States of matter and properties of matter, latent heat, vapour pressure, aerosols - inhalers, sublimation critical point, eutectic mixtures, gas laws, Gibbs phase rule, crystalline structures, 3rd b.pharmacy, sanjo college of pharmaceutical studies, palakkad, kerala

1. STATES OF MATTER AND
PROPERTIES OF MATTER
1
Mrs. JILSHA G
Assistant Professor
Department of Pharmaceutics
Sanjo College of Pharmaceutical Studies
Vellapara, Palakkad

2. State of matter
• Matter is a substance that has a mass and takes up space.
• Matter is made of molecules, atoms and ions.
Classification of Matter
Physical Classification
 Solid (Ex: Tablet,
Capsule
 Liquid (Ex: Oral
Syrup)
 Gas (Ex: Aerosol)
 Plasma
Chemical Classification
Pure Substances like
Elements and Compound
Mixture like Homogenous
and Heterogenous
2

3. Different states of matter
3

4. SOLIDS
• Solids are rigid in defined shapes
• Solids are a state where P.E. > K.E.
• The particles in a solid are moving but
cannot pass thru each other becoz the
attractions of neighbouring atoms/
molecules are too strong to overcome
• As a result, solids have a definite shape and
volume.
4

5. LIQUIDS
• They are less rigid than solids and are fluid
• They are able to flow and take the form of
their containers
• Here P.E. = K.E.
• This allows atoms/ molecules to move
around each other but remain in contact with
each other
• This result in liquid having a defined volume
but an indefinite form
5

6. GASES
• They are fluids, but unlike liquids they can
expand indefinitely
• Here K.E. > P.E.
• The particles are vey distant becoz of this
higher K.E.
• Gas has no definite shape/ volume
• Gases move around, taking up all of the
available spaces.
• This movement is called diffusion
6

7. Properties of state of matter
SI.
NO.
GAS LIQUID SOLID
1.
No definite volume &
shape
Have definite volume but
no definite shape
Have definite shape &
volume
2.
Expand to fill the size &
shape of their container
Molecules are close but
no as close to solid. The
molecules can move
Molecules are close
together & connected
by intermolecular
bonds
3.
Molecules are very far
apart in gas & there are
minimal intermolecular
forces
Intermolecular bonds
are weak, so molecules
are free to slip past each
other flowing smoothly
Molecules have little
free space b/w
particles
4.
Each atom is free to
move in any direction
Flows easily
Does not flow easily &
rigid particles cannot
move/ slide
5. Compressible Not Compressible
Not Compressible
7

8. Changes in the state of matter
• Most substances can be changed from one state to another
by heating/ cooling
• Changing state of matter can be physical/ chemical
8

9. Physical Change
• Does not alter the chemical composition or
identity of the substance, only the form.
– Melting ice (change in state or phase)
– Freezing Kool-aid
– Tearing paper
– Boiling water (change in state or phase)
– Stretching silly putty
– Making a mixture (ex. Sugar water)
– Unmixing a mixture (ex. sorting)
9

10. Chemical Changes
• Does alter the chemical composition or
identity of a substance and makes new
substances.
– Burning paper
– Digesting food
– Rotting
– Iron reacting with oxygen gas
• A chemical change is also called a chemical
reaction.
10

11. 11

12. Latent Heat
• When a solid melts or a liquid boils, energy must
be added but the temperature remains constant
• The amount of energy it takes to melt or boil a
certain amount of material is called a latent heat.
• For water, the latent heat of fusion (heat needed
to melt ice to water) is 79.7 cal/gm.
• For water, the latent heat of vaporization (heat
needed to boil water) is 540 cal/gm.
• For alcohol, the latent heat of vaporization is
less at 204 cal/gm.
12

13. Heat added or subtracted
for a phase change = Latent heat X Mass
Q = Lh X M
Q – heat
Lh - latent heat
M - mass
13

14. Vapour Pressure
14

15. • Consider a case of liq confined in closed
container whose temp is maintained const
• As in case of gases, molecules in liq state are
also in random motion becoz they posses
certain amount of K.E. due to thermal agitation
• Some molecules have greater K.E. than others
• Molecules have higher energies tend to
escape from liq surface into vapor in the head
space. This is vaporization process
• The rate of vaporization depends on conc of
molecules in liq state
15

