Poly alkylene oxide flexible segment-based polyester elastomers

Poly(alkylene oxide) flexible segment-based polyester elastomers 

poly(propylene oxide) (PPrO), and their random or block copolymers are most often used as flexible segments. Poly(alkylene ether) glycols are synthesized mainly by ring-opening polymerization and radical polymerization. Extensive reviews on the chemical structure and synthesis of oligo(alkylene ether)s with functional end-groups and their copolymers were published by Marfechal [11] and Xie [17]. 

PTMO is used as a flexible segment in most of the commercial PEE elastomers (Hytrel , DuPont Elitel , Elana, etc.) [1,2]. The PTMO segments of molecular weight higher than 1500 g/mole tend to crystallize causing a decrease in the rubbery phase content in the material. The use of copolymers, e.g., PTMO with PEO and PTMO with PPrO, allows to preserve the amorphous polyether phase structure [23]. Since the copolymerization of PTMO with PPrO [24] or 

PEO [25] is difficult to perform, mixtures of poly(alkylene ether) glycols are used [26]. The physical properties and structure of polyether segments in PEE differ from those of the mixture of oligoether glycols [27,28]. 

Over the last decade, Fakirov et al carried out extensive studies on the synthesis, structure, and physical properties of PEE based on PBT and PEO [18-21]. The investigations of the oriented PEE structure are particularly interesting [18,19,21,29,30,125-128,130,131]. Textile fibers have been obtained with the use of these copolymers [19]. The hardness of PEO-PBT based PEE changes with temperature and PEO molecular weight similarly to the PTMO-PBT block copolymers [129] 

---