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Review
. 2020 Dec 12;12(12):2973.
doi: 10.3390/polym12122973.

Thermoresponsive Polypeptoids

Dandan Liu  1 , Jing Sun  1
Affiliations
Review

Thermoresponsive Polypeptoids

Dandan Liu et al. Polymers (Basel). .

Abstract

Stimuli-responsive polymers have been widely studied in many applications such as biomedicine, nanotechnology, and catalysis. Temperature is one of the most commonly used external triggers, which can be highly controlled with excellent reversibility. Thermoresponsive polymers exhibiting a reversible phase transition in a controlled manner to temperature are a promising class of smart polymers that have been widely studied. The phase transition behavior can be tuned by polymer architectures, chain-end, and various functional groups. Particularly, thermoresponsive polypeptoid is a type of promising material that has drawn growing interest because of its excellent biocompatibility, biodegradability, and bioactivity. This paper summarizes the recent advances of thermoresponsive polypeptoids, including the synthetic methods and functional groups as well as their applications.

Keywords: polypeptoids; post-polymerization modification; ring-opening polymerization (ROP); solid-phase synthesis; thermoresponsive.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Scheme 1
Scheme 1
Chemical structures of polypeptoids and polypeptides.
Scheme 2
Scheme 2
Synthesis of polypeptoid. (a) “Submonomer” solid-phase synthesis, (b) Synthesis of N-substituted glycine N-carboxyanhydrides (NCA) and N-substituted N-thiocarboxyanhydrides (NTA) monomers, (c) NCA ring-opening polymerization.
Figure 1
Figure 1
(a) The formation of cyclic brush-like polymers from the reaction of azido-terminated poly(ethylene glycol) (PEG) and cyclic poly(N-propargyl glycine)-ran-poly(N-butyl glycine) copolypeptoids bearing propargyl side chains. Reprinted with permission from [42]. Copyright 2011, American Chemical Society. (b) Synthesis of poly(N-propargyl glycine) and subsequent modifications of alkyne side chains. Reprinted with permission from [48]. Copyright 2015, Elsevier.
Figure 2
Figure 2
(a) Thermoresponsive polypeptoid homopolymers poly(N-C3 glycine)s. Plots of the cloud point temperatures versus concentration: poly(N-C3 glycine)s, (b) C3 = n-propyl (PG−n, n = 22, 37, and 55), (c) allyl (PG−n, n = 24, 44, and 68), and (d) isopropyl (PG┴n, n = 16, 27, and 49) reprinted with permission from [53]. Copyright 2013, American Chemical Society.
Figure 3
Figure 3
Time-dependent evolution of aggregate structures, 1 wt% aqueous dispersion of poly(N-n-propylglycine)70-block-polysarcosine23 at 48 °C (T > Tcp). Cryo-SEM images of the thermally annealed dispersion at different time (scale bars = 500 nm). Reprinted with permission from [54]. Copyright 2016, American Chemical Society.
Figure 4
Figure 4
(a) Representative plots of transmittance at λ = 450 nm vs. temperature for the selected aqueous solutions of cyclic copolypeptoids c-NHC-P(NEG70-r-NBG47) (blue); c-NHC-P(NEG65-r-NBG30) (green); c-NHC-P(NEG101-r-NBG34) (red) (polymer concentration = 1.0 mg/mL; heating and cooling cycles are symbolized by the filled and unfilled symbols, respectively) (b) Plots of cloud point temperature (Tcp) versus the molar fraction of NEG segment in the cyclic and linear P(NEG-r-NBG) random copolymers bearing different end groups and their respective linearly fit curves, c-NHC-P(NEG70-r-NBG47) (blue); c-NHC-P(NEG65-r-NBG30) (green); c-NHC-P(NEG101-r-NBG34) (red). (c) Plot of Tcps of c-NHC-P(NEG55-r-NBG26) vs. the polymer concentration in water; (d) plot of Tcps of c-NHC-P(NEG62-r-NBG23) at various salt concentrations (TcpxM) relative to that with no salt (Tcp0M) vs. the salt concentration in water. Reprinted with permission from [55]. Copyright 2012, American Chemical Society.
Figure 5
Figure 5
Crystallization-driven thermoreversible gelation of coil-crystalline cyclic and linear diblock copolypeptoids poly(N-methyl-glycine)-block-poly(N-decyl-glycine) Reprinted with permission from [56]. Copyright 2013, American Chemical Society.
Figure 6
Figure 6
Schematic illustration of the gelation mechanism of the ABC triblock copolypeptoids poly(N-allyl glycine)-block-poly(N-methyl glycine)-block-poly(N-decyl glycine) in aqueous solution. Reprinted with permission from [57]. Copyright 2016, American Chemical Society.
Figure 7
Figure 7
Structure of polypeptoid bottlebrush copolymers and schematic illustration of the level of aggregation in as-prepared or thermally annealed solutions of the polypeptoid bottlebrushes. Reprinted with permission from [58]. Copyright 2014, Royal Society of Chemistry.
Figure 8
Figure 8
Transmittance changes at λ = 450 nm as a function of temperature for the selected aqueous solutions of P(Sar96-r-NBG56) (1 and 4 in blue), P(Sar104-r-NBG53) (2 and 5 in green), and P(Sar108-r-NBG49) (3 and 6 in red) with a concentration of 3.0 mg/mL (a), where heating (4, 5, and 6) and cooling cycles (1, 2, 3) are symbolized by the filled and open symbols, respectively. The P(Sar-r-NBG) aqueous solution is photographed at 20 °C (b) and 50 °C (c). Reprinted with permission from [60]. Copyright 2015, Royal Society of Chemistry.
Figure 9
Figure 9
(a) Schematic illustration of dual-responsive block polypeptoids. (b) TEM micrograph of micelles formed by P(Sar0.51-r-NBG0.49)52-b-PNB7 in diluted aqueous solution (0.2 mg/mL). (c) TEM micrograph of structures formed by P(Sar0.51-r-NBG0.49)52-b-PNB7 in concentrated aqueous solution (5 mg/mL). (d) TEM micrograph of anisotropic structures formed by P(Sar0.51-r-NBG0.49)52-b-PNB7 in concentrated aqueous solution (5 mg/mL) after the annealing process. Reprinted with permission from [62]. Copyright 2020, American Chemical Society.
Figure 10
Figure 10
(a) Structure of HEX-PNPgGn-g-EGx. (b) Plots of transmittance as a function of temperature for aqueous solutions (2 mg/mL) of HEX-PNPgGn-g-EGx. Filled symbol: heating ramp, open symbol: cooling ramp. (c) The photographs of HEX-PNPgGn-g-EGx aqueous solution showing reversible phase transition. Reprinted with permission from [49]. Copyright 2018, Elsevier.
Figure 11
Figure 11
(a) Plots of transmittance versus temperature for aqueous solutions of (PNAG-g-EG3)-b-PNOG at a concentration of 5 mg/mL. Filled symbol: heating ramp and open symbol: cooling ramp. (b) Plots of Tcp versus concentration for aqueous solutions of (PNAG-g-EG3)94-b-PNOG15 and PNAG95-g-EG3 at different concentrations. (c) Scheme of sphere and cylinder structure of the crystalline diblock copolypeptoids. Reprinted with permission from [76]. Copyright 2020, American Chemical Society.
Figure 12
Figure 12
Plots of transmittance as a function of temperature for aqueous solutions (a) PNPG41-(COOH)2 (2 mg/mL) at different pH. Filled symbol: cooling ramp; open symbol: heating ramp. (b) PNAG79-NH2 (10 mg/mL) at different pH. Filled symbol: heating ramp; open symbol: cooling ramp. Reprinted with permission from [51]. Copyright 2018, American Chemical Society.
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References

