Short introduction to polymer structure, crystallization and melt memory

Palestrante: Prof. Dr. Alejandro J. Müller – University of the Basque Country EHU – Espanha

Abstract: When polymer chains crystallize, they experience a dramatic change in their segmental conformation, transitioning from isotropic random chains to well-ordered extended chain segments in fixed and symmetric conformations determined by the resulting crystal structure (e.g., chains closely packed in, for example, orthorhombic or monoclinic unit cells). In this lecture, a short introduction to why polymers crystallize and how they do it will be presented. Crystallization directly influences mechanical and optical properties, permeation, and biodegradation, among other important properties. If polymer crystals are heated above their melting point, they require a specific temperature and duration to revert their ordered conformation into an isotropic random coiled melt. When the temperature is slightly above the melting point, the chains retain a memory of the conformation they had in the crystals. The exact nature of these memory regions in the melt is unknown, but their presence can induce significantly higher crystallization temperatures when cooling from the melt compared to an isotropic melt. Such accelerated crystallization and thus solidification can have practical consequences for material properties and even applications.

Professor Alejandro J. Müller is an IKERBASQUE Research Professor at POLYMAT and at the Department of Polymers and Advanced Materials: Physics, Chemistry, and Technology,
Faculty of Chemistry, University of the Basque Country EHU, in Donostia-San Sebastián, Spain. He leads the Polymer Physics and Advanced Manufacturing research area at POLYMAT and
heads the Polymer Physics of Advanced Multiphasic Materials group. He obtained his Ph.D. from  the University of Bristol (UK) under the mentorship of Prof. Andrew Keller and Dr. Jeffrey Odell.
His research focuses on polymer crystallization, particularly the structure, morphology, nucleation, crystallization, and crystallization kinetics of semicrystalline polymers and complex multiphasic
materials, including polymer blends, block and random copolymers, biopolymers, and nanocomposites. Prof. Müller has made significant contributions to understanding crystallization
in block and random copolymers; isothermal crystallization kinetics; self-nucleation; successive self-nucleation and annealing (SSA) thermal fractionation; melt memory; and structure–property
relationships in advanced polymeric materials. He has co-authored more than 600 scientific  publications, with over 27,000 citations and an h-index of 84, and has delivered more than 120
plenary, keynote, and invited lectures in approximately 30 countries. He has supervised 39 Ph.D., 62 master’s, and 96 undergraduate theses. His scientific contributions have been recognized with
several distinctions, including the Lorenzo Mendoza Fleury Science Prize (Polar Prize, Venezuela), the international Paul J. Flory Polymer Research Prize, and the Zhongguancun Award
for International Cooperation (Beijing, China). He is a Corresponding Member of the National Academy of Engineering and Habitat of Venezuela (ANIH) and of the Latin American Academy
of Sciences (ACAL). He currently serves as European Editor of POLYMER (Elsevier) in Polymer Physics and Physical Chemistry and as a member of the selection committees for the Andrew
Keller Award and the Future Faculty Award for European Scientists.