Investigation of Potential of Blue Phase Liquid Crystals

for Functional MaterialsWilliam Guy

Mentors: Emre Bukusoglu and Xiaoguang WangPI: Prof. Nicholas L. Abbott

BackgroundIntermediate Phase of chiral LCs between their

cholesteric phase and isotropic phaseBPII BPI

50 µm

50 µm

BPII BPI

10 µm-thick film of 35 wt% S-811/MLC2142 on glass substrate exposed to air.

λ= Wavelength of Reflected Lightn = Refractive Indexa = Lattice Parameter h,l,k = Miller Indices

Motivation Investigation of blue phases for use for materials

Sensors Templated Materials

To develop an experimental system to study the underlying phenomena leading to a change in the optical appearance of the BP droplets upon addition amphiphilic molecules.

LC response to lipids (1)Scale bars: 5 µm

LC templated particle synthesis (2); Scale bars: 5 µm

Goals for this SemesterDevelop a suitable experimental procedure to

study consistently stable blue phases Glass: Bare, PVA, DMOAP Solution: Pure water, PBS Grid:

75 mesh 10 µm 400 mesh 10 µm 75 mesh 40 µm

Filling: Overfill, Normal

Study effects of common simple adsorbates on the appearance of blue phases

75 mesh, 10 µm thick

1000 um

PVANo Temp CycleCholesteric

DMOAPNo Temp CycleCholesteric

BareAfter Temp CycleCholesteric

Development of ProcedureVaried type of glass during development of procedure; Bare glass showed dewetting in aqueous environment; PVA prevented a flat film of LC from forming; DMOAP was determined to be best

Varied grid size by which to study BP film; chose 75 mesh in order to observe domains more easily.

400 mesh, 10 µm thick

1000 um 1000 um

Phase Transitions (Cooling)40 um-thick 75 mesh TEM grids; PBS solution, pH=7.4;

35wt% S811/MLC2142

50.1C BPI

53.4CTransitionIso to BPII

52.6C,TransitionBPII to BPI

46C BPI

45.2C BPI

42.6CTransitionBPI to cholesteric

Effects of Additives: SDS40um,75 mesh TEM grids, 1mM SDS in PBS solution, pH=7.4,

35wt% chiral dopant LC 53.4CTransitionIsotropic to BPI/BPII

51.2CBPI

47.3C BPI

46.3CBPI

44.8CBPI

1000 um1000 um 1000 um

1000 um 1000 um

43.2CTransitionBPI to cholesteric

Effects of Additives

No additives 45.2C, 1 mM SDS, 45.5C

1000 um 1000 um

SDS aligned [110] planes parallel to the interface and stabilized the lattice size BPI.

Effects of Additives, SDS40um,75 mesh TEM grid, 1mM SDS in PBS solution, pH=7.4,

35wt% chiral dopant LC, 48°CPrior to SDS

1000 µm 1000 µm

Effects of Additives, SDS40um,75 mesh TEM grid, 1mM SDS in PBS solution, pH=7.4,

35wt% chiral dopant LC, 48°CPrior to SDS After SDS

+0mins

1000 µm 1000 µm

Effects of Additives, SDS40um,75 mesh TEM grid, 1mM SDS in PBS solution, pH=7.4,

35wt% chiral dopant LC, 48°CPrior to SDS After SDS

+0minsAfter SDS+3mins

1000 µm 1000 µm 1000 µm

Effects of Additives, SDS40um,75 mesh TEM grid, 1mM SDS in PBS solution, pH=7.4,

35wt% chiral dopant LC, 48°CPrior to SDS After SDS

+0minsAfter SDS+3mins

After SDS+9mins

1000 µm 1000 µm 1000 µm

1000 µm

Effects of Additives, SDS40um,75 mesh TEM grid, 1mM SDS in PBS solution, pH=7.4,

35wt% chiral dopant LC, 48°CPrior to SDS After SDS

+0minsAfter SDS+3mins

After SDS+9mins

After SDS+14mins

1000 µm 1000 µm 1000 µm

1000 µm 1000 µm

Effects of Additives, SDS40um,75 mesh TEM grid, 1mM SDS in PBS solution, pH=7.4,

35wt% chiral dopant LC, 48°CPrior to SDS After SDS

+0minsAfter SDS+3mins

After SDS+9mins

After SDS+14mins

1000 µm 1000 µm 1000 µm

1000 µm 1000 µm

After SDS+22mins

1000 µm

Effects of Additives, SDS40um,75 mesh TEM grid, 1mM SDS in PBS solution, pH=7.4,

35wt% chiral dopant LC, 48°CPrior to SDS After SDS

+0minsAfter SDS+3mins

After SDS+9mins

After SDS+14mins

After SDS+22mins

1000 µm 1000 µm 1000 µm

1000 µm 1000 µm 1000 µm

StabilizationThe free energy of a BP can be described as

(defect theory)(1):

The free energy of a BP in the presence of amphiphiles can be described as:

The presence of SDS changes the Fcore, Fint, and Fsa leading to a stabilization in the BP lattice size with respect to temperature.

Elastic Surface Core Interfacial

Elastic Surface Core Interfacial Self Assembly

(1) Kikuchi, H. et al. Nature Materials, 1, 2002, 64 - 68.

Effects of Additives

No additives 45.2C, 1 mM SDS, 45.5C 0.1 wt% PVA, 46.5C

1000 um 1000 um 1000 um

SDS aligned [110] planes parallel to the interface and stabilized the lattice size BPI.

PVA led to a distribution of different orientations of BPI lattice with respect to the interface.

ConclusionEvidence that SDS is going into the bulkWith the system developed in this study, we

were able to demonstrate the dynamics of lattice size shrinkage and therefore response to exposure to amphiphiles.

This possible entrance into the bulk would influence the lattice size that leads to a stabilization as function of temperatures

1. Lin, H.; Miller, D.S; Bertics, P.J.; Murphy, C.J.; de Pablo, J.J.; Abbott, N.L.; Science Mag, 2011, 332, 6035, 1297-1300

2. Mondiot, F.; Wang, X; de Pablo, J.J.; Abbott, N.; JACS, 2013, 135, 9972-8875

3. Bukusoglu,E; Wang,X; Martinez-Gonzales, J; de Pablo, J.J.; Abbott, N.L.; Adv. Mater., 2015, 27, 6892-6898

4. Kikuchi, H. et al. Nature Materials, 1, 2002, 64 - 68

References