One-Pot Glovebox-Free Synthesis, Characterization, and Self-Assembly of Novel Amphiphilic Poly(Sarcosine-b-Caprolactone) Diblock Copolymers

Brønsted base mediated one-pot synthesis of catechol-ended amphiphilic polysarcosine-b-poly(N-butyl glycine) diblock copolypeptoids

Catechol moiety offers a versatile platform in the preparation of functionalized polymers, but it is not usually compatible with catalysis in polymerizations. To address these challenges, we suggest employment of one Brønsted base in masking the activity of catechol moiety and to modulate the polymerization. Based on this strategy, the ring-opening polymerization (ROP) of sarcosine N-carboxyanhydrides (Sar-NCA) was carried out using dopamine hydrochloride as an initiator and triethylamine as a Brønsted base. PSar with predicted molecular weights (M n,NMR=3.7 kg mol−1) and narrow dispersities (Đ<1.13) was prepared. Catechol initiator was successfully linked to PSar end as confirmed by MALDI-ToF MS. Subsequently, copolymerization of N-butyl glycine N-carboxyanhydrides (Bu-Gly-NCA) from the PSar in one-pot produced catechol end-functionalized amphiphilic polysarcosine-block-poly(N-butyl glycine) diblock copolypeptoids (cat-PSar-b-PGlyBu). Further, cat-PSar-b-PGlyBu enabled the aqueous dispersion of manganese oxide nanoparticles which was attributable to the anchor of the diblock copolymers onto the surface of the nanoparticles. The strategy for catechol masking and polymerization mediating by one Brønsted base offered a new avenue into the synthesis of catechol-ended block copolymers.

Hybrid block copolymers of polyesters/polycarbonates and polypeptides synthesized via one-pot sequential ring-opening polymerization

Polyester/polycarbonate-b-polypeptide hybrid block copolymers were synthesized by a sequential ring-opening polymerization in a one-pot manner.

Amphiphilic star-shaped poly(sarcosine)-block-poly(ε-caprolactone) diblock copolymers: one-pot synthesis, characterization, and solution properties

We firstly synthesized amphiphilic three-armed star-shaped poly(sarcosine)-block-poly(ε-caprolactone) diblock copolymers (s-PSar-b-PCLs), and investigated the solution properties and biocompatibility of the copolymers.

Dependence of Copolymer Sequencing Based on Lactone Ring Size and ε-Substitution

The copolymerization of an ε-substituted ε-lactone, menthide (MI), and a range of nonsubstituted lactones (6-, 7-, 8-, and 9-membered rings) was investigated in order to determine the factors that affect the sequencing of the MI copolymers. Analysis by quantitative ¹³C NMR spectroscopy showed the copolymerization of MI with a nonsubstituted lactone of ring size 7 or less produced a randomly sequenced copolymer, as a consequence of the smaller lactone polymerizing first and undergoing rapid transesterification as MI was incorporated. Conversely, copolymerization with larger ring lactones (ring size 8 and above) produced block-like copolymers as a consequence of MI polymerizing initially, which does not undergo rapid transesterification side reactions during the incorporation of the second monomer. Terpolymerizations of a small ring lactone, macrolactone, and menthide demonstrated methods of producing lactone terpolymers with different final sequences, depending on when the small ring lactone was injected into the reaction mixture.

Poly(ε-caprolactone)-block-polysarcosine by Ring-Opening Polymerization of Sarcosine N-Thiocarboxyanhydride: Synthesis and Thermoresponsive Self-Assembly

Biocompatible amphiphilic block copolymers composed of polysarcosine (PSar) and poly(ε-caprolactone) (PCL) were synthesized using ring-opening polymerization of sarcosine N-thiocarboxyanhydride initiated by oxyamine-ended PCL and characterized by NMR, SEC, and DSC. Self-assembling of two triblock copolymers PSar8-b-PCL28-b-PSar8 (CS7) and PSar16-b-PCL40-b-PSar16 (CS10) in dilute solution was studied in detail toward polymersome formation using thin-film hydration and nanoprecipitation techniques. A few giant vesicles were obtained by thin-film hydration from both copolymers and visualized by confocal laser scanning microscope. Unilamellar sheets and nanofibers (with 8-10 nm thickness or diameter) were obtained by nanoprecipitation at room temperature and observed by Cryo-TEM. These lamellae and fibrous structures were transformed into worm-like cylinders and spheres (D∼30-100 nm) after heating to 65 °C (>Tm,PCL). Heating CS10 suspensions to 90 °C led eventually to multilamellar polymersomes (D∼100-500 nm). Mechanism II, where micelles expand to vesicles through water diffusion and hydrophilic core forming, was proposed for polymersome formation. A cell viability test confirmed the self-assemblies were not cytotoxic.