Hydrophilization of Fluoropolymers and Silicones

Transcription

1 2017 Adhesive and Sealant Council Spring Meeting Hydrophilization of Fluoropolymers and Silicones Aknowledgements: Wei Chen Mount Holyoke College NSF, NIH, Dreyfus, ACS-RF, MHC Bryony Coupe, Mamle Quarmyne, Lien Nguyen, Akchheta Karki, Yan Yan

2 Introduction Low surface tensions of fluoropolymers and silicones mn/m poor wetting and weak adhesion Common surface modification methods aggressive treatments surface degradation and mixed functionalities Biopolymers spontaneously adsorb to fluoropolymers hydrophobic interactions fouling

3 I. Hydrophilization of Fluoropolymers

4 Our Approach l Adsorption of amphiphilic, synthetic polymers to FE/water interface F E ( ) n H 2 O olymer Adsorption ( ) n X X X X X X ( ) n Variables studied -kinetics -concentration -ionic strength -number of steps CO 2 H NH 3+ Cl - AA AH V Coupe, B.; Chen, W. Macromolecules 2001, 34,1533. Chen, W. U.S. atent 2007,

5 Kinetic Studies Contact Angle Analysis θ A ( ) θ R ( ) XS Analysis FE FE-V 10 min FE-V 30 min FE-V 1 h FE-V 2 h FE-V 5 h FE-V 24 h FE-V 89 h V (cast film)

6 V Adsorption: A General Approach to Hydrophilize olymer Surfaces ol y m er H 2 O ( ) n V FE: -(CF 2 -CF 2 ) m -(CF 2 -CF) n - M: ( ) n CF 3 ET: -(C(O)-h-C(O)-OCH 2 CH 2 O) n /93 63 / /89 58 /16 77 /55 40 /13 Driving forces: hydrophobic interactions V crystallization

7 V Thickness and Film Morphology AFM: 3 x 3 μm; 10 nm θ A /θ R : /10-20 Γ: Å, continuous Kozlov, M.; Quarmyne, M.; Chen, W.; McCarthy, T. J. Macromolecules 2003, 36,

8 V Stability Studies Mechanical Integrity 180 o ressure-sensitive adhesive tape (3M no. 810) FE-V XS analyses indicated cohesive failure in FE substrate Hydrolytic Stability Lightly crosslinked V is stable in water and organic solvents.

9 E T Derivatizations of - groups E T O=C=N-(CH 2 ) 17 CH 3 -O -O CHR CH 3 (CH 2 ) 16 -C(O)-Cl O=C=N-CH 2 CH 2 Cl RCHO/H + + pyridine + [CH 3 (CH 2 ) 10 -CO 2 ] 2 SnBu 2 Cl-C(O)-CF 2 CF 2 CF 3 [CH 3 (CH 2 ) 10 -CO 2 ] 2 SnBu 2 x O=C=N-S(O) 2 -h -O-C(O)-NH-S(O) 2-h x E T E T - + [CH 3 (CH 2 ) 10 -CO 2 ] 2 SnBu 2 CF 3 CF 2 CF 2 CF 2 I + Et 3 N x -O-C(O)-C 16 H 33 - groups in V are 2 alcohols SOCl 2 E T E T E T -O-C(O)-CF 2 CF 2 CF 3 -O -O -Cl - S=O (Major product) (Minor product)

10 V to SiO 2 and TiO 2 SiO 2 Quarmyne, M.; Chen, W. Langmuir 2003, 19, 2533.

11 II. Hydrophilization of Silicones - low T g = -123 C - hydrophobicity, γ = 20 mn/m - good gas permeability - excellent thermal stability - reactivity toward acids and bases - nontoxicity - low cost - optical transparency - hydrophobic recovery

12 Hydrophobic Recovery CH 3 CH 3 CH 3 CH 3 CH 3 O CH 3 O 2 SiO x Δt Silicone Hydrophobic Recovery: spontaneous - reorientation of surface hydrophilic groups - condensation of surface silanol groups - migration of low molecular weight (LMW) species from the bulk to the surface - in-situ generated surface cracks facilitating migration of LMW Solvent extraction? Fritz, J. L.; Owen, M. J. J. Adhesion 1995, 54, 33. Kim, J.; Chaudhury, M. K.; Owen, M. J.; Orbeck, T. J. Colloid Interf. Sci. 2001, 244, 200.

13 Vacuum Extraction: Reduce Hydrophobic Recovery CH 3 CH 3 CH 3 CH 3 CH 3 CH 3 CH 3 CH 3 CH 3 Vacuum extraction O 2 SiOx Dynamic contact angle ( ) Time (day) Adv (DVDH) Rec (DVDH) Adv (Sylgard) Rec (Sylgard) 56 /39 51 /38 Nguyen, L.; Hang, M. et al. ACS Appl. Mater. Interfaces 2014, 6,

14 V Adsorption to Hydrophilize Silicones? D M S H 2 O V X Contact angle and IR analyses: V does NOT adsorb to DMS Thickness analysis? AFM imaging? Wu, D.; Luo, Y.; Zhou, X.; Dai, Z.; Lin, B. Electrophoresis 2005, 26, 211.

