%0 journal article
%@ 1022-1352
%A Kricheldorf, H.R.,Fritsch, D.,Vakhtangishvili, L.,Schwarz, G.

%D 2005
%J Macromolecular Chemistry and Physics
%N 22
%P 2239-2247 
%R doi:10.1002/macp.200500280
%T Cyclic Ladder Polymers by Polycondensation of Silylated Tetrahydroxy-tetramethylspirobisindane with 1,4-Dicyanotetrafluorobenzene
%U https://doi.org/10.1002/macp.200500280
22 
%X 5,5’,6,6’-Tetra(trimethylsiloxy)4,4,4,4’-tetramethyl-1,1-spirobisindane (TTSBI),was polycondensed with 1,4-dicyanotetrafluorobenzene (DCTB) under variation of solvent,temperature, time and feed ratio. Under optimized reaction conditions, all products detectable by MALDI-TOF mass spectrometry (up to masses around 8 000 Da) proved to be cyclic ladder oligomers and polymers. In N-methylpyrrolidone and dimethylsulfoxide oddnumbered,cycles were formed in addition to the prevailing even-numbered ones. However, in sulfolane exclusively even-numbered cycles were obtained (detectable up to masses around,10 000 Da), together with even-numbered linear chains. Temperatures above 100°C enhanced,the molecular weights by side reactions. With the less reactive cyano-2,3,5,6-,tetrafluorobenzene (CTB) again cycles were formed, but their content and the conversions,were lower. Polycondensation of CTB up to 160°C and all polycondensations of,cyanopentafluorobenzene gave crosslinked products.