hyperbranched polymers for coating applications
DESCRIPTION
hyperbranched polymers for coating applicationsTRANSCRIPT
Work Report3rd October,
2012
K.SASIDHAR,Dr.K.V.S.N.Raju’s
Group,PFM Division, IICT.
Development of polyurethane-urea coatings using azide-alkyne click chemistry
NNN
"Click"N
NN
Alkyne Azide Triazole
R NH C
O
O R'R N C O OH R'
Isocyanate Alcohol Urethane
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%)
R NH C
O
O R'R N C O OH R'
Polyisocyanate polyol polyurethane
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
• Polyol with high molecular weight…………. Flexible and soft polymers
• Polyols with long chain……………………....Soft, elastomeric Polymers
• Polyols with short chain………………………Rigid, crosslinked Polymers
(due to high urethane concentration)
Linear Vs Dendritic polyols
Linear polyols Dendritic polyols
(1) Less number of end Functional groups
(2) Newtonian relationship between viscosities and molecular weight polymers show high viscosities at high molecular weights.
(3) Degree of branching is zero
(4) Not readily soluble compared to HBP’s
(5) They show less thermal mechanical stability than dendrimers and HBP’s
(1) Large number of end Functional groups
(2) non-Newtonian relationship between viscosities and molecular weight polymers show low viscosities at high molecular weights.
(3) Degree of branching is very high XRD results shows that these are having spherical or globular structures
(4) High chemical reactivity and enhanced solubility
(5) These materials show outstanding mechanical properties such as initial modulus, tensile strength and compressive moduli which reflect the compact highly branched structures
Polyester polyols & Polyether polyols
polyester polyols polyether polyols
(1) Excellent mechanical properties like abrasion resistance.
(2) Heat resistance
(3) excellent oil resistance
(4) High resistance to oils and chemicals
(5) Polyesters exhibit higher cut/tear resistance and loading capabilities
(6) Not recommended for use in high humidity and exposure to water.
(1) High hydrolysis resistance
(2) Excellent low temperature flexibility
(3) Resistant to microbial degradation
(4) Excellent clarity
(5) more durable than polyester based systems
(6) Better resistance to UV radiation than polyester systems.
Dendrimers Hyperbranched polymers
Dendrimers Vs Hyperbranched polymers
1.Dendrimer = Greek words Dendron (tree)+ meros (part)
2.Made in a very sophisticated fashion 3.Perfectly built onto a core molecule
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).
1.Made in a very easy fashion [ Divergent and convergent process]
2.Polydisperse [ Mw>Mn] and less than 100%degree of branching
3.They are an irregular macromolecules
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)
Dendrimers and hyper branched polymers are synthesized mainly two ways
• Divergent strategy:- Core to Surface
• Convergent strategy :-Surface to core
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.
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
“ 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.
DEFINING A “CLICK”CHEMISTRY
Classes of “Click” Reactions
CYCLO ADDITION REACTIONS
NUCLEOPHILIC OPENING OF HIGHLY STRAINED RINGS
(like epoxides, aziridines cyclic sulphonates etc)
ADDITION REACTIONS OF ALKENES AND ALKYNES
(dihydroxylation of alkenes,
Thiol-ene reaction, Michael addition etc)
Azide- Alkyne cycloaddition
Diels -Alder reaction
NON-ALDOL TYPE CARBONYL CHEMISTRY
(like the formationof oxime ethers, hydrazones ) R1 R2
O
XR3 NH2
R1 R2
XR3
N
R2
N N+ N-
R1
N
NN
R2
R1
R1
R2
R3
R4
R1
R2
R4
R3
ONu
OH
Nu
R1 SH
R2
S
R2
R1
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
R'' R'N3 N NN
R'
R''
1
5
+80oC N NN
R'
R''
1
4
+
R N3 R N N N R N N NH2R N N N
1933- Dipolar nature of azide first recognized by Linus Pauling
1960- Mechanism of 1,3-dipolar cycloaddition of azidesand alkynes pioneered by Rolf Huisgen
2001- Copper catalyzed 1,3-Dipolar cycloaddition by Sharpless/Meldal
R'' R'N3N N
NR'
R''
1
4
+ Cu(I)
rt
Historical Perspective of Azide/Alkyne Cycloaddition
Thermodynamic and kinetically favorable (50 and 26 kcal/mol, respectively)
Regiospecific
Chemo selective
107 rate enhancement over non-catalyzed reaction
R'' R'N3
N NN
R'
R''
1
4
Cu(I)
+
Rostovtsev et al. Angew. Chem. Int Ed. 2002, 41, 2596-2599
Copper Catalyzed Azide/Alkynes Cycloaddition (CuAAC)
Himo, F. et al. J. Am. Chem. Soc, 2005, 127, 210-216.Ahlquist, M., Fokin, V.V. Organometallics 2007, 26, 4389-4391.
