Structural and Mechanical Characterization of 

HPMC/SDS Aggregation

through Rheological and Neutron Scattering 

Measurements

Douglas Scott

NCNR SURF Associate
Hydrophobic Hydrophilic

Surface Active Agents & Micellization Concentration

Total Surfactant Concentration

Monomeric

Micellar

CMC
CAC CMC

x 0% HPMC

o 0.20% HPMC

Nilsson, S., Macromolecules 1995, 28 (23), 7837-7844.

Hydroxypropylmethyl cellulose (HPMC)

Aggregation at Lower Surfactant 

Concentrations Practical Rheological Properties

Polymer-Surfactant Interactions

Sodium dodecyl sulfate (SDS)

Images from: easy-hairstyles.net; offthegridnews.com 

Disclaimer: Certain commercial equipment, instruments, or materials are 

identified in this presentation to foster understanding. Such identification 

does not imply recommendation or endorsement by the National Institute 

of Standards and Technology, nor does it imply that the materials or 

equipment identified are necessarily the best available for the purpose.
0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 0.2 0.4 0.6 0.8 1

Conductivity (mS/cm)

[SDS] (%w/v)

0.10%

0.30%

0.50%

Conductivity Measurements

CMC = 0.236% CAC = 0.156%

cp

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

0 0.5 1 1.5 2 2.5 3 3.5

Conductivity (mS/cm)

[SDS] (% w/v)

CMC = Critical Micelle Concentration

CAC = Critical Aggregation Concentration

PSP = Polymer Saturation Point

= PSP
Proposed Aggregate Structures

SSSSSS tttttt < CCCCCC CCCCCC < SSSSSS tttttt < PP PP

Increasing SDS Concentration

SSSSSS tttttt > PP PP

CMC = Critical Micelle Concentration

CAC = Critical Aggregation Concentration

PSP = Polymer Saturation Point
Rheology 101

Image from: materialssolutions.com.au

ῥέω, “flow”

Viscosity

ττ = ηηγγ̇
Shear Profiles: 3% HPMC Solutions with SDS

100

1000

10000

100000

1000000

10000000

0.001 0.01 0.1 1 10 100 1000 10000

Viscosity (mPa s)

Shear Rate (s-1)

0%

0.25%

1%

2%

Increasing Viscosity 

Shear Thinning

% SDS
Shear Profiles: 3% HPMC Solutions with SDS

100

1000

10000

100000

1000000

10000000

0.001 0.01 0.1 1 10 100 1000 10000

Viscosity (mPa s)

Shear Rate (s-1)

2%

3%

4%

Decreasing Viscosity 

Shear Thinning

% SDS
Shear Profiles: 3% HPMC Solutions with SDS

100

1000

10000

100000

1000000

10000000

0.001 0.01 0.1 1 10 100 1000 10000

Viscosity (mPa s)

Shear Rate (s-1)

4%

4.5%

5%

6%

12%

% SDS

Decreasing Viscosity 

Shear Thickening?
Viscosity Dependence on Concentration

100

1000

10000

100000

1000000

10000000

0 2 4 6 8 10 12

Viscosity (mPa s)

SDS Concentration (% w/v)

0.01 s^-1

0.1 s^-1

1 s^-1

10 s^-1

100 s^-1

1000 s^-1

γγ̇
Small Angle Neutron Scattering (SANS) 101

QQ =

44ππ

λλ ssssss θθ

Grillo, I. Small-Angle Neutron Scattering and Applications in Soft Condensed Matter; 2008

( ) ( ) ( ) ( ) ( ) 2 2 V P Q S Q V

N

d

d Q I Q A B A I

A  ρ − ρ 

 





=

Ω

Σ

=

cross 

section

number 

density

contrast

factor

form 

factor

structure 

factor

particle 

volume
Static SANS: HPMC/SDS Mixtures
Static SANS: More than the sum of its parts...
RheoSANS

γγ̇ = 00. 0000 ss− γγ̇ = ss− γγ̇ = 33 ss−

1.E+02

1.E+03

1.E+04

1.E+05

1.E+06

0.001 0.1 10 1000

Viscosity (mPa s)

Shear rate (s-1)
Shear Thickening or Foaming?

100

1000

10000

10 100 1000 10000

Viscosity (mPa s)

Shear Rate (s-1)

4.5%

5%

6%

12%

*Videos courtesy of Daniel Seeman
Looking Forward

Contrast Matching

Deuterate

SDS

N. Wagner (UD)

M. Liberatore (UD)

F. Nettesheim (UD)

L. Porcar (NIST)

Enclosed Rheology

K. Weigandt (NIST)

Extensional Flow
Acknowledgements

• Katie Weigandt 

• Daniel Seeman

• Javen Weston

• Marie Paul

• NCNR SURF Directors

 Joe Dura

 Julie Borchers

• Proctor & Gamble

 Mark Hammersky

 Seth Lindberg

• Funding: NSF Center for High 

Resolution Neutron Scattering (CHRNS)
Thank you for listening!

Questions?

Disclaimer: Certain commercial equipment, instruments, or materials were identified in this presentation to foster 

understanding. Such identification does not imply recommendation or endorsement by the National Institute of Standards and 

Technology, nor does it imply that the materials or equipment identified are necessarily the best available for the purpose.