Seeking an answer in the context of energy, thermodynamic and validation of work point of view.
Many materials have properties different from bulk properties if made sufficiently small, and often these properties, which are constant for bulk, then scale with size. There are 3 main factors:
1. When material dimensions are on the same order as the wavelength of light, interactions with light change significantly (photonics, plasmonics).
2. When material dimensions are smaller than the Bohr radius of an exciton, the electronic density of states changes, and scales with size (quantum confinement).
3. When material dimensions get smaller the proportion of surface atoms increases. This makes surface effects more pronounced and causes e.g. melting at lower temperature.
Many materials have properties different from bulk properties if made sufficiently small, and often these properties, which are constant for bulk, then scale with size. There are 3 main factors:
1. When material dimensions are on the same order as the wavelength of light, interactions with light change significantly (photonics, plasmonics).
2. When material dimensions are smaller than the Bohr radius of an exciton, the electronic density of states changes, and scales with size (quantum confinement).
3. When material dimensions get smaller the proportion of surface atoms increases. This makes surface effects more pronounced and causes e.g. melting at lower temperature.
I would say that the nanoscale has always been important - atoms... molecules... have not been invented recently! The understanding of the fundamental physics (Bohr, Einstein, Schroedinger etc.) and the abilitiy to visualise and manipulate (TEM, AFM etc.)on this scale has significantly developed over the past hundred year such that we can now really begin to develop nanotechnologies.
It could be the capability to build up materials with almost no defects on the mechanical level, and new packages of novel properties (electronic, magnetic, chemical, optical etc.). This is a combination of rich science-technology with promising realms on economical and social levels.
Sorry I did not notice that you seek an energetic and thermodynamic context.
Although the topic has a rich theory, I may attempt to summarize it as follows;
Roughly speaking, from energy perspective, energy states in a nano-sized particle are broadened, they are closer to molecular state than to a fully developed band structure. This means that the spacing between energy states in nanoparticles is larger in comparison with that in macroscopic materials and electrons are more localized (quantum-confined systems). As a result total energy and thermodynamic stability will be affected, the thing reflected in changes in physical, mechanical, chemical, electronic properties of the material. In relation with this the dispersion increases (number of surface atoms/total number of atmos) in a nanoparticle, and the number of vacancies decreases resulting in much less structural defects.
From a thermodynamic perspective, in bottom-up approaches of nanoparticle synthesis, the process is governed by negative contribution to free energy (as the solid has lower free energy than a liquid solution) and positive contribution to free energy caused by interfacial energy between the 'born' nano solid particles surfaces and the solution. The resulting net change in free energy will determine the ultimate size of the nucleated nanoparticle.
I hope it is useful.
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