University of Lancaster

1
Pyrolysis of PMMA
Sample PMMA
Method probe pulsed for 1/2 second at 500
oC
Pyrolysis Crater
Direct MS sampling
Line Scans of Crater
University of Lancaster
Eötvös Graduate Sch.2001 Atomic resolution
methodsfor advanced materials
Micro-thermalanalysis laboratory
2
Evolved Gas Collector (EGC)
EGA Furnace Required
Separation
Identification
University of Lancaster
Eötvös Graduate Sch.2001 Atomic resolution
methodsfor advanced materials
Micro-thermalanalysis laboratory
3
Thermal Desorption inside EGC
Sample Collection Tube
Purge volatiles out
Purge in
HEAT
Collection Tubes may be re-used (100 times)
University of Lancaster
Eötvös Graduate Sch.2001 Atomic resolution
methodsfor advanced materials
Micro-thermalanalysis laboratory
4
EGC Flow Schematic
Primary (Tube) Desorption
Split on Inlet to Cold Trap
Hot Collection Tube
Cold Trap
GC Column
Secondary (Trap) Desorption
Split on Outlet to Trap
Cooling Collection Tube
Hot Trap
GC Column
University of Lancaster
Eötvös Graduate Sch.2001 Atomic resolution
methodsfor advanced materials
Micro-thermalanalysis laboratory
5
EGC For Micro-TA and TGA

• Micro-TA
• The thermal probe is heated to decompose a small
  volume of sample.
• The evolved gases are trapped on a sorbent
  contained in a collection tube
• The collection tube is heated to release the
  gases for analysis by GC/MS

• TGA
• The TGA heats a sample in the EGA furnace to
  decompose the sample
• The evolved gases are trapped on a sorbent
  contained in a collection tube
• The collection tube is heated to release the
  gases for analysis by GC/MS

University of Lancaster
Eötvös Graduate Sch.2001 Atomic resolution
methodsfor advanced materials
Micro-thermalanalysis laboratory
6
Micropyrolysis Mass spectrometry
Off-line Gas-Chromatography/MS
evolved gases trapped in a sampling tube packed
with a mixture of Tenax (molecular sieve) and
Carbopak (activated charcoal) absorbent material
On-line MS
glass capillary transfer line (10 mm I.d, 1 m
long)
hypodermic tubing (0.8 mm o.d., 0.4 mm i.d.),
Mass spectrometer ThermoStar (Pfeiffer Vacuum)
University of Lancaster
sample
heated jacket
Eötvös Graduate Sch.2001 Atomic resolution
methodsfor advanced materials
Micro-thermalanalysis laboratory
7
(b)
(a)
(c)
(d)
University of Lancaster
Eötvös Graduate Sch.2001 Atomic resolution
methodsfor advanced materials
Micro-thermalanalysis laboratory
8
abundance(total ioncurrent, a.u.)
2
3
4
5
retention time (min.)
28
abundance(a.u.)
104
32
78
51
18
University of Lancaster
0 20
40 60
80
100
Eötvös Graduate Sch.2001 Atomic resolution
methodsfor advanced materials
mass number
Micro-thermalanalysis laboratory
9
Direct micropyrolysis MS
Pyrolysis
University of Lancaster
Eötvös Graduate Sch.2001 Atomic resolution
methodsfor advanced materials
Micro-thermalanalysis laboratory
10
Compositional mapping using direct micropyrolysis
MS
PMMA
A 6?6 array of measurements spaced 20 µm apart
were made over the interface between two sheets
of PMMA and PS. The ions corresponding to the
masses of the molecular ions from the respective
monomers m/z 100 (methyl
methacrylate) m/z 104 (styrene) were monitored
and integrated to reconstruct an image showing
the location of each polymer.
PS
20 mm
University of Lancaster
Eötvös Graduate Sch.2001 Atomic resolution
methodsfor advanced materials
Micro-thermalanalysis laboratory
11
Analysis of coated rubber film
Outside
Inner Layer
Mounting Resin
The images on the right show a cross-section
through a perforated rubber film used in medical
and sanitary applications. The film was embedded
in an epoxy resin block and cut using a
microtome. The mounting resin can be seen on the
right of the image and a 5 µm thick surface layer
can be seen between the bulk of the film and the
resin. Localised thermal analysis of this layer
(marked with a cross on the images) is shown
above. The melting point of the polymer suggests
that the outer layer is made of polyethylene. The
bulk of the film is known to be a rubber of some
type. The thermal probe was used to pyrolyse
this region and the evolved gases were analysed
by GC-MS. The resulting chromatogram (top left)
detected butadiene dimer and trimer as well as
styrene. This suggests that the polymer is the
synthetic rubber - poly(butadiene-styrene) -
rather than natural rubber.
Topography
Thermal Conductivity
Eötvös Graduate Sch.2001 Atomic resolution
methodsfor advanced materials
Micro-thermalanalysis laboratory
12
Localised TMA
Sensor (a.u.)
Temperature (oC)
150
50
100

