Journal of Minerals & Materials Characterization & Engineering, Vol. 11, No.5, pp.519-527, 2012
jmmce.org Printed in the USA. All rights reserved
519
Incorporation of Acetoacetanilide Crystal s in Host PMMA Polymer Matrix
and Characterizations of the Hyb rid Composit e
Sharada G. Prabhu1* and B.Manjunatha Pattabi2
1Dept. of Physics NMAM Institute of Technology, Nitte- 574 110, India.
2Dept. of Materials Science, Mangalore University, Mangalagangotri- 574 199, India.
*Corresponding author e-mail drsha@rediffmail.com.
ABSTRACT
Blending of polymer with organic/inorganic material has given a new direction for developing
novel materials. This is an easy and inexpensive method of modifying various properties of the
individual materials and composites. The aim of the present work is an attempt to incorporate
crystals in polymer host and investigate the effect, on optical properties of the of polymer-
crystal combine. In this paper a novel technique of incorporating inorganic/organic crystal in a
host polymer matrix is reported. Crystals of acetoacetanilide (AA) are grown in the host Poly
Methyl Methacrelate (PMMA) by simple evaporation technique. The scanning electron
micrograph (SEM) studies reveal the growth of Acetoacetanilide crystals of varying sizes and
shapes (flakes) in prepared samples. The results are confirmed by various spectroscopic
characterization studies such as X-ray diffraction (XRD), Fourier Transform Infrared
Spectroscopy (FT-IR) and the UV-Vis spectroscopy. The investigations carried out, show a
change in optical absorption band edge which is attributed due to change in band gap because
of crystal sizes.
Key words: Polymer composite, Optical properties, PMMA-acetoacetanilide composite, Nano
composites, Spectroscopic techniques.
1. INTRODUCTION
Inorganic/organic hybrid materials have attracted increasing interests due to their unique optical
and electronic properties [1-6]. Organic crystals have a narrow transparency and exhibit low
thermal and mechanical resistance. It is established that the polymers are excellent host
520 Sharada G. Prabhu and B.Manjunatha Pattabi Vol.11, No.5
materials. When the nano-particles are embedded or encapsulated in polymer, the polymer acts
as surface capping agent. In addition, the particle size is controlled well within the desired
regime. For application in opto-electronics and electronics, the control of particle size and their
uniform distribution within the polymer is the key to technology based on the nano-particles in
polymers. With these advantages of organic cr ystal and polymer, a new approach, the growth of
organic crystals in polymer matrix has been contemplated. This approach is intended to combine
the properties of both classes of material that is the organic acetoacetanilide and the polymer
PMMA. The authors herein describe the technique of incorporating acetoacetanilide crystals in
PMMA m atrix and to st udy th e effect on the optical propert ies o f acetan ilide crystals due to the
presence of the host PMMA. Various spectroscopic and morphological techniques are useful in
characterizing the nano-composites. In the present paper the preparation, characterisation of the
nano-composites and the effect on optical properties of acetoacetanilide crystals due to the
presence of polymer matrix have been reported. The results are demonstrated by X-ray
diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR) and the UV-Vis
spectroscopy and scanning electron microscopy (SEM) studies.
2. EXPERIMENTAL
2.1 General
Research grade Acetoacetanilide and PMMA from Merck are used to prepare the composites.
Using JEOL JD8p Visual XRD, (with automation software:VISX122D), with cu Kα of -λ=
1.5405 Ǻ (30KV) as a source, the Xrd data has been recorded. The FT-IR spectroscop y analysis
has been carried out using Nicolet AVATAR 330 FT-IR instrument in the wave number range
from 400cm-1 to 4000cm-1. Shimadzu UV-Vis –NIR Spectrophotometer model 3101 PC has b een
emplo yed fo r UV-Vi s m easu rem en ts . JEOL JSM- 5800 LV scanning electron microscope (SEM)
has been used to obtain the microimages of the crystals-polymer composites.
2.2 Preparation of Acetoacetanilide-PMMA Co mp o s it e s
The res earch grad e mate ri als o f aceto acetan ilid e a nd PM MA have be en p rocu red fro m M erk an d
Co. To prepare the PMMA solution 10gm of PMMA is dissolved in 20 ml of double distilled
water. A homogeneous transparent solution of PMMA is obtained after the solution is stirred
continuously at room temperature for 6-8 hours. Then 5 ml of PMMA solution is taken in a
beaker. A saturated solution of acetoacetanilide in chloroform is prepared and filtered. 5 ml of
the filtered solution is mixed with the polymer solution in the beaker and stirred to obtain a
uniform and homogeneous mixture. The blend is obtained by casting the prepared mixture into
a glass petri dish and left for slow evaporation. The resulting thin sheet of acetoacetanilide and
PMMA combined obtained (PM-AA), peels off the petri dish when completely dried. Two
Vol.11, No.5 Incorporation of Acetoacetanilide Crystals 521
samples of the PM-AA blend have been prepared by changing the concentration of
acetoacetanilide ( 10 ml for the first sample and 15 ml for the second sample).