16. • The average K.E. of remaining molecules goes
down
• Hence, the temp of the liq falls
• For this reason, liq on evaporation cools down
• At the same time, some of the molecules
escaped into the vapor return to the liq. This is
condensation process.
• The rate of condensation depends on no: of
molecules present in vapor state. These 2
process continue simultaneously.
• When rate of evaporation = rate of condensation
at definite temp, vapor becomes saturated.
16

17. • Dynamic phase equilibrium is a state at
which no. of molecules leaving the surface =
no. of molecules returning to it at a time at a
given temp
• Similar to gases, the vapor also exerts
certain pressure
• Vapor pressure is defined as the pressure
exerted by the vapor which is in equilibrium
with the liq
• Not all molecules have adequate K.E. so
these remain in liq phase
17

18. • When heat is supplied to the liq the K.E. of
molecules increases and more no. of
molecules vapourise
• As a result, vapor pressure increases
continuously
• At a particular temp vapor pressure = atm
pressure – boiling point of liq
18

19. •Sublimation is the change of state from a solid to
a gas without passing through the liquid state.
•Carbon dioxide is an example of a material that
easily undergoes sublimation.
Critical Point
•It is the point at which the liquid – gas line ends.
•Beyond this point the liq and gas phases become
indistinguishable, they merge into a single phase
Sublimation
19

20. •A eutectic mixture is defined as a mixture of two or more
components which usually do not interact to form a new
chemical compound but, which at certain ratios, inhibit the
crystallization process of one another resulting in a system
having a lower melting point than either of the components .
•Eutectic mixtures, can be formed between Active
Pharmaceutical Ingredients (APIs), between APIs and
excipient or between excipient; thereby providing a vast scope
for its applications in pharmaceutical industry.
Eutectic Mixtures
20

21. Eutectic mixture formation is usually, governed by following
factors:
1.The components must be miscible in liquid state and mostly
immiscible in solid state
2.Intimate contact between eutectic forming materials is
necessary for contact induced melting point depression
3.The components should have chemical groups that can
interact to form physical bonds such has intermolecular
hydrogen bonding etc.
4.The molecules which are in accordance to modified
VantHoff’s equation can form eutectic mixtures .
21

22. Applications of Eutectic Mixtures in
Pharmaceutical Industry
1.During pre formulation stage, compatibility studies between APIs
and excipient play a crucial role in excipient selection.
2.Testing for eutectic mixture formation can help in
anticipation of probable physical incompatibility between drug and
excipient molecules.
3.Eutectic mixtures are commonly used in drug designing and
delivery processes for various routes of administration.
4.During manufacturing of pharmaceutical dosage form, it is
extremely necessary to anticipate the formation of eutectics and
avoid manufacturing problems if any.
5.During pharmaceutical analysis, understanding of eutectic
mixtures can help in the identification of compounds having similar
melting points.
22

23. • Phase rule, which is a relationship for determining the
least number of independent variables (e.g., temperature,
pressure, density, and concentration) that can be changed
without changing the equilibrium state of the system.
• It is known as Gibbs phase rule. It is expressed as:
F = C – P + 2
F : the number of degrees of freedom of the system (number of
independent variables (e.g. temperature, pressure, and
concentration) that may affect the phase equilibrium)
C: number of components
P: Number of phases
The Phase Rule
23

24. Applications of phase rule
1. Phase rule can be applied in determining
purity of a substance
2. Phase rule can be applied in the solubility
phenomena
24

25. Phase
• Phase is a homogeneous, physically distinct portion of a
system that is separated from other portions of the system
by bounding surfaces.
• Phases coexistence can only occur over a limited range.
For example, ice does not last as long in boiling water as
it does in cold water.
•A system may consist of one phase or more than one phase.
1. A system containing only liquid water is a single-phase or single-
phase system (P=1 )
2. A system containing liquid water and steam (a gas) is a two-phase or
two-phase systems (P = 2).
3. A system containing liquid water, steam and solid ice is a three-
phase (P = 3).
25

26. Number of components
The number of components is the smallest number of
constituents by which the composition of each phase in the
system can be expressed in the form of a chemical formula
or an equation, at equilibrium.
Degrees of freedom
The number of degree of freedom is the least number
of intensive properties that must be fixed inorder to
describe the system completely.
26

