Amino‐termined poly(L‐lactide)s as initiators for the polymerization of N‐carboxyanhydrides: synthesis of poly(L‐lactide)‐block‐poly(α‐amino acid)s

Abstract

SUMMARY:Poly(L-lactide)-block-poly(L-amino acids) block copolymers were prepared via polymerization of a-amino acid N-carboxyanhydrides with amino-terminated poly(L-1actide)s as macroinitiators. ?kro types of macroinitiators were used, one with an aminopropoxy head group (number-average molecular weight a, = 22000) and the other one with a phenylalanine end group (a,, = 18OOO). The first macroinitiator was obtained by polymerization of (L,L)-lactide with an initiator prepared in situ from diethylzinc Et,Zn and N-tert-butoxycarbony1-1-amino-3-propano1, followed by deprotection of the amino group. The second macroinitiator was obtained by endcapping of poly(L-lactide) with Ntert-butoxycarbonylphenyldanine and deprotection of the amino group. 'H-and 13C NMR spectroscopies confirm the block structure of the copolymers obtained. In differential scanning calorimetry curves only one melting transition characteristic of the poly(L-lactide) block is observed, on further heating decomposition occurs. By thermogravimetry two steps of decomposition are observed, the first one being assigned to the decomposition of the poly(L-lactide) block, and the second one to that of the poly(amino acid) block, by comparison with the thermal behaviour of the corresponding homopolymers.

Super-hydrophilic zwitterionic poly(carboxybetaine) and amphiphilic non-ionic poly(ethylene glycol) for stealth nanoparticles

“…After covalent binding of PCB-tBu to the hydrophobic moieties, zwitterionic PCB can be readily regenerated by hydrolysis of the tBu ester groups under mild acid conditions such as trifluoroacetic acid (TFA). TFA does not degrade typical ester bonds as observed in PLA [98][99][100], PLGA [11,101], or DSPE [95]. In this way, amphiphilic diblocks with a sharp polarity contrast between super-hydrophilic PCB and hydrophobic PLGA or lipid can be prepared.…”

Polypeptide und 100 Jahre Chemie der α‐Aminosäure‐N‐carboxyanhydride

“…[107] Die meisten Diblockcopolymere, die einen nichtpeptidischen Block enthalten, lassen sich in folgende vier Gruppen unterteilen: I) amphiphile Copolymere mit einem Poly(ethylenoxid)(PEO)-Monomethylether-Block; [130][131][132][133][134][135][136][137][138][139][140][141][142] II) Diblockcopolymere mit einem hydrophilen PolyoxazolinBlock; [143,144] III) Diblockcopolymere, die Ketten aus Vinylmonomeren als hydrophobe Blöcke enthalten; [111,[145][146][147][148][149][150] IV) Kombinationen von Polypeptidblöcken mit biologisch abbaubaren Polyesterblöcken. [151][152][153][154][155][156][157] Alle Diblockcopolymere der Klassen I-III wurden so hergestellt, dass zuerst eine Polymerkette mit einer Aminogruppe synthetisiert und dann als Makroinitiator für die ROP eines NCA verwendet wurde. Ein typisches Beispiel für ein PEO-basiertes Diblockcopolymer ist die Verbindung 47.…”

“…[111] Die Synthesen von Diblockcopolymeren aus l-Lactid (Polymer 56; Schema 29) folgten derselben Strategie. [151][152][153] Ein Boc-geschützter Aminoalkohol diente als Coinitiator in Kombination mit einem metallhaltigen Initiator wie Et 2 Zn für die ROP von l-Lactid. Die Abspaltung der Boc-Gruppe ergab NH 2 -terminierte Polylactide, die als Makroinitiatoren für die NCAs von l-Ala, l-Phe, l-Leu, g-Bzl-l-Glu und gBzl-l-Asp dienten.…”

Synthesis and characterization of novel triblock copolymers comprising poly(tetrahydrofuran) as a central block and poly(γ-benzyl L-glutamate)s as outer blocks

“…In the present study, a phenylalanine-terminated PTHF (NH 2 -Phe-PTHF-Phe-NH 2 ) was first designed as a macroinitiator and produced by the condensation of HO-PTHF-OH with N BOC-Phe in the presence of dicyclohexylcarbodiimide, followed by removing the protecting group [19][20][21][22]. Then, it was utilized to initiate the ROP of BLG-NCA to give rise to the targeted triblock copolymer PBLG-PTHF-PBLG.…”