Molecular weight polyethers

Commercial thermoplastic polyesters are synthesized in a similar way by the reaction of a relatively high molecular-weight polyether glycol with butanediol and dimethyl terephthalate (14,15). The polyether chain becomes the soft segment in the final product, whereas the terephthaUc acid—butanediol copolymer forms the hard crystalline domains. 

Urethane gels and ultrasoft elastomers are a more recent development.18 They are made primarily by reacting high-molecular-weight polyether polyols with a stoichiometric deficiency of isocyanate. The low NCO-to-OH ratio allows for a wide latitude in hardness adjustment. These low-hardness elastomers are used for seating applications (such as gel bicycle seats), shoe inserts, and soft padding for orthopedic devices. 

Most useful polyurethanes are cross-linked. Those commonly used in foams start with a diisocyanate like toluene diisocyanate (TDI) and a low molecular weight polyether such as poly(propylene glycol). Recall that the basic reaction of an isocyanate plus an alcohol gives the urethane functionality. 

D. L (1981) A new polymerization technique for preparing low molecular weight polyether glycols. JANNAF Propulsion Meeting, New Orleans, Louisiana, USA, May 26-28,1981, pp. 29-38. 

When 2,6-dimelhylphenol is oxidized with oxygen in the presence of an amine complex of a copper salt as catalyst a high-molecular weight polyether (PPO) is formed. 

Well-defined catalysts with isolated mononuclear metal species have also been obtained from reactions of diethylaluminium compounds with calix[4]-arenediols. For instance, a catalyst such as (25,27-dimethoxy-p-t-butylcalix[4]-arene-26,28-diolato)aluminium chloride [(dmca)AlCl], characterised by a rigid structure of the AIO4 moiety like a distorted trigonal bypyramid, forms a monomeric species in a benzene solution at freezing temperature. It has been successfully applied for propylene oxide and cyclohexene oxide polymerisations, leading to bifunctional low molecular weight polyethers of relatively... 

Anionic polymerization is not limited to the vinyl kind, involving addition to carbon-carbon double bonds. Ethylene oxide, for example, is converted by a small amount of base into a high-molecular-weight polyether. 

Fluorination of high molecular weight polyethers with elemental fluorine (diluted with helium) at room temperature gave fluorinated polyethers, which were depolymerized by further treatment with flowing F -He at 55-210 "C to produce carbonyl difluoride, amongst the decomposition products [1197c]. COFj is also formed in the oxidative thermal degradation of polyethers derived from hexafluoropropene oxide [1582]. Polymeric C F Oj decomposes, at an unspecified temperature, into carbonyl difluoride [760], The presence of... 

E. Vandenbergh (1) and with the mode of preparation of different active systems, polynuclear structures are clearly a key feature for the design of catalysts able to polymerize substituted oxlranes into very high molecular weight polyethers. In an exploratory approach based on these premises and aimed at the synthesis of well characterized and versatile specie of that type, we have shown indeed (2) that soluble p-oxo-bimetallic trinuclear alkoxides having the general formula RO) m1-0-m2-0-m1 (OR)0 rank cunong the best known... 

Lower molecular weight polyether in the soft segment increases the glass transition temperature and therefore decreases the low temperature limit of elastomeric character of the adhesive. 

Banter resins, carbon fibers, fatty high molecular weight polyether-potyols. high-nitrile copolymer resins, starch/acrykMMnle copolymer. 

High Molecular Weight Polyether Polyols Based on Polyamine Starters. Autocatalytic Polyether Polyols [148-152]... 

Synthesis of High Molecular Weight Polyether Polyols with Double Metal Cyanide Catalysts (DMC Catalysts)... 

Synthesis of High Molecular Weight Polyether Polyols. .. 

The utilisation of a PO with EO mixture (e.g., with 17-18% EO) strongly diminishes the antifoaming effect of the very high molecular weight polyether formed. 

The structure (6.8) is another type of NAD formed in situ by transfer reaction with the tertiary amine type polyethers. Addition of a high molecular weight polyether initiated by an alkanolamine, ethylene diamine, N-methyl substituted propylene diamine, or N,N dimethyl dipropylene diamines in the polyether polyol used for grafting leads to the formation of very stable polymeric dispersions [37]. The solid fraction has particles of low median diameter (<1.5 pm). The resulting polymer polyols have low viscosities which give good stabilisation of the polymeric dispersion. 

The nonreactive NAD are structures without polymerisable double bonds, but have a remarkable stabilisation effect on polymeric dispersions in polyether media. The main characteristic of such kinds of nonreactive NAD is to have an organic segment with high affinity for the carbocatenary vinylic polymer chemically linked to a high molecular weight polyether chain, which has a high affinity for the continuous liquid polyether matrix. 

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