27. Phase diagram – one component
system, water
• A phase diagram is a plot showing the
conditions of pressure and temperature
under which two or more physical states can
exist together in dynamic equilibrium.
• Also known as P-T (pressure – temperature)
diagrams.
27

28. • One component
system, e.g. water
is considered fro
describing the
phase diagram.
• This diagram
consists of :
a)Regions or areas
b)Lines or curves
c)Triple point
28

29. Lines / curves
• 3 regions or areas
are available
• COB – solid state
• AOB – liquid state
• COA – vapour
state
Applying phase rule,
F = C – P + 2
= 1-1+2 = 2
• Each single phase
has 2 degrees of
freedom
• i.e., bi- variant
system
• 3 lines are available
• OA - vapourization
curve
• OB - melting / fusion
curve
• OC – sublimation
curve
Consider line OA ,
applying phase rule,
F = C – P + 2
= 1 – 2 + 2 = 1
• 2 phase equilibrium
has one degree of
freedom
Regions / areas Triple point
•3 boundary lines
intersect at a
common point called
triple point
•Triple point shows
the conditions under
which all 3 phases
coexist in equilibrium
•Applying phase rule,
F = C – P + 2
= 1- 3+ 2 = 0
• Triple point has no
degree of freedom
29

30. Two component system
• When single phase is present in a two
component system, degree of freedom is 3
F = 2 – 1 + 2 = 3
• Where 2 component system (solid and liquid)
are present, the effect of pressure can be
neglected
• Then take the variables like temp and conc
• Such a solid or liquid system with the absent
gas phase is called condensed system
30

31. • Experimental measurements of temp
and conc in condensed system are
generally carried out under atmospheric
pressure
• The degree of freedom in this case is
reduced by 1, the rule of reduced phase
is:
F ’ = C – P + 1
• This is more convenient to apply to the
2 component system
31

32. 32

33. Curve XZ; Freezing point curve of X
• The point X represents freezing point of X
• The curve XZ shows the freezing point of X falls by the addition of Y to X
• The solid X is in equilibrium with liquid solution of Y in X
33
Curve YZ; Freezing point curve of Y
• The point Y represents freezing point of Y
• The curve YZ exhibits the fall of freezing point by the addition of X to Y
• The solid Y is in equilibrium with liquid solution of X in Y
• Applying reduced phase rule equation to the equilibria represented by
curve XZ & ZY
F = C – P + 1 = 2 – 2 + 1 = 1
• Degree of freedom is 1
• Both equilibria are monovariant

34. Area above curves XZ & YZ
• 2 components X & Y are present as liquid solns of varying compositions
• As a homogeneous soln of X & Y constitutes one phase & system is
bivarient
F = C – P + 1 = 2 – 1 + 1 = 2 34
Eutectic point Z
• 2 curves XZ & YZ meet at point Z
• Both the solids X & Y must be in equilibrium with solution phase
• Number of phases is 3
• Applying reduced phase rule equation
F ‘ = C – P + 1 = 2 – 3 + 1 = 0
• System represented by point Z is nonvarient
• Point Z is called Eutectic point, corresponding component (Ce) & temp
(Te) are known as Eutectic composition & Eutectic temperature
• A Eutectic or Eutectic mixture is a mixture of 2 or more phases at a
composition that has the lowest melting point

35. GASES
•Gases are compressible fluid and has no definite
shape
•Gases can be expanded infinitively, therefore gases
can fill containers and take their volume and shape.
•Gases diffuse and mix evenly and rapidly.
•Gases have much lower densities than liquids and
solids becoz there is a lot of free space in a gas,
therefore; It is the most compressible state of matter.
35

36. Properties of Gases
1. A sample of gas assumes both the shape and
volume of the container.
2. Gases are compressible.
3. The densities of gases are much smaller than
those of liquids and solids and are highly variable
depending on temperature and pressure.
4. Gases form homogeneous mixtures (solutions)
with one another in any proportion. 36

37. The Gas Laws
1. Boyle 's law : This law states that the pressure of a
fixed amount of gas at a constant temperature is
inversely proportional to the volume of the gas.
V ∝ 1/P
At constant temp, P1V1 = P2V2
Where,
V- volume of gas
P - pressure
37

