Polyoxypropylene, polymers

Two of the more recendy developed polysulftde polymers are the mercaptan-terminated polyoxypropylene urethane polymer and the polythioether polymer. The urethane-backbone-based polymer is used in many sealant formulations for insulating glass appHcations. The thioether backbone contains sulfur, but no S—S bonds, which are the weakest part of the conventional polysulftde polymer. This polymer improves the thermal stabiHty and reduces the gas—Hquid permeabiHty. 

Polyoxypropylene urethane polymer, mercaptan-terminated, 22 40-41 Polyparabanic acid (PPA) tape material, 17 836... 

McDonald, C. andC. K. V fong. 1974. The effect oftemperature on the micellar properties of a polyoxypropylene-polyoxyethylene polymer in wataf. Pharm. Pharmalol. 26 556-557. 

Very interesting investigations of the fluorination of polymers (H2/F2 blend) were carried out by Lagow et al. [60, 71] for more than ten years. These authors worked on polyoxyethylenes [66], on polyoxypropylenes [67] and even on polyesters [68] on which the fluorination of the carbonyle group by SF4 was performed and finally on several copolymers such as [69, 70] ... 

Lakhanpal, M. L. Conway, B. E., "Studies on Polyoxypropylene Glycols. Part I. Vapor Pressures and Heats of Mixing in the Systems Polyglycols-Methanol," J. Polym. Sci., 46, 75 (1960). 

Polyoxyethylene-polyoxypropylene block co-polymers Poloxomers, Pluronic F-68 o/w ... 

Poloxamer polymers are prepared by reacting propylene oxide with propylene glycol to form polyoxypropylene glycol. Ethylene oxide is then added to form the block copolymer. 

These are stable micelles that are formed with polymeric surfactants. Amphiphilic block copolymers such as the pluronics (polyoxyethylene-polyoxypropylene block copolymers) are able to self-assemble into polymeric micelles and hydrophobic drugs may be solubilized within the core of the micelle or, alternatively, conjugated to the micelle-forming polymer. Although micelles are rather dynamic systems that continuously exchange units between the micelle structure and the free units in solution, those composed of polyoxyethylene - poly(aspartic acid) have been found sufficiently... 

High-molecular-weight propylene oxide polymers (polyoxypropylene glycol... 

Block and graft polymers are widely used as steric stabilizers. Since the two blocks are separated in the molecule, they can be designed chemically, by use of the proper functional groups and degree of polymerization, for optimum efficiency and effectiveness. One block should be designed to adsorb strongly onto the particle surface (and also have limited solubility in the liquid phase), the other block(s) to extend into the liquid phase (good compatibility with and/or interaction with the liquid phase). One commonly used type is the polyoxyethylene-polyoxypropylene... 

In particular, the effects of various stabilizers of the primary emulsion on the encapsulation of SCG were studied. Different hydrophilic polymers were employed namely gelatin (250 Bloom grades) or the polyoxyethylene-polyoxypropylene block copolymer, poloxamer 407. To further optimize the encapsulation yield, some experimental contrivances have been performed dispersion by turbine of the drug within the lipidic matrix, rapid emulsion cooling using an ice bath, and rapid separation of LS by filtration. The optimized procedure resulted in a final encapsulation of the drug of 50% (Table 2.10). 

A promising class of nonionic surfactants are the pluoronics, which are the block co-polymers of ethylene and propylene oxides with molecular weights ranging from 2,000 to 20,000 g mol 1. The solubility and surface activity of these compounds is determined by the ratio of the lengths of polyoxypropylene (carrier of hydrophobicity) to polyoxyethylene chains (carrier of hydrophilicity). 

Atkinson TP, Smith TF, Hunter RL. Histamine release from human basophils by synthetic block co-polymers composed of polyoxyethylene and polyoxypropylene and synergy with immunologic and non-immunologic stimuli. J Immunol 1988 141 1307-1310. 

In the mid-1970s, polysulfide polymer chemistry was advanced when Products Research and Chemical Corporation introduced a polyoxypropylene urethane backbone with mercaptan terminal groups [7]. Molecular weight regulation and minimization of side reactions are important features. The backbone is significantly different from that of conventional polysulfide polymers, yet the curing chemistry is the same and the eured product is a polysulfide rubber. A typical structure of this type of resin is shown below. 

Synonyms Ethylene glycol/propylene glycol block copolymer POE/POP copolymer Polyor hylene/polyoxypropylene copolymer Polyoxypro-pylene/polyo) ethylene block polymer Polyoxypropylen polyoxyeth-ylene copolymer POP/POE copolymer Frnnula (CjHsO CjHjO),... 

---