Strong Variation of Micelle-Unimer Coexistence as a Function of Core Chain Mobility

Ryan J. Carrazzone; Xiuli Li; Jeffrey C. Foster; Veera Venkata Shravan Uppala; Candace E. Wall; Alan R. Esker; Louis A. Madsen; John B. Matson

doi:10.1021/acs.macromol.1c00635

Strong Variation of Micelle-Unimer Coexistence as a Function of Core Chain Mobility

Ryan J. Carrazzone, Xiuli Li, Jeffrey C. Foster, Veera Venkata Shravan Uppala, Candace E. Wall, Alan R. Esker, Louis A. Madsen, John B. Matson

Research output: Contribution to journal › Article › peer-review

2 Scopus citations

Abstract

Polymeric micelles coexist in solution with unassembled chains (unimers). We have investigated the influence of glass transition temperature (Tg) (i.e., chain mobility) of the micelle core-forming blocks on micelle-unimer coexistence. We synthesized a series of seven PEG-b-P(nBA-ran-tBA) amphiphilic block copolymers [PEG = poly(ethylene glycol), nBA = n-butyl acrylate, and tBA = tert-butyl acrylate] with similar molecular weights (12 kg/mol). Varying the nBA/tBA molar ratio enabled the broad modulation of core block Tg with no significant change in core hydrophobicity or micelle size. NMR diffusometry revealed increasing unimer populations from 0 to 54% of total polymer concentration upon decreasing core block Tg from 25 to -46 °C. Additionally, unimer population at fixed polymer composition (and thus core Tg) increased with temperature. This study demonstrates the strong influence of core-forming block mobility on polymer self-assembly, providing information toward designing drug delivery systems and suggesting the need for a new dynamical theory.

Original language	English
Pages (from-to)	6975-6981
Number of pages	7
Journal	Macromolecules
Volume	54
Issue number	14
DOIs	https://doi.org/10.1021/acs.macromol.1c00635
State	Published - Jul 27 2021
Externally published	Yes

Funding

This work was supported by the US National Science Foundation (CBET 1437767 and CHE 1904746 and 2003662) and the US National Institutes of Health (R01GM123508). We thank Prof. Richey Davis for helpful discussions and for the use of the DLS instrument, Prof. Tim Long and Dr. Ryan Mondschein for DSC assistance, and Kearsley Dillon, Sarah Swilley-Sanchez, and Yumeng (Jackie) Zhu for critical readings of the manuscript. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the funding agencies.

Funders	Funder number
National Science Foundation	CBET 1437767, CHE 1904746, 2003662
National Institutes of Health	R01GM123508

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title = "Strong Variation of Micelle-Unimer Coexistence as a Function of Core Chain Mobility",

abstract = "Polymeric micelles coexist in solution with unassembled chains (unimers). We have investigated the influence of glass transition temperature (Tg) (i.e., chain mobility) of the micelle core-forming blocks on micelle-unimer coexistence. We synthesized a series of seven PEG-b-P(nBA-ran-tBA) amphiphilic block copolymers [PEG = poly(ethylene glycol), nBA = n-butyl acrylate, and tBA = tert-butyl acrylate] with similar molecular weights (12 kg/mol). Varying the nBA/tBA molar ratio enabled the broad modulation of core block Tg with no significant change in core hydrophobicity or micelle size. NMR diffusometry revealed increasing unimer populations from 0 to 54% of total polymer concentration upon decreasing core block Tg from 25 to -46 °C. Additionally, unimer population at fixed polymer composition (and thus core Tg) increased with temperature. This study demonstrates the strong influence of core-forming block mobility on polymer self-assembly, providing information toward designing drug delivery systems and suggesting the need for a new dynamical theory.",

author = "Carrazzone, {Ryan J.} and Xiuli Li and Foster, {Jeffrey C.} and Uppala, {Veera Venkata Shravan} and Wall, {Candace E.} and Esker, {Alan R.} and Madsen, {Louis A.} and Matson, {John B.}",

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AU - Carrazzone, Ryan J.

AU - Li, Xiuli

AU - Foster, Jeffrey C.

AU - Uppala, Veera Venkata Shravan

AU - Wall, Candace E.

AU - Esker, Alan R.

AU - Madsen, Louis A.

AU - Matson, John B.

PY - 2021/7/27

Y1 - 2021/7/27

N2 - Polymeric micelles coexist in solution with unassembled chains (unimers). We have investigated the influence of glass transition temperature (Tg) (i.e., chain mobility) of the micelle core-forming blocks on micelle-unimer coexistence. We synthesized a series of seven PEG-b-P(nBA-ran-tBA) amphiphilic block copolymers [PEG = poly(ethylene glycol), nBA = n-butyl acrylate, and tBA = tert-butyl acrylate] with similar molecular weights (12 kg/mol). Varying the nBA/tBA molar ratio enabled the broad modulation of core block Tg with no significant change in core hydrophobicity or micelle size. NMR diffusometry revealed increasing unimer populations from 0 to 54% of total polymer concentration upon decreasing core block Tg from 25 to -46 °C. Additionally, unimer population at fixed polymer composition (and thus core Tg) increased with temperature. This study demonstrates the strong influence of core-forming block mobility on polymer self-assembly, providing information toward designing drug delivery systems and suggesting the need for a new dynamical theory.

AB - Polymeric micelles coexist in solution with unassembled chains (unimers). We have investigated the influence of glass transition temperature (Tg) (i.e., chain mobility) of the micelle core-forming blocks on micelle-unimer coexistence. We synthesized a series of seven PEG-b-P(nBA-ran-tBA) amphiphilic block copolymers [PEG = poly(ethylene glycol), nBA = n-butyl acrylate, and tBA = tert-butyl acrylate] with similar molecular weights (12 kg/mol). Varying the nBA/tBA molar ratio enabled the broad modulation of core block Tg with no significant change in core hydrophobicity or micelle size. NMR diffusometry revealed increasing unimer populations from 0 to 54% of total polymer concentration upon decreasing core block Tg from 25 to -46 °C. Additionally, unimer population at fixed polymer composition (and thus core Tg) increased with temperature. This study demonstrates the strong influence of core-forming block mobility on polymer self-assembly, providing information toward designing drug delivery systems and suggesting the need for a new dynamical theory.

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Strong Variation of Micelle-Unimer Coexistence as a Function of Core Chain Mobility

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