Triblock copolymer Pluronic synthesis

Fig. 22 Images and data representing development and application of DLS on a chip a one iteration in the design of a microfluidic DLS fabricated from aluminum with the surface anodized black to reduce surface reflections b image of a microfluidic chip that integrates polymer synthesis with DLS. The machined channels have been covered by a Kapton sheet fixed with adhesive c data for temperature depended micelle formation of polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer (Pluronic P85) at 2% by volume in water. (Derived from [106] with permission)...

The ordered mesoporous silica (pore diameter 6 nm) was kindly provided by Dr. Ulla Junges and was prepared as described previously by G.D. Stucky et al. [15]. A commercial triblock copolymer (Pluronic-123 ) was used in the synthesis process. This polymer contained ethylene oxide/ propylene oxide/ ethylene oxide blocks, which formed a hexagonal mesophase in the synthesis mixture during the hydrolysis of the silicon alkoxides. 

OMC films were later reported by Tanaka et al. (COU-1) through a similar route, but using triblock copolymer Pluronic F127 as a template. For this synthesis, triethyl orthoacetate (EOA) and resorcinol-formaldehyde resins are used as carbon precursors. However, the ordered mesostructure may undergo partial collapse during the high-temperature carbonizations. ... 

SBA-15 is prepared under acidic conditions using polyethylene oxide)-poly(propylenc oxide)-poly(elhylene oxide) triblock copolymers, (EO)n(PO)7o(EO)n, as templates, e.g. Pluronic P123 (n = 20), Pluronic L121 (n - 5) or Pluronic F127 (n = 106). In a typical synthesis [54,551 based on the original procedures [33], 4.0 g of (EO)2o(PO)7o(EO)2o copolymer was dissolved in 150 g of 1.6 M HC1. To this solution was added 8.50 g of TEOS, and the resulting mixture was stirred until TEOS was dissolved. The mixture was heated in an oven for 24 h at 308 K. and then 24 h more at 373 K. under static condition. Silica products were filtered, dried (without washing), and calcined at 823 K. 

One of the few reports on the preparation of mesoporous sihca nanofibers with a soft template other than triblock copolymers of the Pluronic type deals with the synthesis of sihca nanofibers with high aspect ratios containing linear arrays of mesopores by a solution-induced self-assembly process (Fig. 23), as previously reported for thin-film configurations [184]. To this end, PS-fo-PEO diblock copolymers were employed as structure-directing agents in sol solutions containing toluene/ethanol mixtures. For a Dp-value of 35 nm, a single line of mesopores formed, for a Dp-value of 60 nm two parallel rows of mesopores were obtained [185]. 

For technical purposes, triblock copolymers of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) are frequently used (often called poloxamers) [5]. Since approximately 1950, these polymers have been produced on large scale as Pluronics (BASF), Synperonics (ICI), or Genapol, and the self-assembly of these systems is already the subject of a large number of investigations (see e.g., [6-10]). More recently, BCPs have been used as templates for the preparation of ordered nanostructured inorganic materials such as SBA-15 [11-13], or in the synthesis of inorganic nanoparticles [14-23]. 

Supra-molecular self-assembly provide routes for the synthesis of ordered mesoporous carbon molecular sieves via a soft-template route as recently reported by Meng et al. (2006), Huang et al. (2007), Wan et al. (2007) and Xue et al. (2008). As an alternative to hard-template methods, researchers have focused on the synthesis of OMC by a single-step (soft-template) method, which can eliminate the pre-formed silica (hard) template and tedious infiltration steps. In this regard, commercially available amphiphilic triblock copolymers such as pluronics or symper-onics are used for the preparation of OMCs. The synthesis procedure involves the preparation... 

As mentioned above, several types of PMO were synthesized using different templates and different reaction conditions. So, surfactant molecules are an important factor for the synthesis of PMOs and their numerous apphcations. The surfactants employed can be divided as shown in Figure 3.8. Ionic surfactants generally include C12-C18 alkyl chains with trimethylammonium head groups such as CTAB and octadecyltrimethylammonium chloride (OTAC). Nonionic surfactants consist of alkyl polyether type molecules such the Brij surfactants and the triblock copolymers such as Pluronic PI23 and FI27. 

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