Polymerization of L-alanine N-carboxy anhydride (4-methyl-2,5-dioxo-l-oxa-3-azacyclopentane) was carried out in acetonitrile using hexamethylene diamine (HM), ethylene diamine (ED) and bis(4-aminophenyl) ether (AP) as initiators, in order to investigate the effect of diamines on the crystallization mechanism during polymerization in comparison with that for butylamine already reported.The resultant polymers obtained here had wider molecular weight distributions than those obtained with butylamine, indicating the occlusion of some active growing chain ends into the precipitate during polymerization. The relative width of the molecular weight distribution of the polymers formed in the later stages of the polymerization was larger in the following order as compared among the initiators: HM

The heterogeneous polymerization of glycine N-carboxy anhydride (2,5-dioxo-l-oxa-3azacyclopentane) was carried out in acetonitrile using various kinds of primary diamines as initiators such as ethylene diamine (ED), hexamethylenediamine (HM) and bis(4-aminophenyl) ether (AP) comparing with butylamine previously reported. Electron microscopic observations revealed that most of the precipitates were spherulites. The conformation of polyglycine obtained from all the initiators used, was in the form of polyglycine I. The apparent crystallinity of the resultant polymer was low in the case of AP-as compared with ED-or HM-initiated polymerizations. A growth mechanism of polyglycine crystals formed in the course of polymerization has been proposed. ZUSAMMENFASSUNG:Die heterogene Polymerisation des Leuchs'schen Anhydrids von Glycin (2,5-Dioxo-loxa-3-azacyclopentane) wurde in Acetonitril unter Verwendung verschiedener primarer Diamine als Initiatoren wie Athylendiamin (ED), Hexamethylendiamin (HM) und Bis(4-aminopheny1)ather (AP) durchgefihrt und mit der bereits berichteten entsprechenden Polymerisation mit Butylamin verglichen. Elektronenmikroskopische Beobachtungen zeigten, daIj die ausgefallenen Polymere meist aus Spharolithen bestanden. Die Konformation des Polyglycins wie es mit allen Initiatoren erhalten wurde, war in der Form des Polyglycins I. Die scheinbare Kristallinitat der erhaltenen Polymere war fur den Fall der AP-initiierten Polymerisation niedrig, verglichen mit den durch E D oder HM initiierten Polymerisationen. Es wurde ein Mechanismus fur das Wachstum der im Verlauf der Polymerisation entstandenen Polyglycin-Kristalle vorgeschlagen.

Various amines such as aniline (A), N,N-diethyl-l,3-propanediamine (DPD), and pamino-N,N-diethylaniline (ADA), wereiwed as initiators in the heterogeneous polymerization of L-alanine N-carboxy anhydride (L-alanine NCA), (4-methyl-2,5-dioxo-1-oxa-3azacyclopentane). When ADA is used as initiator, the initiation reaction proceeds via normal amine initiation as for primary nynoamines. On the other hand, in the polymerization initiated by DPD, the initiation reaction takes place from both the primary and tertiary amino groups of the initiator. In all systems, the propagation proceeds by nucleophilic attack of the amino groups of the growing chains on the C(5' of the L-alanine NCA ring.The resultant polymers obtained in the case of the initiators A or ADA had wider molecular weight distributions than those from DPD-initiated polymerization. Oligomers and polymers obtained using DPD as initiator were in the form of 8and a-conformations, respectively. However, mixtures of both p-structure and a-helix were formed in the polymerization initiated by A or ADA. It is suggested that the number of the growing chain ends occluded in the precipitate is increasing in the following order with respect to the initiator used: DPD