Silica isotactic poly

In the present paper the silica-isotactic poly (propylene oxide) (iPPO) stem is examined, with untreated silica and trimethylsilyl coated (1.69 trimethylsilyl grovps/100 A ) silica being the nucleating agents. This system was chosen because ... 

Production of materials in which the daughter polymer and the template together form a final product seems to be the most promising application of template polymerization because the template synthesis of polymers requiring further separation of the product from the template is not acceptable for industry at the present stage. Possible method of production of commonly known polymers by template polymerization can be based on a template covalently bonded to a support and used as a stationary phase in columns. Preparation of such columns with isotactic poly(methyl methacrylate) covalently bonded to the microparticulate silica was suggested by Schomaker. The template process can be applied in order to produce a set of new materials having ladder-type structure, properties of which are not yet well known. A similar method can be applied to synthesis of copolymers with unconventional structure. 

Roy M, Nelson JK, MacCrone RK, Schadler LS, Reed CW, Keefe R, Zenger W (2005) Polymer nanocomposite dielectrics—the role of the interface. IEEE Trans Diel Electr Insul 12 629-643 Roy M, Nelson JK, MacCrone RK, Schadler LS (2007) Candidate mechanisms ctmtrolling the electrical characteristics of silica/XLPE nanodielectrics. J Mater Sci 42 3789-3799 Saccani A, Motori A, Patuelli F, Montanari GC (2007) Thermal endurance evaluation of isotactic poly(propylene) based nanocomposites by short-term analytical methods. TREE Trans Diel Electr Insul 14 689-695... 

Particular studies of the IR spectra of homopolymers include isotactic poly(l-pentane), poly(4-methyl-l-pentene), and atactic poly(4-methyl-pentene) [16], chlorinated polyethylene (PE) [17], aromatic polymers including styrene, terephthalic acid, isophthalic acid [18], polystyrene (PS) [19-21], trans 1,4-polybutadiene [22], polyether-carbonate-silica nanocomposites [23], polyhydroxyalkanoates [24], poly(4-vinyl-n-butyl) [25], polyacetylenes [26], polyester urethanes [27], miscellaneous... 

This molecular weight dependence of adsorption leads to fractionation, when the polymer is polydisperse, and exchange can take place freely. Hamori showed that there were significant differences in the adsorption behaviour of atactic and isotactic poly(methyl methacrylate) (PMMA) on silica from acetonitrile. Isotactic PMMA was adsorbed whereas atactic PMMA was not. Miyamoto et aV used this difference to separate isotactic and syndiotactic polymers. Botham and Thies found that isotactic poly(isopropyl acrylate) had a higher fraction of segments in direct contact with the surface than its syndiotactic or atactic equivalents. These experiments show the importance, even if second order, of the orientation and accessibility of the polymers adsorbing groups to the solid surface. 

Fig. 9.67 Plots of Tp against filler content for isotactic poly(propylene oxide) with silica additives, o polymer plus untreated silica polymer plus Me4SiCl treated silica. (From Cole and St. Pierre (247))...

Poly(methyl methacrylate) which has a low heterotactic content compared with isotactic and syndiotactic one was first called a stereoblock polymer, but afterwards it was found that the pdymer often was a mixture of isotactic and ndiotactic polsmaers. The two tactic isomers in the mixture could be recog nized by thin layer chromatography on silica-gel, and recently separated by a competitive adsorption method. ... 

In general, silane-coupling agent is used to modify the surface of nanoparticles to enhance the compatibility of nanoparticles and polymers and to improve the mechanical properties of the resulting nanocomposites. The results of melt blending are often ideal. Bikiaris et al. [138] studied the better dispersion of silica in isotactic polypropylene (iPP) matrix by adding poly(propylene-gra/t-maleic anhydride) copolymer (PP-g-MA) containing 0.6 wt% maleic anhydride as compatibility enhancer. This phenomenon could accoimt for the reaction between the maleic... 

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