Bent-Core LC Elastomers and Side-Group LC Polymers Using

Reactive Bent Core LCs

Thursday, September 24

Rafael Verduzco1,2, Brad Lokitz2, Seung Hong3, Martin Chambers3,4, Paul

Luchette4, John Harden4, Peter Sálamon4, Peter Palffy-Muhoray4, Elaine

DiMasi5, Antal Jákli4, Samuel Sprunt3, and James T. Gleeson3

1Department of Chemical and Biomolecular Engineering, Rice University2Center for Nanophase Materials Sciences Oak Ridge National Laboratory

3Department of Physics, Kent State University4Liquid Crystal Institute, Kent State University

5Brookhaven National Laboratory

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

Bent-core (banana) liquid crystals exhibit spontaneous polarity

OO

OO

N

OR

N

RO

• Restricted rotational freedom

• Supramolecular chirality

• Polar order

• Unique LC phases

Temperature

IsotropicNematicColumnar

(B1)

Tetrahedratic;

Dark

congolmerate

Lamellar

(SmCP, B6)

Crystal

Reddy, R. A.; Tschierske, C. J. Mater. Chem. 2006, 16, 907-961. (Review)

Etxebarria, J.; Blanca Ros, M. J. Mater. Chem. 2008, 18, 2919-2929. (Review)

Lubensky, T. C.; Radsihovsky, L. Phys. Rev. E., 2002 , 66, 031704.(Phase Behavior)

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

Bent-core LCs show a large flexoelectric coupling

Measurement of Flexoelectric

coefficientsNo net

polarization

++

+ ++ + + + +

++

++

+ ++ + + + +

++

Banana

Rod-like

Meyer, Phys. Rev. Let., 22, 918, 1969.

Pd = e1 n (div n) + e3 (curl n) x n

Dewar, et al., J. Chem. Phys., 123, 174907,

2005.

Mechanically induced

polarization

Harden, et al., Phys. Rev. Let., 97, 157802,

2006.

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

Bent-Core Polymers and Networks for Flexoelectric Networks

• How can we prepare a free-standing bent-core LC material?

• How does the LC-polymer coupling influence or enhance the

properties observed for bent-core LCs?

• How does the presence of a polymer network affect mesophase

ordering?

• Preparation/Characterization of bent-core LCs

• Route 1: Polysiloxane elastomers swollen with bent-core LCs

• Route 2: Preparation of pure bent-core elastomers

• Route 3: Controlled Polymerization of bent-core LC

Outline:

LC polymer gels/elastomers: Finkelmann, Warner, Kornfield, Hammond, Urayama, Mather

Bent-core LC polymers: Tschierske, Ikeda, Hsiao

Bent-Core LCPolymer/Rubber

elasticity

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

X-ray Scattering can reveal pretransitional phenomena and cybotactic clustering

Pretransitional phenomena in Calamitic

LCs:

McMillan, et al., Phys. Rev. A, 6, 936, 1972.

Pretransitional phenomena in Bent-Core

LCs (?):

Bailey, Jakli et al.

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

Route 1 towards bent-core LC elastomers

Finkelmann, H.; Greve, A.; Warner, M. Eur. J. Phys. E 2001, 5, 281 crosslink LC side-group

Polymer network

OO

OO

OR2R1O

Cl Cl

Chambers, M., Verduzco, R., Sprunt, S, Gleeson, Jakli, Advanced Materials, 2009

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

Materials: Bent-Core Liquid Crystals

Material R1 R2 TI-N(oC)

TN-C(oC)

BC2-ss C8H17 C8H17115 82

BC2-us C8H15 C8H17106.9 58

BC2-uu C8H15 C8H1592.7 38

Material R TI-N(oC)

TN-S(oC)

TS-C(oC)

BC1-ss C10H21 89 62 55

BC1-uu C10H19 106.9 17.4 58

OO

OO

OOC

OR

C

RO

O O

Cl

OO

OO

OR2R1O

Cl Cl

“Giant” Flexoelectricity (Harden, et al.,

Phys. Rev. Lett. 2006, 157802)

BC1: Fodor-Csorba et al., J. Mater. Chem. 2004, 14,2499-2506

Monotropic nematic phase

Enantiotropic nematic phase

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

OO

OO

OR2R1O

Cl Cl

Cl Cl

OO

O O

O O

Cl Cl

OO

O O

O O

Cl Cl

OO

O O

O O

BC2-ss

BC2-us

BC2-uu

Materials: Bent-Core Liquid Crystals

BC1: Fodor-Csorba et al., J. Mater. Chem. 2004, 14,2499-2506

BC1

Monotropic

Nematic Phase

“Giant”

Flexoelectricity

Harden, et al.,

Phys. Rev. Lett.

