FUNDAMENTALS OF SELF-ASSEMBLY AND SELF-ASSEMBLED MONOLAYERS

FUNDAMENTALS OF SELF-ASSEMBLY AND SELF-ASSEMBLED MONOLAYERS 

1. Self-assembly is the spontaneous organization of building blocks with dimensions that are beyond the sub-nanometer scale of most molecules or macromolecules.

2. There are five prominent principles that need to be taken into consideration. These are 

i) building blocks,scale,shape,surface structure

ii) attractive and repulsive interactions between building blocks, equilibrium seperation

iii) reversible association-dissociation and adaptable motion of building blocks

iv) building block interactions with solvents, interfaces

v) building-blocks dynamics,mass transport and agitation.

3. A challenge for perfecting structures made by self-assembly chemistry is to find ways of synthesizing(bottom-up) or fabricationg(top-down) building blocks with right composition, size and shape. 

4. A demanding task is to make building blocks with a particular surface structure, charge and functionality.

5. Surface properties will control the interactions between building blocks, which ultimately determines the geometry. 

6. Relative motions between building blocks facilitates collisions between them, whereas energitically allowed aggregation deaggregation processes and corrective movements of the self-assembled structure will allow it to attain the most stable form. 

7. Building bloacks can be made out of most known organic, inorganic, polymeric, and hybrid materials.

8. Creative ways of making spheres and cubes, sheets and discs, wires and tubes, rings and spirals with nm to cm dimensions, abound in the materials self-assembly literature. 

9. They provide the basic construction modules for materials self-assembly over all scales, a new way of synthesizing electronic, optical, photonic, magnetic materials wiith hierarchical structures and complex form. 

10. Nanomaterials characteristically exhibits physical and chemical properties different from the bulk as a consequence of having at least one spatial dimension in the size range of 1-1000nm.

11. It is the "synthesis, manipulation and imaging of materials having nanoscale dimensions, the study and exploitation of the differences between bulk and nanoscale materials, and the utilization of nanomaterials scaling laws".

LESSONS FROM NATURE:

1) " The chemists find illustration, inspiration, and stimulation in natural processes, as well as confidence and reassurance since they are proof that such highly complex system can indeed be achieved on the basis of molecular components. - Jean Marie Lehn, 1995

2) "Nature has evolved functional assemblies over millions of years. Hence, scientists often gather inspiration from the beautiful structures that are encountered". -E.W.Meijer, 2005

3) Hientz Lowenstam is considered to be the father of biomineralization. He first proposed his theory of organic matrix mediated mineralization in the 1970s.

4) Lowenstam noticed that the chiton (sea urchin) he found in a water pool created Chevron marks in the rocks as it fed by scraping off algae attached to the rock. He reasone that the radula ( teeth on the tongue of the chiton) must be harder than the rock. 

5) Returning to the laboratory, he found that the radula were comprimised of magnetite. This is now the basis of all mineralization processes in biological systems- mineralization processes occur intracellularly.

6) Lowenstam documented about CO minerals that are formed biologically and classified the phyla amongs which they are distributed.

7) Most biominerals are composed of calcium carbonate, phosphate and oxalate, silica and iron oxides. 

8) Biological minerals display hierarchical organization of structure. At each level of this hierarchy, distinctive building rules are apparent. 

9) Some of these levels do not demand periodicity in the strict definition of ideal crystals, and their definition requires a break from standard crystallography. 

10) Biological minerals are of astonishing array of curved shapes, surface patterns and hierarchical order. These are not the characteristics of conventional crystals with their limited range of polyhedral habits. 

11) Nature has learned how to introduce long-range order and curvature into materials.

12) It is  all a matter of balance: it is energetically favorable for atoms to lay in a classical crystal unless other interactions bring the non-classical shapes to a lower free energy.