Cellulose Under Pressure For New 

Biopolymer Materials

By: Josh Devorkin

Mentors: Dr. Susana Teixeira and Dr. Yimin Mao 
Outline 

• Background: Cellulose and Nanomaterials 

• Cellulose is a natural polymer 

• Tempo-oxidation to extract nanofibers 

• Building block for new materials 

Goal:

Towards greener processing: can High hydrostatic pressure promote a more efficient 

oxidation reaction?

Assessing multi-characterization techniques to adequately probe the surface 

interactions and topography

• Results: SANS, AFM, POM 

•Future work 
Cellulose as a building block for novel materials 

The abundance of cellulose gives rise for current and future 

novel applications 

Complex Hierarchy structure rich in 

hydrogen bonding from the 

crystallization during biosynthesis 

Fiber Bundles

Fiber networks Microfibers

Nanofibers

Adapted from T. Heinze et al. 

1 um
Commercial Applications of Cellulose 

Nanocomposites for lightweight 

durable materials 

Coatings for Medical devices

• Drug delivery

• Antibacterial resistance 

• Good biocompatibility and wear

High aspect ratio films to collect 

small dust particles 

New lightweight, durable 

material for 3-D printing

Paper industry
TEMPO-mediated oxidation for processing of cellulose

•Tempo treatment attacks the C6 primary hydroxyls on the surface of the individual cellulose 

microfibers 

•Oxidation into carboxyl groups creates an electrostatic repulsion in water leading to the 

disintegration of the cellulose nanofibers/crystals

Crystalline

Amorphous

Individualized 

microfibril

Motivation: New methods 

to extract cellulose 

nanofibers using green 

chemistry to reduce the 

use of chemicals 

Adapted from Okita et al. 

Major drawback is the price and toxicity arising 

from the use of TEMPO
High hydrostatic pressure as a probing tool

•Emerging as a useful tool for probing changes in the structure and 

functional properties of polymers 

•Pressure does not introduce other agents into the system, helps aid with 

green chemistry

• Samples/ Applications 

• Solutions of soft matter polymers 

• Proteins, lipids, polysaccharides 

• Pressure assisted self aggregation

• Cellulose processing 

Image from: Meersman & McMillan, 2014. Chem. Comm. 50, 766-765

HP cell ~3kbar Hypothesis: High pressure to aid in the oxidation of cellulose 

through the TEMPO-reaction to dissociate cellulose 

nanofibers 
What neutrons can do 

•Structure, conformation of biomaterials Function and behavior 

Reciprocal space 

Real space

qq =

4ππ

λλ sin θθ

Scattering variable q

λλ: nnnnnnnnnnnnnn wwwwww ww ww w

θθ: ssss ss

0.001 AȦ

−1< q < .45 AȦ−1
Pressure: up to 3.5 kbar. 

Temperature : -15°C to +65°C

q-range: 0.001-0.6 Å-1. 

Sample volume: 

2.5-5 ml

Teixeira et al.(2018) J. Neutron Res. 20(1) 

HP- SANS System At The NCNR
Multiscale characterization of cellulose

Length Scale 

AFM

SANS

Optical Microscopy

Time Scale 

Macro Meso Micro Molecular/Atomic

Investigation of the optical 

properties of materials such as 

birefringent patterns 

Scanning probe to measure 

surface topography

Scattering techniques 

used to investigate the 

structure of materials 
Recipe for extraction of nanofibers

1) Pristine bacteria Cellulose

2) Homogenizer 3) TEMPO treatment 4) Viscous gel solution 

at 1.5 wt%

After Tempo 

treatment 

POM images taken at UMD facilities

5 um
Simulated scattering curves using Sasview

~qq−1

Data fitted with a parallelepiped model with a uniform 

scattering length density 

Assumption:

1. Rod-like particles due to the crystallographic packing

2. L is very long in the micron scale which SANS cannot 

probe with our configurations

3. b>a due to crystallographic packing of cellulose chains

Figure 1: Calculated 1-D curves using the parallelepiped model 

with different lengths (c). Cross section width b and thickness 

a are fixed at 3 and 30 nm. 

Guinier region shown for low q at 50nm. 

