Polytetrahydrofuran with acrylate and methacrylate endgroups

Abstract

Oligomers with polymerizable endgroups are of increasing interest. These "macromers" 1, can be obtained by a transfer reaction with a telogen acting as transfer agent and initiator (inifer2)).This method can be applied to synthesize polytetrahydrofuran with acrylate and methacrylate endgroups (I)*), respectively. The polymerization is performed in bulk using protic initiators (super acids) and the corresponding carboxylic acid anhydride as a transfer agent. 8 0 II Acf-OCH,CH,CHzCHz+OAc Ac = H,C=$-C or H,C==CH-C 1 CH3 Experimental PartTHF was destilled from potassium/benzophenon under nitrogen immediately before use. To 150 ml of THF the anhydride (amount given in Tabs. 1 and 3) and 100 to 200 mg of 2,6-dimethylphenol (ionol, as inhibitor of radical polymerization) were added. The mixture was cooled to about -10°C and the initiator was added (e.g. 0,i ml of HSbF6 or 0,4 g of acetyl-hexachloroantimonate~, The mixture was heated to the reaction temperature of 40 "C.The course of the reaction was followed by IR-spectroscopy. When the complete consumption of the anhydride was indicated 0,5 ml of water were added. The mixture was diluted by adding 100 ml of THF, and the SbF6-ions were removed by an anion exchanger (Serva IRA 400). The solution was treated i.vac. to remove solvent and water. The product is a colourless to pale yellow viscous liquid or wax like material depending on the molecular weight.M,, values were obtained by vapour pressure osmometry using a Knauer instrument. The ester functionality was determined by titration of the hydrolyzed sample. 0,4 to 1 g of the product were dissolved in 100 ml of dry THF. 3 -5 ml of 1 N KOH were added and the mixture was heated to reflux for 3 h. After adding 100 mi of water the acid was titrated by use of a Mettler Memo-Titrator DL 40.The initiators HSbF6 (from Aldrich), CF,SO,H (from Fluka), and acetylhexachloroantimonate (from Ega) were used as received. Acrylic anhydride (from Atlanta) contained 16% *) Systematic name: a-methacryloyl-(or acryloyl)-o-methacryloyIoxy-(or acryIoy1oxy)poly-(oxytetramethylene).