Polytetramethylene adipate polyol

Core-shell PU NPs can also be prepared by appropriate choice of isocyanate [166]. Blocked amphiphilic prepolymers were prepared by Cheong et al., where the hydrophobic block is composed of IPDI-polytetramethylene adipate polyol (PTMA) and the hydrophilic block is MDI-DMPA. The resulting polymer is added drop-wise to water under stirring, resulting in a core-shell structure with the hydrophobic IPDI-PTMA in the core and hydrophilic MDI-DMPA in the shell (80-100 nm diameter) [166]. 

The polyol employed may be a polyether or a polyester. Du Pont use polytetramethylene ether glycol (polytetrahydrofuran, poly(l,4-oxybutylene glycol)) for Lycra whilst US Rubber originally used a polyester of molecular weight c. 2000 made by condensing adipic acid with a mixture of ethylene and propylene glycols for Vyrene. A polyether-based material, Vyrene 2, was introduced in 1%7. All of these polyols have terminal hydroxyl groups. 

SMPU is usually synthesized from long-chain polyols, diisocyanate and short-chain extenders. The polyols that have typically been used to date include polycaprolactone (PCL), polytetramethylene ether glycol (PTMG), polybutylene adipate (PBA), polyhexamethylene adipate (PHA) and polylactic acid (PLA)... 

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