Samuel Dodoo, Anna Burmistrova, Kornelia Gawlitza, Adrian Carl, Marcel Richter, Regine v. Klitzing

Transcription

1 2) Stimuli responsive polyelectrolyte coatings Samuel Dodoo, Anna Burmistrova, Kornelia Gawlitza, Adrian Carl, Marcel Richter, Regine v. Klitzing Stranski-Laboratorium Technical University of Berlin, Germany

2 Polymer coatings: Motivation Design and characterisation of stimuli responsive surface coatings Nano- and Mesoscopic polymer films (thickness: nm) External stimuli: temperature, ionic strength, ph, humidity Sensitivity <=> Stability

3 Layer-by by-layer technique Polycations Polyanions H CH 2 JR400 (CH 2 CH 2 ) 2 CH 2 CHCH 2 H H R H CH 3 N + CH 3 H CH 2 CH 2 CH 2 H Cl CH 3 * P(DADMAC-NMVA) * n m * N N + CH 3 H 3 C CH CH 3 3 Cl n * + NH 3 Cl PAH R * R R R=C - Na + HA * n * S - 3 Na + R R n R PSS CMC Decher, G.; Hong, J.D.; Schmitt, J. Thin Solid Films 1992, 210, 831.

4 1) Ion specific Effects

5 Ion specific effects: Effect of anions Thickness, d / Å PSS/PDADMAC [NaX]=0.25mol/l Number of layers, N Br - Cl - F - Si Br - Br - Br - Br - Si F - F - F - coiled flat d d Increasing ion diameter (decreasing hydration shell) => Increasing interaction between anions and polycations J.E. Wong, R.v.K, Macromolecules, submitted

6 Ion specific effects: AFM studies (PSS/PDADAMAC) 6 prepared in 0.25 mol/l salt NaBr NaCl CsCl RMS 25 Å 15 Å 21 Å Increasing roughness with increasing ion size J.E. Wong, R.v.K, Macromolecules, accepted

7 Kovacevic et al., Langmuir, 2002 Biesheuvel et al. Langmuir, 2004 Garza et al., Langmuir 2004 Different types of multilayer growing thickness linear Si number of layers

8 Kovacevic et al., Langmuir, 2002 Biesheuvel et al. Langmuir, 2004 Garza et al., Langmuir 2004 Different types of multilayer growing exponential thickness linear Si number of layers

9 Kovacevic et al., Langmuir, 2002 Biesheuvel et al. Langmuir, 2004 Garza et al., Langmuir 2004 Different types of multilayer growing thickness Si number of layers

10 Effect of degree of charge Preparation in NaBr, 2 different PDADMAC charge densities %, 0.1 mol/l %, 0.1 mol/l thickness / Å number of adsorbed layers

11 Effect of ionic strength Preparation in NaBr, 2 different PDADMAC charge densities %, 0.1 mol/l %, 0.1 mol/l 100%, 0.25 mol/l 500 thickness / Å number of adsorbed layers Transition from linear to exponential increase by increasing ionic strength

12 Effect of degree of charge Preparation in NaBr, 2 different PDADMAC charge densities %, 0.1 mol/l %, 0.1 mol/l 100%, 0.25 mol/l %, 0.25 mol/l thickness / Å number of adsorbed layers Effect of polymer charge density on the type of growth

13 Effect of type of salt %, 0.25 mol/l NaBr thickness / Å number of adsorbed layers

14 Effect of type of salt Comparison NaBr <-> NaCl 75%, 0,25 mol/l NaBr 75%, 0,25 mol/l NaCl thickness / Å number of adsorbed layers Tuning of type of growth by changing salt during preparation

15 Mobility: Fluorescence Recovery after Photobleaching (FRAP) Deposition of the probing layer FITC-PAH * NH 3 n* * SC NH 3 m * after bleaching after treatment NH H Grey value /a.u Distance/µm Polyanion/polycation D / cm 2 /s PSS/PAH < C(x,t) = 2 M πdt exp( 2 x 4Dt ) PSS/PDADMAC PSS/PDADMAC (75 %) PSS/PDADMAC (NaBr) P. Nazaran, R.v.K. et al. J. Phys. Chem B (2007) HA/PDADMAC 10-11

16 Internal structure: Exposure to high ionic strength Si/PEI/[(PSS/PAH) 2 /d-pss/pah] Reflectvity E-3 D2 1M NaCl 3M NaCl 4M NaCl t d Reflectivity E-3 1E-4 1E-5 1E tth / deg Film swelling for c NaCl 3 M Non-homogeneous swelling R. Steitz, R.v.K. (Adam, ILL Grenoble) Normalized thickness 1.06 tth / deg t d silicon substrate NaCl concentration / M

17 Swelling: free water vs. void water (neutron reflectometry) vacuum φ void D 2 liquid or vapor φ free d 1 d 1 d 2 Silicon substrate d 2 /d 1 φ free φ void φ total (PSS/PDADMAC) (PSS/PAH) (PSS/PAH) 9 /PSS S. Dodoo, J.E. Wong, R. Steitz, R.v.K.

