This presentation describes the technological advancement of today's engineering field.These explains the application of chemistry in adhesives bucky balls and many more nano particles. This also covers the topic of liquid crystals.

1. Engineering Materials

2. Adhesives
The material or substance which is capable of
uniting or bonding two other materials
(adherends) together by adhering strongly to
the surface of both.
Example: Glue, gum and cement

3. Characteristics of an ideal adhesive
 Should give a strong bond.
 Should not be affected by air, heat or moisture.
 Should resist chemicals, acids and bases.
 Can be easily spread over the surface.

4. Quality of an adhesive is evaluated by
 Persistence
 Strength of bond setting upon drying
 Quickness of bonding
 Degree of stickiness

5. Adhesive Action
Adhesive action resulting in the bond between adherends by physical or chemical
forces.
I. Specific Adhesion:
 Physical or Chemical forces are responsible for the adhesion between the
surfaces.
 Permanent bond is formed when the interfacial boundary energy of the
adhesive and adherent surfaces is lower than the sum of the surface
energies of the adhesive and the surfaces of adherends.

6. II. Mechanical Adhesion:
When the adhesive simply fills the
voids or pores in the surfaces of
the adherends and hold them by an
interlocking action.
III. Fusion Adhesion:
When the adhesive or its solvent
dissolves partly the surfaces and
hold them together.

7. CLASSIFICATION OF ADHESIVES
Adhesives
Based on the composition of the
principal components
Based on Mechanism of adhesion
Natural
Synthetic
1. Solvent Responsive
2. Heat sealing
3. Pressure sensitive
4. Chemically reactive
 Starch
 Glues
• Blood albumin
• Casein
 Epoxy
 Phenol
Formaldehyde
 Melamine
• Animal
• Vegetable
 Phenol
formaldehyde

8. Classification of Adhesives
 Adhesives based on the composition of principal components
1. Adhesive based on naturally occurring materials
Ex. Vegetable gums, starches
Animal glues.
2. Adhesive based on synthetic materials
Ex. Phenol formaldehyde, epoxy,
Polyvinyl acetate(Fevicol)

9. Classification of Adhesives
 Adhesives based on their mechanism of adhesion
1. Solvent Responsive Adhesive – Used in the form of solvent
Main component of these adhesives are:
 Adhesive bases
 Volatile liquid carriers
 Plasticizer
 Adhesion augmenting resins
Ex. Vinyl polymers, alkaloid resins,
natural resins and vegetable gums

10. 2. Heat sealing adhesives
 Inactive solids at room temperature.
 They can work at high temperature.
 Bonding strength depends on temperature, pressure and time.
Ex. Waxes, cellulose esters, polyvinyl resins, rubber, and its
derivatives.

11. 3. Pressure sensitive adhesive
 Used in the form of adhesive tape.
 Able to provide instantaneous adhesion by applied small pressure and
similarly can be removed from the surface using a small energy.
 Main Components:
a. Tape backing b. Adhesive c. Tackifying resins
d. Plasticisers e. Minerals f. Fillers
g. Antioxidants
.

12. 4. Chemically reactive adhesives
These type of adhesives undergo chemical changes
during the formation of the bond, chemical changes
like crosslinking, condensation or polymerization.
Ex: Phenol formaldehyde,
melamine formaldehyde, urea,
epoxy resin etc.

13. Nano-Materials
Nanoscience
Nanotechnologies
Nanomaterials

14. Important Definitions
Nanoscience Nanotechnology Nanomaterials
Study of phenomena
and manipulation of
materials at atomic,
molecular and
macromolecular
scales, where
properties differ
significantly from
those at larger scale.
It is design,
characterization,
production and
application of structures,
designs and systems by
controlling shape and size
at nanometer scale.
Materials with at least
one dimension less than
100 nm.
E.g. thin film,
nanowire, nanotube,
colloids, quantum dots,
etc.

15. Properties of Nanomaterial
Relatively Larger Surface area
Make material more chemically reactive.
Also affect its strength and chemical
properties.
Quantum Effect
 Affects the optical, electrical and
magnetic behaviour of material.

16. Synthesis of Nanomaterials

17. Applications of Nanomaterial
 Sunscreens and cosmetics
 Composites
 Coatings and Surfaces
 Tougher and Harder cutting tools
 Fuel Cells
 Displays
 Medical Implants
 Paints
 Catalysts
 Magnetic material
 Military Battle Suits
 Machinable Ceramics

18. FULLERENES

19.  The first fullerene was discovered in 1985 by Sir Harold W. Kroto,
Richard E. Smalley and Robert F. Curl.
 Fullerene, also called buckminsterfullerene.
 A closed spherical cage shape – Buckyballs
 A cylindrical shape - Carbon Nanotubes
 A cage like molecules composed of 60 carbon atoms (C60) joined together
by single and double bonds to form a hollow sphere with 12 pentagonal
and 20 hexagonal faces.
 Each C-atom on the cage surface is bonded to three other C-atoms. So,
each C-atom is sp2 hybridized.

