Synthesis of Colloids and Polymers Topic: Anionic Polymerization And Macromolecular Engineering Pierre J. LUTZ

1. Synthesis of Colloids and Polymers Topic: Anionic Polymerization And Macromolecular Engineering Pierre J. LUTZ 5th Worhshop of the IRTG (International Research Training Group Soft Condensed Matter) Kontanz, April 3-5, 2006

2. Anionic Polymerization and Macromolecular Engineering Some Problems that require well-defined Polymers ● How does the width of molar mass distribution influence the mechanical properties of a polymer ? ● What is the effect of branching on polymer properties ? ● What protecting effect is exerted by soluble grafts on an insoluble backbone in Graft Copolymers ? ● What is the size of a cyclic macromolecule as compared with that of the linear homologue ? ● How does compositional heterogeneity affect the properties of a Copolymer ? ● What are the conditions required for a block copolymer to exhibit phase separation ?

3. Anionic Polymerization and Macromolecular Engineering Some structures to be discussed ● LINEAR HOMOPOLYMERS or COPOLYMERS ● FUNCTIONAL POLYMERS or COPOLYMERS INCLUDING MACROMONOMERS ●BRANCHED POLYMERS - GRAFT-COPOLYMERS - STAR-SHAPED HOMO (CO-)POLYMERS vaious cores: DVB, C60, Polygycerol, Sisesquioxanes - COMB-LIKE POLYMERS HOMOPOLYMACROMONOMERS ● WELL-DEFINED  POLYMERIC NETWORKS ●CYCLES or STRUCTURES derived from CYCLES

4. Anionic Polymerization and Macromolecular Engineering Characterization Methods to be used to determine the structural parameters or the behavior of Complex Macromolecular Architectures ● Static and Dynamic LIGHT SCATTERING To get Molar Mass, Mw, and Radius of Gyration and Hydrodynamic Radius, … ● SIZE EXCLUSION CHROMATOGRAPHY (GPC) Detectors required * Differential Refractometry : to get c * UV Spectrometry to check for the presence of a chromophore * Light scattering to get Mw * Viscometry (necessary for universal calibration) ●ELEMENTAL ANALYSIS ● DIFFERENTIAL REFRACTOMETRY / to get overall composition ● NMR, UV SPECTROMETRY (microstructure, composition, functionality) ● VISCOMETRY ● Maldi-TOF MS ● AFM, ● X-Ray measurements In solution, in the bulk !

5. Anionic Polymerization and Macromolecular Engineering Functionalization Functionalization

6. Anionic Polymerization and Macromolecular Engineering Macromonomers ●Macromonomers well defined polymers - Low molar mass - Polymerizable end-groups - Accessible via anionic, cationic, polymerization ATRP (FRP), - PB, PE, PMMA, P2VP, PEO, PDMS - Linear, block copolymer, star-shaped…. • ●Major interest • Graft copolymers by (free) radical copolymerization, branch length • - Access to new branched topolygies by • homopolymerization Macromonomers by b-elimination reactions in coordination Polymerization

7. Anionic Polymerization / Macromolecular Eng. Macromonomer Synthesis Deactivation w-allyl w-undecenyl PS (atactic): undecenyl end group w-styrenyl • Characterization: • Molar mass: SEC: Mn exp = Mn,th, • (1000 to 10 000 g.mol-1) • Sharp molar mass distribution, no coupling • Functionalization: 1H NMR • Chemical Tritration • Maldi-Tof

8. Anionic Polymerization / Macromolecular Eng. Macromonomer Synthesis Initiation Anionic Polymerization of Oxirane With K (and not Na or Li) RT • Well functionalized • Heterofunctional Polymer OH • Deactivation also possible for PEO Initiation not possible for PS macromonomers

