Fluorescence Resonance Energy Transfer (FRET) in Polymer Films and Polymer Blends

Transcription

1 Fluorescence Resonance Energy Transfer (FRET) in Polymer Films and Polymer Blends Neda Felorzabihi, Jeffrey C. Haley, Pablo Froimowicz, Ghasem R. Bardajee and Mitchell. Winnik epartment of Chemical Engineering and Chemistry University of Toronto IPR Symposium, Waterloo May 15, 7

2 Introduction Polymer blends a route to obtain new high performance materials Blend systems: Two immiscible polymers Three immiscible polymers matrix/dispersed core/shell (composite/droplet) I am interested in core/shell structures Many morphologies I want to use core/shell 3-component blends as a means of studying partial miscibility and interfaces between the components.

3 Fluorescence Resonance Energy Transfer (FRET) * + 1/τ * fluoresces + hν Shell w(r) Core Rate of ET + * Spectroscopic ruler. Rate of ET w * r nm Characteristic distance R ( r) = κ τ r Matrix w(r) ~ r -6 3

4 Long Term Goal To obtain information about the interface between the components of a polymer blend. ividing surface ur group uses FRET to study polymer-polymer interfaces. This technique works well for block copolymers. It has not yet been used for the quantitative study of polymer blends. ispersed phase Matrix Core Shell Matrix 4

5 Steps to Meet ur Goals 1. Study core/shell morphology development in a ternary blend.. Select the chromophores ( and ) based on spectroscopic properties. 3. Synthesize dye-labeled polymers. 4. Test our models for fitting the experimental data. 5. etermine key parameters. 6. Carry out FRET experiments on polymer blends. 5

6 1. Study core/shell morphology development in a ternary blend

7 Study of Core/Shell Morphology evelopment in PS/PMM/HPE Blend PS PMM 1 µm Material HPE PS PMM HPE Ternary blend of PS/PMM/HPE (5/5/9), after 9 min. mixing Reigneier, J. and Favis, B. Macromolecules (), 33, Mw (g/mol) 79 3, 11,9 Mn (g/mol) 4 14, 7,8 MI (g/1 min) MM and styrene for synthesizing dye-labeled PMM and PS 7

8 PS/PMM/HPE Blend Preparation Blend Preparation Solution precipitation Melt mixing in a twin screw extruder (at C and rpm). Then quenching the samples in cold water PS is labeled with an HY dye, λ ex = 488 nm 8/ (14+86) HPE/(PS+PMM) PS 5 µm Blend at 6 min. of mixing Image depth: 7-1 µm 8

9 Effect of Mixing Time on Morphology evelopment min. 9 min. 1 µm 8 min. 6 min. PS 17 min. µm µm 8/ (14+86) HPE/(PS+PMM) Image depth: 7-1 µm µm µm 9

10 Blend System Using core/shell structures to study miscibility and interfaces in 3-component polymer blends by FRET Shell Matrix Core FRET PS PMM 1

11 . Select the chromophores ( & ) based on spectroscopic properties.

12 Intensity (cps) 1.E+5 1.E+4 1.E+3 1.E+ 1.E+1 Systematic Study of Fluorescence ecay of Coumarin yes in Polymer Films I need to find the proper donor dyes for my FRET experiments. * + + * The donor dye should have an exponential fluorescence decay profile in polymer matrices. I( t) t = exp τ Intensity (cps) 1.E+5 1.E+4 1.E+3 1.E+ 1.E+1 t I = I () exp[ τ t P( τ ) 1/ ] 1.E Time (ns) 1.E Time (ns) Exponential decay Non-Exponential decay 1

13 Selected mino-coumarin onor yes CH 3 H 3 C N CH 3 CH 3 N N H 3 C CH 3 H N (a) Coumarin-1 (b) Coumarin- (c) Coumarin-3 (d) Coumarin-1 CH 3 CH 3 H 3 C N H CH 3 H N (e) Coumarin-314 (f) Coumarin-343 CH 3 N H 3 C (g) Coumarin-3-ester 13

