“…Degree of randomness 29 and its other similar forms, which are based on the determination of the possibility of three or more types of dyads or n-ads, have been widely used in the characterization of copolymer sequence structure, such as vinyl copolymers, 30 symmetrical copolyesters, [31][32][33] and segmented poly(urethane urea). 34,35 However, this method was unsuitable for TCL copolyesters because there is not always a common unit, OOCH 2 CH 2 OO, between ET and CL segments, and the molecular structure of the CL unit is unsymmetrical, having two different functional groups. Fortunately, another parameter, run number (R), also can be used to characterize the sequence structure of copolymers 36 ; it is the average number of sequence runs occurring in a copolymer chain per 100 monomer units.…”