Advanced Multiphasic Polymers (AMP) Group


Research

polimerization

The AMP group is devoted to understanding structure, morphology, functionality and properties of semi-crystalline multiphasic polymers. It studies a wide diversity of multiphasic materials by designing and compounding blends, nano-structured blends, nanocomposites and bionanocomposites or by collaborating with different polymer synthesis group that can prepare novel materials capable of providing insights on self-assembly and physical properties.

The techniques commonly employed by the group for its research include Differential Scanning Calorimetry (DSC), Thermogravimetry (TGA), cone microcalorimetry, polarized optical microscopy (PLOM) and atomic force microscopy (AFM). Aditionally, electron microscopy (SEM and TEM) and x-ray diffraction are employed for morphological and structure characterization in collaboration with other groups or using UPV/EHU central facilities. Diverse multiphasic materials are prepared by different techniques of melt compounding and mechanical properties (DMTA, tensile and impact) are also determined as well as rheological behavior in collaboration with the Processing and Rheology groups at Polymat.

Current research lines include:

   1. Nanoscopic confinement in infiltrated polymers and copolymers within nanoporous alumina (AAO). Both the nucleation and the growth can be dramatically altered by confinement to such a degree that crystallinities can be tailored from a maximum value down to 0%. This means that other properties like permeability, conductivity and mechanical properties can also be tailored for specific applications.

   2. Multiphasic biodegradable polyesters, including several isodimorfic random copolyesters, bionanocomposites and double crystalline diblock and random copolymers. In particular the group has focussed its attention to random copolyesters that can exhibit double crystalline behaviour. Tailoring their supramolecular morphology by means of changing their crystallization conditions and compositions can lead to different biodegradation rates. Additionally, fully biodegradable polyester blends are being studied based on polylactic acid matrices. The compatibility, crystallization kinetics and mechanical properties of such blends are studied with the aim of expanding their application range.

   3. Effect of nanofillers to stabilize nanostructured blends of immiscible polymers. Driving nanofillers to interphases can have an effect similar to Pickering emulsions that stabilizes polymer blends, prevent coalescence and may produce significant changes in mechanical properties, permeability and flammability. Therefore, several nanostructured blends are being developed with functionalized nanosilicas.

   4. How does chain topology affects polymeric nucleation and crystallization?: cyclic chains, myktoarm block copolymers and linear analogs. The effect of chain topology can have a large impact on molecular diffusion, rheology and crystallization. A relatively small topological change, i.e., the absence of chain ends, can dramatically affect both the nucleation and the crystallization of polymer chains. The group is investigated the reasons behind such behaviour and has recently made important contributions to the literature indicating a dependence of supercooling (since linear and cyclic chains were found to have different equilibrium melting points) and diffusion. New research is also being carried out under fast chip calorimetry experiments and on the effects of blending linear and cyclic chains. The study of polymer topology is also complimented by the study of star shape polymers and copolymers.

   5. Crystalline memory, self-nucleation and thermal fractionation by SSA (Successive Self-nucleation and Annealing). One important contribution of the group is the development of advanced calorimetry protocols to study semi-crystalline polymeric materials. Amongst those, complex self-nucleation protocols, different ways to study isothermal crystallization kinetics and thermal fractionation techniques, such as Successive Self-Nucleation and Annealing (SSA) which was originally created by Prof. A.J. Müller and is now widely employed by the international research community working with thermal analysis of polymers. Such techniques are now being expanded to cover ultra-fast heating and cooling conditions.

Image taken from: Arandia, I.; Mugica, A.; Zubitur, M.; Arbe, A.; Liu, G.; Wang, D.; Mincheva, R.; Dubois, Ph.; Müller, A. J., Macromolecules, 2015, 48, 43-57 (January). “How composition determines the properties of isodimorphic poly(butylene succinate-ran-butylene azelate) random biobased copolymers: from single to double crystalline random copolymers”