Poly(2-isopropyl-2-oxazoline)−Poly(l-glutamate) Block Copolymers through Ammonium-Mediated NCA Polymerization

Poly(2‐oxazoline)s as Smart Bioinspired Polymers

“…[27] Initiators and quenching agents carrying functional groups were used to synthesize end-functionalized or telechelic polyoxazolines; functional groups mainly included unsaturated hydrocarbon, [28][29][30] alkyne, [31] naphthalene, [32] siloxane, [33][34][35][36] hydroxyl, [33,37,38] tosylate, [39] amine, [38,40,41] trialkyl ammonium, [36,[42][43][44] bi-and terpyridine. [45][46][47][48][49][50] Statistical copolymers have been prepared by the copolymerization of mixtures of oxazoline monomers.…”

“…[71] Likewise, polyoxazoline-polypeptide block copolymers were prepared by polyoxazoline-NH 2 initiated ring-opening polymerization of amino acid N-carboxyanhydrides. [41,[72][73][74] Block copolymers could also be produced by the coupling of living cationic polyoxazoline chain ends to the amine terminus of glycopeptide chains. [75] Poly(2-methyl-2-oxazoline)-block-polystyrene was synthesized employing a dual initiator, a-bromo-isobutyrylbromide, by a combination of cationic ring-opening polymerization and atom transfer radical polymerization (ATRP).…”

“…Block copolymers could be isolated in high yields (>90%) but exhibited rather broad molecular weight distributions (PDI ¼ 1.2-1.6), pointing to a rather poor control of the NCA polymerization. Other block copolymers prepared by this route were poly(2-methyl-2-oxazoline)-block-poly(L-phenylalanine), poly(2-alkyl-2-oxazoline)-block-poly(g -benzyl-L-glutamate), (alkyl ¼ methyl, phenyl, [72] and ethyl [74] ), poly(2-isopropyl-2-oxazoline)-block-poly(L-glutamic acid), [41] poly-(2-isopropyl-2-oxazoline)-block-poly(aspartic acid), and poly(2-isopropyl-2-oxazoline)-block-poly(L-lysine). [73] Polyoxazoline macroinitators were synthesized by quenching the oxazolinium chain ends either with ammonia [72] or with water, followed by the conversion of terminal hydroxyl groups into primary amines (Mitsunobu reaction), [73,74] or with 4-(N-tert-butyloxycarbonyl-amino)-piperidine, followed by an acidic hydrolysis of the Boc protecting group.…”

“…[73] Polyoxazoline macroinitators were synthesized by quenching the oxazolinium chain ends either with ammonia [72] or with water, followed by the conversion of terminal hydroxyl groups into primary amines (Mitsunobu reaction), [73,74] or with 4-(N-tert-butyloxycarbonyl-amino)-piperidine, followed by an acidic hydrolysis of the Boc protecting group. [41] Polymerization of the amino acid NCA was done applying conventional or ammonium-mediated protocols. [41] The prepared block copolymers had molecular weights in the range of 4-75 kDa and polydispersity indexes of 1.1-1.3.…”

Synthesis and Self-Assembly of Well-Defined Block Copolypeptides via Controlled NCA Polymerization

“…This result was attributed to termination of some fraction of initiator species by traces of impurities in the NCA monomers, although the presence of unreacted polystyrene chains was not reported. Recently, this methodology was extended to the preparation of new hybrid copolymers of poly(Bn-Glu) from poly(2-isopropyl-2-oxazoline) [51] and PEG-amine hydrochloride [52] macroinitiators.…”