FTIR - College of Engineering

Fourier Transform Infrared (FTIR) Spectroscopy
Mohammed Alzayer, Chris Clay, Xinhang Shen
Mat E 453, Department of Materials Science and Engineering, Iowa State University, Ames, IA 50011
 PS showed an O-H peak at approximately
cm -1, an aromatic C-H stretch at 3050 cm -1, and
an aliphatic C-H stretch at 2950 cm -1. The O-H
bond may result from the water in the sample. [4]
FTIR spectroscopy is a method that uses
absorption of IR radiation by polar molecules
transitions.[1] Vibrations, in the form of bond
stretching or bending, within polymeric
structure will be observed after excitation by
IR radiation.
Certain frequencies of IR can interact with the
dipole moments of various functional groups
of the polymer. These frequencies are
dependent on the bond strength, length, and
the mass of the atoms in the bonds. IR
spectral transmittance of an unknown polymer
can be collected and correlated to known
values to determine the functional groups
present within the polymer.
Poly(methyl methacrylate)
 PMMA showed an O-H peak at approximately
3400 cm -1, a C-H stretch at 3050 cm -1, C=O
stretch at 1700 cm -1 , and a C-O stretch at
1100 cm -1.[5]
Fig 2. PEG spectral and reference graph
Fig 3. PVC spectral and reference graph
Testing Procedures
Four polymer samples were tested:
1. Polyethylene glycol (PEG)
2. Polyvinyl chloride (PVC)
3. Polystyrene (PS)
4. Polymethyl methacrylate (PMMA)
10-50 mg of each polymer was dissolved in
approximately 1 mL of THF. A few drops of this
solution were placed in a KBr plate. A minute or
so was allowed for the THF to evaporate.
An FTIR spectrum was taken of a clean KBr
plate and used as a background. Afterwards,
the FTIR spectrum of the four polymer samples
were taken with the following parameters:
Scan Range:
400-4600 cm -1
Scan Resolution:
4 cm -1
Scan Number:
Fig 1. Inner chamber of FTIR8000 and the sample holder[1]
 FTIR is a valuable tool to assess the
functional groups present in an organic
compound or polymer.
 Experimental results were consistent with
reference spectra, with the exception of the
2300 cm-1 peak in PVC.
 It is important to keep the IR samples as dry
as possible, as water is IR absorbent and can
affect results.
 KBr plate is used instead of a typical glass
plate as glass is IR opaque (IR light cannot
penetrate glass)
 THF is a good choice of solvent as it can
dissolve all the polymers we tested and
volatilizes easily.
Fig 4. PS spectral and reference graph
Fig 5. PMMA spectral and reference graph
Polyethylene Glycol
 PEG showed an O-H peak at approximately 3400 cm -1, a C-H stretch at 2850
cm -1, and a C-O-C stretch at 1100 cm -1, all of which agreed with the
reference spectrum. [2]
Polyvinyl Chloride
 PVC showed an O-H peak at approximately 3400 cm -1, a C-H stretch at 2850
cm -1 which both of agreed with the reference spectrum [3]. It also showed a
peak at 2300 cm -1, which corresponds to an impurity of some kind.
This laboratory report utilized data from an
actual laboratory performed by our group and
Steven Kmiec , Chenhao Ren, and Khalid
Alamri, supervised by Nathan Podjenski at Iowa
State University.
[1].Mendoza, J. D. Lab 3: FTIR, Iowa State University
[2] National Institute of Science and Technology, Polyethylene
Glycol, 2009
[3] ISU MatE 453/MSE 553 – Lab 3-FTIR
[4] Leon-Bermudez, A, and Salazar, R, Synthesis and
Characterization of the polystyrene, UIS. 2008.
[5] Duan G, Zhang C, Li A, Yang X, Lu L, Wang X,
Preparation and Characterization of Mesoporous Zirconia Made by
Using a Poly (methyl methacrylate) Template. 2008