Synthesis of telechelic and three-arm polytetrahydrofuran-block-amylose

Abstract

Telechelic amine terminated polytetrahydrofuran (PTHF) is prepared via cationic ring opening polymerization (CROP) of THF, initiated by trifluoromethanesulphonic anhydride (triflic anhydride). Hexamethylene tetramine (HMTA) is used as a terminating agent. The resulting HMTA terminated PTHF is hydrolyzed to result in an amine terminated PTHF. Reductive amination is carried out by reacting the PTHF with maltoheptaose resulting in maltoheptaose-b-PTHF-b-maltoheptaose. The product is prepared as a primer for the enzymatic polymerization to synthesize amylose-b-PTHF-b-amylose. In addition, a three-arm PTHF is prepared via CROP of THF. The initiator is synthesized in situ by the reaction of triflic anhydride and triethanol amine. The resulting amine terminated three-arm PTHF is reacted with maltoheptaose to synthesize a three-arm PTHF-b-maltoheptaose which can be used for the enzymatic synthesis of three-arm PTHF-b-amylose. Characterization of the products is difficult due to the amphiphilic behavior of both telechelic amylose-b-PTHF-b-amylose and three-arm PTHF-b-amylose. Therefore, the analysis of the products is mainly based on attenuated total reflectance Fourier transform infrared spectroscopy. Telechelic and three-arm polytetrahydrofuran-block-amylose can be synthesized by coupling telechelic and three-arm polytetrahydrofuran with maltoheptaose, followed by enzymatic polymerization to elongate the saccharide blocks. The covalently attached amylose in these block copolymers can form inclusion complexes with suitable guest molecules which leads to a facile approach in modifying block copolymers to result in highly ordered supramolecules.