Block copolymer stabilizer

Table 9.1 Activity of block copolymer-stabilized Pd colloids in selective hydrogenation of 1,3-cyclohexadiene.

Figure 10.1. Schematic drawing of an amphiphilic block copolymer stabilizing the oil-water interface.

Meier MAR, FUali M, Gohy J-F, Schubert US (2006) Star-shaped block copolymer stabilized palladium nanoparticles for effident catalytic Heck cross-coupling reactions. J Mater Chem 16 3001-3006... 

This model was used in dispersion polymerization to predict the size of polymer particles stabilized through grafting on hydrophilic polymers such as PVPo. It provides a reasonable description of, for example, PVPo-stabilized polymerization of styrene in polar solvents. The present model does not apply to other types of dispersion polymerization where grafted comb or block copolymer stabilizers are active. The key controlling parameters in this model are the availability of graft and the minimum and maximum coverage, Qmin and Qmax. 

Dispersion Polymerization. AB block copolymer stabilizers were prepared using anionic polymerization techniques by the addition of hexamethylcyclotrisiloxane to "living" polystyryl-... 

As an example, iron(III) chloride hexahydrate was melted by heating above 37°C and miniemulsified in the continuous phase (IsoparM, cyclohexane, etc.) to a stable miniemulsion using at least 5 wt% (with respect to salt) of the block copolymer stabilizer. Decreasing the temperature leads to nanoscopic salt crystals dispersed in a continuous oil phase. The average size of these particles is about 350 nm, a typical number for inverse dispersions. 

The interaction potentials described in previous sections for adsorbing homopolymer and terminally anchored layers in good solvents clearly indicate the ability of polymers to stabilize colloidal dispersions against flocculation due to van der Waals dispersion forces. Indeed, the practice preceeded the analyses by centuries in some cases and decades in others, since the use of adsorbing polymers dates to ancient times, and block copolymer stabilizers emerged from industrial laboratories in the 1960s (Napper, 1983). 

Johnson, B.J. (2003). Flash nanoprecipitation of organic actives via confined micromixing and block copolymer stabilization. Ph.D. dissertation, Princeton University, Princeton, NJ. 

Hayward R, Utada A, Dan NR, Weitz D (2006) Dewetting instability during the formation of polymersomes from block-copolymer-stabilized double emulsions. Langmuir 22(10) 4457-4461... 

Wang, C.-W. and Moffltt, M. G. (2004) Surface-Tunable Photoluminescence from Block-Copolymer Stabilized Cadmium Sulfide Quantum Dots. Langm., 20,11784-96. 

Rahme, K., Vicendo, P, et al. A Simple Protocol to Stabilize Gold Nanoparticles using Amphiphilic Block Copolymers Stability Studies and Viable Cellular Uptake. Chemistry - A European Journal, 5(42), 11151-11159 (2009). 

Block copolymer dispersants were also synthesized using PDMS as the stabilizer and PS as the anchor, as shown in Figure 11 (27). These block copolymers were not soluble in pure CO2 under supercritical conditions (65°C, 340 bar) but required the presence of styrene as a cosolvent. Similar to the PS/poly(FOA) block copolymer stabilizer, polymerizations with added stabilizers resulted in... 

Gindy, M.E., Panagiotopoulos, A.Z., and Prud homme, R. (2008) Composite block copolymer stabilized nanoparticles simultaneous encapsulation of organic actives and inorganic nanostructures. Langmuir, 24,83 90. 

Johnson, B.K., Saad, W., and Prud homme, R. (2006) Nanoprecipitation ofpharmaceuticals using mixing and block copolymer stabilization. ACS Symposium Series, 924,278-291. 

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