2006, 157802

OO

OO

OOC

O

C

O

O O

Cl

OO

OO

OOC

O

C

O

O O

Cl

BC1-uu

BC1-ssOO

OO

OOC

OR

C

RO

O O

Cl

BC2

Enantiotropic

Nematic Phaseelectr

onic-

Liquid

Crys

tal Pr

esen

tation

s

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

Bent-Core LCs swell Calamitic LC Elastomers

Chambers, M., Verduzco, R., Sprunt, S, Gleeson, Jakli, Advanced Materials, 2009.

0 5000 10000 15000 20000 25000 30000

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0 1/ /0 1

t te e

t0 =3 60s, t

1 = 176

t (s)

t = 0 h

t = 3 h

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

Bent-Core LCs swell Calamitic LC Elastomers

LCE

solvent

V/Vo c

(% mol)

TI-N(oC)

TN-SmX(oC)

TSmX-C(oC)

Tg(oC)

LCE 1.0 0 73.8 -- -- -6.0

BC1-ss 1.93 32 81.0 52.4 30.2 --

BC1-uu 1.70 39 85.9 65.4 29.3 --

BC2-ss 2.11 35 99.1 66.7 21.8 --

BC2-us 2.29 41 85.4 -- -- -1.2

BC2-uu 2.13 30 86.8 -- -- -3.6

Chambers, M., Verduzco, R., Sprunt, S, Gleeson, Jakli, Advanced Materials, 2009.

V/Vo: Ratio of the final swollen volume to the initial unswollen volume

c: Molar concentration of LC in the swollen elastomer at equilibrium

TI-N: Isotropic to Nematic phase transisition temperature on cooling

TN-SmX: Isotropic to Smectic phase transisition temperature on cooling

Tg: Glass-transition temperature

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

Swollen LC Elastomer Exhibits Flexoelectricity

OO

OO

OR2R1O

Cl Cl

R1 = C8H15R2 = C8H17

Chambers, M., Verduzco, R., Sprunt, S, Gleeson, Jakli, J. Mater. Chem., in press.

See presentation this Saturday by John

Harden for details on flexoelectric

measurements (RA3, 11:05 on Saturday)

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

X-ray scattering of magnetically aligned bent-core LCs reveals four-peak structure

T > TNI T < TNI T

Swollen elastomers exhibit a broad-low angle peak

95 ℃ 70 ℃ 30 ℃

I N Sm86.8 oC 25.0 oC

Chambers, M., Verduzco, R., Sprunt, S, Gleeson, Jakli, et al., J. Mater. Chem., in press.

25

30

35

40

45

50

55

0.05 0.25

Inte

ns

ity (

a.u

.)

q (Å-1)

38

30

29

85 oC

T

BC2-us

Monofunctional Bent-Core Liquid Crystals for Bent-core Elastomers and Polymers

BC2

Enantiotropic

Nematic Phase

Cl Cl

OO

O O

O O 66

Polymerizable bent-

core LCele

ctron

ic-Liq

uid C

rystal

Pres

entat

ions

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

Synthesis of asymmetric bent-core LC

O

O

HO

DMF, K2CO3

OTs

O

O

O87 %

recryst. EtOH

EtOH, KOH

90 oC, 12 hreflux, 12 h

94 %

SOCl2reflux, 12 h

6

ClCl

OHHO

THF, TEA

OH

O

O

6

Cl

O

O

ClCl

OHO

O

O24 h, 75 %

6

THF, TEA

6

Cl

O

O

24 h, 85 %

Cl Cl

OO

O O

O O 66

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

Route 2: Pure Bent-Core Elastomers

BC2-us

crosslink

Bent-core

LC side-group

Polymer network

OO

OO

OR2R1O

Cl Cl

Luchette, Harden, J. P. Palffy-Muhoray, P. via LC Materials Facility

Near Room temperature (~30 oC) bent-core nematic materials

See presentation this Saturday by John Harden for flexoelectric

measurements of this material (RA3, 11:05 on Saturday)

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

110℃ 90℃70℃ 50℃

Pure bent-core elastomer exhibits four-peak pattern with marked temperature dependence

I N107 oC

Samples aligned by stretching

Orientation angle of peaks increases

from 35o near the TNI to 45o near

room temperature

85 oC

T

Route 3: Controlled polymerization of bent-core LC macromonomer leads to end-functionalized polymers

Initiator CTA [M] Conversion Mp PDI

AIBN None 0.20 88 %

(40 h)

29.1K

(DP = 30)

1.5

AIBN

(5:1 ratio)

4-Cyano-4-

(dodecylsulfanylthiocarbonyl)

sulfanylpentanoic acid

0.40 80%

(20 h)

15.2 K

(DP = 15)

1.2

Phase behavior: Polymer is rubbery and nematic at room temperature. It shows

a nematic-isotropic transition at ~ 145 oC and Tg at ~ 25 oC.

