Teresa Dib Zambon AtvarsInstituto de Química

Universidade Estadual de CampinasCampinas, São Paulo, Brasil

E-mail: tatvars@iqm.unicamp.br

Some Some applicationsapplications of of photoluminescencephotoluminescence for for probingprobing polymerpolymer relaxationrelaxation processesprocesses

Summer School - Stereochemical Aspects of Novel Materials, UCSB, august 14-27, 2005

Part 2 p1

Slide 1

p1 roprpg, 7/2/2005

outline

Polymer systems and morphologyPolymer motions, phase transitions and polymer relaxation processesPhotoluminescence spectroscopy and polymer relaxation processes

fluorescencephosphorescencequenching processes time resolved spectroscopy

Luminescence in polymers Non-fluorescent polymers (host-guest systems)Polymers modified with luminescent groupsIntrinsically luminescent polymersConjugated luminescent polymersElectroluminescence and photoluminescence

Summer School - Stereochemical Aspects of Novel Materials, UCSB, august 14-27, 2005

Types of luminescent polymers : 1. non-fluorescent polymers (host-guest systems)

Amorphous materials

Semicrystalline polymers

How the guest interacts with the polymer?Which site is the guest sensing?

Guest in semicrystalline polymers

Amorphous region

Surface of a lamellae

Interfase between amorfous and

crystalline phase

Probing orientation in stretched materials

Molecules changes from one site to other

and can be preferentially oriented in the stretching direction

They can sense the new environment

Relaxation processes in oriented polymers

Talhavini et al. Polymer, 1986

Talhavini, et al, Polymer 1986

Relaxation processes associatedwith the interface crystalline

amorphous interface are more defined

There is a larger population ofanthracene molecules located

in the interface comparedwith non-stretched material

α-relaxation process

How important is the distance for a guest sensor?

Pyrene in LDPEand some coplolymers

with vinyl acetate (EVA)

II/IIII ratio changes

Lifetimes also change

Linear correlation with lifetime and II/IIII ratio

because the random distribution of the polar groups

1st (open) and 2nd run (dark) Yamaki, Eur. Polym. J., 2002

First (dark) and second (open) scans

Naylons = condensation of an amide a carboxylic acid

Naylon-6

Poly(caprolactone)

Naylon-11

Naylon-6,6

Naylon-6,9

Naylon-6,10

Naylon-6,12

constant

Photophysical properties of pyrene in naylons

310 ns1.29Naylon-6,12

296 ns1.30Naylon-6,10

276 ns1.31Naylon-6,9

250 ns1.44Naylon-6,6

276 ns1.27Naylon-11

260 ns1.41Naylon-6

265 ns1.15Poly(caprolactam)

Decrease of the polarity

Polymers modified with luminescent groups

Will sense the environment around the molecule

More sensivity to the motions involving the segments where they were bonded

Selective attachment should enhance the sensitivity and coupled motions can be analyzed.

Weiss, et al., 1992

Polyethylene and vinyl acetate copolymers modified with pyrenyl groups

Not observed

Yamaki, et al., Photochem. Photobiol. Sci. 2002.

Relaxation processeswill be associated with

these groups

Selective attachment

3 8 0 4 0 0 4 2 0 4 4 0 4 6 00

2 0 0 0

4 0 0 0

6 0 0 0

8 0 0 0 a .

4 1 0 K

3 0 K

Rela

tive

inte

nsity

(a.u

.)

W a v e le n g th ( n m )

3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0

0

3 0 0 0

6 0 0 0

9 0 0 0

1 2 0 0 0 b .

4 1 0 K

3 0 K

Rela

tive

inte

nsity

(a.u

.)

W ave len g th (n m )

pyrenyl attached to LDPE

Pyrene as a guest in LDPE

0 100 200 300 4000,0

0,2

0,4

0,6

0,8

1,0

Tm

Tα

Tg (β)Tγ

a.

Nor

mal

ized

inte

nsity

Temperatura (K)

Normalized and integrated fluorescence intensities versus temperature for pyrene (n) and 1-pyrenyl groups ( ) in (a) LDPE and (b) PVAC.

0 100 200 300 400

0,0

0,2

0,4

0,6

0,8

1,0

Tβ

Tg

Tβ́

b.

Nor

mal

ized

inte

nsity

T ( K )

Schur, Weiss et al., Macromolecules, 2003

Weiss et al., Macromolecules, 2003

Intrinsically luminescent polymers: poly(2-vinyl naphthalene)

Poly(2-vinyl naphthalene)

Cruz, et al. J. Appl. Polym. Sci. 2001

Intrinsically luminescent polymers:

Deus, Akcelrud, et al. Chem. Phys. 2004

Deus, Akcelrud, et al. Chem. Phys. 2004

Deus, Akcelrud, et al. Macromolecules 2004

Conjugated luminescent polymers

O

O

*

*n

Poly(2-methoxy-5-(2-ethylhexyloxy)-p-phenylene vinylene)

MEH-PPV

Steady-statefluorescenceemission

Blue shift

Increase of intensity

Cossiello, et al. Macromolecules 2005

DMTA dataArrhenius plots

Relaxation processes

T = 320 ± 10 KT = 220 ± 10 KFluorescence

T = 310 ± 10 K

Ea = 62.4 kJ mol-1 K-1

T = 210 ± 10 K

Ea = 22.5 kJ mol-1 K-1TSC

T = 330 ± 10 K

Ea = 85.4 kJ mol-1 K-1

T = 210 ± 10 K

Ea = 29.1 kJ mol-1 K-1DMTA

α-relaxationβ-relaxationTechniques

Cossiello et al. Macromolecules, 2005

Molecular Motions by 13C NMR

Bloise, et. al. Phys. Rev. B. 2005

Bloise et al. Phys. Rev. B, 2005

Conclusions from 13C RMN

Carbons 11, 12, 13, 14, 15, 16, and 17 gain mobility after the β-relaxation process

Implications of the relaxation processes on the electroluminescence properties

Electroluminescence and photoluminescence

poly(9,9-(di-n,n-octyl-fluorene))

Winokur et al. Phys. Rev. B. 2003

Spectral profiles and condensed medium

Spectral profiles and condensed medium

Spectral profiles and condensed medium

Relaxation process and spectral broadening

Brown, et.al. J. Polum Sci. Polym. Phys. Ed. 2004

Martins, et. Al. J. Phochem. Photobiol. A Chem. 2002

Thank you!

Summer School - Stereochemical Aspects of Novel Materials, UCSB, august 14-27, 2005

Fred

Miguel

Jennifer