9. Anionic Polymerization / Macromolecular Engineering GRAFT COPOLYMERS Valuable polymeric materialsconstituted of a polymer backbone (Poly(A) carrying a number of grafts of different chemical nature (Poly(B)distributed at random INTEREST: Arises from the incompatibility between backbone and grafts ● High segment density because of the branched structure ● High tendency to form intramolecular phase separation ● Micelles are formed in a preferential solvent of the grafts (surface modification, compatibiliziers, micelles…. ) (enhancing or depressing surface tension, making a surface hydrophobic or hydrophilic In Graft Copolymers a variety of Molecular Parameters can be varied - Main chain and side chain polymer type - Degree of polymerization and polydispersities of the main and side chain - Graft density (average spacing density between side chains) - Distribution of the grafts (graft uniformity) PS PEO

10. Anionic Polymerization / Macromolecular Engineering GRAFT COPOLYMERS Selected polymerization techniques can be used to tailor graft copolymers on request : Well defined Graft copolymers Ionic Polymerization ●grafting from : Grafting by anionic initiation from sites created on the backbone ●grafting onto : Anionic deactivation of living chains by electrophilic functions located on a polymeric backbone ●grafting through : Use of dangling unsaturations to attach grafts onto a polymeric backbone (Macromonomer free radical poly) . Classical free radical polymerization not well adapted absence of control of molar mass and polymolecularity (homopolymer, crosslinked material) NEW DEVELOPMENTS : CFR POLYMERIZATION, COORDINATION POLYMERIZATION

11. Anionic Polymerization / Macromolecular Engineering GRAFT COPOLYMERS Graft copolymers via Macromonomers Macromonomer/Comonomer Copolymerization Kinetics : free radical In such copolymerizations, owing to the large differences in molar mass between Macromonomer M and Comonomer A, the monomer concentration is always very small : consequently the classical instantaneous copolymerization equation Reduces to As in an « ideal » copolymerization the reciprocal of the radical reactivity of the comonomer is a measure of the macromonomer to take part in the process Controlled Free Radical Copolymerization

12. Anionic Polymerization / Macromolecular Engineering BRANCHED POLYMERS Interest of branched Polymers - Compactness - High segment density ●Statistical branching (free radical polymerization) Branched pE’s ● Well defined branched polymers - Homopolymerization of macromonomers - Grafting onto or from (each monomer unit of the main chain with a function) ● Star-shaped polymers - « Arm-first » by deactivation, by copolymerization - « Core-first » plurifunctional initiator - In-out, heterostar … Miktoarm ● More complex star-shaped or branched architectures Umbrella,

13. Anionic Polymerization / Macromolecular Engineering PolyMacromonomers • Anionic Polymerization • (Controlled) free radical polymerization • ROMP • GTP • Coordination Polymerization ? ? •The Nature of the Unsaturation, • The Chemical Environment of the Unsaturation • The Length of the Macromonomer Chain • The Thermodynamic Interactions between the macromonomer and the backbone to be formed • The Presence, the Amount of solvent Bottlle brush structure DP > 80 Star-shaped DP < 80

14. Anionic Polymerization / Macromolecular Engineering PolyMacromonomers n T i A r O M e F F O N F B A r ' P d 4 N H C C l A r 3 T i S i Z r H C N 3 C l T i C l O M e C l M e O C H 3 H C O M e 3 C H 3 Some Catalysts Tested Mn 1000 to 10 000g.mol-1 Activated with MAO • Homopolymerization possible ! but never quantitative • Degree of Polymerization: DP Ti > DPZr around 7- 10 • Polym. yield decreases with increasing PS molar mass, DPE • Polym time increases, DP constant, conversion increases • Highest DP obtained with CGC-Ti around 300 M PM Elution volume SEC

15. Dilute Solution characterization of PS poly(macromonomer)s SEC: Smaller hydrodynamic volume SEC: Transition comb-shaped / Star SEC: Smaller Radius of gyration q2. I(q) SANS Asymptotic Behavior of the particle Scattering function of a PS PM (CP)

