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Development of Hyperbranched Polymers for Coatings & Allied Field Applications
K.Sasidhar
UGC-SRF, ID.No-7742
Research Supervisor: Dr.K.V.S.N.Raju
Polymers & Functional Materials Division
CSIR-IICT, Hyderabad.
Scheme of Presentation
Coatings
Dendritic Polymers
Dendrimers Vs Hyperbranched Polymers
Advantages of HBPs
HBPs for Eco-friendly High Solids Coatings
Synthesis of HBPs
Degree of branching in HBPs
Applications of Hyperbranched Polymers
Research at CSIR-IICT
Linkage to my research work
Summary
Coatings
Coating is defined as materials which on application to substrates form a uniform coherent film with good adhesion and functional properties. (paint -color, generally paint is used for decorative purposes)
Decoration
Protection
Medical
..
Self Cleaning
Self Healing
Scratch Resists
Anti Reflective
Heat Resists
Self Stratifying
Antimicrobial
Conductive
Solar Paint
Functions
TiO2
ClayCal. carbonateTalc Iron oxideZinc oxide etc.PhthalocyanineAl-flakes ……
Levelling, Antisettling, Flow, Optical, Defoamer etc.-Surfactants
SOLVENT
AlkydPolyesterPolyurethaneAcrylicsPhenolicsPolyamide;;renewable
Polymer/Binder Filler/Pigment
Additives
The Constituents
Dendritic polymers are macromolecular architecture. They represent highly
branched globular macromolecules,
They are subdivided according to their degree of structural control into
three different categories,
(a) random hyperbranched polymers
(b) dendrigraft polymers
(c) dendrimers
Dendritic polymers
Polymers 2012, 4, 355-395
Dendrimers Vs Hyperbranched polymers (HBPs)
Dendrimers Hyperbranched polymersDendrimers are highly uniform, 3-dimensional,monodisperse polymers with a tree-like, globularstructure and a large number of functional groupsWith perfect molecular architecture.
Hyperbranched polymers represent another class of globular, highly branched macromolecules with a large number of functional groups. However, unlike dendrimers, hyperbranched polymers exhibit irregularity in terms of branching and structure.
Dendrimers are monodisperse [Degree of branching (DB) =1]
HBPs are polydisperse [DB<1]
Highly symmetrical in nature Unsymmetrical in nature
Dendrimer synthesis requires absolute control over all the synthetic steps.
HBPs can be prepared by a one pot polycondensation process
The synthesis of dendrimer is quite tedious job and requires several protection and deprotection steps.
Easily synthesized by a one pot method
Final yield is very low so can not be applicable industrially
Final yield is high so can be synthesized in large scale
Applications of Hyperbranched Polymers
Coatings Electrolytes for DSSC Energy Harvesting Drug Delivery Super hydrophobic Renewable
Advantage Hyperbranched Polymers for Coatings
Advantages of HBPs:-1. Possess many similar properties of dendrimers2. Can be produced in large scale at a reasonable cost3. Have a multitude of end-groups4. The highly branched architecture leads to globular and void-
containing shapes, high solubility, low solution or melting viscosity compared to linear analogues
Commercially developed HBPs
NH
HO
HO
diethanolamine
O
O
O
phthalic anhydride
MonomersOH
OHHO
Trimethylol propane
O
OH
Glycidol
Monomers
O
OHHO
HO Bis-MPA
Monomer
HN
aziridine
Monomer
HBPs for Eco-friendly High Solids Coatings
• Generally in case of linear polymers viscosity of a polymer solution increases linearly
with increase in molecular weight but in case of hyperbranched and dendritic polymers this
increment is not linear they show low viscosities at high molecular weights which is mainly
due to less number of molecular engagements in HBPs
• Low Viscosity at higher molecular weight which in turn results in higher solids with excellent
Mechanical properties is key for low VOC eco-friendly coatings
• The peripheral reactive functional groups helps in crosslinking and adding functional
properties (e.g. dual cure systems)
Prog. Polym. Sci. 32 (2007) 352–418
Synthesis of HBPs
Divergent Approach
Convergent Approach
Divergent approach: Core to periphery
Convergent approach: Periphery to core
Divergent approach is easier than Convergent approach
Degree of branching in HBPs
Fr´echet and coworkers gave an equation for the DB at first, as shown in Eq.There are three types of units present in HBPs
Linear (L), Terminal (T) and Dendritic (D) units
• The degree of branching of a perfect Dendrimer equals 1, linear polymer has a DB of 0
• For HBPs DB is less than 1
• The fractions of D-, L- and T- repeating units are usually determined by NMR spectroscopy
Prog. Polym. Sci. 29 (2004) 183–275
Degree of branching=(D+T)/(D+L+T)= (0.1+0.5)/(0.1+0.4+0.5)=0.6
HO
HO
C
O
O
O
HO
C
O
O
O
O
C
O
O
Terminal UnitLinear UnitDendrintic Unit
This Hyperbranched polyester has 60 %degree of branching
Example for Degree of Branching Calculation
N
HO OH
OH
O OH
OH OH
3 N
O O
O O
OHOH
O
HO
HO O
OH
OH
Triethanolamine Bis-MPA1st Generation HBP
a
b
c
d
e
0.900.951.001.051.101.151.201.251.301.35
0.1
0.4
0.5
Dendrintic Unit
Linear UnitTerminal Unit
Applications of Hyperbranched Polymers
The large number of reactive groups will, upon reaction, rapidly form a network to give a fast cure.
