Synthesis of Poly(methylene‑b‑ε-caprolactone) and Poly(ε-caprolactone) with Linear Alkyl End Groups: Synthesis, Characterization, Phase Behavior, and Compatibilization Efficacy

Diblock copolymers of poly­(methylene-b-ε-caprolactone) (PM-b-PCL) were synthesized in two steps: (a) polyhomologation, to obtain, following oxidative cleavage of the carbon–boron (PM, block1), an α-hydroxyl-ω-methyl polymethylene (PMOH, CH3–[CH2] m –OH) and, following the transfer reaction to the ring-opening polymerization catalyst, (b) ring-opening polymerization (ROP) of ε-caprolactone (CL) (PCL, block2). In addition, a series of homopolymers derived from poly­(ε-caprolactone) (PCL) oligoesters containing an end group of docosyl (CH3–[CH2]21– or C22; C22–PCL) were obtained as a model to compare their physical properties by DSC with those of PM-b-PCL. The oligomers derived from PM-b-PCL and C22–PCL were characterized by 1H and 13C NMR, AFM, DSC, GPC, and MALDI-TOF. PM-b-PCL and C22–PCL were evaluated as compatibilizers for PE/PCL polymer blends. Identification and analysis of optimized blocks of PM-b-PCL by POM and SEM showed improved mixing of PE/PCL blends.