38. 2. Charles Law: At a fixed pressure, the volume of a gas is
proportional to the absolute temperature of the gas."
V ∝ T
V1/T1=V2/T2
3. Gay-Lussac's law: This law is a special case of ideal gas
law. This law applies to ideal gases held at a constant volume
allowing only the pressure and temperature to change.
P1/T1 = P2/T2
P1 - Initial pressure
T1 - Initial absolute temperature
P2 - Final pressure
T2 - Final absolute temperature 38

39. 4.Avogadro’s law: This law states that the volume
of a sample gas is directly proportional the
number of moles in the sample at constant
temperature and Pressure.
V  n
V1/n1 = V2/n2
V- volume of gas
N- number of moles of gas
39

40. IDEAL GAS EQUATION
• Boyle’s law = V  1/P
• Charles law = V  T
• Avagadro’s law = V  n
• Combining all these,
V  nT/P
V = RnT/P
R- gas const
PV = nRT
40

41. • An ideal gas is a hypothetical sample of gas
whose pressure – vol- temp behavior is
predicted accurately by the ideal gas
equation.
• The gas constant R, is the proportionality
const and its value and units depend on the
units in which P & V are expressed.
41

42. Kinetic Molecular Theory of Gases
The basic assumptions of the Kinetic Molecular Theory are:
1. The volume occupied by the individual particles of a gas is negligible
compared to the volume of the gas itself.
2. The particles of an ideal gas exert no attractive forces on each other or
on their surroundings.
3. Gas particles are in a constant state of random motion and move in
straight lines until they collide with another body.
4. The collisions exhibited by gas particles are completely elastic;
when two molecules collide, total kinetic energy is conserved.
5. The average kinetic energy of gas molecules is directly proportional to
absolute temperature only; this implies that all molecular motion
ceases if the temperature is reduced to absolute zero. 42

43. Liquefaction of Gases
• Liquefaction of Gases means converting gases into liquids.
pressure is
cooled applied
Gas ------------------> velocity of mol. decreases --------------------- liquid
loss of some mol. are brought
K.E. or heat within sphere of
van der waals forces
• When pressure on a gas is increased, its molecules come
closer together, and its temperature is reduced, which removes
enough energy to make it change from the gaseous to the liquid
state. 43

44. AEROSOLS
• Aerosols may be defined as disperse phase system, in
which very fine solid particles or liquid droplets get
dispersed in the gas which acts as continuous phase.
• These are also called pressurized dosage form.
44

45. Advantages of Aerosols
1. The medicament can be delivered directly to the affected area such
as burnt skin and wound. So it minimises the discomfort caused by
mechanical or manual application.
2. Absence of air prevents oxidation of the product.
3. The hydrolysis of medicaments can be prevented.
4. Drugs can be given by oral inhalation.
5. The sterility of the products can be maintained.
6. The application of medicament is easier.
7. A fine mist is easily formed for inhalation purpose.
8. Manual contact with medicaments can be avoided.
9. Drugs given by oral inhalation do not pass through G.I.T. Hence its
chances of decomposition are less.
45

46. Disadvantages of Aerosols
1. Aerosols are costly preparations.
2. Some of the propellants are very toxic.
3. The cooling effect of highly volatile propellants may
cause discomfort on injured skin.
4. Lotof difficulties are facedin aerosol formulation
when the drug is not soluble in propellant.
46

47. 47

48. 1. Container:
• In pharmaceutical aerosol packaging, the
containers are made from metal (such as tin
plated steel, aluminium and stainless steel) glass
and plastic.
• These containers can withstand high pressure.
48

49. 2. Valves:
•The valves used should be such that it can be
easily opened and closed.
•It should also deliver the content in the desired
form. So three types of valves are used
nowadays:
(i) Continuous spray valve (ii)Metering valve (iii)Foam valve
•By using continuous spray valve, the medicament is expelled
continuously as long as pressure is applied on the actuator. But
by using metering valve, only a definite quantity of
medicament is expelled when actuator is pressed.
49

50. 3. Actuator:
• Actuator is fitted on the valve stem.
• It helps in the easy opening and closing of the valve,
whenever it is required.
• There are various typesof actuators which can
produce spray, fine mist or foam.
50

