It was about cross-linked polymers and the way they percolate in the volume that is offered to them, linear polymers and their reptation-like motion or their movements at a particular temperature called theta.

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