16. Anionic Polymerization / Macromolecular Engineering BRANCHED / STARS PE stars by Arm-first Methods

17. Anionic Polymerization / Macromolecular Engineering BRANCHED / STARS Arm-first: Typical molecules used as core

18. Anionic Polymerization / Macromolecular Engineering BRANCHED / STARS Arm-first Methods ● Synthesis of a w-living polymer (PS, PI) • ● Core formation • either by reacting it with a plurifunctional electrophile in stoechiometric amount • or by using the carbanionic sites to initiate the polymerization a small amount of biunsaturated monomer such as DVB, DEMA PS, PI, PMMA Advantages: - Low fluctuations in molar mass - Low composition heterogeneity (copo) - Characterization of the individual branches - Average number of branches accessible Functionalization at the outer end of the branches not possible

19. Anionic Polymerization / Macromolecular Engineering BRANCHED / STARS Arm-first Methods ● Synthesis of a w-living diblock polymer (PS-b-PI)

20. Anionic Polymerization / Macromolecular Engineering BRANCHED / STARS • Polyfunctional Initiators: CORE FIRST Method • - Metalorganic sites tend to strongly associate, even in aprotic polar solvents • - Aggregate formation is frequent : some sites may remain hidden • As polymerization of the monomer proceeds gelation of the reaction medium is to be expected • - However Molar mass not directly accessible From PolyDVB Cores FIRST STEP: Preparation of a dilute solution of living cores A solution of (DVB) is added dropwise to a dilute solution of Potassium naphtenide in THF Conditions to be observed to avoid microgel formation - [DVB] / [K] ratio should be below 2 - high dilution Avoid any local excess of DVB - efficient stirring OE:First the solution becomes turbid, After a few hours the medium becomes biphasic Finally it gets homogeneous and clear again when the branches are long enough to contribute also to the solvatation of the cations

21. Anionic Polymerization / Macromolecular Engineering BRANCHED / STARS 2,0 Sample 460 1,9 Sample 462 Sample 467 1,8 1,7 I1 / I3 1,6 1,5 1,4 H(Rh) cmc 1,3 0 1 2 3 4 5 6 4 mol DVB/L (10 ) Polyfunctional Initiators: CORE FIRST Method CMC Determination Molar Mass and Viscosity QELS measurements of core-first star-shaped PEO ’s

22. Anionic Polymerization / Macromolecular Engineering BRANCHED / STARS Polyfunctional Initiators: CORE FIRST Method Other Multifunctional Iniatiators Living poly(divinylbenzene) cores Living poly(diisopropenylbenzene) cores Hydrophobic Core more or less Polydisperse + A Bifunctional coupling agent Other Initiators Tris-alkoxides Modified Carbosilane dendrimers + B Polyglycerol cores

23. Anionic Polymerization / Macromolecular Engineering BRANCHED / STARS PEO Stars Based on Polyglycerol Cores Controlled Polymerization of glycerol Polyglycerol core Star-shaped PEO

24. Anionic Polymerization / Macromolecular Engineering BRANCHED / STARS Purification via fractional precipitation in THF/DE fractional precipitation in THF/Heptane dialysis in H2O dialysis in THF possible PEO/POLYGLYCEROL STARS

25. Anionic Polymerization / Macromolecular Engineering BRANCHED / STARS « In-out » Star Polymers ● Use of a w-living seed polymer (PS, PI) as initiator (Protection and solubilization of the poly(DVB) core ● Addition to the living core of another monomer exhibiting higher electrophilicity (EO ) • Typical Amphiphic behavior • High solubility in many solvents • Protection exerted by the hydrophilic parts on the hydrophobic core • High tendency to form stable emulsions in water • Tendency to phase separation in concentrated media Addition of styrene results in crosslinking (remaining double bond)

26. Anionic Polymerization / Macromolecular Engineering BRANCHED / STARS Living PS, PI, diblock Well-defined star-shaped or related branched structures base on anionic polymerization But very time consuming synthesis, fractionated, interesting morphologies

27. Anionic Polymerization / Macromolecular Engineering BRANCHED / STARS Star-shaped Polymers Based on Diphenylethylene Derivates Quirk, Dumas

