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