I q =

Scale

V Δρ. V 2 < P q > + Background

I q - Measured intensity

P(q)- Form factor to derive a/b
Ex-situ SANS data on Flask TEMPO oxidation (RT, 1am) 

NG7 SANS NG7 SANS 

Samples were collected on aliquots taken from the reaction mixture after quenching 

with ethanol, centrifuging and washing. 
b a

SASVIEW fits: http://www.sasview.org/

Cellulose SLD: 

(1.65±0.2)x10-6 Å-2

a<b<<L

II qq = SSSSSSSSSS

VV ΔΔΔΔ.VV 22 < PP qq > + Background

Parallelepiped model

Nayuk & Huber, Z. Phys. Chem., 226 (2012) 837-854

Mao et al., J. Phys. Chem. B (2017), 121, 1340−1351

Ex-situ Fitting of Reaction (100% TEMPO) vs Time

Reaction 

time

a 

(nm)

b 

(nm)

1h 4.6 ± 0.3 38 ± 1.4

3h 4.1 ± 0.3 37 ± 1.3

3h30 3.9 ± 0.1 32 ± 0.5

4h 3.9 ± 0.1 19 ± 0.3

0 2 4

0.000

0.002

0.004

Volume (um3)

Time of Reaction (Hr)

L
In-situ High pressure at 3kbar

Due to the complexity of the mixture (ex-situ data came from samples that were filtered and washed) the fits are 

more difficult. In the first 40 mins the presence of the long fibers still dominates the signal (upturn at low-q)

t0

Pressure release 

(relaxation monitored for 2h) 

In the first 40 mins the presence of 

the long fibers still dominates the 

signal (upturn at low-q)
In-situ Reaction (50% TEMPO) Under High Pressure

NGB30 SANS NGB30 SANS NGB30 SANS

Pressurized

De-pressurized

Reaction 

time

a 

(nm)

b 

(nm)

P

(kbar)

40min 5.0 ± 0.06 180 ± 33 0.001

1h20 4.5 ± 0.02 151 ± 12 3

2h 4.4 ± 0.03 152 ± 10 3

2h40 4.4 ± 0.01 151 ± 10 3

3h20 4.3 ± 0.03 137 ± 8 3

4h 4.2 ± 0.03 128 ± 7 3

5-6h 4.3 ± .02 128 ± 8 0.001
Atomic Force Microscopy 

HP_3kbar_3hr

Half amount of TEMPO

• Complementary technique to 

SANS data 

• Confirms the dissociation of 

bundles of fibers to individual 

nanofibers

40.8 nm

18.5 nm

HP_3kbar_4hr

No pressure Tempo Reaction

Wood pulp courtesy of

D. Henderson research 

group at UMD

2 um
• High pressure was able to alter the Tempo-oxidation reaction

• Dissociate nanofibers under high pressure using half the amount of reagents 

• Produced long fibers able to form viscous gel solutions at low weight 

percentages 

• Cross link individual nanofibers to create a hydrogel 

• Alter surface properties, to create a biocompatible, antimicrobial wound 

dressing 

Conclusions and Future work 
NGB30 SANS instrument

Sample environment team at the NCNR

Surf organizers: Joe Dura, Julie Borchers 

Mentors: Dr. Susana Teixeira and Dr. Yimin Mao 

This work benefited from the use of the SasView application, originally developed under NSF 

award DMR-0520547. 

Acknowledgements
Testing Ex-situ sampling effects on HP-cell TEMPO oxidation

NG7 SANS 

Supernatant (SN)

Pellet (Long Fibers)

Mix

SN

Pellet
Polarized Optical Microscopy

Control _ No tempo

Tempo 

High pressure_ 

3kbar 

POM images taken at 

UMD facilities
Effects of Tempo reaction 

Sharp interface of NF

Structural factor and 

~qq indication of network −1 Long fibers ~qq−2
Reaction 

time

a 

(nm)

b 

(nm)

c 

(nm)

Chi2/

#points

# 

points

0h 3.3 ±

0.3

84 ±

4.8

12200 ±

684

1.66 174

1h 4.6 ±

0.3

38 ±

1.4

7632 ±

709

0.86 178

3h 4.1 ±

0.3

37 ±

1.3

3075 ±

686

1.21 161

3h30 3.9 ±

0.1

32 ±

0.5

1858 ±

460

1.95 168

4h 3.9 ±

0.1

19 ±

0.3

1536 ±

157

1.22 167
0.01 0.1

1E-4

0.001

0.01

0.1

1

10

I(q)

Ex-Situ investigation for time dependence of TEMPO reaction

Cross-section dimensions derived from SANS 

methods (one STD in parentheses)

Fibers cross-section size inversely related to 

the reaction time 

Dissociation of NF’s after 4 hour of TEMPOoxidation 

Figure 2: Scattering profiles of the time dependency of TEMPO-oxidation. 

4 hour and 3.5 hour curves were offset to better illustrate the fitting