51. 4. Dip tubes:
•
•
The dip tubes are made from polyethylene or polypropylene.
Dip tube is used for the following purposes:
(i) It conveys the liquid from the bottom of the container to the
valve at the top.
(ii)It prevents the propellant to come out without dispensing the
contents of the package.
•
•
• The dip tube should be extended almost to the bottom of the
container.
In case the length of the dip tube is short, the contents of the
aerosol container will not come out of it.
However, if thediptube is touching thebottom of the
container, it will block the passage of liquid.
51

52. Packaging of aerosols
• The aerosol products can be filled in two ways:
1. Cold-fill process.
2. Pressure-fill process.
• Depending on the nature of the product concentrate,
the aerosol can be filled by a cold filling or a pressure
filling process.
52

53. 1. Cold-fill process
• This process is used to fill metered aerosol products
using a fluorocarbon propellant.
• By lowering the temperature of a propellant below its
boiling point, the propellant becomes liquid at
atmospheric pressure.
• The active ingredients or concentrate and propelant are
cooled to a low temperature of about -300
to 400
F.
• The concentrate is generally cooled to below 00
in
order to reduce loss of propellant during the filling
operation.
53

54. • The chilled concentrate is poured into the chilled container and
propellant is added.
Sufficient time is given for the propellant to partially vaporise,
in order to expel the air present in the container.
The valve is fitted on to the container which is placed into a
water bath so that the contents are heated to 1300F (540C) in
order to check any leakage and strength of container.
A dry ice-acetone bath is used to obtain the desired low
temperature for laboratory scale preparation whereas
refrigeration equipment is used for the large scale production of
aerosols.
•
•
•
1. Cold-fill process
54

55. 2. Pressure-fill process
• This process is used for filling aerosols containing
hydrocarbon propellant.
• The product concentrate is placed into the container
and the valve is sealed.
• The propellant is forced through the valve under
pressure. After this the container is immersed in a
water bath at 1300
F (or 540
C) in order to check any
leakage and strength of the container.
• It is essential that the air present in the container must
be expelled before filling the contents into the aerosol
container. 55

56. Application of Aerosols in
Pharmacy
1. The use of aerosols as a dosage form is particularly
important in the administration of drugs via the
respiratory system.
2. In addition to local effects, systemic effects may be
obtained if the drug is absorbed into the bloodstream
from the lungs.
3. Topical preparations are also well suited for
presentation as aerosols.
56

57. TYPES OF AEROSOLS INHALATION DELIVERY SYSTEMS
• There are currently two main types of aerosol generating devices.
• 1-Inhalers 2-Nebulizers
• Inhalers are portable, handheld devices that are available in two
types: Metered dose inhalers (MDI) and Dry Powder Inhaler DPI.
• MDI are the most commonly prescribed. These devices push out a
pre-measured spray of medicine. When the perso
inhaler, a measured "puff" of medicine is released.
• ADVANTAGES: Short treatment time, Reproducible dose emitted.
• DISADVANTAGES:
• Fixed drug concentrations
• Failure to shake can alter drug dose causing variability
• Limited range of drugs
• Hand–breathing coordination is difficult for many patients
• Proper inhalation pattern (slow inspiration to total lung capacity)
and breath-hold can be difficult 57

58. TYPES OF AEROSOLS INHALATION DELIVERY SYSTEMS• Dry Powder Inhalers
• DPIs are bolus drug delivery devices that contain solid drug, suspended in
a dry powder mix that is fluidized when the patient inhales.
• In dry powder inhaler (DPI) systems, drug is inhaled as cloud of fine
particles.
• The drug is either preload in an inhalation device or filled into hard gelatin
capsules or foil blister disc which are loaded into a device prior to use.
• ADVANTAGES:
• DPI formulations are propellant free and do not contain any excipient
hence environmental sustainability.
• Little or no patient coordination required.
• Formulation stability.
• DPIs can also deliver larger drug doses than MDIs.
• DISADVANTAGES:
• DPIs are generally less efficient at drug delivery than MDIs, such that twice
the dose is usually required for delivery from a DPIs than from the
equivalent MDI.• Deposition efficiency dependent on patient’s inspiratory airflow.
• Development and manufacture more complex/expensive.
• Potential for dose uniformity problems. 58

