Biodegradable aliphatic polyphosphoester-based particles — green production by batch and flow processes

Nano- and microparticles are used as carriers for the controlled delivery of an active ingredient with a high potential for applications for, among others, the health care and personal care industry. Particles made up of aliphatic polylactones, typically, polylactide, polyglycolide and polycaprolactone are very well-known since many years. Aliphatic polyphosphoesters less popular even though they this class of polymers has witnessed a renewed interest. This communication aims at comparing the potential of aliphatic polylactones and aliphatic polyphophoesters with a special attention paid on particles, based on the recent developments carried out in the Center of Education and Research of Macromolecules of the University of Liège.
Ring-opening polymerization of 5-membered cyclic polyphosphoesters is very efficient for the synthesis of high molar mass aliphatic polyphosphoesters. As far as cyclic 5-memberd phosphates are concerned, their extremely high sensitivity to hydrolysis remains a strong limitation at the time being. In this context, efficient processes allowing the synthesis of a wide range of aliphatic polyphosphoesters, functionalized or not, will be reported based on: (1) flow technologies, (2) organocatalysis and (3) chemical modification of the polymers. Advantages and drawbacks of aliphatic polyphosphoesters compared to polyesters will be detailed with a special attention on both the synthesis of these polymers and their properties, to assess their potential for future applications.
Particles made up of biodegradable poly(phospho)esters will be shown to be prepared by the self-assembly of amphiphilic polymers or by nanoprecipitation in batch or in flow reactors. Depending on the preparation process and the chemical structure of the polyesters, the size and size-dispersity of particles as well as the loading content, loading efficiency and release rate of a model active ingredient will be discussed.

Acknowlegements: Philippe Lecomte is research associate by the belgian FNRS. The authors thanks all the partners of the IN-Flow project carried out under the Interreg V-A Euregio Meuse-Rhine Programme, with €2.1 million from the European Regional Development Fund (ERDF). By investing EU funds in Interreg projects, the European Union invests directly in economic development, innovation, territorial development, social inclusion, and education in the Euregio Meuse-Rhine.