Characterization of thermal properties of porous microspheres bearing pyrrolidone units
M. Maciejewska
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Porous polymers TG DSC
0
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M. Maciejewska (&) Faculty of Chemistry, Maria Curie-Skodowska University
,
Pl. M. Curie-Skodowskiej 3, 20-031 Lublin
,
Poland
Porous microspheres of glycidyl methacrylate(GMA) cross-linked with trimethylolpropane trimethacrylate (TRIM) were prepared with toluene as porogen by suspension-emulsion polymerization. In order to obtain adsorbents bearing functional groups, the porous methacrylate network was modified by subsequent reaction with pyrrolidone. The thermal behavior of the obtained material was studied using TG and DSC. It was found that the process of modification considerably changed the textural and thermal properties of the polymers.
DBJH
Microstructure
Solubility parameter/(MPa)1/2
Pore diameter/A
Temperature of final decomposition/ C
Initial decomposition temperature/ C
Pyrrolidone
Specific surface area/m2g-1
Temperature of the first maximum rate of
mass loss/ C
Temperature of the second maximum rate
of mass loss/ C
Temperature of 20 % mass loss/ C
Temperature of 50 % mass loss/ C
The parent copolymer, molar ratio of
trimethylolpropane trimethacrylate to
glycidyl methacrylate equal 1:1
TRIM
GMA2
TRIM
GMA3
TRIM
GMA4
TRIM
GMA5
TRIM
GMA1 ? P
TRIM
GMA2 ? P
TRIM
GMA3 ? P
TRIM
GMA4 ? P
TRIM
GMA5 ? P
The parent copolymer, molar ratio of
trimethylolpropane trimethacrylate to
glycidyl methacrylate equal 1:2
The parent copolymer, molar ratio of
trimethylolpropane trimethacrylate to
glycidyl methacrylate equal 1:3
The parent copolymer, molar ratio of
trimethylolpropane trimethacrylate to
glycidyl methacrylate equal 1:4
The parent copolymer, molar ratio of
trimethylolpropane trimethacrylate to
glycidyl methacrylate equal 1:5
The copolymer modified with pyrrolidone,
molar ratio of trimethylolpropane
trimethacrylate to glycidyl methacrylate
equal 1:1
The copolymer modified with pyrrolidone,
molar ratio of trimethylolpropane
trimethacrylate to glycidyl methacrylate
equal 1:2
The copolymer modified with pyrrolidone,
molar ratio of trimethylolpropane
trimethacrylate to glycidyl methacrylate
equal 1:3
The copolymer modified with pyrrolidone,
molar ratio of trimethylolpropane
trimethacrylate to glycidyl methacrylate
equal 1:4
The copolymer modified with pyrrolidone,
molar ratio of trimethylolpropane
trimethacrylate to glycidyl methacrylate
equal 1:5
Pore volume/cm3g-1
Porous polymers possess a number of distinguishing
properties like highly developed internal structure, hydrophobic/
hydrophilic character, and the presence of various functional
groups on the surface. These features make them very
attractive from scientific and industrial point of view.
Consequently, porous polymers are subject of many scientific
investigations and have attracted the attention of producers.
They are used as effective materials for many separation
processes and various kinds of sorbents [19]. They can be
obtained from numerous types of monomers as well as by
modification of copolymers that contain reactive groups
[1018]. One of the convenient routes to incorporate new
functional group into polymer matrix is ring-opening
reaction of oxirane ring with required agent. Widespread
practice is reaction of epoxy group with amines [1922].
This process leads not only to the introduction of the
active pendant group to the network but also to the changes
in the textural and thermal properties of the newly obtained
materials.
Recently, we have described the synthesis and some
properties of porous microspheres of glycidyl methacrylate
(GMA) cross-linked with trimethylolpropane
trimethacrylate (TRIM) modified with pyrrolidone [23].
It was of interest to investigate in detail, how the process
of modification influences the thermal resistance of the
newly formed copolymers. To achieve this goal, a set of ten
copolymers was synthesized. The thermal properties of the
parent and modified copolymers were evaluated by the
means of TG and DSC. Additionally, the textural
characterization was carried out on the basis of the
low-temperature nitrogen adsorption on the studied copolymers.
Experimental
2,3-Epoxypropyl methacrylate (GMA) and TRIM (Sigma
Aldrich, Steinheim, Germany) were washed with 5 %
aqueous sodium hydroxide in order to remove inhibitors.
Pyrrolidone bis(2-ethylhexyl) sulfosuccinate sodium salt
(DAC,BP) and a,a0-azoisobutyronitrile (AIBN), purchased
from Fluka AG (Buchs, Switzerland), were used without
purification. Toluene, n-dodecane, acetone, and methanol
(reagent grade) were from POCh (Gliwice, Poland).
Preparation of the GMATRIM microspheres
Copolymerization was performed in an aqueous suspension
medium. In a typical experiment, 195 mL of distilled water
and 2.2 g of bis(2-ethylhexyl)sulfosuccinate sodium salt
were stirred for 2 h at 80 C in order to dissolve the
surfactant. Then the solution containing 15 g of monomers
(GMA and TRIM), and 0.2 g of a,a0-azoisobutyronitrile
dissolved in 22.5 mL of toluene was prepared and added
while stirring to the aqueous medium. Molar ratios of
GMA (...truncated)