Chain Extension and Cyclization of Telechelic Polysarcosines

Summary: Sarcosine N‐carboxyanhydride (Sar‐NCA) was polymerized with 1,12‐diaminododecane (DAD) or 1,13‐diamino‐4,7,10‐trioxatridecane (DATT) as initiators, and telechelic blocks having two secondary amino endgroups were obtained. Their structure was proven by 1H NMR and MALDI‐TOF mass spectrometry. The SEC measurements indicated narrow molecular weight distribution with polydispersity indices in the range of 1.1–1.2. These difunctional polysarcosines were reacted with three different coupling agents: 4,4′‐diisocyanatodiphenylmethane (MDI), N‐hydroxysuccinimide sebacate, and sebacoyl bisimidazolide. Although the 1H NMR spectra proved high conversions, only a moderate chain extension was observed. The MALDI‐TOF mass spectra indicated a high extent of cyclization, which limited the chain growth. MALDI‐TOF mass spectrum of a DATT‐initiated polysarcosine after reaction with sebacoyl bisimidazolide. magnified image MALDI‐TOF mass spectrum of a DATT‐initiated polysarcosine after reaction with sebacoyl bisimidazolide.