Cl Cl

OO

O O

O OO CH37 7

O

Cl Cl

OO

O O

O OO CH37 7

O

AIBN, THF, 65 oC

S

SSCH3

CNHOOCH2CH2C CH2(CH2)10CH3

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

X-ray scattering of bent-core polymer in 5CB reveals cooperative alignment of LC and polymer

62 OC 40 OC 34 OC

Solution of 10 % LC polymer in 5CB:

60 OC 50 OC 46 OC

Solution of 30 % LC polymer in 5CB:

Low-angle peak

( > 8 nm)

Polymer Backbone

Bent Core LC

(42 Angstroms)

wide-angle peak

( 25 Angstroms)

5CB

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

Acknowledgements

General

Martin Chambers

Seung Hong

Sam Sprunt

Jim Gleeson

Antal Jakli

Jon Harden

Paul Luchette and P. Palffy-Muhoray

Elaine DiMasi and Ron Pindak (BNL)

K. Fodor-Csorba

Funding

CNMS

NSF (DMR 0606160)

Office of Naval Research

(N00014-07-1-0440)

Facilities

CNMS User Facilities

Liquid Crystal Materials Facility

(http://nlcmf.lci.kent.edu/)

Brookhaven National Lab Beamline X6B

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

http://nlcmf.lci.kent.edu/

Pure BCLC polymer (polyBCLC_rv187)

122 OC 106 OC

At 126oC the halo becomes anisotropic, and on further cooling in the nematic phase more intense low-angle peaks appear. The d-spacing of the broad halo that first appears is roughly 42 Angstroms. The d-spacing of the additional, sharper low-angle peak is roughly 78 Angstroms. As the samples is cooled below 100 oC, these two peaks at 42 and 78 Angstroms become sharper and more intense. A third broad peak at higher angles also emerges, and this peak has a d-spacing of roughly 25 Angstroms

Below 65oC, the low-angle peak at 78 Angstroms becomes very sharp and intense, suggesting smectic-like order

76OC 45OC

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

85 90 95 100 105 110 115

-10

0

10

20

30

40

50

60

70

0

10

20

30

40

An

gle

(d

eg

ree

s)

Peak Intensity

Inte

nsity (

a. u

.)

Temperature (oC)

Peak Angle

Fig. 3. Temperature dependent changes in scattering profiles of BC1 and BC2. a) Scattered intensity averaged over a rectangular area centered around low-angle scattering peak (Qx = 0.15 Å). b) Plot of the temperature dependence of the peak intensity normalized by the maximum scattered intensity at Qy=0.

-0.20 -0.15 -0.10 -0.05 0.00 0.05 0.10 0.15 0.20450

500

550

600

650

85 oC

95 oC

100 oC

103 oC

107 oC

Inte

nsity (

a.

u.)

Qy (Å

-1)

113 oC

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

-60 -40 -20 0 201.0

1.1

1.2

1.3

1.4

1.5

1.6

0.00

0.04

0.08

0.12

0.16

L/L

0

T-TNI

(K)

n

Length Change in Bent-Core Swollen Elastomers

-40 -30 -20 -10 0 101.0

1.2

1.4

1.6

0.00

0.04

0.08

0.12

0.16

L/L

0

T-TNI

(K)

n

Unswollen Elastomer

-40 -20 01.0

1.1

1.2

1.3

1.4

1.5

1.6

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

L/L

0

T-TNI

(K)

n

BC1-ss

BC2-su

http://www.tcm.phy.cam.ac.u

k/~mw141/

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

POM and XRD reveals phase behavior of bent-core LCs (BC2-ss)

Isotropiccrystal 1

crystal 2

Polarized optical

microscopy

118 oC102 oC

cooling:

heating:

Nematic

IsotropicNematic crystal 1

115 oC75 oC

105 oC

10 20 30 400

10000

20000

30000

40000

50000

60000

70000

80000

90000

140 - 117.5 oC, isotropic

Sca

tte

red

In

ten

sity (

arb

. u

nits)

2 (degrees)

4.2

Å

23

.7 Å

10 20 30 400

10000

20000

30000

40000

50000

60000

70000

80000

90000 140 - 117.5

oC, isotropic

115.0 oC, nematic

112.5 oC, nematic

110.0 oC, nematic

90.0 oC, nematic

Sca

tte

red

In

ten

sity (

arb

. u

nits)

