Surfactant-Free Oil-in-Water Emulsion

Stabilized by Chitin Nanocrystals: A

Green Recipe
Overview

INTRODUCTION PREPARATION OF 

NANOCRYSTALS CHARACTERIZATION THOUGHT EXPERIMENT

Pickering Emulsion

Technology and

Chitin Background

TEMPO and PA chitin

nanocrystals

Single particle using

SAXS and emulsion

using microscopy

Using SANS for

future experiments

2 2
What are Pickering emulsions...

3

• Conventional emulsions are

stabilized by amphiphilic molecular

emulsifiers

• Pickering emulsions are more

resistant to Ostwald ripening and

coalescence

• Attributes needed for the particles:

• Must be partially wet by both

oil and water phases

• Lower surface potential

• Must be greatly smaller in scale

compared to the target oil

droplet size

3
Chitin Background and Research Objective

• Second most abundant

polymer after cellulose

• In the form of highly

crystalline fibrils in its

biological environment has

biocompatibility, and good

biodegradability

Objective: To test the

chitin nanocrystals and

their properties as

colloidal particles to an

emulsion to provide a

green recipe applicable

to various food products.

4
Preparation of TEMPO oxidized Chitin Nanocrystals

• Preparing Reaction Medium:

• Chitin + water + TEMPO + NaBr + NaClO

• Alkaline conditions for 2 hours:

• pH 10.8 at room temperature

• Quenching reaction:

• adding a small amount of ethanol to the mixture

• Adjust pH to 7

• Post Processing:

• Centrifuge 3x at 12000 rpm for 10 min. Remove supernatant by

decantation.

• Stored at 4 °C as a permanently wet TEMPO-oxidized

chitin sample before use.

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Task 1: Producing and Analyzing Chitin Nano-whiskers
Preparation of Phosphoric Acid Chitin Nanocrystals

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Task 1: Producing and Analyzing Chitin Nano-whiskers

• Preparing Reaction Medium:

• Purified chitin powder + H3PO4 (65wt%)

• Sealed and refrigerated (2-8 °C) for 30 min

• Centrifuge for 5 min

• Processing:

• Heat in hot bath, 55°C for 2h

• Washed with DI and centrifuged 3x (12000 rpm, 10 min)

• Post-processing:

• Sediment was dialyzed for 48h, pH=6.28

• The chitin solution was stored at 4 °C.
Small Angle X-ray Scattering

• Located at the UMD X-ray

Crystallography Center

• Used to measure cross

sectional size of ChNWs

X-ray

Beam

Sample

Detector

7 7

Single Particle Characterization

Task 1: Producing and Analyzing Chitin Nano-whiskers

Dynamic Light Scattering

• Used to measure Length

of ChNWs

https://lsinstruments.ch/en/theory/dynamiclight-scattering-dls/introduction
Parameter Value Units

Scale 5.9e-10

Background 2e-09 Cm-1

Sld 13.13 10^- 6/Å

Sld Solvent 9.47 10^- 6/Å

Length A 47.809 Å

Length B 1232.2 Å

Length C 4000 Å

Min range 0.007 Å^-1

Max range 0.18 Å^-1

X^2 1.6e-15

Weighting – |Data I|

Form factor - Parallelepiped

0.1wt% PA Chitin Emulsion

Parallelepiped Form with

lengths a, b, and c.

This area still

does not fit

well and will

be studied

further

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Single Particle Characterization
Parameter Value Units

Scale 3.62e-10

Background 3.9804e10Cm-1

Sld 13.13 10^- 6/Å

Sld Solvent 9.47 10^- 6/Å

Length A 70.8 Å

Length B 282.94 Å

Length C 4000 Å

Min range 0.006 Å^-1

Max range 0.14 Å^-1

X^2 4.7e-09

0.1wt% TEMPO Chitin Emulsion 9

Weighting – |sqrt(l Data)|

Form factor - Parallelepiped

Single Particle Characterization
Summary of the

single particle

characteristics

from SAXS data

and Dynamic

Light Scattering

• SAXS data à Cross-sectional area of a

single CNW

• DLS à Length of a single CNW

Task 1: Producing and Analyzing Chitin Nanowhiskers

Type of

processing

ChNW

Cross

sectional

Area (nm)

Length

(nm)

TEMPO ChNW 71x283 139.8+/- 10.5

PA ChNW 48x1232 ~200

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Task 2: Preparing

and Analyzing

the Emulsion

• 1:9 Oil in Water

volume percent +

0.1wt% Chitin

• Sonication to

fully disperse oil

droplets in the

water

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10% O/W emulsion with 0.1wt% TEMPO oxidized chitin under

20x polarized light microscope

• The white shining is the chitin nanocrystals acting as colloidal particles surrounding the oil droplets

12

μm

Task 2: Preparing and Analyzing the Emulsion

Morphology of the TEMPO-ChNW stabilized emulsion
• 10% O/W

emulsion with

0.1wt% PA chitin

under 50x

microscope

• Cryo-SEM will be 

used to produce 

better images as 

the PA ChNW

emulsion is too 

thick

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Task 2: Preparing

and Analyzing the

Emulsion

μm

Morphology of

the PA-ChNW

stabilized

emulsion
• 10% O/W Emulsion stabilized by 0.1wt% TEMPO-oxidized ChNW

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Morphology of the

TEMPO-ChNW

stabilized

emulsion

Task 2: Preparing

and Analyzing the

Emulsion
• Reason TEMPO

chitin and PA

chitin are different

à concentration

and properties

• TEMPO is more

hydrophilic and

more negatively

charged so more

dispersed

Conclusion

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Type of

processing

ChNW

Cross

sectional

Area (nm)

Length

(nm)

Microscopy +

Confocal

TEMPO

ChNW

72x286 139.8+/- 10.5

broad size

distribution

ranging from a

few microns up

to ~20 microns

PA ChNW 48x1709 ~200 ~2 microns

with a

relatively

narrow size

distribution
So, what is the next step...

• Use contrast variation techniques

with SANS by making the SLD of

the oil the same as the water to

measure the structure of the chitin

in the emulsion in order to be able

to fully characterize the colloidal

particles’

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Calculated

Neutron SLD’s

MCT Oil 0.215×10-6/Å2

Chitin 2.157×10-6/Å2

• Correlate the microstructure of the colloidal particles with the

macroscopic properties of the Pickering emulsions emulsions

to support the design of Food Applications
Acknowledgements

• Yimin Mao

• Susana Teixeira

• Xiaoxue Jia

• Robert M. Briber

• Qin Wang

• Marie-Ann Fitzgerald

• Joseph A. Dura

• Julie A. Borchers

• Brandi K. Toliver

• Susan T. Krueger

• Paul D. Butler