3. RESULTS AND DISCUSSIONS
3.1 XRD Analysis
The Xray diffraction scan is a useful tool to examine the influence of PMMA contents on the
crystalline structure of acetoacetanilide. From the Xrd data recorded, the Xrd spectrograph for
pure PMMA, acetoacetanilide and the composites acetoactanilde-PMMA (PM-AA1 and PM-
AA2) is shown in the Figure1.
From the fig. 1 it is clear that for the prestine acetoacetanilide (AA) the diffraction peaks
observed at 80 (2θ) is due to crystalline structure of acetoacetanilide. Pure PMMA exhibits an
amorphous feature which is characterized by a hump at 16 degrees (2θ) with no sharp peaks.
From the diffraction scans of the samples it is found that
Amorphous hump is prominent in the sample of PM-AA1
A decrease in the relative intensity of peaks appearing at 8 degrees is observed in the
samples of PM-AA1 and PM-AA2. This is attributed to the complexation of the PMMA-
acetoacetanilide blend.
Fig. 1 XRD spectrograph patterns of the composites
522 Sharada G. Prabhu and B.Manjunatha Pattabi Vol.11, No.5
The peaks in Xray diffraction patterns of the PM-AA combined are well in agreement with that
of acetoacetanilide. More peaks are observed in the prepared composite PM-AA2 than the
pristine acetoacetanilide. This may be due to the presence of crystals of bigger sizes and
orientation. In the XRD pattern of PM-AA1, broadening of peaks is seen. This is attributed to
the presen ce of t he cr ystal lites of smal ler si zes. Large inten sit y peaks and the in crease i n 7-8].the
number of peaks observed in the sample of PMAA-2 are correlated to a high degree of
orientation [
3.2 FT-IR Studies
The FT-IR spectrographs of PMMA-AA composites are depicted in Fig. 2.
Fig. 2 FT-IR of PM-AA composites
In the spectra of the PM-AA blend characteristic absorption bands have been identified and
assigned, by comparison with the pristine acetoacetanilide and P MMA. T hes e band s are l ist ed in
the table 1. The details of functional groups of PMMA are a sharp intense peak at 1731 cm-1
appeared due to the presence of ester carbonyl group stretching vibration. The broad peak
ranging from 1260-1000 cm-1 is owing to the bending of C-O stretching vibration. The stretching
vibration is shown by the presence of a broad peak between 3100-2900 cm-1. In spectra of
acetoacetanilide the absorption peak appearing at 1650 cm-1 is due to NH bending and the CH
bending at 1425 cm-1. The IR spectra of the PM-AA composites (Sample 1 and Sample 2) show
the major peaks observed in the individual PMMA and acetoacetanilide, with a small shift and
change in the intensity of the observed peaks . This confirms the presence of acetoacetanilide
crystals in PMMA matrix [9-10].
Vol.11, No.5 Incorporation of Acetoacetanilide Crystals 523
Table 1. Characteristic absorption peaks of PMMA, AA and the composite PMMA-AA
PMMA
Acetoacetanil ide
Composite PM-AA1 and PM-
AA2
Peak
position
cm-1
Peak
Position
cm-1
Bond Assignment
Peak
Position
cm-1
Bond Assignment
752
3300
--OH Stretching
3252
--OH Stretching
987
2950
CH aliphatic str
2948
CH aliphatic str
1650
NH bending
1597
NH Bending
1200
1425
CH bending
1200
(C-O) Str
1723
1723
Str C=O
3.3 UV-Vis Spectral Analysis
The UV-Vis spectral data recorded in the wavelength range from 200-3000 nm for the pure and
PM-AA composites samples are shown in the Fig. 3.
050100 150 200 250 300 350 400450 500 550 600
0
1
2
3
4
5
6
7
[240 nm ]PM- AA2
[360 nm ]
AA
[310 nm ]
PM-AA1
Absorbance [arb.u]
W avelength (nm )
Fig. 3 UV-Vis Absorption spectra of Pure A A an d composi te PM-AA Samples
The strong absorption peaks are evident from the UV absorption spectr a of the samples sho wn in
Fig. 3. A sharp absorption peak is exhibited by acetoacetanilide at 360 nm. The addition of
524 Sharada G. Prabhu and B.Manjunatha Pattabi Vol.11, No.5
acetoacetanilide in the host polymer environment causes the growth of crystals that is realized in
very strong absorption peaks in the PM-AA1 sam ple at 240 nm and a peak at 310 nm in the case
of the PM-AA2 sample. This suggests the blue shi ft in the absorption edge of acetoacetanilide in
the polymer matrix (PM-AA1 and PM-AA2) with respect to bulk ac etoacetanilide. The observed
blue shift indicates decrease in particle size.