• LTA results from this sample show that the higher
  thermal conductivity phase (upper, yellow area)
  softens around 100C. This then is the
  polystyrene.
• The LTA result for the lower thermal conductivity
  phase (lower, read area) show a softening at
  around 30C lower. This is the contaminant.
  However, this is not enough information in itself
  to identify the contaminant

GC-MS
University of Lancaster
Eötvös Graduate Sch.2001 Atomic resolution
methodsfor advanced materials
Micro-thermalanalysis laboratory
13
Multiple analysis on a contaminated film
Micro-pyrolysis GC-MS analysis
The upper phase is confirmed as polystyrene as
the GC/MS detects mostly styrene monomer. The
lower phase decomposes to yield amethyl styrene.
Indicating that the contamination is from poly
amethyl styrene. This is confirmed as the Tg of
poly amethyl styrene is around 30 C lower than
polystyrene, as observed in the LTA experiments.
Eötvös Graduate Sch.2001 Atomic resolution
methodsfor advanced materials
Micro-thermalanalysis laboratory
14
Localised pyrolysis-GC/MS of leaf
Topographic images of feverfew leaf before (left)
and after (right) pyrolysis
GC/MS data from pyrolysis crater showing
detection of camphor present in leaf nodule.
University of Lancaster
Eötvös Graduate Sch.2001 Atomic resolution
methodsfor advanced materials
Micro-thermalanalysis laboratory
15
Combined thermo-mechanical characterisation
infrared analysis
University of Lancaster
Wavenumber (cm-1)
Eötvös Graduate Sch.2001 Atomic resolution
methodsfor advanced materials
Photothermal IR spectra
Micro-thermalanalysis laboratory
16

• MOTIVATION
• To develop an integrated instrument which uses
  the same probe to carry out chemical, physical
  and morphological analysis of surfaces, with high
  spatial resolution and from precisely the same
  area of the sample.
• The instrument would combine Scanning Probe
  Microscopy with
• Thermal and thermo-mechanical analysis
• Infra-red spectroscopy
• Mass spectrometry
• Applications analysis and characterisation of
  polymers and other organic systems.

University of Lancaster
Eötvös Graduate Sch.2001 Atomic resolution
methodsfor advanced materials
Micro-thermalanalysis laboratory
17
Scanning microanalysis
Deposition of thermal energy and temperature
measurement at the scale of tens of
nanometres New combinations of microscopy with
thermal, spectroscopic and chemical
analysis Novel use of temperature
modulation Applications in polymer science and
biomaterials
Eötvös Graduate Sch.2001 Atomic resolution
methodsfor advanced materials
18
Eötvös Graduate Sch.2001 Atomic resolution
methodsfor advanced materials
Micro-Thermal Analysis
L-TA
Localisedspectroscopy
Imaging(where image contrast is determined by a
thermal or spectroscopic signal)
Measurement localised thermomechanometryAnalysis
L-TMA2
Measurement localised calorimetryAnalysis L-CA3
(d.c.) a.c. L-TMA L-TMA
(d.c.) a.c. L-CA L-CA
Dynamic L-TMA(d.c. or a.c.)
Localised Localised FT-IR4
GC-MS5
H M Pollock, A Hammiche, M Conroy,L Bozec, M J
German Lancaster University
SThM6 SThEM7 CASM8 MASM 9
IS-SM 10 (d.c. thermal images a.c.
thermal images)
with M Reading, D J Hourston, M Song, D M
Price,D Grandy (Loughborough University)
also N J Fullwood, S Rimmer (Lancaster
University.)
andJ MR Weaver, G Mills, H Zhou(Glasgow
University)
and Sheffield University (R H Smallwood)
and N A Burnham,A Kulik, F Oulevey, M Dupas
(EPFL Lausanne)
with acknowledgments toEPSRC, MoD, T A
Instruments, ThermoMicroscopes, Bruker UK
1. Localised Thermal Analysis. 2. Localised
ThermoMechanical Analysis. 3. Localisd
Calorimetric Analysis. 4. Localised Fourier
Transform - Infra-Red spectroscopy. 5. Localised
Gas-Chromatographic Mass Spectroscopy. 6.
Scanning Thermal Microscopy. 7. Scanning Thermal
Expansion Microscopy. 8. Calorimetric Analysis
with Scanning Microscopy (also loosely used to
include L-CA). 9. Mechanothermal Analysis with
Scanning Microscopy (also loosely used to include
L-TMA). 10. Infrared Spectrsoscopy with Scanning
Microscopy. indicates technique under
development, not yet described in the literature.