Solid state polymerization (SSP) is a well-established polymerization technique used as an extension of the solution/melt process in polycondensates (eg PA 66, PET, PBT) to increase molecular weight (MW) without the risk of polymer thermal degradation. SSP involves heating the low-molecular-weight base polymer (prepolymer) to a temperature higher than the Tg, but lower than the onset of melting: reactions occur in the amorphous regions, where the chain mobility is high enough for reactive end groups to diffuse and react. Any formed by-product can be removed through convection caused by passing inert gas or by maintaining reduced pressure. At the same time of MW increase, residual amounts of monomers and oligomers can be removed, while an improvement of polymer thermal properties occurs; melting point usually increases with SSP temperature and time as a result of crystal reorganization and perfectioning, melting behavior changes from multiple-endotherm-scheme to narrower melting curves, and crystallinity may also increase due to annealing. Such an annealing effect can be beneficial when applying SSP on already formed polymeric materials (e.g. post-extrusion SSP), such as fibers, films, polymeric microcapsules.
Apart from fossil-based polymers, SSP has been applied successfully also on biobased/biodegradable polycondensates, such as PBS and PLA. In the context of enhancing sustainability, a solid-based polymerization process can be low-cost and eco-friendly due to the low operating temperature, the use of solid reacting particles and the relevant easy handling of reactors. PolymeReEng group holds an extensive research activity on SSP processes, while the last 10 years research strategy is based on the multipurpose character of SSP: apart from being a finishing step in polymerization layouts, SSP is a valuable tool for properties upgrade in new materials fields, such as polymeric microcapsules, vitrimers and recycled polymers.
Indicative References
- Papaspyrides C, Vouyiouka S, Εditors. Solid state polymerization. NJ: John Wiley & Sons, Inc. 2009 (Invited) 294 pp, doi.
- Vouyiouka S, Papaspyrides C. Solid state polymerization. In: Encyclopedia of Polymer Science and Technology. 4th edition. NJ: John Wiley & Sons, Inc. 2011 (Invited) pp.1-32.
- Panagiotopoulos Chr, Porfyris A, Korres M.D, Vouyiouka S. Solid-state polymerization as a vitrimerization tool starting from available thermoplastics: The effect of reaction temperatures. Materials 2021:14;9, doi.
- Gkountela Chr, Rigopoulou M, Barampouti E-M, Vouyiouka S. Enzymatic prepolymerization combined with bulk post-polymerization towards the production of biobased polyesters: the case of poly(butylene succinate). Europ Polym J. 2021; 143(15): 110197, doi.
- Chronaki K, Korres MD, Papaspyrides C, Vouyiouka S. Poly(lactic acid) microcapsules: Tailoring properties via solid state polymerization. Polym Degrad Stab. 2020;179:109283, doi.
- Papaspyrides C, Vouyiouka S, Georgousopoulou I-N, Marinkovic S, Estrine B, Joly C, Dole P. Feasibility of solid-state postpolymerization on fossil- and bio-based poly(butylene succinate) including polymer upcycling route. I&EC research. 2016;55(20):5832-5842, doi.
- Filgueiras V, Vouyiouka S, Konstantakopoulou M, Boussia A, Papaspyrides C, Lima E-L, Pinto J-C. Modelling of polyamide 66 solid state polymerization: Drawing a chemical reaction scheme. Macromol. React. Eng. 2015;9(2): 65-89, doi.
- Pfaendner R, Papaspyrides C, Diamanti P-C, Vougiouka S, Chronaki K, Porfyris A. Method for manufacturing aliphatic polyesters and use of phosphorus-containing organic additives. Fraunhofer-Gesellschaft, WO2018224672, 2018, pp 24.
- Pfaendner R, Fink J, Simon D, Papaspyrides C, Vougiouka S. Process for the preparation of polyamides in the presence of a phosphonate. Ciba Specialty Chemicals Lampertheim GmbH, WO2007/006647, 2007, pp.36.
On-going PhDs
Panagiotopoulos Christos. Design and production of advanced polymeric materials via solid state polymerization. November 2020 – today.
Chronaki Konstantina. Solid state polymerization as a post-treatment tool for polymers upgrade. March 2017-today.
On-going Funded Projects
PRecycling. Plastics Recycling from and for home appliances, toys and textiles. Horizon Europe (GA 101058670), 2022 - 2026
SucciVitr. Comprehending and controlling the dynamics of the adaptable network in biobased vitrimers. Design and production of advanced polymeric materials via solid state polymerization. November, PEVE0050, 2020 – today.
