Copolymer Pluronics

Polyoxyethylerie-polyoxypropylene block copolymers (Pluronics or Poloxamer) 29.0... 

Time-resolved in situ Small Angle Neutron Scattering (SANS) investigations have provided direct experimental evidence for the initial steps in the formation of the SBA-15 mesoporous material, prepared using the non-ionic tri-block copolymer Pluronic 123 and TEOS as silica precursor. Upon time, three steps take place during the cooperative self-assembly of the Pluronic micelles and the silica species. First, the hydrolysis of TEOS is completed, without modifications of the Pluronic spherical micelles. Then, when silica species begin to interact with the micelles, a transformation from spherical to cylindrical micelles takes place before the precipitation of the ordered SBA-15 material. Lastly, the precipitation occurs and hybrid cylindrical micelles assemble into the two-dimensional hexagonal structure of SBA-15. 

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)...

Figuer 9.1 Schematic illustration of various polycation structures used for preparation of polyplexes (A) linear (PEI) (B) randomly branched (PEI) (C) dendrimer (PAMAM) (D) block and graft copolymers (Pluronic-g-PEI and PEO-g-PEI modified with a targeting moiety by one PEO end) (E) nanoscale cross-linked network (PEO-c7-PEI). 

Recently, a new class of inhibitors (nonionic polymer surfactants) was identified as promising agents for drug formulations. These compounds are two- or three-block copolymers arranged in a linear ABA or AB structure. The A block is a hydrophilic polyethylene oxide) chain. The B block can be a hydrophobic lipid (in copolymers BRIJs, MYRJs, Tritons, Tweens, and Chremophor) or a poly(propylene oxide) chain (in copolymers Pluronics [BASF Corp., N.J., USA] and CRL-1606). Pluronic block copolymers with various numbers of hydrophilic EO (,n) and hydrophobic PO (in) units are characterized by distinct hydrophilic-lipophilic balance (HLB). Due to their amphiphilic character these copolymers display surfactant properties including ability to interact with hydrophobic surfaces and biological membranes. In aqueous solutions with concentrations above the CMC, these copolymers self-assemble into micelles. 

Li and Caldwell used S-FFF to determine the mass and surface concentration of absorbed PEO-PPO-PEO triblock copolymers (Pluronics) onto PS latex standards [185]. Fl-FFF was found to work equally well for this problem. As experimental absorption problems are widespread and extremely relevant, it is expected that FFF will play an important future role in such studies, as long as the mass of the absorbed layer is sufficiently high. 

These inerts are mostly polymeric or oligomeric in nature and can be both nonionic and anionic. They have multiple binding / interaction sites to the interface, so that a displacement becomes improbable. Several materials have been made available to the industry [6d,ej. The chemistries range from sulfonic condensates (Morwet) or lignin sul-phonates (Reaxx) to EO-PO-block copolymers (Pluronics), comb graft polymers, acrylate based copolymers or various other block copolymers. 

The use of polymeric micelles to deliver drugs to the central nervous system (CNS) has been reviewed recently. One strategy employs polymers with specific ligands to enhance transport across the blood-brain barrier (BBB), via interaction with receptor proteins on the BBB. Many of the polymers employed are derivatives of PEO- PPO PEO block copolymers (Pluronics). 

Attwood, D. Collett, J.H. Tait, J.C. The micellar properties of the poly(oxyethylene)-poly(oxypropylene) copolymer Pluronic FI27 in water and electrolyte solution. International Journal of Pharmaceutics 1985, 26, 25-33. 

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. 

PEO-PPO-PEO triblock copolymers (Pluronics or Poloxamers) form reversible physically cross-linked hydrogels under certain concentration range and temperature. The use of this system in tissue engineering is scarce because of its inability to degrade. Di- or tri-block copolymers of PEG with PLA have been developed to overcome this problem. Multiple blocks of PEG and PLA, synthesized by condensation reaction of L-lactic acid in the presence of succinic acid. 

Stable W/C macroemulsions for either liquid or supercritical CO2 have been formed with the surfactants (PFPE 000 )2 Mn2+ (13), PFPE COO-NH4 " (672-7500 MW) (9), and block copolymer pluronic surfactants composed of poly(propylene oxide) (PPO) and poly(ethylene oxide) (PEO) (51), PDMS and poly(acrylic acid) (PAA), or poly(methacrylic acid) and PDMS and PEO (2). The emulsions may be formed by shear through a 130 gm capillary or commercial homogenizer. The ratio of water to CO2 has been varied from 9 1 to 1 9 with less than 1 wt % surfactant. W/C microemulsions, on the other hand, contain less than 5 wt % water for this level of surfactant owing to the much higher interfacial area. 

Secondary O/W emulsifiers High-HLB surfactants or polymers may be used, such as Tween 20, polyethylene oxide-polypropylene oxide (PPO) block copolymers (Pluronics) may be used. 

More recently, investigations of the solution behavior of block copolymers of the polyethylene oxide) (PEO)-poly(propylene oxide) (PPO) type have been extended to nonaqueous, polar solvent systems. The block copolymer Pluronic... 

The use of synthetic emulsifiers gave different results for instance, the use of 1% (w/w) of the polyoxyethylene-polyoxypropylene block copolymer Pluronic PE... 

With the purpose of conferring thermosensitivity to chitosan-based hydrogels. Park et al. proposed the grafting of carboxylic acid-terminated poly(ethylene oxide-h-propylene oxide) block copolymer (Pluronic) onto the primary amine of chitosan, mediated by EDC coupling agent [102]. With the same purpose, Wang et al. grafted poly(N-isopropyl acrylamide) (NiPAM) chains onto chitosan by the copolymerization of acrylic acid-derivatized chitosan and N-isopropylacrylamide (NIPAAm) in aqueous solution [103]. 

Rassing, J. and Attwood, D., 1983. Ultrasonic velocity and hght-scattering smdies on the polyoxyethylene-polyoxypropylene copolymer Pluronic F127 in aqueous solution. Int. J. Pharm., 13, 47-55. 

On the basis of the unit-cell size and pore diameter, one can estimate that the distance between adjacent spherical mesopores of the LP-FDU-12 sample calcined at 450°C was 6 nm. This distance is likely to correspond to the pore entrance length. Given that the pore entrance diameter (in the narrowest point) was 2 nm, the pore entrance length-to-diameter ratio was 3 1, and thus one can readily envision that the reduction of the pore entrance diameter through the thermal treatment would eventually lead to the closure of the entrance. The obtained ordered closed-pore silicas were white powders. It is clear that the block copolymer template was removed without the formation of the carbon residue, which was observed in an ordered closed-pore silica templated by PEO-PS copolymer. Pluronic (PEO-PPO-PEO) copolymers usually decompose at relatively low temperatures, so they may be inherently more convenient than PEO-PS copolymers, whose PS block has an appreciable tendency to carbonize. 

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