It is believed that the rapid cure also contributes to the reactive groups being predominantly at the surface which, in combination with the dense structure, which makes them less possible to entanglement and hence more readily accessible for reaction.
Fast Cure Coatings
Surface Coatings International Part B: Coatings Transactions 333 Vo189, B4,269 380, December 2006
• Large amounts of epoxy resins are used world-wide in coatings,
adhesives, moulding compounds and polymer composites
• Dendritic hyperbranched polymers (HBPs) show outstanding
performance as tougheners in epoxy resins
• When using 10% of the HBP toughener, the largest toughening
effect
is observed with a 10-fold increase in GIc (toughness)
• With core–shell particles, it is necessary to use up to 30% of
modifiers in order to obtain a comparable toughening effect to 5% of
HBPs
• The critical strain energy release rate, GIc, of a DGEBF resin is
increased by a factor of 6 from 120 J/m2 to 720 J/m2 using only a 5%
modifier weight content
Hyperbranched Epoxies as Tougheners for
Enhanced Mechanical Properties
Dendritic hyperbranched polymers as tougheners for epoxy resins Polymer, Volume 40, Issue 9, April 1999, Pages 2249-2261Louis Boogh, Bo Pettersson, Jan-Anders E. Månson
N
O
N
O N O
O
OO
OO
O
OO
OO
O
O
O
O
O
O
O
O
O
O O
O O
diglycidylether of bisphenol-A
O O
O
O
O
OO
O
O
O
O
OO
O
O
O
OO
OO
O
O
O
H2N
HN
NH2
diethylene triamineHardener
Hyperbranched Epoxy compound10% by weight
Crosslinkednetworks
HBPs in Nanocapsules
Molecular nanocapsules and their corresponding host/guest compounds offer an attractive potential for use in a wide variety of applications ranging fromcontrolled drug release, phase-transfer agents, dispersion of polar dyes in hydrophobic polymers, preparation of inorganic/organic hybrid nano particles.
Amphiphilic molecular nano capsule
Congo Red
C15H31COCl
Palmitoyl acid chloride
Angew. Chem. Int. Ed. 1999, 38, No. 23
N
O
O
O
OH
OH
O
HO
HO
O
OH
OH
O
O
OH
OH
OO
OHOH
O
OHO
HO
O
O
OH
OHO
O
HO
HO
O
O
HO
HO
O
O
OH
OH
O
N
NN
O
O
O
OH
OH
O
OH
OH
N
N NO
O
OHO
HO
O
HO
HO
NOO
O
OO
O
O
O
O
O
ON
OH
HO
N OH
HO
N
HO
O
OH
O
OH
HO
O
HO
OH
O
HO
HO
Hyperbranched polymers developed by our research
group
Summary & Conclusions
1. Hyperbranched polymers show better thermal and mechanical properties than linear polymers.
2. Hyperbranched polymer based coatings are with low VOC, high solid content Eco-friendly because they show lower viscosities at high molecular weights.
3. Due to large number of end functionalities, HBP based coatings curing is very fast.
4. HBPs crosslinked epoxies are showing excellent toughness than linear one’s.
5. These are better alternatives to dendrimers for many applications.
Acknowledgements
Dr. K.V.S.N. Raju- Research Supervisor (Head PFM Division)
Dr.Ramanuj Narayan
Mr.Amit Kumar
Mr.Yugandhar Raju
Colleagues:Dr.Aswini Kumar MishraDr.Kishore Kumar JenaMr.Siyanbola ToluMr.Shaik AllauddinMr.Nagaraj GoudMr. Ram Keval YadavMr.Rajnish KumarMr.Rupchand prajapathMr.VaraprasadMr.Rajnish pandey
University Grants Commission (UGC) for Financial support
Director-IICT for granting permission to carry research work