Supramolecular Chemistry for Pressure Sensitive Adhesives ? Gordon Seminar 2014 Xavier Callies, 3 nd year Phd Student Guylaine Ducouret, Costantino Creton SIMM, ESPCI ParisTech, Paris, France Olivier Herscher, Cécile Fonteneau Sandrine Pensec, Laurent Bouteiller LCP, UPMC, Paris, France
PSA = Pressure Sensitive Adhesives A material which sticks on almost any surface by simple contact, without chemical reaction Solid Liquid 2 1 2 1 Non flowing Dissipative Viscoelastic Materials σ 0 Introduction Bis-Urea PnBA Copolymer & Resins
PSA = Pressure Sensitive Adhesives A material which sticks on almost any surface by simple contact, without chemical reaction Solid Liquid 2 1 2 1 Non flowing Dissipative Viscoelastic Materials σ 0 O Low T g < -40°C For ex, PnBA ≈ -50°C O Classic Formulation n Long entangled polymers Chains (Acrylic) Light cross-linking + Pendant Short Chains Introduction Bis-Urea PnBA Copolymer & Resins
Challenge of our project : Is it possible to get a viscoelastic behavior required for a PSA with unentangled molecules with strong but reversible interactions ? New Chemical Parameters High Solubility in Organic Solvent What is required ? Strongly interacting moieties separated by flexible polymer chains. Supramolecular System Introduction Bis-Urea PnBA Copolymer & Resins
Challenge of our project : Is it possible to get a viscoelastic behavior required for a PSA with unentangled molecules with strong but reversible interactions ? New Chemical Parameters High Solubility in Organic Solvent What is required ? Strongly interacting moieties separated by flexible polymer chains. Supramolecular System Strategy Synthesize Supramolecular Model Systems with a highly controlled chemical structure. Systematic Rheological and Adhesive Characterization Introduction Bis-Urea PnBA Copolymer & Resins
Model System n°1 Bis-urea Xylene Center-Functionalized PnBA Urea O O O O O O O O Br Br N N N N n H H H H n O O Side Chain Polar Core Side Chain Self-assembly of Stickers 1 1 Pensec et al, Macromolecules, 2010, 43, 2529-2534 1 Courtois et al, J. Adv. Funct. Mater,2010, 20, 1803-1811 Introduction Bis-Urea PnBA Copolymer & Resins
Strategy for Synthesis Sticker is the initiator of the polymerization. Growth of two symmetric side chains by ATRP (Ip < 1,4). Influence of M w 5 kg/mol M w 120 kg/mol 4% Φ sticker (w%) 0,2% Introduction Bis-Urea PnBA Copolymer & Resins
Viscoelastic behavior at 25°C (in the melt state) 5 5 10 10 4 4 10 10 G' & G'' (Pa) G' & G'' (Pa) 3 3 10 10 2 2 10 10 G’’ G’ PnBAX5 1 10 1 PnBAX40 G’’ G’ PnBAX8 G’’ G’ 10 PnBAX115 G’’ G’ PnBAX20 G’’ G’ 0 10 0 10 4 5 6 2 3 4 5 6 2 3 4 5 6 2 3 4 5 6 2 3 1 10 1 10 Angular Velocity (rad/s) Angular Velocity (rad/s) At a fixed ω, G’ & G’’ ↘ if M w ↗ At a fixed ω, G’ & G’’ ↗ if M w ↗ All Viscoelastic Fluids at RT Introduction Bis-Urea PnBA Copolymer & Resins
Viscoelastic behavior at 25°C (in the melt state) η*=√(G’ 2 +G’’ 2 )/ ω 1 2 η *(1 rad/s, 25 C) τ ≈ f(φ sticker )t for M w ≤ 20kg/mol Two regimes τ ≈ f( L PnBA ) for M w ≥ 20kg/mol Introduction Bis-Urea PnBA Copolymer & Resins
Adhesion of thin acrylic films Probe-tack Experiments – Flat Punch Steel probe ( Ф ≈1cm) Thin Film (h≈100µm) Contact (t ≈ 10s) Debonding (V= 100µm/s) Adhesion Energy W adh (J/m 2 ) Elastic Viscoelastic / Viscous Introduction Bis-Urea PnBA Copolymer & Resins
Adhesion test Probe-tack test (100µm/s) Steel Probe σ (MPa) 1.0 0.8 0.6 PnBAX5 0.4 PnBAX8 PnBAX115 0.2 0.0 0.0 0.5 1.0 1.5 2.0 2.5 ε W adh ≈ 30 -50 J/m 2 W adh << W adh (PSA) ≈ 100J/m 2 Introduction Bis-Urea PnBA Copolymer & Resins
Adhesion test Probe-tack test (100µm/s) Steel Probe σ (MPa) 1.0 0.8 0.6 PnBAX5 0.4 PnBAX8 PnBAX115 0.2 0.0 0.0 0.5 1.0 1.5 2.0 2.5 ε Entangled Chains How to strengthen W adh ≈ 30 -50 J/m 2 + our supramolecular system ? W adh << W adh (PSA) ≈ 100J/m 2 A high Density of Sticker Introduction Bis-Urea PnBA Copolymer & Resins
Supramolecular Copolymers & Resins Entangled Chains with several stickers per chain Incorporate reactive monomers in the side chains of our PnBAX Cross-link partially with cross-linker (or hardener) Introduction Bis-Urea PnBA Copolymer & Resins
Supramolecular Copolymers & Resins Side Chain Side Chain Polar Core Hardener NH 2 H 2 N Epoxy Diamine M w ≈ 10kg/mol Chemical Parameters for the copolymer structure 8 GMA per polymer chain Introduction Bis-Urea PnBA Copolymer & Resins
Copolymer without Xylene Core Uncross-linked Copolymer Lightly Cross-linked Copolymer w%(hardener) = 0,8% 4 10 G' & G'' (Pa) 3 10 2 10 G’ 1 10 G’’ 0 10 0.01 0.1 1 10 100 Angular Velocity (rad/s) Frequency Dependence for G’ & G’’ at 25 °C Introduction Bis-Urea PnBA Copolymer & Resins
Copolymer without Xylene Core Uncross-linked Copolymer Lightly Cross-linked Copolymer w%(hardener) = 0,8% 4 10 G' & G'' (Pa) 3 3 47 J/m 2 Adhesive Failure 600x10 10 2 10 Stress (Pa) 400 11J/m 2 Cohesive Failure G’ 1 10 G’’ 200 0 10 0.01 0.1 1 10 100 0 Angular Velocity (rad/s) 0 1 2 3 4 Frequency Dependence for G’ & G’’ at 25 °C Strain Strengthening our PnBA Matrix by Chemical Cross-linking Introduction Bis-Urea PnBA Copolymer & Resins
Copolymer with Xylene Core O R R Strong Interactions between N N High Viscoelastic Moduli H H Epoxy / Xylene O R Strengthening our PnBA Matrix by Epoxy / Urea Interaction Introduction Bis-Urea PnBA Copolymer & Resins
Copolymer with sticker 35 J/m 2 Cohesive Debonding Stress (Pa) 104 J/m 2 Cohesive Debonding Strain Probe-tack 100µm/s – Steel Probe 0,04% 104 J/m 2 Adhesive Debonding High Improvement of Adhesive Properties Introduction Bis-Urea PnBA Copolymer & Resins
Conclusion Center-functionalized PnBA Viscoelastic Fluids Center-functionalized Pn(BA-GMA) lightly Cross-linked Soft Dissipative Solid Supramolecular Interactions + Chemical Cross-linking Promising Adhesion
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