Soft segment chemistry

Polyesters are hydrolytically labile and offer excellent mechanical properties compared to the other commonly used polyols for biomedical applications. Table 1.1 provides a list of common polyester diol structures used in resorbable polyurethanes. Although polyester urethanes were generally considered unsuitable for biostable 

Poly(ethylene oxide) (PEO) Poly(propylene oxide) (PPO) 

Poly(tetramethylene oxide) (PTMO) Poly(hexamethylene oxide) (PHMO) 

An emerging class of soft segments that has fonnd a niche in biodegradable polyurethanes is block copolymers in an A-B-A stmcmre that are variations of the commonly nsed polyols. Table 1.3 provides a list of common triblock structures used in resorbable 

---

Wiggins MJ, MacEwan M, Anderson JM, Hiltner A. Effect of soft-segment chemistry on polyurethane hiostability during in vitro fatigue loading. Journal ofBiomedical Materials Research A 2004, 68, 668-683. 

A. Takahara, A.J. Coury, R.W. Hergenrother, S.L. Cooper, Effect of soft segment chemistry on the biostabihty of segmented polyurethanes. 

We have prepared novel polyurethane elastomers with modified soft segment chemistry that has been designed to enhance stability. The new tliermoplastic polyurethanes are based on conventional diisocyanates and chain extenders, but contain macrodiols with a reduced number of ether linkages when compared with PTMO. As part of the development process, improved synthetic procedures involving condensation polymerization were devised (8,9) to prepare the macrodiols, poly(hexamethylene oxide) 1, poly(octamethylene oxide) 2, and poly(decamethylene oxide) 3. 

The chapter is structured as follows. In Section 2.2 (see also our recent paper [33]), we discuss recent developments in relating linear elastic properties of polyur ethane elastomers to their formulation (hard and soft segment chemistry, soft segment molecular weight, and hard segment weight fraction). In Section 2.3, the extension of the model to describe tensile stress-strain behavior... 

MICROSTRUCTURE AND BIOSTABILITY OF BIOMEDICAL POLYURETHANE BLOCK COPOLYMERS WITH DIFFERENT SOFT SEGMENT CHEMISTRIES... 

---