Oligomeric ester cyclics, polymerization

Bis(maleimides) prepared from aromatic diamines (benzidine, p-phenylcne-diamine, o-tolidine, o-anisidine) were condensed with 1,8-diphenyloctatetraene and related bis(dienes). Polymers that softened above 300°C with molecular weights of approximately 3000 were obtained (18). A Diels-Alder polymerization has been described that yields a ladder polymer. The cyclic oligomeric esters [13] and [14] give low molecular weight polymer when heated in toluene (7). p-Benzoquinone has also been polymerized with [14]. A chloroform-soluble product with a molecular weight of about 2000 was obtained (7). 

Instead of using a bis(diene), several Diels-Alder polymerizations have been performed with trienes (6). An example is shown in Eq. (III-IO). Initially the reactants form an intermediate that possesses both the diene and dienophile groups. Self-polymerization of this intermediate yields the polymer. The cyclic oligomeric ester from maleic acid and 1,4-butanediol described earlier... 

Cationic oligomerization of 6,8-dioxabicyclo[3.2.1]octan-7-one at temperatures below —30 °C yields cyclic esters with degrees of polymerization dependent upon solvent polarity. ... 

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