Polyfpropylene oxide

From ref. 116. The Q range is centered at 0.5 A Abbreviations PDMS, poly(dimethylsiloxane) PPO, polyfpropylene oxide) PTHF, poly(tetrahydrofuran) PEO, polyfethylene oxide) PIB, polyisobutylene. 

Problem 2.10 Explain why polypropylene of relatively high molecular weight is optically inactive despite having an asymmetric center at every other carbon, while, on the other hand, polyfpropylene oxide) is optically active. 

In surface emulsion treaters (e.g. oil-water separators), the occurrence of foams is generally undesirable and any such foams will have to be broken, either downhole or at the surface [12, 15). Oilfield-produced water may also foam, which can also cause problems in handling and in gas separation. This is usually dealt with by adding antifoaming or defoaming chemicals such as silicones, polyglycol esters or polymers such as polyfethylene oxide)—polyfpropylene oxide) block copolymers. 

On the other hand, polyfpropylene oxide) (PPO) is hydrophilic at low temperatures and hydrophobic at high temperatures. Thus, water is a good solvent for PPO below approximately 15 °C, whereas at higher temperatures aggregates are formed in aqueous solutions. With blocks of PEO and blocks of PPO combined into single polymer chains, one can therefore expect amphiphilic characteristics and aggregation phenomena. It has to be emphasized that, for this triblock copolymer, the outer PEO blocks are more water soluble than the inner PPO blocks, and thus the mechanism of gel formation will be different from the above mentioned triblock copolymers and is still a matter of discussion. 

From their DSC studies on aqueous solutions of polyfpropylene oxide) and Pluronic 94, Hvidt et al. [393] concluded that endotherms are present in both cases at around the same temperature, whereas both endothermic effects amount to 98 8 J/(g of PPO). This shows that the PPO blocks in Pluronic 94 are involved in the micelle formation, whereas the poly(ethylene oxide) blocks... 

Schilling, F. C., Tonelli, A. E. 1986. Carbon-13 NMR determination of polyfpropylene oxide) microstructure. Macromolecules 19 1337-1343. 

Lee S, Iten R, Muller M, Spencer ND. Influence of molecular architecture on the adsorption of polyfethylene oxide)-polyfpropylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) on PDMS surfaces and implications for aqueous lubrication. Macromolecules 2004 37 8349-8356. 

SCHEME 24.12 Syndiotactic polyfpropylene oxide) prepared with 10. 

Ugur, N. Alyuruk, K. Stereoregularity of fractionally crystallized polyfpropylene oxide) samples by carbon-13 NMR spectroscopy. J. Poly. Sci., Part A Polym. Chem. 1989, 27,1749-1761. 

Chisholm, M. H. Navarro-Llobet, D. NMR assignments of regioregular polyfpropylene oxide) at the triad and tetrad level. Macromolecules 2002, 55, 2389-2392. 

Polyether Soft Segments. Polyftetramethylene oxide), polyfethylene oxide) and polyfpropylene oxide) and their random and block copolymers are most often used as soft segments. 

The macromolecular surfactants possess considerable advantages for use in cosmetic ingredients. The most commonly used materials are the ABA block copolymers, with A being poly(ethylene oxide) and B polyfpropylene oxide) (Pluronics). On the whole, polymeric surfactants have much lower toxicity, sensitization and irritation potentials, provided they are not contaminated with traces of the parent monomers. As will be discussed in the section on emulsions, these molecules provide greater stability and in some cases they can be used to adjust the viscosity of the cosmetic formulation. 

PPOX polyfpropylene oxide) UF urea-formaldehyde resin... 

Fig. 6.28. The 500-MHz proton NMR spectrum of a commercial atactic polyfpropylene oxide) in CDCI3 at 25 t showing extensive overlap resulting from the presence of stereosequences. The simulated spectrum (inset) was calculated by using the values of the J couplings that were obtained from the 2D spectrum. (Reproduced from Ref. [71]. 1985 American Chemical Society.)...

Fif ure 2. Dipropylene glycols resulting from a-butyllithium cleavage of polyfpropylene oxide)... 

Figure 6. Carbon-13 NMR spectrum of amorphous polyfpropylene oxide) made with an Al(C,H,),-HiO (1 1) catalyst. This polymer is known to contain head-to-head and tail-to-tail linkages (8).

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