7 Outlook
Organic/inorganic nanocomposites prepared by in situ polymerization methods
have received extensive attention in recent years. Unlike microscale fillers, nanoscale fillers can offer excellent properties to a polymer matrix. Nanosized filler,
with a few weight percent in the reinforced polymer nanocomposites, strongly
influences the macroscopic properties of the polymer. The resultant polymer
nanocomposites can significantly improve some of their properties, such as higher
heat distortion temperatures, enhanced flame resistance, increased modulus, better
barrier properties, reduced thermal expansion coefficient, and altered electronic and
optical properties.
A wide variety of polymer/clay nanocomposites can be synthesized by in situ
coordination polymerization methods, which gives the advantage of controlled
molecular weight of the polymer nanocomposite. In the case of late transition
metal-based coordination polymerization, the process is tolerant to the polar groups
or to a little moisture in the clay or catalytic system. This moisture sensitivity can
also be overcomed by treating the excess MAO or by in situ formation of MAO
using TEA, TMA, or TIBA on the surface of clay, clay–MgCl 2 , or clay–silica
hybrid material.
Regarding synthesis of polyolefin nanocomposites with wider applications,
copolymerization of ethylene with other olefinic monomers, including higher
α-olefins and polar comonomers still needs to be investigated in more detail. To
make the present coordination polymerization-induced formation of polyolefin/clay
nanocomposites applicable to industrial bulk or slurry processes, more efforts are
needed with regard to the preparation of catalytic species with regular morphology,
prevention against re-aggregation or stacking recovery of the already intercalated or
exfoliated MMT sheets, and the rheological properties of the nanocomposites with
various structures and different MMT loadings.
References
1. Friedlander HZ (1963) Spontaneous polymerization in and on clays. ACS Polym Preprints
4:300–306
2. Bittles JA, Chaudhuri AK, Benson SW (1964) Clay-catalyzed reactions of olefins.
I. Polymerization of styrene. J Polym Sci A2:1221–1231
3. Bittles JA, Chaudhuri AK, Benson SW (1964) Clay-catalyzed reactions of olefins. II. Catalyst
acidity and mechanisms. J Polym Sci A2:1847–1862
4. Kusnitsyna TA, Ostrovskaya LK (1967) Catalytic activity of acid alumina-silicates in the
styrene polymerization reaction. Vysokomolekulyarnye Soedineniya Seriya A9:2510–2514
5. Solomon DH, Rosser MJ (1965) Reactions catalysed by minerals. I. Polymerization of
styrene. J Appl Polym Sci 9:1261–1271
6. Usuki AKY, Kawasumi M, Okada A, Fukushima Y, Kurauchi T et al (1993) Synthesis of
nylon 6-clay hybrid. J Mater Res 8:1179–1184
Polyolefin/Layered Silicate Nanocomposites Prepared by In Situ Polymerization
333
Organic/inorganic nanocomposites prepared by in situ polymerization methods
have received extensive attention in recent years. Unlike microscale fillers, nanoscale fillers can offer excellent properties to a polymer matrix. Nanosized filler,
with a few weight percent in the reinforced polymer nanocomposites, strongly
influences the macroscopic properties of the polymer. The resultant polymer
nanocomposites can significantly improve some of their properties, such as higher
heat distortion temperatures, enhanced flame resistance, increased modulus, better
barrier properties, reduced thermal expansion coefficient, and altered electronic and
optical properties.
A wide variety of polymer/clay nanocomposites can be synthesized by in situ
coordination polymerization methods, which gives the advantage of controlled
molecular weight of the polymer nanocomposite. In the case of late transition
metal-based coordination polymerization, the process is tolerant to the polar groups
or to a little moisture in the clay or catalytic system. This moisture sensitivity can
also be overcomed by treating the excess MAO or by in situ formation of MAO
using TEA, TMA, or TIBA on the surface of clay, clay–MgCl 2 , or clay–silica
hybrid material.
Regarding synthesis of polyolefin nanocomposites with wider applications,
copolymerization of ethylene with other olefinic monomers, including higher
α-olefins and polar comonomers still needs to be investigated in more detail. To
make the present coordination polymerization-induced formation of polyolefin/clay
nanocomposites applicable to industrial bulk or slurry processes, more efforts are
needed with regard to the preparation of catalytic species with regular morphology,
prevention against re-aggregation or stacking recovery of the already intercalated or
exfoliated MMT sheets, and the rheological properties of the nanocomposites with
various structures and different MMT loadings.
References
1. Friedlander HZ (1963) Spontaneous polymerization in and on clays. ACS Polym Preprints
4:300–306
2. Bittles JA, Chaudhuri AK, Benson SW (1964) Clay-catalyzed reactions of olefins.
I. Polymerization of styrene. J Polym Sci A2:1221–1231
3. Bittles JA, Chaudhuri AK, Benson SW (1964) Clay-catalyzed reactions of olefins. II. Catalyst
acidity and mechanisms. J Polym Sci A2:1847–1862
4. Kusnitsyna TA, Ostrovskaya LK (1967) Catalytic activity of acid alumina-silicates in the
styrene polymerization reaction. Vysokomolekulyarnye Soedineniya Seriya A9:2510–2514
5. Solomon DH, Rosser MJ (1965) Reactions catalysed by minerals. I. Polymerization of
styrene. J Appl Polym Sci 9:1261–1271
6. Usuki AKY, Kawasumi M, Okada A, Fukushima Y, Kurauchi T et al (1993) Synthesis of
nylon 6-clay hybrid. J Mater Res 8:1179–1184
Polyolefin/Layered Silicate Nanocomposites Prepared by In Situ Polymerization
333