Cyclization of L-(-)-arabitol as a cyclic building block in poly(butylene succinate) copolymer

Cyclic biochemicals are essential building blocks as they play important roles in the thermal and mechanical properties as well as the gas barrier performance required for biodegradable polymers in daily-life applications. The present work focuses on the acetalization of an L-(-)-arabitol-derived cyclic compound and its application as a new type of building block in bio-based polyesters, particularly poly(butylene succinate) (PBS). The optimal cyclization yields monocyclic 2,4-, 1,2-, and 2,3-O-methylene-L-(-)-arabitol (AraC). By simply carrying out copolymerization via melt condensation using 100 mol% dimethyl succinate, 95 mol% 1,4-butanediol (BD), and 5 mol% AraC, a copolyester, namely PB95AraC5S100, with a molecular weight of 21,000 g/mol containing 12 mol % AraC can be obtained. PB95AraC5S100 exhibits rapid crystallization and shows two melting temperatures (Tm) at 95.5 degrees C and 107.5 degrees C, along with a higher glass transition temperature (Tg = -22.5 degrees C) compared to neat PBS (Tg = -33.5 degrees C). The film obtained from an optimized blend of PB95AraC5S100 (20 wt%) and PBS exhibits miscibility, as evidenced by a narrow range of phase shift in AFM tapping mode and a single Tg at approximately -30 degrees C. This film also demonstrates an increase in elastic modulus by 5.3 %, as well as improvements in OQ and COQ barrier performances by 11.3 % and 57 %, respectively, compared to PBS film. The present work demonstrates how the AraC cyclic structure can be synthesized and copolymerized with bio-based polyesters, as well as its performance in bio-copolymers and bio-copolyester blends.