Development of polyurethane-urea coatings
using azide-alkyne click chemistry

K.SASIDHAR,
Dr.K.V.S.N.Raju’s
Group,
PFM Div...
Brief chemistry of polyurethanes


The underlying chemistry behind polyurethane was first developed
by Professor Dr. Otto...
Types of Polyols
•The name polyol refers to chemical compounds containing multiple hydroxyl groups.
•Polymeric polyols may...
Linear Vs Dendritic polyols
Linear polyols

Dendritic polyols

(1) Less number of end Functional groups

(1) Large number ...
Polyester polyols & Polyether polyols
polyester polyols

polyether polyols

(1) Excellent mechanical properties like
abras...
Dendrimers Vs Hyperbranched polymers
Dendrimers

Hyperbranched polymers

1.Dendrimer = Greek words Dendron (tree)+ meros
(...
Dendrimers and hyper branched polymers are
synthesized mainly two ways
• Divergent strategy:- Core to Surface
•Convergent ...
Functionalization of Polyurethanes
 Functionalization of PU leads to highly functional materials
 For many high-tech app...
Concept of Click Chemistry
“click chemistry” is a chemical philosophy introduced by k.barysharpless
in 2001, which describ...
DEFINING A “CLICK”CHEMISTRY
“ A click reaction must be
modular, wide in scope, high
yielding, create only inoffensive
by-p...
Classes of “Click” Reactions
Azide- Alkyne
cycloaddition

CYCLO ADDITION
REACTIONS
Diels -Alder reaction
NUCLEOPHILIC OPEN...
Historical Perspective of
Azide/Alkyne Cycloaddition
1933- Dipolar nature of azide first recognized by Linus Pauling
R N3
...
Copper Catalyzed Azide/Alkynes
Cycloaddition (CuAAC)


Thermodynamic and kinetically
favorable (50 and 26
kcal/mol, respe...
CuAAC Catalytic Cycle
CuLx
R'

H

R2
N N N
R'

CuLx
CuLx

Himo, F. et al. J. Am. Chem. Soc, 2005, 127, 210-216.
Ahlquist, ...
Importance of Triazoles



high thermal stability,



anti-microbial nature,



chemical inertness,



easy to prepare...
SCHEME-1

Hyperbranched polyether
using click chemistry and
their polyurethane coatings
C-H Str
C-O-C Str

O-H Str
4000

3500

3000

2500

2000

1500

1000

500
Hyperbranched polyurethane-urea coatings
SCHEME-2
( Future work)

Development of fluorescent
polyurethane coatings
using click chemistry
Fluorescent polyurethane coatings
Fluorescent paints 'glow' when exposed to the long-wave “ultraviolet" frequencies
and t...
Synthesis of azidated silica nano particles
Synthesis of perylene fluorophore containing silica nano
particles
Step-3:- Synthesis of perylene tetra propargylate molec...
Other synthesized HBP’s

Triazole core Hyperbranched
polyester
Acknowledgements

Dr. K.V.S.N. Raju
Dr.Ramanuj Narayan
Dr.Ch.Ramakishan Rao
Dr. Aswini Kumar Mishra
Dr. Kishore Kumar Jena...
THANK YOU
hyperbranched polymers for coating applications
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hyperbranched polymers for coating applications