15 DMS Substrates React DMS (2 kda, 9 kda, 17 kda, 49 kda, 116 kda) to Si wafers Krumpfer, J. W.; McCarthy, T. J. Langmuir 2011, 27,

16 Experimental rotocols 1. Clean wafers with O 2 plasma 2. Drop cast DMS on wafers 3. React DMS at 100 C for 24 h 4. Dissolve V at 95 C 5. Adsorb V at r. t. for 24 h Si/ SiO 2 Si(CH 3 ) 2 O 2 DMS D Si(CH 3 ) 2 V M Si(CH 3 ) 2 S Si(CH 3 ) 2 D M S V O H Contact Angle Goniometry Ellipsometry Optical Microscopy Atomic Force Microscopy Transmission Electron Microscopy

17 DMS Substrates: thickness, roughness, hydrophobicity Log (thickness (nm)) y = x R² = Log (molecular weight (Da)) AFM Images (size: 2.5 x 2.5 μm; height: 10 nm): DMS Thickness α (MW) 0.57 (1 to 11 nm) DMS 2k DMS 9k DMS 17k DMS 49k DMS 116k RMS(nm) θ A /θ R ( ) 101/79 107/ / /95 113/98

18 V 99% Thin Film Morphologies on DMS Optical micrographs (scale bar: 500 μm): 500 μm AFM images (size: 20 x 20 μm): 20 nm 30 nm 40 nm 100 nm 400 nm DMS 2k DMS 9k DMS 17k DMS 49k DMS 116k continuous honeycomb fractal (small to large) Karki, A.; Nguyen, L.; Sharma, B.; Yan, Y.; Chen,W. Langmuir 2016, 32, 3191.

19 Film Formation Mechanism: In situ Optical Microscopy In-situ Time Lapse Movie: Dried Films: V 99% -DMS 2k V 99% -DMS 49k V dewetting on higher MW DMS: higher contact angles, more surface defects, more liquid-like. 19

20 V 88% Thin Film Morphologies on DMS Optical micrographs (scale bar: 200 μm): 200 μm AFM images (size: 20 x 20 μm): 20 nm 20 nm 30 nm 100 nm 100 nm DMS 2k DMS 9k DMS 17k DMS 49k DMS 116k continuous honeycomb droplets

21 Morphologies of Dewetted Thin Films: Fractals Spin cast ZnO SS with added salt EO Adsorption (collagen on S) Crystallization is required to form fractal features? Chen, L. et al. J. hys. Chem. C 2008, 112, Haberko, J. et al. Synth. Met. 2010, 160, Bi, W.; Teguh, J. S.; Yeow, E. K. L. hys. Rev. Lett. 2009, 102, Jacquemart, I.et al. J. Colloid and Interface Sci. 2004, 278,

22 TEM Electron Diffraction of V 99% and V 88% V-DMS 2k SiO 2 (200) (110) (010) (010) V 99% V 88% Crystallization of V 99% V 88% fractal morphology common droplets Karki, A.; Nguyen, L.; Sharma, B.; Yan, Y.; Chen,W. Langmuir 2016, 32, 3191.

23 Minimize V Dewetting I. Light plasma oxidation of DMS nm to create pinning sites DMS 49k : 109 /95 to 101 /80 (1 s O 2 plasma), similar to DMS 2k. V 99% -DMS 49k V 88% -DMS 49k native plasma treated native plasma treated Minimized V dewetting Improved wettability Karki, A.; Nguyen, L.; Sharma, B.; Yan, Y.; Chen,W. Langmuir 2016, 32, 3191.

24 Minimize V Dewetting II. Attach DMS 2k to DMS μm films SiO 2 Spin cast D V D H D M S O 2 D M S 118 /97 27 /12 DMS 2k 100 C D M S V D M S V O H 111 /91 93 /20

25 Hydrophobic Recovery of DMS-Vs? Dynamic Contact angles ( ) V (continuous) on DMS 2k Time (h) V (honeycomb) on O 2 -DMS 49k Time (h) V on DMS 2k -DMS μm w/o vac extraction w/ vac extraction Time (h) Negligible hydrophobic recovery Vacuum extraction is not necessary V is a good barrier layer

26 Conclusions H 2 O ( ) n V spontaneously adsorbs to hydrophobic substrates from aqueous solution hydrophobic interactions crystallization of V V adsorption can be used to hydrophilize and functionalize fluoropolymers and silicones Hydrophilization of silicones has additional challenges: dewetting and hydrophobic recovery light plasma oxidation and attachment of DMS 2k Vacuum extraction V layer is an effective barrier

27 Thank you! Questions?