self assembly process

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SELF-ASSEMBLED STRUCTURES
GRAVITATIONAL FIELD ASSISTED ASSEMBLY
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What is Self-Assembly.???
Self-assembly is a type of process in which a
disordered system of pre-existing components
forms an organized structure or pattern as a
consequence of specific, local interactions among
the components themselves, without external
direction. 
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In Other Words..
Self-assembly is a phenomenon where the
components of a system assemble themselves
spontaneously via an interaction to form a larger
functional unit.
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Types Of Self-Assembled Structure

• Capillary Forces
• Dispersion Interactions
• Shear Forced Assisted Assembly
• Electric-field Assisted Assembly
• Covalently Linked Assembly
• Gravitational Field Assisted Assembly
• Template Assisted Assembly

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Parameters

• Order
• Interaction
• Building Blocks
• Rate of Sedimentation

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Gravitational Field Assisted Assembly
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• It is also called as Field Assisted Assembly
• To produce ordered aggregates of molecules and
  colloidal particles
• It is an Bottom-up approach
• The sedimentation process should be slow enough
  so that the colloids concentrated at the bottom
  of the container
• It will undergo a hard-sphere disorder-to-order
  phase transition to form a 3-D ordered structure

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To Improve Results

• Field can accelerate ordering by improving the
  kinetics of assembly
• Fields can potentially shift order-disorder
  transition boundaries
• Generating spatial gradient

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Factors To Be Considered

• Sedimentation in a gravitational field involves
  a coupling between Brownian motion, which is a
  function of temperature, and gravitational
  settling
• Sedimentation velocity is influenced by
  particle size and density
• To achieve minimum energy lattice position

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Advantages

• It is a linear ordered structure
• Occurred either directly or indirectly through
  environment interactions

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Disadvantages

• It is a slow process
• It has very little control over the morphology
  of the top surface and the number of layers

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Drawbacks

• The control over morphology is very difficult
  to handle

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