Coating, high solids, chain extendable

Chain Extendable Oligomers for High-Solids Coatings... 

Recently, Athey (49) reviewed telechelic polymer synthesis and illustrates with examples that these materials may be used effectively in high solids coatings to chain extend or cure in situ to form appropriate coating vehicles. 

Adhesion between the propellant and the case in solid rocket fuel propellants was studied. The adhesion mechanisms between an inert propellant (a highly filled PU, based on hydroxy-terminated polybutadiene prepolymer, diisocyanate and inert loadings) and a liner of the same nature of prepolymer, diisocyanate, chain extenders and carbon black were investigated. The interfacial properties were found to be influenced by the properties of the prepolymer used. The adhesion of the assembly was only slightly affected by the state of cure of the liner before propellant coating. In peel tests, cohesive failure occurred in the propellant near the interface, IR spectrometry of the propellant surface after separation showed the formation of an interphase in the propellant, dependant on the prepolymer. 3 refs. 

Building onto the concept of molecularly wired sensors for signal amplification, Swager reported in 1998 the synthesis of a series of porous PPE derivatives in which pentiptycene modules are incorporated into the PPE main chain. The incorporation of the pentypticene moieties makes 29 and 30a (Chart 5) efficient solid-state emitters unaffected by aggregation i.e., their emission spectra in solution and in the solid state are almost identical. The authors found that thin films of these highly fluorescent PPEs are excellent sensors for the detection of trinitrotoluene and dinitrotoluene. Both aromatics suppress the fluorescence of 29 or 30a effectively but reversibly. The headspace, i.e., the atmospheric volume above land mines, contains measurable quantities of dinitrotoluene. As a consequence, polymers 29 and 30 coated on top of a fiber optic sensor will allow their simple detection by these very sensitive molecular wire-type materials. This elegant concept should be extendable and applicable to any other analyte, (a) which has the ability to quench fluorescence and (b) for which a receptor can be attached to PPEs. 

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