Toughening Glassy Poly(lactide) with Block Copolymer Micelles

Tuoqi Li; Jiuyang Zhang; Deborah K. Schneiderman; Lorraine F. Francis; Frank S. Bates

doi:10.1021/acsmacrolett.6b00063

Toughening Glassy Poly(lactide) with Block Copolymer Micelles

Tuoqi Li, Jiuyang Zhang, Deborah K. Schneiderman, Lorraine F. Francis, Frank S. Bates

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

75 Scopus citations

Abstract

Poly(lactide) (PLA), a compostable bioderived polyester, can be produced at a cost and scale that makes it an attractive replacement for nondegradable petroleum-derived thermoplastics. However, pristine PLA is brittle and unsuitable for use in applications where high impact strength and ductility are required. In this work we demonstrate that poly(L-lactide) (PLLA) in the glassy state can be toughened significantly via addition of an amphiphilic diblock polymer. Notably, a PLLA blend containing only 5 wt% poly(ethylene oxide)-b-poly(butylene oxide) (PEO-PBO) exhibited tensile toughness and notched Izod impact strength over an order of magnitude higher than neat amorphous PLLA without a significant reduction in transparency or elastic modulus. For a series of PLLA blends containing PEO-PBO of fixed composition (∼70% volume fraction PBO), the toughness was inversely related to the molar mass of the added modifier with the highest toughness observed for the blend containing the smallest diblock (∼7 kg/mol). Interestingly, at fixed composition and molar mass poly(L-lactide)-b-poly(butylene oxide) (PLLA-PBO) exhibited a substantial but reduced toughening efficiency compared to PEO-PBO. We attribute this difference to a change in the solubility parameter of the amphiphilc block. Using TEM, we show that the greatest toughening is observed when the diblock modifier forms small cylindrical micelles that are well dispersed in the PLLA matrix. This morphology is facilitated by a negative Flory-Huggins interaction parameter (χ) between PEO and PLLA. These insights suggest a new and versatile strategy for the facile and efficient toughening of brittle thermoplastics. (Graph Presented).

Original language	English (US)
Pages (from-to)	359-364
Number of pages	6
Journal	ACS Macro Letters
Volume	5
Issue number	3
DOIs	https://doi.org/10.1021/acsmacrolett.6b00063
State	Published - Mar 15 2016

Bibliographical note

Funding Information:
This work was supported by the National Science Foundation through the University of Minnesota MRSEC under Award Number DMR-1420013 and the Center for Sustainable Polymers under Award Number CHE-1413862. T.L. and D.K.S. acknowledge support from the University of Minnesota Doctoral Dissertation Fellowship program. The authors extend their gratitude to Fang Zhou for assistance with TEM specimen preparation. We also appreciate help with impact strength test setup and specimen preparation from Dr. Chris M. Thurber, and Liangliang Gu. D.K.S. acknowledges Marc Hillmyer for support. Portions of this work were carried out in the Characterization Facility, University of Minnesota, a member of the NSF-funded Materials Research Facilities Network (www.mrfn.org) via the MRSEC program.

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© 2016 American Chemical Society.

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title = "Toughening Glassy Poly(lactide) with Block Copolymer Micelles",

abstract = "Poly(lactide) (PLA), a compostable bioderived polyester, can be produced at a cost and scale that makes it an attractive replacement for nondegradable petroleum-derived thermoplastics. However, pristine PLA is brittle and unsuitable for use in applications where high impact strength and ductility are required. In this work we demonstrate that poly(L-lactide) (PLLA) in the glassy state can be toughened significantly via addition of an amphiphilic diblock polymer. Notably, a PLLA blend containing only 5 wt% poly(ethylene oxide)-b-poly(butylene oxide) (PEO-PBO) exhibited tensile toughness and notched Izod impact strength over an order of magnitude higher than neat amorphous PLLA without a significant reduction in transparency or elastic modulus. For a series of PLLA blends containing PEO-PBO of fixed composition (∼70% volume fraction PBO), the toughness was inversely related to the molar mass of the added modifier with the highest toughness observed for the blend containing the smallest diblock (∼7 kg/mol). Interestingly, at fixed composition and molar mass poly(L-lactide)-b-poly(butylene oxide) (PLLA-PBO) exhibited a substantial but reduced toughening efficiency compared to PEO-PBO. We attribute this difference to a change in the solubility parameter of the amphiphilc block. Using TEM, we show that the greatest toughening is observed when the diblock modifier forms small cylindrical micelles that are well dispersed in the PLLA matrix. This morphology is facilitated by a negative Flory-Huggins interaction parameter (χ) between PEO and PLLA. These insights suggest a new and versatile strategy for the facile and efficient toughening of brittle thermoplastics. (Graph Presented).",

