PMMA/silica composites

Yeh, J. M., C. J. Weng, K. Y. Huang, and C. C. Lin, 2006. Effect of baking treatment and materials composition on the properties of bulky PMMA-silica hybrid sol-gel materials with low volume shrinkage. J Appl Polym Sci 101 1151-59. 

Figure 3. Plot of the molar mass (MM gjmol) as a function of the retention volume (mL). The calibration curves for narrow PMMA standards in a mixed eluent (toluene-methanol) at various compositions. The sorbent was bare silica gel with 100-nm pores.

Special considerations according to inverse gas chromatography, PMMA is considered acidic, it therefore interacts better with fillers which have basic character PMMA was found to form thick layers adsorbed on the surface of glass, titanium dioxide, silica and mica (1400, 51-70, 17, and 110 nm thick, respectively) very strong interaction between polymer and titanium dioxide caused formation of brittle coatings which failed prematurely formation of clay/K2S2O complex is a reason for catalytic effect on polymerization, the composites formed have better thermal stability, hardness, and compression strength ""... 

Density of transparent silica-PMMA composites as a function of PMMA (Reproduced from Ref. 41.)... 

Figure 13 Fluorescence emission spectrum of europium-doped silica-PMMA composite.

Figure 14 Large monolithic dye-doped silica-PMMA composites. (Courtesy of MATECH, Westlake Village, CA.)...

The materials which have been mentioned here so far are predominantly shaped in planar films of hierarchical order. However, the synthesis of hierarchically structured particles is also highly desirable, as they might be further processed and used for the preparation of composite porous materials. Wu et al. showed the synthesis of raspberry-like hollow silica spheres with a hierarchically structured, porous shell, using individual PS particles as sacrificial template [134]. In another intriguing approach by Li et al. [135], mesoporous cubes and near-spherical particles (Fig. 10) were formed by controlled disassembly of a hierarchically structured colloidal crystal, which itself was fabricated via PMMA latex and nonionic surfactant templating. The two different particle types concurrently generated by this method derive from the shape of the octahedral and tetrahedral voids, which are present in the template crystal with fee lattice symmetry. 

After these initial considerations, the complete analysis of a number of diblock copolymers of styrene and methyl methacrylate shall be discussed in detail. The poly(styrene-ftlodc-methyl methacrylate)s under investigation were prepared via anionic polymerization of styrene and subsequent polymerization of methyl methacrylate, varying molar mass and composition (B1-B3). The polystyrene precursors (P1-P3) were isolated and characterized separately. As the PMMA block is the more polar block in the block copolymer, a polar (silica gel) column was chosen for establishing the critical point of PMMA. According to case (1) in Fig. 14, the PS block is then eluted in the SEC mode. The behavior of PMMA of different molar masses on silica gel Si-100 in eluents comprising methylethylketone and cyclohexane is shown in Fig. 15A [37]. 

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