hyperbranched polymers-coating applications


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hyperbranched polymers-coating applications

  1. 1. 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.
  2. 2. 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
  3. 3. 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) Functions Levelling, Antisettling, Flow, Optical, Defoamer etc.-Surfactants  Decoration  Protection Additives  Medical .. The Constituents Alkyd Polyester Polyurethane Acrylics Phenolics Polyamide ;; renewable Polymer/Binder SOLVENT TiO2 Clay Cal. carbonate Talc Iron oxide Zinc oxide etc. Phthalocyanine Al-flakes ……  Self Cleaning  Self Healing  Scratch Resists  Anti Reflective  Heat Resists  Self Stratifying  Antimicrobial  Conductive Filler/Pigment  Solar Paint
  4. 4. Dendritic polymers 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 Polymers 2012, 4, 355-395
  5. 5. Dendrimers Vs Hyperbranched polymers (HBPs) Dendrimers Hyperbranched polymers Dendrimers are highly uniform, 3-dimensional, monodisperse polymers with a tree-like, globular structure and a large number of functional groups With 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
  6. 6. Applications of Hyperbranched Polymers  Coatings  Electrolytes for DSSC  Energy Harvesting  Drug Delivery  Super hydrophobic  Renewable
  7. 7. Advantage Hyperbranched Polymers for Coatings Advantages of HBPs:1. Possess many similar properties of dendrimers 2. Can be produced in large scale at a reasonable cost 3. Have a multitude of end-groups 4. The highly branched architecture leads to globular and voidcontaining shapes, high solubility, low solution or melting viscosity compared to linear analogues
  8. 8. Commercially developed HBPs
  9. 9. 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
  10. 10. Synthesis of HBPs Divergent Approach Divergent approach: Core to periphery Convergent approach: Periphery to core Divergent approach is easier than Convergent approach Convergent Approach
  11. 11. 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 Trepeating units are usually determined by NMR spectroscopy Prog. Polym. Sci. 29 (2004) 183–275
  12. 12. Example for Degree of Branching Calculation Linear Unit Terminal Unit O O HO O O HO O Dendrintic Unit C HO O O Dendrintic Unit O C C Linear Unit 0.5 0.4 Degree of branching=(D+T)/(D+L+T)= (0.1+0.5)/(0.1+0.4+0.5)=0.6 This Hyperbranched polyester has 60 %degree of branching 0.1 O Terminal Unit
  13. 13. Applications of Hyperbranched Polymers
  14. 14. Fast Cure Coatings 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. Surface Coatings International Part B: Coatings Transactions 333 Vo189, B4,269 380, December 2006
  15. 15. Hyperbranched Epoxies as Tougheners for Enhanced Mechanical Properties • 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 Dendritic hyperbranched polymers as tougheners for epoxy resins Polymer, Volume 40, Issue 9, April 1999, Pages 2249-2261 Louis Boogh, Bo Pettersson, Jan-Anders E. Månson
  16. 16. HBPs in Nanocapsules Molecular nanocapsules and their corresponding host/guest compounds offer an attractive potential for use in a wide variety of applications ranging from controlled drug release, phase-transfer agents, dispersion of polar dyes in hydrophobic polymers, preparation of inorganic/organic hybrid nano particles. C15H31COCl Palmitoyl acid chloride Amphiphilic molecular nano capsule Angew. Chem. Int. Ed. 1999, 38, No. 23 Congo Red
  17. 17. Hyperbranched polymers developed by our research group
  18. 18. 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.
  19. 19. Acknowledgements University Grants Commission (UGC) for Financial support Director-IICT for granting permission to carry research work Dr. K.V.S.N. Raju- Research Supervisor (Head PFM Division) Dr.Ramanuj Narayan Mr.Amit Kumar Mr.Yugandhar Raju Colleagues: Dr.Aswini Kumar Mishra Dr.Kishore Kumar Jena Mr.Siyanbola Tolu Mr.Shaik Allauddin Mr.Nagaraj Goud Mr. Ram Keval Yadav Mr.Rajnish Kumar Mr.Rupchand prajapath Mr.Varaprasad Mr.Rajnish pandey