59. TYPES OF AEROSOLS INHALATION DELIVERY SYSTEMS• NEBULIZERS: Distinctly different from both pMDIs and DPIs, in that
the drug is dissolved or suspended in a polar liquid, usually water.
• Used for drugs that cannot be conveniently formulated into MDIs or
DPIs, or where the therapeutic dose is too large.
• Nebulizers are electric- or battery-powered machines that turn
liquid drugs into a fine mist that's inhaled into the lungs. The user
breathes in the mist through a mouthpiece or facemask.
• Nebulizers are used mostly in hospital and ambulatory care settings
and are not typically used for chronic-disease management because
they are larger and less convenient, and the aerosol is delivered
continuously over an extended period of time.
• ADVANTAGES: Nebulizers deliver relatively large volumes of drug.
• Drug concentrations can be modified.
• Normal breathing patterns can be used.
• Useful in very young, very old, debilitated, or distressed patients
• An inspiratory pause (breath-hold) is not required for efficacy
59

60. TYPES OF AEROSOLS INHALATION DELIVERY SYSTEMS
• NEBULIZERS:
• DISADVANTAGES
• Treatment times are lengthy for pneumatically-powered
nebulizers
• Equipment required may be large and cumbersome
• Need for power source (electricity, battery, compressed gas)
• Variability in performance characteristics among different brands
• Possible contamination with inadequate cleaning
• Wet, cold spray with facemask delivery
• Potential for drug delivery into the eyes with facemask delivery.
• It usually takes about 5 or 10 minutes to give medication by
nebulizer, and sometimes longer.
• Nebulizers can be less effective if a child is crying during use,
since less medicine will be inhaled. 60

61. Relative Humidity
• It is the ratio of the air’s actual water content
to its potential water vapour content at a
given temperature.
Relative humidity = wt. of water vapor in air
wt. of potential water vapor
in air at saturation
• It is measured by using hygrometer.
61

62. Liquid complexes
•Complex fluids are binary mixtures that have a
coexistence between two phases: solid–liquid
(suspensions or solutions of macromolecules such as
polymers), solid–gas (granular), liquid–gas (foams) or
liquid–liquid (emulsions).
• They exhibit unusual mechanical responses to applied
stress or strain due to the geometrical constraints that the phase
coexistence imposes.
• The mechanical response includes transitions between
solid-like and fluid-like behavior as well as fluctuations.
•Their mechanical properties can be attributed to
characteristics such as high disorder, caging, and clustering on
multiple length scales.
62

63. • Shaving cream is an example of a complex fluid.
• Without stress, the foam appears to be a solid: it does not
flow and can support (very) light loads.
• However, when adequate stress is applied, shaving
cream flows easily like a fluid.
• On the level of individual bubbles, the flow is due to
rearrangements of small collections of bubbles.
• On this scale, the flow is not smooth, but instead consists
of fluctuations due to rearrangements of the bubbles and
releases of stress
63

64. Liquid Crystal
• Some organic molecules do not melt to give liquid directly
• They pass through intermediate state known as ‘liquid
crystal state’
• These substance have long rod-shaped molecules
• E.g. p-oxyanisole
• Liquid crystal have structure between liquid and crystalline
solid.
• As Liquid molecules can move randomly and solid crystal
have ordered and fixed arrangement while liquid crystals
are arranged parallel to each other and they can flow.
• Hence, liquid crystals have fluidity of liquid and optical
property of solid
64

65. TYPES OF LIQUID CRYSTALS
1. Thermotropic liquid crystals
• liq crystals are said to be thermotropic if liq crytalline properties
depend on temp
• 3 types: nematic, smectic, cholestric
2. Lyotropic liquid crystals
• liq crystals are prepared by mixing two or more substances, of
which one is polar molecule, are known as Lyotropic liquid
crystals
• Eg: soap in water
65

66. Types of Thermotropic
liquid crystals
• Nematic liquid crystal: They
have molecules parallel to
each other like soda straw
but they are free to slide or
roll individually
• Smectic liquid crystal: The
molecules in this type are
also arranged parallel but
these are arranged in layers.
The layers can slide on each
other.
• Cholesteric liquid crystal:
Like nemetic they also have
molecules parallel but
arranged in layers. Due to
sliding of layers it form
spiral structure. 66

