Complex Nanoarchitectures built by combining soft chemistry, self assembly and surface reactivity

G.J. A. A. SOLER ILLIA

Conferencia; 46th World Chemistry Congress; 2017

The creation of highly controlled nanosystems with well-defined properties in controlled spatial locations is one of the major challenges of current materials chemistry. In the last two decades, there has been an impressive advance in the creation of complex materials with hierarchical architectures at different length scales that mimic the complexity of those found in Nature. One of the most developed examples of this approach is the combination of sol?gel synthesis and surfactant self-assembly to produce mesoporous materials with high surface area and highly controlled mesopore diameter (2-50 nm). To date, the synthetic strategies to produce these systems have evolved to achieve highly controlled pore systems that can be ?decorated?with organic, biological or nanoscale functions located in the inorganic framework, pore surface or interior. The properties of these nanosystems are tuned by the pore size and geometry, wall composition and surface features. These materials are indeed a ??nanofacility??, in which positional chemistry can be achieved from the molecular to the mesoscale level. In this presentation, we will exemplify the richness of this field by analyzing the particular case of Mesoporous Thin Films (MTF). These advanced materials with complex architecture are interesting for the possibility of tailoring optical, electronic or catalytic properties, and the compatibility with the electronics industry. Production of MTF relies in the accurate control of the self-assembly of inorganic amorphous or nanocrystaline nano-building blocks (NBB) with supramolecular templates. Mesopores also provide monodisperse cavities that can be modified by adding small molecular species, biomolecules or even polymers, leading to hybrid MTF with an amazing variety of chemical behaviors, which include responsivity to temperature, pH or the presence of molecules. Nanoparticles (NP) can also be included in the mesopores, leading to NP@MTF nanocomposites with novel catalytic or optical properties. In order to achieve a high degree of tuning in these modified MTF, a thorough control of the pore surface features and confinement effects is necessary. Each highly controlled MTF originated from a reproducible and modular synthesis is in itself a building block for more complex structures. Multilayer MTF structures can be designed to act as spatial scaffolds to host different chemical or biochemical groups with well-defined positioning. In addition, MTF multilayers present photonic crystal properties. Size tailoring or organic functionalization of their mesopores systems lead to optical devices with selective response to molecular polarity or diameter. The combination of sol-gel and soft matter chemistry, the adequate use of local, colloidal and surface interactions as well as confinement effects permits to achieve an enormous variety of complex nanosystems with novel chemical and physical properties. The synergic properties obtained are derived from the control of the spatial location of well controlled components at different length scales (molecular, mesoscopic, macroscopic).