    1. Stuart M.A.C., Huck W.T.S., Genzer J., Müller M., Ober C., Stamm M., Sukhorukov G.B., Szleifer I., Tsukruk V.V., Urban M., et al. Emerging applications of stimuli-responsive polymer materials. Nat. Mater. 2010;9:101–113. doi: 10.1038/nmat2614. - DOI - PubMed
    1. Hoffman A.S. Stimuli-responsive polymers: Biomedical applications and challenges for clinical translation. Adv. Drug Deliv. Rev. 2013;65:10–16. doi: 10.1016/j.addr.2012.11.004. - DOI - PubMed
    1. Mura S., Nicolas J., Couvreur P. Stimuli-responsive nanocarriers for drug delivery. Nat. Mater. 2013;12:991–1003. doi: 10.1038/nmat3776. - DOI - PubMed
    1. Vanparijs N., Nuhn L., De Geest B.G. Transiently thermoresponsive polymers and their applications in biomedicine. Chem. Soc. Rev. 2017;46:1193–1239. doi: 10.1039/C6CS00748A. - DOI - PubMed
    1. Pasparakis G., Tsitsilianis C. LCST polymers: Thermoresponsive nanostructured assemblies towards bioapplications. Polymer. 2020;211:123146. doi: 10.1016/j.polymer.2020.123146. - DOI

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