20. Preparation of Fullerenes
Methods:
 Arc Vaporization of Graphite (Kratcshmer-Huffmann
apparatus)
 Laser Ablation Method
 Other methods includes:
i. Hydrocarbon combustion
ii. Low pressure helium sputtering
iii. Electron beam evaporation
iv. Inductively coupled RF evaporation of graphite

21. Structure of Fullerene (C60)
 It has Truncated Icosahedron structure.
 Soccer ball shape
 An icosahedron is a polygon with 60 vertices and 32
faces (12 – pentagonal & 20 hexagonal) 90 covalent
bonds between them, 60 single bonds and 30 double
bonds.
 C-atom is present at each vertex of this structure.
 Aromatic and has resonating structures.
 C60 is also known as bulky ball because it is a spherical
cluster of C-atoms arranged in series of 5- & 6-
membered rings)

22. Properties of Fullerene
 Aromaticity
 Has π-bonding electrons which are free to localize or
delocalize in different chemical situations.
 C60 in water tends to pick up two more electrons and
become an anion.
 Chemistry
 The reactive characteristics of fullerenes is
electrophilic at double bonding, which reduces angle
stress by changing hybridized orbit carbons into sp3
hybridized one.
 This decrease in hybridization permits the bonds to
bend lesser on closing the tube making the fullerene
molecule more stable.

23.  Solubility
Soluble in Solvents
Common solvent used is Carbon disulfide
Solutions of pure fullerene have deep
purple and violet colour.
Properties of Fullerene

24. Applications of Fullerene
 Used as a lubricant
 As a superconductor when mixed with alkali metals
 As a soft Ferromagnets
 Used in electronic and microelectronic devices
 Non-linear optical devices
 In Composites
 In Drug delivery

25. Carbon Nanotubes(CNTs)
 A nanotube is a nanometer-scale tube-like structure.
 They are like nanowires, in terms of aspect ratio.
 But unlike nanowires, nanotubes are hollow.
 It’s diameter is in the order of few nanometers.
 It’s length is in order of few milimeters.
 Exhibit extraordinary strength and unique electrical
properties and are efficient conductors.
 Applications: Nanotechnology, electronics, optics and
material science.

26. Structures of Nanotubes
 Structure of single walled nanotube(SWNT)
A. Zig-Zag nanotubes B. Armchair nanotubes C. Chiral nanotubes
Apex of Hexagon Parallel to length Apex perpendicular to length All other orientations of Hexagons

27. Structures of Nanotubes
 Structure of multi walled nanotube (MWNT)
Russian Doll model
Sheet arranged in concentric cylinders.
Parchment Model
Single sheet is rolled in around itself.(Like
rolled paper)
Distance between graphene layers is 3.3 Å

28. Properties of Nanotubes
 Nanotubes have the highest strength to
weight ratio of any known material.
 Can easily penetrate membranes such as cell walls.
 Can function like needle at cellular level.
 Their electrical resistance changes significantly when
other molecules attach themselves to carbon
atoms.(used to develop sensors to detect chemical
vapour)

29. Nanowires are 1D nanostructures which generally have
diameters of the order of tens of nanometers, with
unconstrained length scales! The length to diameter ratio
may be as much as 1000.
Nanorods are also 1D nanostructures where each of their
dimensions range from 1–100 nm. Standard aspect ratios
(length divided by width) are 3-5.
Nanowires

30. Liquid Crystals
 The intermediate state exists between the crystalline solid state and the
liquid state.
 Condensed fluid phases with spontaneous anisotropy.
 First observed in Cholesterol myristate.
 Molecules in this state are oblong and rigid rod-shaped.
 In the cell wall of living organism, molecules are in liquid crystal state.
Temperature State of substance
<71 0C Solid crystalline
71 0C Cloudy Liquid Crystal State
86 0C Clear Liquid State

31.  Liquid Crystals can defined as condensed fluid
phases with Spontaneous anisotropy.
Liquid Crystals
Liquid Crystals

32. Classification of Liquid Crystals
 Thermotropic Liquid Crystal – The organic compounds which
exhibit liquid crystalline phases as the temperature varies.
Example: p-Azoxyanisole.
 Lyotropic Liquid Crystal – It consist of two or more components
that exhibit liquid crystalline properties in certain concentration
ranges.
Example: Soap

33. Molecular Arrangement in Different Mesophase
 Nematic Phase:
The nematic liquid crystal phase is characterized by
molecules that have no positional order but tend to point
in the same direction (along the director).

34. Smectic A Phase
Molecules in this phase show a positional order.
The increased order means that the smectic state is more
“solid-like”.

35. Molecules are arranged as in the
smectic-A mesophase, but the
director is at a constant tilt angle
measured normally to the
smectic plane.
Smectic C Phase

36. Cholesteric Phases:
• Composed of nematic mesogenic molecules containing chiral
center which produces intermolecular forces.
• This favour alignment between molecules at a slight angle to
one another.
• Can be visualised as a slack of very thin 2D nematic-like
layers with the director.

37. Columnar Phases:
• Shaped like disks instead of long rod.
• It is characterized by stacked columns of molecules.
• Columns are packed together to form a 2D-crystalline array.

38. Applications of Liquid Crystals
Liquid Crystal Displays(LCDs)
Thermographic Behaviour
Optical imaging and recording
Used for non Destructive mechanical testing of
material under stress.
Visualisation of Radio Frequency(RF) waves
Erasable optical Disks
Light modulator ,etc.

39. Organic Electronic Materials
 Called “Organic” because materials consist of polymers
and small molecules
 Used in electronic and optoelectronic devices.
OEM Generally split into to groups:
1. Small polymers
Deposited by vapour method and have a well
defined molecular mass.
2. Polymers
Must be processed from solution and have molecule
weight distribution.
These OEM has lead to the synthesis of new class of
polymers known as Conducting polymers.

40. Organic Electronic Materials
 The most successful application of OEM is OLED(Organic
light emitting device).
 This is generally used in long lived and highly
efficient colour displays.