Acetylene-terminated oligomers functionality

Acetylene-terminated oligomers, incorporation of isoimide functionality, 462 Acid functionalities, block copolymers, 258... 

The Michael addition reaction of dimercaptodiphenylether with N-(3-ethynyl phenyl) maleimide allowed the synthesis of ethynyl-terminated imido-thioether as shown in Fig. 50 (139). This acetylene terminated imidothioether was blended with acetylene terminated polyarylene ether oligomers of different molecular weights and tested as composite resins (140). Blends of functionalized thermoplastics such as the acetylene terminated polyarylene ethers with brittle high-Tg imide resins are finding increased attention for tough high-Tg composites. 

The above-described two-step processes yield polymers that evolve volatiles upon further heating because the condensations continue. To overcome this drawback, prepolymers were developed thatundeigo addition-type reactions at fairly moderate time-temperature schedules. Such prepolymers are terminated by functional groups. The following is an example of one such material, an oligomer, polyquinoxaline-terminated by acetylene groups ... 

Such prepolymers are terminated by functional groups. Following is an example of one such material, an oligomer, polyquinoxaline terminated by acetylene groups ... 

The bromo end-capped oligomers were converted to the acetylene terminated systems by the reaction with 2-methyl-3 butyn-2-ol, utilizing the catalyst system composed of triphenylphosphine, bis-tri-phenylphosphine palladium chloride, and cuprous iodide. Conversion of the generated butyn-adducts to the acetylene functionality was carried out by the hydrolytic displacement of acetone with potassium hydroxide in toluene. The displacement of acetone under basic conditions is an equilibrium reaction therefore, the acetone must be removed by codistillation with toluene. 

Other laboratories have used FTIR spectroscopy to determine the kinetics of reactions on different polymer supports39 and to enumerate factors regulating site interactions in different types of supports (see Chapter 7, p. 219).40 A major weak point of the procedure is the need for IR diagnostic functions or changes in hybridization to be involved in the transformation to be investigated. For phenylacetylene oligomers, however, the TMS and terminal acetylene absorptions are ideal. 

In this method mono- or dihydroxy-terminated polyoxyethylene oligomers are reacted in bulk with potassium metal at 120 °C, thus converting quantitatively the hydroxy groups into potassium alcoholate functions. Then, the medium is heated up to 180 °C and acetylene is added. This addition to the alcoholates quantitatively produces mono- or divinyl-terminated polyoxyethylenes, respectively ... 

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