In this presentation recent findings on the crystallization and morphology of isodimorphic random poly(butylene succinate)-ran-poly(ε-caprolactone) copolyesters, PBS-ran-PCL, will be presented. Polymers with 3 different molecular weights were synthesized covering the range from approximately 10 to 60 kg/mol. An increase in the molecular weight of the copolyesters does not influence the crystallization or melting temperatures significantly, as their values are determined by the randomness of the comonomer distribution that controls the average length of the crystallizable sequences. However, crystallinity values are higher for lower Mn copolymers because of their faster crystallization rate. Copolymers with higher Mn exhibit higher Tg values as expected for random copolymers that are characterized by a single phase in the amorphous regions. Therefore, changing composition and molecular weight, a remarkable separate control over Tg and Tm values is achieved in these biodegradable copolyesters. We have performed nucleation and spherulitic growth kinetics by polarized light optical microscopy (PLOM) and overall isothermal crystallization kinetics by differential scanning calorimetry (DSC). Selected samples were also studied by real-time wide angle X-ray diffraction (WAXS). Under isothermal conditions, only the PBS-rich phase or the PCL-rich phase could crystallize as long as the composition is away from the pseudo-eutectic point. In comparison with the parent homopolymers, as comonomer content increased, both PBS-rich and PCL-rich phases nucleated much faster (see Figure 1), but their spherulitic growth rates were much slower. Therefore, the overall crystallization kinetics was a strong function of composition and supercooling. The only copolymer with the eutectic composition exhibited a remarkable behavior. By tuning the crystallization temperature, this copolyester could form either a single crystalline phase or both phases, with remarkably different thermal properties.

Conferencia "Catalizadores inteligentes para una química verde", en la cual se analizará brevemente el tema de la organocatálisis, especialmente con motivo del Premio Nobel de Química 2021 otorgado a los Drs. List y MacMillan en esta área de la catálisis homogénea.

In the last decades computational materials science has transformed itself from a discipline used for validation to a tool for materials discovery and optimization. In the area of block copolymer self-assembly, computational methods have advanced to the point that it is possible today to predict correctly and in a timely fashion a myriad of phases from even the most complex of macromolecules. In this talk I will present an overview of the methods employed today and show how they are able to predict some of the most complicated phases found experimentally to date. Emphasis will be made in the use of newly developed force fields for dissipative particle dynamics that combine ease of use with robust behavior at an affordable computational cost. More importantly, by employing optimization and evolutionary algorithms it is possible to perform inverse design of these systems and achieve 3D self-assembly of non-periodic and designer structures. I will conclude with an outlook in this exciting area of soft matter.

Ultrasonic waves are widely used in many different fields from the non-destructive inspection to imaging and processing. High-frequency ultrasound has shown its reliability as a characterization technique for monitoring the viscoelastic properties of polymers and composite materials and their transitions caused by thermal treatments or chemical reactions [1-2]. The acoustic response of a polymer can provide information about the macroscopic and microscopic structural changes and the state of dispersion of nanostructures in polymer matrices [3]. On the other hand, high power ultrasound continues to attract interest representing a flexible “green” alternative for more efficient manufacturing and joining processes especially in the multi-material design, where metallic and non-metallic materials are merged to hybrid components [4-5]. The talk will overview the results obtained by the authors’ research group also both with low intensity and high intensity ultrasound including the development of new methods for measuring the out-of-plane permeability of carbon fiber preforms for composite materials. The results obtained on the application of high power ultrasound in manufacturing and joining of polymer composites will be presented. Finally, a brief overview on a new research activity focused on the production and characterization of polyethylene terephthalate (PET) nanoparticles for environmental impact studies will be presented.

• [1] Lionetto et al. Adv Polymer Technol 2008, 27, 63
• [2] Lionetto et al., Materials 2013, 6, 3783
• [3] Espinoza-Gonzalez, IEEE Transact Nanotechnology 2016, 15, 731
• [4] Lionetto et al. Composites: Part A 2016, 82, 119
• [5] Lionetto et al. Composites Part B 2018, 144, 134