Chain Extension and Cyclization of Telechelic Polysarcosines

Abstract

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: 4,40-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.