Controlled Synthesis of Well Defined Poly(3‐hydroxyalkanoate)s‐based Amphiphilic Diblock Copolymers Using Click Chemistry

A modular synthesis of short chain length and medium chain length poly(3‐hydroxyalkanoate)s‐b‐poly(ethylene glycol) (PHAs‐b‐PEG) diblock copolymers is described. First, length‐controlled oligomers of hydrophobic poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBHV), poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) (PHBHHx), and poly(3‐hydroxyoctanoate‐co‐hydroxyhexanoate) (PHOHHx) containing a carboxylic acid end group were obtained by thermal treatment, with molar masses ranging from 3 800 to 15 000 g · mol^?1. After quantitative functionalization with propargylamine, ligation with azide‐terminated poly(ethylene glycol) of 5 000 g · mol^?1 was accomplished using the copper (I) catalyzed azide alkyne cycloaddition (CuAAC). Well‐defined diblock copolymers were obtained up to 93% yield, with molar masses ranging from 9 900 to 23 100 g · mol^?1. All products were fully characterized using ¹H NMR, COSY, SEC, TGA, and DSC.