67. Applications
•
• Digital Number display:
When liquid crystal is kept
between electrodes the
change in arrangement of
crystal make it opaque …
transparency return when
current is removed
Monitoring body
temperature: Cholesteric
liquid crystal diffract light
differently. As temperature
changes colour of
reflected light changes
correspondingly.
• Liquid-crystal display
(LCD): It is a flat panel
display, electronic visual
display, or video display
that uses the light
modulating properties of
liquid crystals
67

68. Glassy states
•The glassy state of materials refers to a nonequilibrium, solid state, such as is
typical of inorganic glasses, synthetic noncrystalline polymers and food components.
•Characteristics of the glassy state include transparency, solid appearance and
brittleness.
•In such systems, molecules have no ordered structure and the volume of the
system is larger than that of crystalline systems with the same composition.
•These systems are often referred to as amorphous (i.e., disordered) solids (e.g.,
glass) or supercooled liquids (e.g., rubber, leather, syrup).
•Glasses are generally formed by melting crystalline materials at very high
temperatures.
•When the melt cools, the atoms are enclosed in a random (disordered) state
before they can form in a perfect crystalline arrangement.
68

69. Types of glassy states
1. The first type: It is characterized by the cessation of the vibratory
movement of rotation of the molecules in a defined (critical)
temperature region. This results in stabilization of the chain
structures of rigidly associated polar molecules (by means of
dipoles).
2. The second type: It is consists of organic glassy polymerization
products. These glass in the stabilized state have fibrous structure
of rigid valence bonded carbon atoms with small lateral branches
in the form of hydrogen atoms or more complex radicals.
3. The Third type: The third most extensive type of glassy
state consists of refractory inorganic compounds of multivalent
elements. These glasses in the stabilized state have the most
thermostable chemical structure in the form of a three-
dimensional rigid atomic valency-bonded spatial network.
69

70. Solid state: Solids have definite shape and volume
They cannot be compressed
70
SOLIDS
Crystalline
- Molecules are arranged in
3D
- Sharp melting point
- Low thermodynamic
energy, so low solubility rate
Amorphous
- molecules are randomly
arranged
- no definite melting point
- high thermodynamic
energy, so high solubility rate

71. Crystalline solids
• Atoms arranged in regular and repetitive manner
forming a 3D array
• Eg: diamond, graphite
• Smallest repeating pattern of crystalline solids is
known as unit cell
• Unit cells are like bricks
Properties of crystalline solids
1.Molecules are held by strong intermolecular forces
2.They have characteristic shape
3.They have sharp melting point
71

72. 72

73. Types of Crystalline solids
73

74. Amorphous
•Amorphous material is one kind of non equilibrium material; its
characteristic of atomic arrangement is more like liquid and has no
long-range periodicity.
•The glass-forming ability of an alloy is closely related to its
composition, and is quite different in various alloys.
•Generally, amorphous alloy can be produced by a rapid
solidification method to freeze the liquid structure of the alloy melt,
or other methods may be used that can mix atoms to achieve a
disordered state.
•Amorphous materials have become one of the most actively
researched fields.
• The deep theoretical understanding of the amorphization
and nonequilibrium state guides and promotes research and
development of amorphous materials.
74

75. What is the difference between glassy and amorphous?
• Glassy systems feature the phenomenon of
glass transition: transition from supercooled liquid -->
amorphous solid (glass); however, all amorphous
systems do not necessarily arise from such
phenomenon. Consequently, all amorphous materials
are not necessarily glasses.
75

76. Polymorphism
• Polymorphism is the ability of solid materials to exist in two or more
crystalline forms with different arrangements or conformations of the
constituents in the crystal lattice.
• These polymorphic forms of a drug differ in the physicochemical
properties like dissolution and solubility, chemical and physical
stability, flowability and hygroscopicity.
• These forms also differ in various important drug outcomes like drug
efficacy, bioavailability, and even toxicity.
• Polymorphic studies are important as a particular polymorph can
be responsible for a particular property which might not be exhibited
by any other form.
Types of polymorphs
1. Enantiotropic : one polymorph can be reversibly changed into
another one by varying the temperature and pressure
2. Monotropic : the change between the 2 forms is irreversible
76

77. References
1. Physical Pharmaceutics I by Dr. Shalini
Sharma and Dr. Surajj Sarode.
2. Text Book of Physical Pharmaceutics by
CVS Subrahmanyam.
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