Quantitative Nanoscale Property Mapping with Automated ... · quantitative local Tm, aiding material ID. In packing applications the outside layers often consist of HDPE and the inside

Nanoscale Thermal Analysis

Quantitative Nanoscale Property Mapping

with Automated Transition Temperature Microscopy

Thomas Mueller, Ph.D., Product Line Manager, Bruker Nano Surfaces

[email protected]

Agenda

1. Introduction

a. AFM for polymers

2. Bruker Nano Thermal Analysis

a. Operating Principle

b. Application Examples

c. Correlation With Bulk Measurements

3. Transition Temperature Microscopy

a. Operating Principle

b. Application Examples

c. Quantification

4. Summary & Conclusions

Bruker NanoSurfaces Division 2/15/2012 2

Introduction to AFM: Tool for Nanoscale Topographic Information

2/15/2012 3 Bruker NanoSurfaces Division

Array of engineered DNA, 2µm scan

Monolayer of C60H122 alkane, 600nm scan

Atoms on HOPG, 8nm scan

Introduction to AFM: What you want to know about polymers - quantitative nanomechanical properties


PeakForce QNM can quantitatively and unambiguously identify modulus and

adhesion variations. Phase imaging and multifrequency imaging techniques cannot.

• Comparison of the adhesion and phase

images clearly shows that the phase contrast

is primarily due to adhesion, whereas one

might more commonly assume that it reflects

modulus variations

• Section plot illustrates ability to measure the

modulus across the polymer layers

PFQNM-Height

PFQNM-Adhesion

PFQNM-Modulus

Tapping-Height

Tapping-Phase

Multilayered polymer film,

10 µm scans

Left: PeakForce QNM

Right: TappingMode

Introduction to AFM: What you want to know about polymers - electrical properties


• Current map on PEDOT-P3HT overlaid on nm-scale topography.

• Achieving highest resolution in topography and current (2mm image size, 10nm height scale, 5pA current scale)

• Very soft samples cannot be imaged in contact mode based CAFM.

• Only possible with PeakForce TUNA.

High-resolution current mapping on organic photovoltaics

Enabled by PeakForce TUNA and ppm-level environmental control

Sample courtesy of Prof. Nguyen, UCSB

Introduction to AFM: What you want to know about polymers - thermal properties? chemistry?


6

Topography

Quantitative nanomechanics – PFQNM

Nanoscale electrical properties – PFTUNA

Thermal properties – Tg, Tm

What is it – Chemistry

Influence of processing, wear, UV exposure on component distribution, aggregation etc

Conventional Material Analysis Quantitative, bulk


TMA

Material-specific information, but no spatial resolution

Thermal Mechanical Analysis (TMA) setup shown

Bringing Thermal Analysis to the Nanoscale The Tip


V I

I

Topography Phase

Controllable probe temperatures up to

400˚C

0.7 mm scan

Bringing Thermal Analysis to the Nanoscale Operating Principle


Current

Heater

control

Deflection

High-Resolution

AFM Image

Local Tg & Tm

Temperature

measurement

Nanoscale Thermal Analysis Solutions


PS/LDPE Blend on Silicon Clear ID Domain vs Matrix


8 x 4 µm Scan

Domains (LDPE, Tm)

Matrix (PS, Tg)

Before

After

Food Packaging Understand/Design/(Reverse-)Engineer – Starting with AFM


Distinct layers, distinct fine structure. Material and function?

Food Packaging Understand/Design/(Reverse-)Engineer – Nanothermal Analysis


30µm scan

VITA clearly distinguishes

the two outside layers

from the inside one.

VITA provides

quantitative local Tm,

aiding material ID.

In packing applications

the outside layers often

consist of HDPE and the

inside (barrier) layer is

EVOH.

Toner Particle Analyzing Composition and Core Shell Structure


Sample: Toner particles embedded

in epoxy and microtomed

Toner Particle

Center Region

Middle layer

Outer layer

Epoxy

74.3 ºC

70.4 ºC

60.4 ºC

15 x 7.5 µm topographic scan

Nanoscale Drug Analysis Formulation: Crystallinity


Data courtesy of M. Reading, D Craig and L. Harding, UEA

The existence of different solid-state forms, such as polymorphs, solvates, hydrates,

and crystallinity in pharmaceutical drug substances and excipients, have

downstream consequences in drug products and biological systems.

