Transcript Effect of Hydrogen Bonding

Effect of Hydrogen Bonding on
the Copolymerization of Styrene with
Methacrylic Acid
ALİ DURAN
POLYMER TECHNOLOGY
EXPERIMENTAL PART
1. MATERIALS
 Distillation of ST and MAA under
reduced pressure,
 Purification of Benzene and Dioxane,
 Preparation of TMA according to the
literature,[17]
 Recrystalization of AIBN from
methanol,
 Chloroform was passed through activated
alumina,
EXPERIMENTAL PART
2. PREPARATION OF POLYMERS
 The copolymerizations of ST and MAA were carried
out at 600C with AIBN as an initiator,
 The copolymers were precipitated three times from
benzene solution with methanol and dried over
diphosphorus pentoxide in vacuum for several days,
 Hydrolysis of Poly(ST-co-TMA) was dissolved in
benzene, and methanol and conc. HCl were added,
EXPERIMENTAL PART
The solution was refluxed for 3 hours,
The solvent was removed by distillation
under reduced pressure, and the residue was
dissolved in a small amount of benzene and
precipitated into methanol,
The completed hydrolysis of the TMA
moiety was ascertained by FT-IR spectra,
EXPERIMENTAL PART
3. CHARACTERIZATION OF POLYMERS
 Gel permeation chromotography (GPC) was
performed,
 The weight average molecular weights were
estimated by using the calibration curve of
poly(ST) standards,
 The contents of MAA in the copolymers were
determined by titration in a benzene-methanolsodium methoxide system,
EXPERIMENTAL PART
4. MEASUREMENT OF FT-IR SPECTRA AND
ANALYSIS
 FT-IR spectra were measured with a Perkin
Elmer 1720 FT-IR spectrometer,
 The hydrogen bonds of carboxyls in the
copolymers were analyzed from the C=O
streching bands observed around 1695 and 1735
cm-1,
 The molar absorption coefficients at the band
maxima were estimated by lineer regression,
EXPERIMENTAL PART
 The proportion (Pas) of associated
carboxyls to total carboxyls was estimated from
the band intensities (A1695 and A1735) and the
molar absorption coefficients,
EXPERIMENTAL PART
5. VISCOSITY MEASUREMENTS
 The viscosities of the polymer solutions in
chloroform were measured with an
Ostwald viscometer at 250C,
 The intrinsic viscosities were estimated
from the data of the solutions by the
method of single point determination,
EXPERIMENTAL PART
6. NMR MEASUREMENTS

1H
NMR spectra were measured at 400
MHz,
 The measurements were performed on 10
wt.-% solutions in deuterated
dimethylsulfoxide (DMSO-d6) at 1400C,
 Tetramethylsilane was used as the
reference,
RESULTS AND DISCUSSION
 The Pas values of the
copolymers prepared in
benzene are greater than
those of the copolymers
prepared in dioxane,
 This suggests that the
hydrogen bonding
between MAA monomers
is closely related to the
formation of highly
associating copolymers,
RESULTS AND DISCUSSION
 The difference in the
association ability
between copolymers
having the same
composition means that
the copolymers differ
from one another in their
microstructure.
RESULTS AND DISCUSSION
 The degree of shrinkage of
polymer chains by intramolecular
association is closely related to
the location of the associating
functional groups in the polymer
chain,
 The degree of shrinkage is
related to the position of
associating MAA segments in the
copolymer chain,
 The degree of shrinkage of the
copolymers by intramolecular
association was examined by the
ratio (g)
RESULTS AND DISCUSSION
 The relationships between the g
value and the number of
associations (Nas) by
intramolecular association are
shown in Figure 4,
 The g values decreased almost
linearly with an increase in the
Nas value,
 The near linear relationships
mean that association occurs
mainly between MAA segments
closely located in the polymer
chain.
RESULTS AND DISCUSSION
 The monte-Carlo
simulation of the
copolymerization was
performed in order to
ascertain the effects of
the supposed intrachain
reaction on the
copolymerization and
the sequences of the
formed copolymers.
RESULTS AND DISCUSSION
 The apparent reactivity of
MAA increased by the
contribution of the intrachain
reaction, and the features of
the known solvent effects were
qualitatively reproduced,
although the degree of
increase was rather small
compared to the known
solvent effects.
RESULTS AND DISCUSSION
 The underestimation of the
solvent effects may be due
to the ‘bootstrap’ effect,
which may decrease the
concentration of MAA
monomers in the
macroradical in the
distribution between
macroradicals and
hydrogen-bonding solvents,
RESULTS AND DISCUSSION
CONCLUSION
 A close relationship between the hydrogen bond of
hydrogen-bonding monomers in the
copolymerization and the association properties of
the prepared copolymers was found.
 It was supposed that the intrachain reaction of the
end radicals with MAA monomers hydrogenbonding to MAA segments in the growing
macroradicals forms copolymers with sequences
and configurations favorable for intrachain
association.
CONCLUSION
The copolymerizations at lower monomer
concentrations in benzene gave copolymers
with exceedingly higher intramolecular
association ability compared to the
copolymerizations in dioxane and at higher
monomer concentration in benzene.