Supramolecular Networks Obtained by Block Copolymer Self-Assembly in a Polymer Matrix: Crystallization Behavior and Its Effect on the Mechanical Response

In recent years, there has been growing interest in the study of supramolecular networks obtained by self-assembly of amphiphilic molecules due to their responsive behavior to different external stimuli. The possibility of embedding supramolecular networks into polymer matrices opens access to a new generation of functional polymers with great potential for various applications. However, very little is known about how the dynamics of the supramolecular network is affected by diffusional and topological limitations imposed by the polymer matrix. In this work, we investigate the behavior of supramolecular networks embedded into a rubbery polymer. Crystallization-driven self-assembly of a poly(ethylene-block-ethylene oxide) (PE-b-PEO) diblock copolymer was used to generate supramolecular networks in dimethacrylate monomers, which were then photopolymerized at room temperature. PE-b-PEO self-assembles into nanoribbons with a semicrystalline PE core bordered by coronal chains of PEO, and the nanoribbons, in turn, bundle into lamellar aggregates with an average stacking period of around 45 nm. The nanoribbons are interconnected through crystalline nodes in a 3D network structure. Small-angle X-ray scattering experiments show that the polymer matrix preserves the structure of the supramolecular network and avoids its disintegration when the material is heated above the melting temperature of PE cores. Successive self-nucleation and annealing studies reveal that the polymer matrix does not influence the crystallization–melting processes of PE, which take place through the interconnected cores of the supramolecular network. In contrast, the matrix imposes strong effects of topological confinement on the crystallization of PEO, limiting the dimensions of the crystalline lamellae that can be formed. Mechanical tests show that the deformation capacity of these materials can be precisely tuned by programming the temperature within the melting range of the supramolecular network. This behavior was also characterized by shape memory cyclic tests.The financial support of the following institutions is gratefully acknowledged: National Research Council (CONICET, Argentina), National Agency for the Promotion of Research, Technological Development and Innovation (AgenciaI + D + i, Argentina), and University of Mar del Plata. This work has received funding from the Basque Government through grant IT1503-22. R.N.S. thanks Iberoamerican Association of Postgraduate Universities (AUIP) for a mobility fellowship

Crystallization-Driven Supramolecular Gelation of Poly(vinyl alcohol) by a Small Catechol Derivative

Catechol-containing molecules have been recognized as versatile building blocks for polymer structures with tailor-made functional properties. While catechol chemistry via metal-ligand coordination, boronate complexation, and oxidation-driven covalent bonds has been well examined in the past, the hydrogen bonding ability of these intriguing molecules has been dismissed. In this research, we investigated the gelation of poly(vinyl alcohol) (PVA) triggered by the crystallization of a 3,4-dihydroxy-catechol in water. Strong hydrogen bond interactions between PVA and catechol groups afforded supramolecular hydrogels with near-covalent elastic moduli, yet dynamic, exhibiting reversible gel-to-sol phase transitions around 50-60 °C. We studied the impact of the catechol derivative concentration on the gelation kinetics and physicochemical properties of these dynamic materials. Isothermal experiments revealed that heterogeneous crystallization governs the gelation kinetics. Moreover, because of the quasi-permanent cross-links within the supramolecular polymer network, these hydrogels benefit from ultrastretchability (∼600%) and high toughness (900 kJ·m-3). Our gelation approach is expected to expand the toolbox of catechol chemistry, opening up new avenues in designing dynamic soft materials with facile control over the phase transition, mechanics, and viscoelastic properties.Fil: Bonafe Allende, Juan Cruz. Universidad Nacional de Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada; ArgentinaFil: Schmarsow, Ruth Noemí. Universidad del País Vasco; España. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Matxinandiarena, Eider. Universidad del País Vasco; EspañaFil: García Schejtman, Sergio David. Universidad Nacional de Córdoba; ArgentinaFil: Coronado, Eduardo A.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Alvarezigarzabal, Cecilia I.. Universidad Nacional de Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada; ArgentinaFil: Picchio, Matías Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentina. Universidad del País Vasco; EspañaFil: Müller, Alejandro J.. Universidad del País Vasco; Españ

Core-crystalline nanoribbons of controlled length <i>via</i> diffusion-limited colloid aggregation

The mobility of the medium during crystallization-driven self-assembly plays a crucial role in the elongation process of 1D nanoribbons.</p