  1. 1. Development of polyurethane-urea coatings using azide-alkyne click chemistry K.SASIDHAR, Dr.K.V.S.N.Raju’s Group, PFM Division, IICT. Work Report 3rd October, 2012
  2. 2. Brief chemistry of polyurethanes  The underlying chemistry behind polyurethane was first developed by Professor Dr. Otto Bayer (1902-1982). He invented the Diisocyanate Polyaddition Process which is the base patent in the polyurethane industry.  Polyurethanes are formed by the reaction between a polyisocyanates and hydroxyl(-OH) containing resin blend Some properties of Polyurethanes Have high strength if crosslink density is high Good solvent resistance High abrasion resistance High corrosion resistance High resistance to O2 and O3 Major use of PU’s in foams(65%)
  3. 3. Types of Polyols •The name polyol refers to chemical compounds containing multiple hydroxyl groups. •Polymeric polyols may be (a) Polyether polyol, (b) Polyester polyol (c) Acrylic polyol •Polyol with low molecular weight………….. hard and stiff polymers (due to high urethane concentration) •Polyol with high molecular weight…………. Flexible and soft polymers •Polyols with long chain……………………....Soft, elastomeric Polymers •Polyols with short chain………………………Rigid, crosslinked Polymers
  4. 4. Linear Vs Dendritic polyols Linear polyols Dendritic polyols (1) Less number of end Functional groups (1) Large number of end Functional groups (2) Newtonian relationship between viscosities and molecular weight polymers show high viscosities at high molecular weights. (2) non-Newtonian relationship between viscosities and molecular weight polymers show low viscosities at high molecular weights. (3) Degree of branching is zero (3) Degree of branching is very high XRD results shows that these are having spherical or globular structures (4) Not readily soluble compared to HBP’s (4) High chemical reactivity and enhanced solubility (5) They show less thermal mechanical stability than dendrimers and HBP’s (5) These materials show outstanding mechanical properties such as initial modulus, tensile strength and compressive moduli which reflect the compact highly branched structures
  5. 5. Polyester polyols & Polyether polyols polyester polyols polyether polyols (1) Excellent mechanical properties like abrasion resistance. (1) High hydrolysis resistance (2) Heat resistance (2) Excellent low temperature flexibility (3) excellent oil resistance (3) Resistant to microbial degradation (4) High resistance to oils and chemicals (4) Excellent clarity (5) Polyesters exhibit higher cut/tear resistance and loading capabilities (5) more durable than polyester based systems (6) Not recommended for use in high humidity and exposure to water. (6) Better resistance to UV radiation than polyester systems.
  6. 6. Dendrimers Vs Hyperbranched polymers Dendrimers Hyperbranched polymers 1.Dendrimer = Greek words Dendron (tree)+ meros (part) 1.Made in a very easy fashion [ Divergent and convergent process] 2.Made in a very sophisticated fashion 2.Polydisperse [ Mw>Mn] and less than 100%degree of branching 3.Perfectly built onto a core molecule 3.They are an irregular macromolecules 4.Monodisperse [ Mw =Mn] and 100% degree of branching 5.They are symmetrical and layered macromolecules 6.These polymers consist of three distinct areas : polyfunctional central core ( center of symmetry); radial symmetrical layers of repeating units (generations); end standing groups (terminal groups). 4.These polymers structure consist of three distinct groups : dendritic groups ;linear groups and terminal groups. Examples of hyper branched polymers: Boltorns (P( bis -MPA) hyper branched polymer), Hybranet (poly(ester amide)
  7. 7. Dendrimers and hyper branched polymers are synthesized mainly two ways • Divergent strategy:- Core to Surface •Convergent strategy :-Surface to core
  8. 8. Functionalization of Polyurethanes  Functionalization of PU leads to highly functional materials  For many high-tech applications, PU materials and especially PU films and coatings need to bear functionalities to improve their intrinsic properties such as wettability, adhesion, biocompatibility, conductivity, cross-linking density and many others.  Functionalization possible by physical & chemical methods but it should not affect the other properties of polymer In general, the chemical modification of such functional polymers can also suffer of a certain lack of efficiency since the reactivity of functional groups may be affected by the structure of the polymer and also by the efficiency of the chemical reactions used.  In 2001, Sharpless and co-workers introduced innovative approaches, named “click” chemistry, allowing quantitative reactions. Among the listed reactions, Huisgen 1,3- dipolar Cycloadditions between an azide and an alkyne compound have been widely explored due to, among others, its efficiency, versatility and inertness toward other functional groups.