28. Anionic Polymerization / Macromolecular Engineering BRANCHED / STARS Model architectures : 6-6 bond   5-6 bond I - Addition of living polymers onto C60 C60 is constituted of 12 pentagons et 20 hexagons, 6 pyracylene units Small molecule (d  10 Å) et plurifunctional (30 double bonds) * Control the number of grafts * Control of the polymer chain : -The chain end must be able to react with C60 - Control molar mass and polymolecularity - Grafting of block copolymers.. • Anionic Polymerization C. Mathis

29. Anionic Polymerization / Macromolecular Engineering BRANCHED / STARS Exemple : grafting of PSLi onot C60 in toluene

30. Anionic Polymerization / Macromolecular Engineering BRANCHED / STARS C60 being a conjugated molecule, charge (introduced by the carbanion present at the living chain end) delocalizes. Therefore a second living chain cannot be added onto pyracyclene units and hexagones h1 to h4. (addition to the 6-6 ring double bonds)

31. Anionic Polymerization / Macromolecular Engineering BRANCHED / STARS  hexafunctional Star-shaped polymers Charge delocalisation and geometrical form of C60 limit the number of grafts to 6 (molar masses up to 2 106 g mol-1

32. Anionic Polymerization / Macromolecular Engineering BRANCHED / STARS II – Hexa-aducts can be used as plurifunctional initiator for the anionic polymerization  Synthesis of Palmtree and Dumbbell architectures

33. Anionic Polymerization / Macromolecular Engineering BRANCHED / STARS (PS)6C606-(Li+)6 + MMA  (PS)6C60(PMMA)2 [6PS + 2PMMA] “hetero-stars”

34. Anionic Polymerization / Macromolecular Engineering BRANCHED / STARS Synthesis of Palm tree or Dumbbell Architectures [6PSa + 1PSb] “palm-tree” 2 (PS)6C605-(Li+)5PSb-Li+ + BrCH2PhCH2Br (PS)6C60PSb- CH2PhCH2-PSbC60(PS)6

35. Anionic Polymerization / Macromolecular Engineering BRANCHED / STARS X • POSS Polyoctaedralsilsesquioxanes New class of nanostructured materials: • Higher thermal stability • Higher mechanical properties • Bette resistance to fire… • Silsesquioxane: hydrophobic! Function, epoxy, alcohol, C=C Non reactive Group   Eight corn substituted cage Further Chemical Reactions, (co-) polymerization Solubilization R= H , OSi(CH3)2H Stable Bond  • Functions: Chemical Modification or grafting of existing polymers (modulation of the number of grafted chains ? ?) • Polymerizable group (copolymerization with other monomers via ATRP, Coordination Polymerization, ring opening…)

36. Anionic Polymerization / Macromolecular Engineering BRANCHED / STARS Macromonomers: New hybrid Materials Well defined Polymers - Controlled functionality Mono, bifunctional, - Controlled Molar Mass • Star-shaped Polymers • Controlled core functionality • Controlled branch lenght Hydrosilylation • Networks or Hydrogels • Controlled functionality of the cross-linking points • - Controlled length of the elastic chains Allyl / SiH H2PtCl6 - 8 SiH functions, cubic Silsesquioxanes:

37. Grafting of Monofunctional PEO macromonomers onto Silsesquioxanes 75°C Toluene H2PtCl6 ( Hydrosilylation reaction ) CH2=CH-CH2-O-(CH2-CH2-O)n-CH2-CH2-OCH3 + 8-10 fois molar POE -allyle or OH Q8M8H or OH Star-shaped Polymers with 8 branches (Q8M8PEO) New Multifuntional initiator Extended to PS arms

38. Anionic Polymerization and Macromolecular Engineering End-linking Stoichiometric reaction betwenn a bifunctional linear polymer and a plurifunctional antagonist compound As result : the precursor chains become the elastically effective chains of the network The plurifunctional compound becomes the branch points of the network Ideal Network : macrocopically homogenous contains a known number of elastic chains of known length and branch points of known functionality However : some defects are to be expected

