Introduction to polymers - Classifications of Polymers - Dendrimers structure - Classifications and preparation methods - Properties and Applications

2. Nanoscience&
Nanotechnology
Steps To the future
Usama Abd Elhafeez
28/7/2018

3. Last Session
Crystal structures
Classification of nanomaterials

4. Sliver Nanoparticles
Ranges from 30 – 50 nm
High surface to volume ratios
High electrical & thermal conductivity
Chemical Stability – Catalytic activity

5. Antibacterial Applications
It is well known that silver ions and silver
based compounds are highly toxic to
microorganisms.
Used to control bacterial growth in a variety of
applications, including dental work, surgery
applications, wounds and burns treatment, and
biomedical devices.

6. How silver ions kills bacteria:

7. How silver ions kills bacteria:
Step 1 : Bacteria contaminates the surface
Step 2 : Silver ions are available to act against contaminated
bacteria
Step 3 : They Combines with bacteria proteins in the cell and cell
wall and promote formation of active oxygen species
Step 4 : Bacteria dies

9. Applications
Used in biosensors
Biological tags for quantitative detection

10. Conductive applications
Used in conductive inks and
integrated into composites
to enhance electrical and
conductive properties
Used in conductive inks and
integrated into composites
to enhance electrical and
conductive properties

11. Introduction To polymers
What is a polymer?
•A long molecule made up from lots of small molecules called monomers.
•“Poly” “meros” = many parts
•Monomer = non-linked “mer” material

12. What is a polymer?
•Polymers = long continuous chain molecules formed from repeated
sequences of small organic units (mers).
molecular weight in excess of 10,000.

13. Why Polymers
Polymers Such as cotton, wool, rubber, Teflon and plastics are used
in every industry
Natural & Synthetic Polymers can be produced in wide range of
stiffness , strength , heat resistance.

15. Some Definitions

21. According to Mechanical response
Thermoplasts
• Soften when heated &harden when cooled
• Simultaneous application of heat and pressure is required to
fabricate these materials.
• very soft and ductile.
• Polyvinyl Chloride (PVC) and Polystyrene
• Polymethyl methacrylate
• Polystyrene

22. According to Mechanical response
Thermosets
• Soft during their first heating and become
permanently hard when cooled.
• They do not soften during subsequent heating.
• They cannot be remolded/reshaped by subsequent
heating
• Epoxies
• •Phenolic
• •Polyester resins

27. What Are Dendrimers !!
The name comes from Greek word “Dendron” which means
“tree”.
Also called as ‘’arborols/ cascade molecules’’
They are family of Nano sized, highly branched three
dimensional molecules.

28. STRUCTURE OF DENDRIMER
1) An interior core
2) Interior layers composed of
repeating units radically
attached to cores.
3) Exterior layer (terminal
functionality) attached to
interior generations.

29. STRUCTURE OF DENDRIMER

30. STRUCTURE OF DENDRIMER
Are built from a starting atom, such as nitrogen, to which carbon and other
elements are added by a repeating series of chemical reactions that produce a
spherical branching structure.
As the process repeats, successive layers are added, and the sphere can be
expanded to the size required by the investigator.
The result is a spherical macromolecular structure whose size is similar to
albumin and hemoglobin

31. 3D STRUCTURE OF DENDRIMER

32. PROPERTIES OF DENDRIMERS
Biodegradable.
Nanoscale size and shape
Viscosity
High aqueous solubility
High solubility in non polar solutions

33. PROPERTIES OF DENDRIMERS
Non crystalline
Low compressibility
Inert and non-toxic
Able to cross barriers such as blood-tissue barriers, cell membranes etc
Able to stay in circulation for the time needed to have a clinical effect.
Able to target to specific structures

34. SYNTHESIS OF DENDRIMERS
There are two methods of synthesizing
dendrimers:
1) Divergent method
2) Convergent method

35. 1)Divergent methodDendrimer grows from core.
The core molecule reacts with the monomer molecule having two dormant
and one reactive group.

36. 2-CONVERGENT METHOD
Small molecules come together and reaction proceeds inward.
Eventually the molecules become attached to the core.

38. APPLICATION OF DENTRIMERS
MEDICAL
NON-MEDICAL

39. Medical
Dendrimers in Biomedical field
Dendrimers are analogous to protein, enzymes and viruses .
PAMAM dendrimers can be used to target tumor cells.
Targeting groups can be conjugated to the host dendrimers surface.

40. Medical
Dendrimer as magnetic resonance imaging contrast
agents
Dendrimer based metal chelates act as a magnetic resonance imaging
contrast agent.
Larger hydrophilic agents were useful for blood and lymphatic imaging.
Smaller sized used for kidney imaging

41. Medical
In-vivo degradation of drug dendrimer

42. Medical
Drug delivery Due to change in temperature

43. Medical
Drug delivery Due to change in pH

44. NON MEDICAL APPLICATIONS
Dendrimers as catalysts/enzymes
The combination of high surface area and high solubility
makes dendrimers useful as nanoscale catalysts.
Dendrimers have a multifunctional surface and all
catalytic sites are always exposed towards the reaction mixture.

45. NON MEDICAL APPLICATIONS
Dendrimers for additives, printing inks and paints
Dendritic polymers ensure uniform adhesion of ink to polar and
non-polar foils.
Dendritic polymers used in polyurethane paints impart surface
hardness, scratch resistance, chemical resistance, light,
fastness, weathering resistance as well as high gloss.

46. Mechanisms of Drug Delivery
Simple encapsulation:-It directly encapsulates guest molecules into
macromolecule interior.

47. Mechanisms of Drug Delivery
Electrostatic interaction:-
Surface functional groups enhances solubility of
hydrophobic drugs by electrostatic interaction e.g.
Ibuprofen, ketoprofen.

48. Mechanisms of Drug Delivery
Covalent conjugation:-
The drug is covalently bound to dendrimers via
chemical or enzymatic cleavage of hydrolytically
labile bonds. It allows tissue targeting &
controlled delivery as drug-dendrimer conjugate
diffuse slower than the free.