Crystalline only Crystalline and amorphous

Indomethacin

PEO/SPP Blend (1) Microscale Analysis


15 µm Scan Domains (PEO, Tm)

Matrix (sPP, Tm)

PEO/SPP Blend (2) Uncovering Additional Nanoscale Variation


Height 4 µm Scan Phase

sPP Melt Transition

PEO Melt Transition

Measurement Location

Small PEO

domains on sPP

Correlation with Bulk Thermal Analysis Validation of nano-TA


Three crystalline samples and three amorphous samples were measured by bulk ThermoMechanical Analysis (TMA) and compared against VITA measurements

y = 1.0088x - 3.8173

R2 = 0.9811

y = 1.0027x + 0.2778

R2 = 0.9701

y = 1.0047x + 2.9657

R2 = 0.95810

50

100

150

200

250

300

0.0 100.0 200.0 300.0

TMA onset

Nan

oT

a O

nset

0.1°C/s

1°C/s

10°C/s

Slopes: 1.003 - 1.009

Offsets: -4 to +3ºC

Data courtesy of G. Meyers and A. Pasztor, DOW

Summary – Nanothermal Analysis Quantitative characterization & material ID


• Nanothermal analysis provides phase transition temperatures (Tg/Tm) with sub-100nm resolution

• Enables local material identification in heterogeneous samples for R&D or Failure Analysis, in blends/composites/multilayers

• Good correlation with results from standard Bulk TMA, a trusted method at macro-level

• High probe temperature enables use with most polymers

But That’s Not All Missing a Key Part


• Thermal property variations may not correlate with topography

• Neither bulk nor single-point nanoscale measurements capture the distribution of properties

• Nanoscale property variation is intrinsic to polymers

How much more

complexity in this

PEO/SPP blend?

Transition Temperature Microscopy Completing the Picture with Fast Automated Mapping


AFM Configurations for

Transition Temperature Microscopy



Applications Example (1)

1. Multilayer films revisited

• Complex: support, adhesive, functional layers

• Here: reveal property variation in tie layer

• Obtain complete property distribution


1. Navigation & point / array selection

Import AFM image to navigate and define locations for initial single point measurements.


2. Automatic peak softening detection

Automatic peak detection guarantees unbiased extraction of transition temperatures from raw data.


3. Embedded cursor for effortless data mgt

Retains information about location of measurements, guaranteeing correct spatial correlation in analysis post acquisition.


4. TTM mapping for structure property correlation

Fully automated acquisition and analysis. Reveals transition temperature variations within the tie layer that would not have been expected or predicted based on AFM image alone or based on single point nano-ta measurements.


37 70 103 136 169 202 235

6. Histogram analysis

Provides complete statistics on nanoscale thermal property variation, characterizing variations within each layer.

Note: Currently released version provides the measurement data. Built-in histogram function planned for next SW release.



Applications Example (2)

2. Solvent recrystallized surface

• Surface modification and coatings are common

• Evades bulk characterization

• Here: gradient of solvent concentrations, nontrivial property distribution


Solvent Crystallization Example

Spatial Variation

Transition temperature microscopy maps out surface thermal properties after crystallization. Sample was exposed to gradient of high (left) to low (right) solvent concentrations resulting in measurable increase in softening temperature.


Solvent Crystallization Example

Histogram Analysis


Quantifying thermal property distribution as function of surface treatment


Applications Example

3. Pharmaceutical copolymer

• In-situ measurement on pharmaceutical delivery vessel

• Elucidates variation in copolymer blending that is not obvious from other measurements


Pharmaceutical Copolymer

Spatial Variation


AFM does not reveal obvious variation in mixing and the rough surface of the in situ sample (sectioning not an option) presents a challenge to mechanical measurements and phase imaging.

Transition temperature microscopy clearly shows spatial variations in thermal properties indicating variation in copolymer mixing.

Pharmaceutical Copolymer

Histogram Analysis


Systematic, automated execution of literally 100’s of nano-ta measurements provides valid statistics, allowing true quantification of thermal property distribution and therefore mixing variation.

Summary

Quantitative Sample Characterization with TTM

• Transition temperature microscopy reveals nanoscale spatial variation in thermal properties

• Those variations may not be reflected in other (mechanical, electrical) AFM property measurements, so single point nanothermal measurements with location chosen based on an AFM image would miss them.

• Transition temperature microscopy provides fully automated execution of large numbers of nanoscale thermal measurements

• Uncovers new information beyond single point and average quantities: The finite property distribution that is intrinsic to polymers and relevant to their application in many cases.

• Transition temperature microscopy perfectly complements Bruker’s exclusive PF QNM and PFTUNA

• Making Dimension Icon and MultiMode8 the platforms that provide the most complete property information on polymer samples


www.bruker.com

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Quantitative Nanoscale Property Mapping with Automated ... · quantitative local Tm, aiding material ID. In packing applications the outside layers often consist of HDPE and the inside