14 bsorption & Emission Spectra of Coumarin yes in Ethyl acetate Normalized bsorbance Coum-1 Coum (a) bsorption Coum-1 Coum-1 Coum3-ester Coum-1 Coum-343 Coum-314 Coum Wavelength (nm) Normalized Intensity 1..8 Coum Coum- (b) Emission Coum3-ester.4 Coum-3 Coum Wavelength (nm) 14

15 Fluorescence ecays (a) Intensity 1 Coumarin- (d) 1 N H - In PMM film (a) (b) Time (ns) χ τ=3. ns (c) Time (ns) (e) =.99 1 Intensity Time (ns) 1 τ=.9 ns (b) (c) Intensity 1 H 3 C In PS film Time (ns) I( t) Res. Res. - (d) (f) Res. - t = exp τ 1 3 Time (ns) χ =1.15 CH Time (ns) N (a) 1 β=.74 Intensity (b) Time (ns) 1 <τ>=1.7 ns Intensity <τ>=1.8 ns β= Time (ns) I( t) Res. Res. H Coumarin-343 (c) - (d) t = exp τ In PMM film χ = Time (ns) χ = Time (ns) β In PS film 15

16 Selected onors and cceptor yes Model dyes onors CH 3 N (a) Coumarin-314 λ bs =45 nm λ Em =458 nm N N N N (b) ispersed Red red λ bs =491 nm H H 3 C CH 3 H S Functional dyes N (a) Coumarin-3 monomer (CH ) 6 N λ bs =416 nm λ Em =441 nm λ bs =455 nm λ Em =58 nm (b) HY monmer cceptors 16

17 3. Synthesizing dye-labeled polymers

18 Characterization of ye-labeled PS and PMM UV-vis results: Coum3-PS Retention Volume (ml) ye incorporation into polymer HY-labeled PMM:.99 mmol/g HY-Labeled PS:. mmol/g Coum3-labeled PS=.9 mmol/g UV RI Mn HY-PMM RI HY-PS 31, UV Retention Volume (ml) HY-PMM 56 Coum3-PS 3, PI p UV 18

19 4. etermine Key parameters

20 etermination of the Förster istance (R ) From Spectral verlap Method K RET κ 1 = τ R ( r = (cosθ ) 6 9(ln1) κ Φ R = F λ ε λ λ dλ π Nn 4 ( ) ( ) cosθ R cosθ ) 4 1/ 6 =.18[ κ n Φ J ( λ)] 4 J ( λ) F( λ) ε ( λ) λ = b a FL spectrum of donor Extinction coefficient spectrum of acceptor

21 etermination of Extinction Coefficient of cceptors in Polymer Films The Beer Lambert Law C =.53 mm = εc I varied film thickness instead of dye concentration d.18 cm Pressure Pressure 1

22 Beer s Law Plots for Two cceptor yes (λ max ) Extinction coefficient etermination for ispersed red 19 in PMM Film ε=.55x1 4 M -1 cm -1 at λ max (455 nm) y = x R = Thickness (cm) = εc d ispersed red 19 Thickness (cm) (λ max ) I varied film thickness instead of dye concentration. HY-3G ε = 1.73x1 4 M -1 cm -1.1 at λ.5 max (491 nm) Thickness (cm)

23 ε(λ) Spectra for R Calculations ε(λ) = (λ)/c.l ispersed red Wavelength (nm) Wavelength (nm) ε(λ) = (λ)/c.l HY-3G Wavelength (nm) 3

24 Spectral verlap Calculation Intensity Intensity Coum-314 λ max=457.5 nm 4 J ( λ ) F ( λ ) ε ( λ ) λ ispersed Red 19 λ max =491.5 nm = b a J ( λ) J ( λ) coum 3, PS / HY 3G, PS = 1.3E15 coum 314/ disp. red19 = E Coum-314 λ max =457 nm isp. Red 19 λ max =491.5 nm Intensity Coum-3 PS λ max =441 nm HY-3G in PS λ max =455 nm Wavelength (nm) Wavelength (nm) Wavelength (nm) 4