2 (degrees)

4.2

Å

23

.7 Å

10 20 30 400

50000

100000

150000

200000 140 - 117.5

oC, isotropic

90.0 oC, nematic

87.5 oC, crystal 2

85.0 oC, crystal 2

72.5 oC, crystal 2

Sca

tte

red

In

ten

sity (

arb

. u

nits)

2 (degrees)

21

.5 Å

3.8

Å

Wide-angle x-ray

diffraction

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

Liquid crystal networks enable functional devices

Palffy-Muhoray et al. http://www.tcm.phy.cam.ac.uk/~mw141/mw_talk/index.html

Mark Warner et al.

Ikeda et al.

Liquid Crystal Elastomer Gel

Liquid Crystal Elastomers, Terentjev E. and Warner, M.

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

http://www.tcm.phy.cam.ac.uk/~mw141/mw_talk/index.htmlhttp://www.tcm.phy.cam.ac.uk/~mw141/mw_talk/index.htmlhttp://www.tcm.phy.cam.ac.uk/~mw141/mw_talk/index.html

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0.2

0 50 100 150 200

Strain

Vis

co

sit

y (

Pa

s)

5 wt % polymer

5 CB

Bent-core LC shows an oblate conformation in calamitic liquid crystal

n v

5 wt. % polymer

solution shows

director tumbling

behavior

Electro-optic

experiments show

K3 >> K1

prolateoblate

Jamieson, Kornfield, et al.

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

Measurement of Flexoelectric Coupling in Liquid Crystal Materials

0

20

40

60

-50 -25 0

BCN1+BCN3BCN3+6008BCN1

T-TN-I

e 3 (

nC

/m)

BC1-uu + BC2-uu

BC2-uu + 6008

BC1-uu

Harden, et al., Phys. Rev. Lett. 2006, 157802

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

Converse Flexoelectric Effect

0

20

40

60

80

100

-30 -20 -10 0 10 20

converse

direct

Adjusted temperature T-TNI

(oC )

e3 (

nC

/m)

Figure : The set-up (left) and the temperature dependence of the bend flexoelectric constant measured by the converse (red) and direct (blue) effects

(right).

Harden, et al., Phys. Rev. E 2008, 78, 031702

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

Conclusions

Bent-core elastomers can be prepared by swelling polysiloxane

networks, and they exhibit properties characteristic of unswollen LC

elastomers

RAFT affords well-defined LC homopolymers, and these can be used

as building blocks for complex polymeric architectures

Bent-core molecules exhibit an enhanced flexoelectricity, and this can

be measured using a direct flexing device and by studing the converse

flexing effect

Future work includes investigating block copolymers to form self-

assembled gels and elastomers and investigating the

supramolecular clustering of bent-core molecules

Lubensky, T. C.;

Radsihovsky, L. Phys.

Rev. E., 2002 , 66,

031704.(Phase

Behavior)

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

0 10 20 30 40

1

2

3

4

5

K3/K

1

%wt BCLC polymer in 5CB

Electro-optic measurements indicate an oblate polymer conformation in solution

0 1 2 3 4

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

n

Voltage (V/m)

Red – 0% polyBCLC in 5CB

Blue – 20% polyBCLC in 5CB

Green – 40% polyBCLC in 5CB

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

Swollen LC Elastomers

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

0

20

40

60

-50 -25 0

BCN1+BCN3BCN3+6008BCN1

T-TN-I

e 3 (

nC

/m)

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

Length Change in Bent-Core Swollen Elastomers

http://www.tcm.phy.cam.ac.u

k/~mw141/

-40 -30 -20 -10 0 101.0

1.2

1.4

1.6

0.00

0.04

0.08

0.12

0.16

L/L

0

T-TNI

(K)

n

Unswollen Elastomer

OO

OO

OOC

OR

C

RO

O O

Cl

-40 -20 01.0

1.1

1.2

1.3

1.4

1.5

1.6

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

L/L

0

T-TNI

(K)

n

-60 -40 -20 0 201.0

1.1

1.2

1.3

1.4

1.5

1.6

0.00

0.04

0.08

0.12

0.16

L/L

0

T-TNI

(K)

n

OO

OO

OR2R1O

Cl Clele

ctron

ic-Liq

uid C

rystal

Pres

entat

ions

electr

onic-

Liquid

Crys

tal Pr

esen

tation

s

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03

http:/

/www

.e-lc.

org/pr

esen

tation

s/doc

s/200

9_10

_01_

12_2

3_03