Two preparation methods are described [57], in which the monomer, methylacrylate, is the starting material.
In the first, Fe(CO) 5 and distilled methylacrylate were sonicated as a mixture
of neat liquids. During the sonication, the glass cell was wrapped in a dark cover
to avoid photopolymerization. After 30 min of irradiation (avoiding degradation) at
a dry ice–acetone temperature, the solution was treated with cold methanol, precipitating the polymeric product. In the second method, amorphous iron nanoparticles were prepared following Suslick’s recipe [6]. The dried amorphous iron
powder was introduced into the sonication cell without exposure to air and mixed
with a solution of the methylacrylate monomer in N,N
0 -dimethylformamide
(DMF). The concentration of the methylacrylate solution in DMF was 5.5 M. 35 ml
of this solution was mixed with various amounts of amorphous iron nanoparticles. The amounts of the iron powder were changed from 50 mg to 200 mg.
The chemical analysis of polymers prepared by the two methods is presented in
Table 6.1.
The percentages presented in Table 6.1 are weight percentages of the iron in the
mixture of Fe(CO) 5 and methylacrylate (first row, first column) in the starting solution. The second row presents the weight percent of iron in the starting solution
(first column) and in the composite material (second column). The results according to Table 6.1 indicate that it is easier to introduce the iron by starting with
amorphous iron as the precursor rather than Fe(CO) 5 . Molecular weights of the
polymers are presented in Table 6.2.
When the molecular weight (M w ) values of the polymeric composite material are
compared with those of the polymeric product obtained from the irradiation of the
monomer alone at the same irradiation time and concentration of the monomer,
a 20% reduction is detected. This can be ascribed to the influence of the iron on
the growth of the polymer. This would mean that the recombination of the iron
Tab. 6.1. The concentration of iron in polymers prepared by the two methods.
Starting Materials
Fe in starting
solution product
(%)
Fe in final (%)
Methylacrylate Fe(CO) 5
0.5
0.56
Methylacrylate (DMF) – 50 mg amorphous Fe
0.3
5.4
Tab. 6.2. Molecular weights of polymers obtained from various sonications.
Monomer
Sonication time
(min)
M w (g mol
C1
)
Methylacrylate
30
134,000
Methylacrylate in DMF
90
1,760,000
Methylacrylate in DMF containing 50 mg Fe
90
142,000
6.1 Sonochemistry 125
In the first, Fe(CO) 5 and distilled methylacrylate were sonicated as a mixture
of neat liquids. During the sonication, the glass cell was wrapped in a dark cover
to avoid photopolymerization. After 30 min of irradiation (avoiding degradation) at
a dry ice–acetone temperature, the solution was treated with cold methanol, precipitating the polymeric product. In the second method, amorphous iron nanoparticles were prepared following Suslick’s recipe [6]. The dried amorphous iron
powder was introduced into the sonication cell without exposure to air and mixed
with a solution of the methylacrylate monomer in N,N
0 -dimethylformamide
(DMF). The concentration of the methylacrylate solution in DMF was 5.5 M. 35 ml
of this solution was mixed with various amounts of amorphous iron nanoparticles. The amounts of the iron powder were changed from 50 mg to 200 mg.
The chemical analysis of polymers prepared by the two methods is presented in
Table 6.1.
The percentages presented in Table 6.1 are weight percentages of the iron in the
mixture of Fe(CO) 5 and methylacrylate (first row, first column) in the starting solution. The second row presents the weight percent of iron in the starting solution
(first column) and in the composite material (second column). The results according to Table 6.1 indicate that it is easier to introduce the iron by starting with
amorphous iron as the precursor rather than Fe(CO) 5 . Molecular weights of the
polymers are presented in Table 6.2.
When the molecular weight (M w ) values of the polymeric composite material are
compared with those of the polymeric product obtained from the irradiation of the
monomer alone at the same irradiation time and concentration of the monomer,
a 20% reduction is detected. This can be ascribed to the influence of the iron on
the growth of the polymer. This would mean that the recombination of the iron
Tab. 6.1. The concentration of iron in polymers prepared by the two methods.
Starting Materials
Fe in starting
solution product
(%)
Fe in final (%)
Methylacrylate Fe(CO) 5
0.5
0.56
Methylacrylate (DMF) – 50 mg amorphous Fe
0.3
5.4
Tab. 6.2. Molecular weights of polymers obtained from various sonications.
Monomer
Sonication time
(min)
M w (g mol
C1
)
Methylacrylate
30
134,000
Methylacrylate in DMF
90
1,760,000
Methylacrylate in DMF containing 50 mg Fe
90
142,000
6.1 Sonochemistry 125