25 etermination of Quantum Yields a) Coumarin -314 in PMM film Φ, coum 314 = Φ x = Φ ref n n x ref.68 * Φ Φ (1 1 (1 1 z y = n n ref x z y ( λ ) τ τ ( λ ) z y F ( λ) d( λ) ( λ) d( λ) F x ref n PMM n ethanol =1.49 =1.36 τ coum 314, EtH = τ coum 314, PMM= Φ coum 314, PMM = * Jones et al., J. Phys. Letters (1983), 1,

26 Measuring Quantum Yield using Integrating Sphere b) Coumarin-3 PS film Φ, coum 3PS =? By Gisela Schulz, S. Holdcroft, Simon Fraser University 6

27 Förster istance for Coum-314 in PMM & Coum-3 PS (Spectral verlap Method) Intensity Intensity R, coum 314PMM = Coum-314 λ max=457.5 nm Coum-314 λ max =457 nm R ispersed Red 19 λ max =491.5 nm 4 1/ 6 =.18[ κ n Φ J ( λ)] 4.8 isp. Red 19 λ max =491.5 nm nm Intensity R, coum 3PS =? Coum-3 PS λ max =441 nm Hy-3G in PS λ max =455 nm Wavelength (nm) Wavelength (nm) Wavelength (nm) 7

28 5. Test our models for fitting the experimental data * FRET + + *

29 Fluorescence ecay Measurements for Coum- 314/ispersed Red 19 in PMM Films Counts Plot of Coum-314 decay decay in in PMM PMM Films films Containing Various Concentrations of ispersed Red Pure coum-314 C =5.5 mm Time (ns) Coum-314 Pure C=4.49 mm C=4. mm C=3.7 mm C=3.4 mm C=.58 mm C=1. mm C=.84 mm Prompt N N N N N Increasing Increasing acceptor acceptor concentration concentration Coum-314 onor ispersed Red red-19 cceptor C a = mm CH 3 H 9 H

30 Fluorescence ecay Measurements for Coum- 314/ispersed Red 19 in PMM Films (Cont d) Förster Model t I = I () exp[ τ P t P( τ ) 1/ ] P = π N κ 3 Plot of P versus cceptor Concentration for Coum-314 in PMM Films y =.4999x R =.9857 R =4.8 nm R =5.1 nm R 1/ 3 C C (mm) 3

31 Fluorescence ecay Measurements for Coum-3 PS & HY-3G in PS Films Intensity (Counts) H 3 C C a = mm Pure coum3-ps C a =.86 mm C a =1.43 mm Increasing C C a =.9 mm a C a =3.4 mm C a =4.48 mm C a =5.4 mm C a =5.7 mm Lamp CH 3 N Coum-3 Monomer onor C 17 H 35 N S HY-3G cceptor Time (ns) C a = mm 31

32 Fluorescence ecay Measurements for Coum-3 PS & HY-3G in PS Films (Cont d) ur Generalized Förster Model β t t / 3 I( t) = exp P P = π N κ RC τ < τ > 3 P Plot of P versus cceptor Concentration for Coum-3-PS & HY-3G dyes RR =4.9 =4.9 nm nm y =.4439x R = C (mm) 3

33 Summary Core/shell morphology development within the dispersed phase for ternary polymer blend of HPE/PS/PMM. Formation of dispersed particles of PMM in a PS shell in a HPE matrix upon melt mixing (t>3 min). Systematic study of the fluorescence decay of coumarin dyes in polymer films and solutions (In press, J. Polym. Sci,. B). Many of the dye-polymer pairs exhibit exp. decays with τ 3 ns. These dyes are well suited for FRET in Polymers. Testing our Generalized model by comparing R values obtained from spectral overlap method and FRET. 33

34 Future Work To carry out FRET experiments on (PS/PMM/HPE) blends using Monte Carlo simulations. Shell Matrix Core Coum-3 PS () FRET HY-PMM () PS δ PMM Interface thickness 34

35 Thank you for your attention 35