Novel Photochemical/Thermal Dual-Cure initiating system for cationic polymerization of thick materials

Transcription

1 Novel Photochemical/Thermal Dual-Cure initiating system for cationic polymerization of thick materials M. LECMPEE (1,2), X. ALLNAS* (1), D. MAECHAL (2), A. CIQUI (2) (1) Laboratory of Macromolecular Photochemistry and Engineering University of Haute Alsace, Mulhouse (FANCE) (2) Mäder Group Parc de la mer rouge, Mulhouse (FANCE) 1

2 Introduction Epoxide characteristics Properties Good chemical resistance Sailing Aeronautic Good thermal and dimensional stabilities High adhesion strength High moisture and solvent resistance Advanced applications Coating and composite field Sport tools Initiating systems for epoxy resin curing remain highly interesting Prosthesis Security Automobile 2

3 Introduction Epoxide characteristics Two polymerization methods could be used to cure an epoxide resin: Thermal curing Epoxy-anhydride and epoxy-amine systems Anionic/Cationic polymerization or Polyaddition Photo curing Iodonium et sulfonium salts Cationic polymerization Thick and pigmented systems Long processing times High temperature process Thin films Fast curing New structures is required New process is required 3

4 SMAT technologies Multi-using Fast curing of thick polymers Cure-on-Demand What about Dual-Cure concept New opportunities in industrial processes Ecofriendly Different possibilities (Depending of application requirements) Multi-wavelenght photopolymerization Photo-thermal polymerization Thermal-Thermal polymerization 4

5 Epoxide conversion (%) Temperature ( C) 3 Pyrylium compounds BF 4 - Scarcely reported for : Free radical polymerization Photosensitizers Strong electron acceptors Main drawback : Thermally unstable Turned in an advantage! % Photopolymerization Thermal polymerization (25 C) 142 C for 400 s for 460 s Time (s) Time (s) New photoinitiators New thermal initiators Novel dual-cure system 5

6 Epoxide monomer GENME 7210 (dicycloaliphatic epoxide) Pyrylium compounds Thermal activity + Co-initiator NuH NuH 3 I II III good sites for nucleophilic attack + BF 4 - H NuH 3-4h Pyrylium only 3-4h Pyrylium + Isobutylvinylether 20 min Gel point Pyrylium + Hydrogen peroxide 15 min > 24h << 24h Promising result to design a dual-cure system Initial concept already confirmed but not sufficient for us! Glass polymer D. Maréchal, X. Allonas, M. Lecompère, A. Criqui, Macromol Chem. Phys., (2016) 217, D. Maréchal, A. Criqui, X. Allonas, M. Lecompère, W

7 Pyrylium compounds Thermal activity Mechanism aspect Case of Hydroperoxide + X - + H ' ' + H-X Fast acid release for cationic polymerization initiation Case of Vinylether + X - H 2 C + X - Evidence of «kick-starting» effect M. Lecompère, X. Allonas, D. Maréchal, A. Criqui, Polym. Chem. (2017), 8, 388. M. Lecompère, X. Allonas, D. Maréchal, A. Criqui, Macromol. apid Commun. (2017), 38,

8 Absorption (a.u.) Absorption (a.u.) Absorption (a.u.) Quantum calculations : Prediction of absorption spectra! Pyrylium compounds Photochemical activity LED Gaussian 09, TD-DFT B1LYP/6-311+G** PCM (Acetonitril) + BF 4 - LED + BF Wavelenght (nm) LED Cl Wavelenght (nm) Cl + BF 4 - Cl Wavelenght (nm) M. Lecompère, X. Allonas, D. Maréchal, A. Criqui, J. Photopolym. Sci. Techn. (2017), 30,

9 Photopolymerization (T-FTI) Pyrylium compounds Photochemical activity Pyrylium structures selected 400 mw/cm² Lamp Hg-Xe 20 µm (bar coater) p max (M -1.s -1 ) 0.08 Epoxide resin : GENME BF 4 - %Conv 400s 97% p max (M -1.s -1 ) %Conv 400s 75% BF 4 - Cl p max (M -1.s -1 ) %Conv 400s 57% Cl BF 4 - Cl p max (M -1.s -1 ) 0.01 Key parameters + BF 4 - %Conv 400s 20% Pyrylium ring structure Well balance electronic distribution p max (M -1.s -1 ) 0.03 Best compromise : + 2,4,6-triphenylpyrylium tetrafluoroborate S + Cl 4 - %Conv 400s 18% 9 BF 4 -

10 Epoxide conversion (%) Temperature ( C) Pyrylium compounds Dual-Cure system? Photopolymerization process Thermal polymerization process % C for 400 s Time (s) for 460 s Time (s) Tunable efficiency Tunable efficiency Dual-Cure 10

11 temperature temperature Cationic photo-thermal dual-cure system bjectif : high tickness in one step process 3 Polymer Monomers depth BF 4 Thermal curing Characterized by a given latency Success Monomers (+ initiator) Shadowed area? depth Photoinduced thermal frontal polymerization Polymer Monomers Front of polymerization Characterized by a front speed 11

12 Proof of concept Dual-Cure experiments (frontal polymerization) Front of temperature followed by Infra-ed camera Irradiation started stoppedled 395 nm, 1W/cm² Temperature ( C) Sample TPP : 3wt% H 2 2 : 1wt% GENME 7210 Depth (px) 12

13 Distance (mm) Distance (mm) Temperature ( C) Irradiation stoped Temperature ( C) Irradiation stoped Proof of concept Dual-Cure experiments (frontal polymerization) Case of HP Case of IBVE mm 8mm 0mm mm 32 mm 24 mm 16 mm 8 mm 0 mm Time (s) Time (s) 15 H mol% Velocity 21 mm/min IBVE 1.5wt% Velocity 0.9 mm/min Time (s) Time (s) 13

14 14 14 Proof of concept Caméra I bturateur Guide d onde (source lumineuse) Mélange Moule PTFE

15 Proof of concept 17 cm Photoinduced frontal polymerization of epoxy resin 15

16 Application : Carbon fiber composites Infusion system 16

17 Conclusion and results 20 layers of glass fibers Photoinduced thermal frontal polymerization of carbon/glass-reinforced polymer 17

18 Acknowledgements for financial supports 18

19 5 th European Symposium of Photopolymer Science Mulhouse, France September 3-6, 2018