18 Swelling in water: Effect of preparation parameters (PSS/PDADMAC) 6 Addition of different amount and type of salt during preparation 0, M 0.25 M 0.50 M water content 0,5 0,4 0,3 0,2 NaF NaCl NaBr => Increasing water content with increasing ionic strength and increasing anion polarizibility S. Dodoo, R. Steitz, R.v.K.

19 Conclusion: ion specific effects Treatment: Dissolution of complexes by Increasing ionic strength (stronger for bromide) Intrinsically compensated Less mobile (Glassy) Lower amount water Low Ionic strength Chloride ion 100% charged PE Preparation conditions Extrinsically compensated More mobile (Liquefied) Higher amount of water High Ionic strength Bromide ion 75% charged PE

20 2) Temperature effects

21 Effect of heating (PSS/PDADMAC[75%)]) 6 against water Diffusion coefficient / cm²/sec Room tem p. 65 C 0.1MNaCl 1MNaCl 0.1M NaBr 1M NaBr Ionic condition of film preparation Temperature induced increase in the mobility: Transition from a glassy state to a swollen and liquefied structure accompanied with softening of the film.

22 Effect of charge distribution: NIPAM-copolymers AMPS Na-SS Block-copolymers statistical copolymers NH NIPAM H 3 C CH 3 S3 H + S 3 Na + DADMAC DEAEM NH H 3 C CH 3 H 3 C N + CH 3 Cl N + CH 3 CH 3 U. Voigt, V. Khrenov, K. Tauer, M. Hahn, W. Jaeger, R. v.k., J. Phys: Condens. Matter (2003)

23 I/I C 40 C C C Effect of temperature on solvent swollen films Neutron reflectometry at solid/liquid interface: (PSS-b-PNIPAM/PDADMAC) n ,00 0,02 0,04 0,06 0,08 Q [Å -1 ] Nb x 10-6 [Å -2 ] Si 20 C 40 C 50 C 60 C z [Å] D 2 Small decrease in thickness Irreversible shrinking process Irreversible annealing of the film => Strong interdigitation Film thickness [Å] R. Steitz, V. Leiner, K. Tauer, V. Khrenov, R.v.K. Appl. Phys. A (2002) Temperature [ C]

24 Stimuli responsive coatings Strategy: Formation of stimuli-repsonsive coating by adsorption of microgel particles => Effect of geometrical confinement on sensitivity Hydrogel microparticles in bulk at interfaces ΔpH ΔT?? ΔpH, ΔT

25 Control of hydrogel particle density P(NIPAM-co-AA) particles on Si/PEI After spin coating, ph 2 After rinsing in ph 2 Explanation for 2D pattern: Capillary attraction vs. dipolar repulsion Shrinking of swollen (single) particles S. Schmidt, T. Hellweg, H. Motschmann, R. v. K. Polymer (2008)

26 Swelling / shrinking of hydrogel particles P(NIPAM-co-AA) particles (ph = 2) Ellipsometry => decrease in LCST Reflectivity 1 0,1 0,01 1E-3 Neutron reflectometry => reversibility Reflectivity 0,04 0,03 0,02 0,01 25 C 40 C 25 C 0,4 0,5 0,6 theta / deg 15 μm 1E-4 SFM (amb./liquid) => Compactisation (T > LCST) 400 nm: 90% D nm: 80% D 2 0,2 0,4 0,6 0,8 1,0 1,2 theta / deg 25 C, air 25 C, H 2 55 C, H 2 (HMI 2006) S. Schmidt, T. Hellweg, H. Motschmann, R. v. K. Polymer (2008) M. Karg, T. Hellweg, R.v.K. et al. Langmuir (2008) S. Schmidt, T. Hellweg, R.v.K., Langmuir (2008)

27 Fresh from the lab: : Fluctuation length close to phase transition GISANS (D16, ILL Grenoble) P(NIPAM-co-AA) particles on Si/PEI (ph = 6) rnstein Zernike => fluctuation length ξ 4 3 ξ / nm T / C T c => Increase in fluctuation length ξ close to T c Zone close to the surface remains unaffected M. Medebach, R.v.K., Cooperation: P. Müller-Buschbaum, TU Munich

28 Conclusion: Temperature sensitivity Polyelectrolyte multilayers: Sensitivity to temperature rather low due to interdigitation Si Thermosensitive coatings by adsorption of hydrogel microparticles Control of particle density Reversible shrinkage and swelling Small shift of the LCST to lower temperature Unchanged interphase between solid surface and continuum of the particle ΔT

29 Current projects New strategies for embedded biocatalysts: Stabilisation of catalyst Selective permeability Easy separation Fast response to external stimuli Cooperation: CoE Unicat (Berlin-Potsdam): M. Ansorge-Schumacher TU Berlin H. Möhwald MPI-KG, Potsdam Rainer Haag, FU Berlin Self-assembly at interfaces (bottom up) Patterned surfaces Actuation by light Au particles nm (-> Photovoltaics) GISANS: new set-up at ISIS (BMBF project) hν (VIS)