Studies on preparation of silicon-containing polyester via ring-opening polymerization and new type of elastomers derived from the resulting diols

Abstract

Silicon-containing polyesters represent a novel class of polymers that integrate silicone and polyester units within their main chain. Polysiloxanes typically consist of flexible chain segments, while polyesters are characterized by their rigidity. The combination of these two components in the main chain offers the potential for tunable properties across a broad range. For the first time, a new organosilicon cyclic ester monomer (Si-Mon) was synthesized using a pseudo-high dilution condensation method. Both theoretical and experimental studies confirm that the ring-opening reaction site of Si-Mon is the ester group, rather than the Si-O-Si bond. Silicon-containing polyesters (SiPET-Series 1) with molecular weights exceeding 20,000 Da were efficiently and rapidly synthesized at room temperature, utilizing benzyl alcohol as the initiator and t-BuP₄ as the catalyst. Organosilicon polyester diols (SiPET-Series 2) with varying molecular weights were produced using 1,4-benzenedimethanol as the initiator. Additionally, a new type of organosilicon polyester elastomer (SiPET-E) was developed by employing SiPET-Series 2 as the base gum and (2,4,6-trioxotriazine-1,3,5(2H,4H,6H)- triyl)tris(hexamethylene)isocyanate (THDI) as the crosslinking agent. The stress–strain behavior of SiPET-E is influenced by the molecular weight of SiPET-Series 2. Notably, SiPET-E exhibits remarkable properties; for instance, it demonstrates superelastic characteristics when the molecular weight of SiPET-Series 2 is 13,000 g/mol, achieving a tensile strength of 2.56 MPa and an elongation at break of 776 % without the use of reinforcing fillers.