CuLxR'
N N N
R2
CuLx
HR'
CuLx
CuAAC Catalytic Cycle
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'' R'N3
N NN
R'
R''
1
4
Cu(I)
+
Importance of Triazoles
Hyperbranched polyether using click chemistry and
their polyurethane coatings
SCHEME-1
OH
CuSO4.5H2ONa.Ascorbate
t-BuOH:H2O1:1 (Solvent)
O
OH
NN
N
OH
OHO
NN
N
HO
O
O
ON3
HO
OH
N3
HON3
G-1-N3
O
OH
N
N N OH
1st Generation polyether
OO
N3
OHN3O
O N3
HO
N3
OO
N3
HO
N3
G-2-N3
OH
CuSO4.5H2ONa.Ascorbate
t-BuOH:H2O1:1 (Solvent)
O
O
N
OHN
NN
N N OH
OHOO
N
HO
N
N N
NNHO
HOO
O NHO
NN
N
N
N
HO
HO
2nd Generation polyether
OO
N3
ON3
O
O N3O
N3
OO
N3
O
N3
N3
OH
HO
N3
OHN3
G-3-N3
OH
CuSO4.5H2ONa.Ascorbate
t-BuOH:H2O1:1 (Solvent)
OO
O
OH
N N
N
OH
NN
N
OH
NN
N
HO
O
O
OHO
NN
N
HO
NN
N
HO
NN N
OH
O
O O
OH
N
NN
OH
NN N
OH
NN
N
OH
3rd Generation polyether
STEP-3 : Click Reaction
4000 3500 3000 2500 2000 1500 1000 500
C-O-C Str
C-H Str
O-H Str
4000 3500 3000 2500 2000 1500 1000 500
C-O-C Str
C-H Str
O-H Str
OH
OH
OHHO
HO OH
HOOH
G-1 or G-2 or G-3
NCO
NCO
H12-MDI
OH:NCO1:1.2
NCO terminated Polyurethane pre polymer
Moisture Curing
polyurethane-urea
coatings
O
C O
NH
OO NCOOCN
O
CO
NH
O
C
O
HN
O
C
O
NH
O
C
O NH
O
C
O
HN
Hyperbranched polyurethane-urea coatings
Development of fluorescent polyurethane
coatings using click chemistry
SCHEME-2 ( Future work)
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.
Fluorescent polyurethane coatings
fluorescence-based materials have attracted rapidly growing interest based on their optical characterization for Biological sensingCell imagingDisease diagnostics and real-time detection
Fluorescent paint used in contemporary art
Synthesis of azidated silica nano particles
Si
EtO
EtOOEt
Cl
3-Chloro propyl triethoxy silane
NaN3,TBAB
Acetonitrile, Reflux
Si
EtO
EtOOEt
N3
3-Azido propyl triethoxy silane
Step-1:- synthesis of 3-azido propyl triethoxy silane
Si
OEt
OEtEtO
EtO
Tetraethoxysilane
CTAB, NaOHH2O
SiNP
N3
N3
N3 N3
Azide terminated Silica nano particles
Step-2:- synthesis of azide terminated silica nano particles
Si
EtO
EtOOEt
N3
3-Azido propyl triethoxy silane
Synthesis of perylene fluorophore containing silica nano particles
O
OO
O
OO
perylene-3,4,9,10-tetracarboxylic dianhydride
KOHH2O, Reflux
COOH
COOHHOOC
HOOC OH
DCC, DMAPDCM Solvent
O
O
O
O
O
O
O
O
Step-3:- Synthesis of perylene tetra propargylate molecule
Step-4:-synthesis of silica nano particles with perylene through click chemistry
O
O
O
O
O
O
O
O
SiNP
N3
N3
N3 N3
OH
SiNP
N
NNN
N
NPerylene
N
N
N
Perylene
NN
N
Perylene
HO
silica nano particles withperylene units
Step-4:- synthesis of f lourocent PU coatings
OH
OH
OH
OH
HO
HO
OHHO
Hyperbranched polyol
SiNP
NN
NN
NN
Perylene
N
NN
Perylene
NN N
Perylene
HO
silica nano particles withperylene units
H12 MDIFlourocent PU coatings
Other synthesized HBP’s
NN
N N
NN
HO
OH OH
OH
1500c,8 hrs
NN
N N
NN
O
O O
O
O
OH
OH
O
OH
OH
O
OH
OH
HO
HO
OOH OH
COOH
4
1st Generation polyester
2nd generation
polyester
3rd generation
polyester
o
o
o
o
o
o
NaN3 ,NH4Cl
Methanol, Water(7:1)
Trimethylol propaneTriglycidyl ether
o
o
o
N3
N3
N3
OH
OH
OHReflux, 48 Hrs
(TMPTE)
(N3TMPTE)
HO
OH
o
o
o
N
NN
OH
OH OH
NN N N N
N
HO
HO
OH
HO
OH
OH
Polyol-1(PL-1)
OH
o
o
o
N
N
N
OH
OH
OH
NN
N NN
N
OH
OH
OH
Polyol-2(PL-2)
Triazole core Hyperbranched polyester
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 AllauddinMr.Nagaraj Goud
Mr.A.RaviMr.Sarath
Mr. Ram Keval YadavMr.Rajnish Kumar
Mr.Rupchand prajapathMr.Varaprasad
Mr.Rajnish pandeyMs.Amulya
Acknowledgements
THANK YOU