Energy band of materials is related to absorption coefficient α by the Tauc relation
(αhν)=A(hν-Eg)n .
Where A is a constant, hν is the photon energy, Eg is the band gap and n is an index which
assumes values ½, 3/2, 2 or 3 d epending on the nature of electronic transition responsible fo r the
absorption. By taking the least index n=1/2 , (αhν)2 and hν in eV, the plot at room temperature
shows a linear behaviour of the absorption edge. The extrapolation of the li near part of the curve
on X axis gives the energy gap. The plot made for the samples (PM-AA1, PM-AA2) is shown in
the Fig. 4.
2.5 3.0 3.54.0 4.55.0 5.56.0 6.5
-50
0
50
100
150
200
250
300
350
400
3.25 eV3.75 eV4.95 eV
PM-AA2
PM-AA1
Bulk AA
(αhν)
2
E
g
eV
Fig . 4 (αhν)2 and hν plot for the samples of PM-AA
The optical energy gap for the samples of PM-AA1 and PM-AA2 is increased to 3.75 eV and
4.95 eV respectively compared to bulk AA, which is 3.25 eV [11-12]. The absorption peaks and
the calculat ed energy gap from the absorption peaks (Fig. 3) and the energy gap from (αhν)2 and
hν plot for the bulk AA and composites of PM-AA1 and PM-AA2 are tabulated in the table. 2
shown below.
Vol.11, No.5 Incorporation of Acetoacetanilide Crystals 525
Table. 2. Absorption peaks and Energy Gap of acetoacetanilide and the composites of PM-
AA.
Samples
Absorption peaks
[λ Vs Absorbance]
Calculated energy
gap E
g
in eV
Energy gap in eV
[(αhν)2 Vs E
g
plot]
AA
360 nm
3.45
3.25
PM-AA1
240 nm
5.175
4.95
PM-AA2
310 nm
4
3.75
3.4 SEM Analysis
The morphology of PM-AA blends has been studied using SEM. The SEM image of PM-AA
sample is shown in Figure 5.
(a)
(b)
Fig. 5 SEM micrograph images of PM-AA1 (a) and PM-AA2(b) composites
526 Sharada G. Prabhu and B.Manjunatha Pattabi Vol.11, No.5
The SEM images of PM-AA1 and PM-AA2 samples are shown in the Figure 5. The images
show pl at e type ( flak es) cr ystals with high crystal density. This is attributed to the agglomeration
of smaller crystals [13] due to high surface to volume ratio of the crystals.
3.5 SHG Meas urement
The second harmonic generation (SHG) measurement using the 1.06 μm pulsed radiation of a
Nd:YAG laser, as a fundamental wave has been carried out. It is demonstrated that PMMA and
acetoacetanilide are both non-linear and has second harmonic conversion efficiency. The blends
of PM-AA1 and PM-AA2 samples do not show an y second order conversion. That is the second
harmonic conversion efficiency is absolutely absent [14] for the composites of PM-AA.
4. CONCLUSIONS
The XRD an alysis reve a l s th at t he P MM A and acet oacetanil i de com po si te h as b een fo rmed . The
studies suggest the effectiveness of crystal size control, by temperature and evaporation
restriction and volume of the solutions used. Characteristic absorption bands from FTIR
spectrum of composites PM-AA are identified and assigned by comparison with the values found
for PMMA and acetoacetanilide individual materials. The presence of absorption peaks of
individual materials in the PM-AA composites confirms the incorporation of acetoacetanilide in
the PMMA host polymer. The change in the UV-visible spectrum is due to complex formation
which can be r efle cted in th e form of chan ge (d ecreas e in PM-AA s amples ) in the op tical ener gy
gap. Morphology of PM-AA shows crystalline domains uniformly shaped. The blend PM-AA
does not show any second harmonic conversion though acetoacetanilide has SHG property.
ACKNOWLEDGEMENTS
The authors gratefully acknowledge the financial support extended by Vishveshwaraya
Technological University, Belgaum, Karnataka, India by funding the project under VTU research
grant scheme. The author thanks Dr. Udaya Bhat and the research scholor Mr. Hebbar, Dept. of
Material s S ci ence an d M et al lu rg y, N ITK, S urat hkal, Karnataka, Indi a fo r p rov id in g XRD fa ci l ity
and Dr. Shyam Prasad, The Scientist, National Institute of Oceanography, Goa, India in helping
to make use of SEM facility. The author sincerely acknowledges Dr. Umesh, Dept of
Physics,NITK, Surathkal, for helping in carrying out laser facility.
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