  9. 9. Concept of Click Chemistry “click chemistry” is a chemical philosophy introduced by k.barysharpless in 2001, which describes the chemistry that can generate substances quickly and reliably by joining small units together with high thermodynamic force. Requirements for the click reaction are : The reaction must be 1. Modular 2. Wide in scope 3. High yield of product (nearly 100%) 4. Generate only inoffensive or no byproducts 5. Stereo specific 6. High atom economy The process must be: 7.simple reaction conditions 8.readily available starting materials and reagents 9.simple product isolation by non-chromatographic methods
  10. 10. DEFINING A “CLICK”CHEMISTRY “ A click reaction must be modular, wide in scope, high yielding, create only inoffensive by-products (that can be removed without chromatography), are stereo specific, simple to perform and that require benign or easily removed solvent. ” - Barry Sharpless Kolb, H.C.; Finn, M.G.; Sharpless, B.K. Angew. Chem. Int. Ed. 2001, 40, 2004-2021. 10
  11. 11. Classes of “Click” Reactions Azide- Alkyne cycloaddition CYCLO ADDITION REACTIONS Diels -Alder reaction NUCLEOPHILIC OPENING OF HIGHLY STRAINED RINGS (like epoxides, aziridines cyclic sulphonates etc) NON-ALDOL TYPE CARBONYL CHEMISTRY (like the formation of oxime ethers, hydrazones ) ADDITION REACTIONS OF ALKENES AND ALKYNES (dihydroxylation of alkenes, Thiol-ene reaction, Michael addition etc)
  12. 12. Historical Perspective of Azide/Alkyne Cycloaddition 1933- Dipolar nature of azide first recognized by Linus Pauling R N3 R N N N R N N NH2 R N N N 1960- Mechanism of 1,3-dipolar cycloaddition of azides and alkynes pioneered by Rolf Huisgen + N3 R' R'' N 1 N R' N 80oC 5 R'' + N 1 N R' N R'' 4 2001- Copper catalyzed 1,3-Dipolar cycloaddition by Sharpless/Meldal R'' + N3 R' Cu(I) rt N 1 N R' N R'' 4 L. Pauling. Proc. Natl. Acad. Sci. USA 1933, 19, 860-867; Huisgen, R. Angew. Chem. Int. Ed. 1963, 2, 633-696 Sharpless, K.B. et al. Angew. Chem. Int. Ed 2002, 41, 2596-2599; Meldal,M.J. et al. J. Org. Chem. 2002, 67, 3057-3064
  13. 13. Copper Catalyzed Azide/Alkynes Cycloaddition (CuAAC)  Thermodynamic and kinetically favorable (50 and 26 kcal/mol, respectively) R''  + N3 R' Regiospecific Cu(I)   Chemo selective 107 rate enhancement over noncatalyzed reaction Rostovtsev et al. Angew. Chem. Int Ed. 2002, 41, 2596-2599 N 1 N R' N R'' 4
  14. 14. CuAAC Catalytic Cycle CuLx R' H R2 N N N R' CuLx CuLx Himo, F. et al. J. Am. Chem. Soc, 2005, 127, 210-216. Ahlquist, M., Fokin, V.V. Organometallics 2007, 26, 4389-4391.
  15. 15. Importance of Triazoles  high thermal stability,  anti-microbial nature,  chemical inertness,  easy to prepare,  stable to oxidation and acid hydrolysis.  Triazoles can act as good corrosion inhibitors. R'' + N3 R' Cu(I) N 1 N R' N R'' 4
  16. 16. SCHEME-1 Hyperbranched polyether using click chemistry and their polyurethane coatings
  17. 17. C-H Str C-O-C Str O-H Str 4000 3500 3000 2500 2000 1500 1000 500
  18. 18. Hyperbranched polyurethane-urea coatings
  19. 19. SCHEME-2 ( Future work) Development of fluorescent polyurethane coatings using click chemistry
  20. 20. Fluorescent polyurethane coatings Fluorescent paints 'glow' when exposed to the long-wave “ultraviolet" frequencies and this effect is known as black-light effect. There are both visible and invisible fluorescent paints. The visible appear under white light to be any bright color, turning peculiarly brilliant under black lights. Invisible fluorescent paints appear transparent or pale under daytime lighting, but will glow only under UV light- and in a limited range of colors. these paints have extensive application where artistic lighting effects are desired, particularly in "black box" entertainments and environments such as theaters, bars, shrines, etc. fluorescence-based materials have attracted rapidly growing interest based on their optical characterization for Biological sensing Cell imaging Disease diagnostics and real-time detection Fluorescent paint used in contemporary art
  21. 21. Synthesis of azidated silica nano particles
  22. 22. Synthesis of perylene fluorophore containing silica nano particles Step-3:- Synthesis of perylene tetra propargylate molecule Step-4:-synthesis of silica nano particles with perylene through click chemistry
  23. 23. Other synthesized HBP’s Triazole core Hyperbranched polyester
  24. 24. Acknowledgements Dr. K.V.S.N. Raju Dr.Ramanuj Narayan Dr.Ch.Ramakishan Rao Dr. Aswini Kumar Mishra Dr. Kishore Kumar Jena Dr. Siyanbola Tolutope Mr.Amit Kumar Mr.Yugandhar Raju Mr.Shaik Allauddin Mr.Nagaraj Goud Mr.A.Ravi Mr.Sarath Mr. Ram Keval Yadav Mr.Rajnish Kumar Mr.Rupchand prajapath Mr.Varaprasad Mr.Rajnish pandey Ms.Amulya
  25. 25. THANK YOU

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