39. CYCLIC POLYMERS Introduction • Synthesis of Cyclic Structures - Ring-chain equilibria - End-to-end Cyclization • Properties of Cyclic Structures - Dilute solution Behavior - Influence of the nature of the preparation solvent - Solid State • Structures Derived from cyclic Polymers Conclusion and Future

40. Anionic Polymerization and Macromolecular Engineering: Cyclic Polymers  * MAY APPEAR AS A SUBJECT FOR PURE MATHEMATICS OR THEORY NO ENDS * TO COMPARE THE MOLECULAR DIMENSIONS OF WELL-DEFINED CYCLIC AND LINEAR MACROMOLECULES Same molar mass, Low polydispersity in solution as well as in the bulk * TO STUDY THE ABILITY OF CYCLIC) MACROMOLECULES TO DIFFUSE IN A POLYMER MATRIX (REPTATION) OR IN NETWORK Accessible only by Anionic Polymerization ? Introduction

41. Anionic Polymerization and Macromolecular Engineering: Cyclic Polymers * RING-CHAIN EQUILIBRIA IN POLYCONDENSATION Low molar mass CYCLES are formed preferentially * BACK BITTING REACTIONS IN IONIC POLYMERIZATION Reaction of a function on the chain with a functional link of the same chain – an alkoxide with an ester function -a Silanolate function with a siloxane bridge - an oxonium with an ester bridge - increase of the number of macromolecules - decrease of their average molar mass  EX : Upon heating of a PDMS in the presence of some basic catalyst  implies the presence of a functional link in the chain Synthesis of Cyclic Structures Ring-chain equilibria

42. Cyclic Polymers BACK BITTING REACTIONS IN CATIONIC POLYMERIZATION Reaction of a function on the chain with a functional link of the same chain an oxonium with an ester bridge Synthesis of Cyclic Structures Ring-chain equilibria

43. Anionic Polymerization and Macromolecular Engineering: Cyclic Polymers SEC PDMS Logarithmic plots of the root-square radius of gyration vs molar mass for linear and cyclic PDMS fractions After SEC Fractionation Semlyen et al. Synthesis of Cyclic Structures Ring-chain equilibria

44. Anionic Polymerization and Macromolecular Engineering: Cyclic Polymers End-to-end Cyclization : effect of the concentration on the cyclization yield Intramolecular reaction Intermolecular reaction Synthesis of Cyclic Structures End-to-end Cylization

45. Cyclic Polymers PS a,w -difunctional Couplig agent + + K CHCH CH CH K BrCH CH Br 2 2 2 2 CH CHCH CH CHCH 2 2 2 2 CH CH CHCH 2 2 CH CH 2 2 Synthesisvia anionic polymerization + Cycle chain extension Cyclization Chain extension * Coupling reaction has to be fast, quantitative and free of side reactions * Exact stoichiometry (balance active sites / functions) * High dilution to favor intramolecular coupling with respect to intermolecular coupling * Efficient stirring to prevent local fluctuations in concentrations Synthesis of Cyclic Structures End-to-end Cylization

46. Cyclic Polymers Experimental Procedure Solvent •THF •Cyclohexane • THF/Heptane Initial concentration 10 wt.-% after dilution 0.1 wt.- % Synthesis of Cyclic Structures End-to-end Cyclization

47. Cyclic Polymers SEC trace of the raw reaction product SEC trace of cyclic and linear PS Big difference in molar mass Cycle linear Cycle Chain extension Elution volume Adequate separation of linear polycondensate from the cycles Cyclization yield from 20 to 50 wt-.% decreases with increasing molar mass Without dilution 2.5 wt.-% 20 % (2500) Molar mass domain from 5000 to 200 000g.mol-1 Elution volume Synthesis of Cyclic Structures End-to-end Cylization

48. Cyclic Polymers Synthesis of Cyclic Structures End-to-end Cylization

49. Cyclic Polymers Different strategies for the synthesis of block copolymer cycles Synthesis of Cyclic Structures Block copolymer cycles

50. Cyclic Polymers Cyclization reactions based on unimolecular processes Synthesis of Cyclic Structures End-to-end Cylization