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note = "Funding Information: This work was supported by the National Science Foundation through the University of Minnesota MRSEC under Award Number DMR-1420013 and the Center for Sustainable Polymers under Award Number CHE-1413862. T.L. and D.K.S. acknowledge support from the University of Minnesota Doctoral Dissertation Fellowship program. The authors extend their gratitude to Fang Zhou for assistance with TEM specimen preparation. We also appreciate help with impact strength test setup and specimen preparation from Dr. Chris M. Thurber, and Liangliang Gu. D.K.S. acknowledges Marc Hillmyer for support. Portions of this work were carried out in the Characterization Facility, University of Minnesota, a member of the NSF-funded Materials Research Facilities Network (www.mrfn.org) via the MRSEC program. Publisher Copyright: {\textcopyright} 2016 American Chemical Society.",

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N1 - Funding Information: This work was supported by the National Science Foundation through the University of Minnesota MRSEC under Award Number DMR-1420013 and the Center for Sustainable Polymers under Award Number CHE-1413862. T.L. and D.K.S. acknowledge support from the University of Minnesota Doctoral Dissertation Fellowship program. The authors extend their gratitude to Fang Zhou for assistance with TEM specimen preparation. We also appreciate help with impact strength test setup and specimen preparation from Dr. Chris M. Thurber, and Liangliang Gu. D.K.S. acknowledges Marc Hillmyer for support. Portions of this work were carried out in the Characterization Facility, University of Minnesota, a member of the NSF-funded Materials Research Facilities Network (www.mrfn.org) via the MRSEC program. Publisher Copyright: © 2016 American Chemical Society.

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N2 - Poly(lactide) (PLA), a compostable bioderived polyester, can be produced at a cost and scale that makes it an attractive replacement for nondegradable petroleum-derived thermoplastics. However, pristine PLA is brittle and unsuitable for use in applications where high impact strength and ductility are required. In this work we demonstrate that poly(L-lactide) (PLLA) in the glassy state can be toughened significantly via addition of an amphiphilic diblock polymer. Notably, a PLLA blend containing only 5 wt% poly(ethylene oxide)-b-poly(butylene oxide) (PEO-PBO) exhibited tensile toughness and notched Izod impact strength over an order of magnitude higher than neat amorphous PLLA without a significant reduction in transparency or elastic modulus. For a series of PLLA blends containing PEO-PBO of fixed composition (∼70% volume fraction PBO), the toughness was inversely related to the molar mass of the added modifier with the highest toughness observed for the blend containing the smallest diblock (∼7 kg/mol). Interestingly, at fixed composition and molar mass poly(L-lactide)-b-poly(butylene oxide) (PLLA-PBO) exhibited a substantial but reduced toughening efficiency compared to PEO-PBO. We attribute this difference to a change in the solubility parameter of the amphiphilc block. Using TEM, we show that the greatest toughening is observed when the diblock modifier forms small cylindrical micelles that are well dispersed in the PLLA matrix. This morphology is facilitated by a negative Flory-Huggins interaction parameter (χ) between PEO and PLLA. These insights suggest a new and versatile strategy for the facile and efficient toughening of brittle thermoplastics. (Graph Presented).

AB - Poly(lactide) (PLA), a compostable bioderived polyester, can be produced at a cost and scale that makes it an attractive replacement for nondegradable petroleum-derived thermoplastics. However, pristine PLA is brittle and unsuitable for use in applications where high impact strength and ductility are required. In this work we demonstrate that poly(L-lactide) (PLLA) in the glassy state can be toughened significantly via addition of an amphiphilic diblock polymer. Notably, a PLLA blend containing only 5 wt% poly(ethylene oxide)-b-poly(butylene oxide) (PEO-PBO) exhibited tensile toughness and notched Izod impact strength over an order of magnitude higher than neat amorphous PLLA without a significant reduction in transparency or elastic modulus. For a series of PLLA blends containing PEO-PBO of fixed composition (∼70% volume fraction PBO), the toughness was inversely related to the molar mass of the added modifier with the highest toughness observed for the blend containing the smallest diblock (∼7 kg/mol). Interestingly, at fixed composition and molar mass poly(L-lactide)-b-poly(butylene oxide) (PLLA-PBO) exhibited a substantial but reduced toughening efficiency compared to PEO-PBO. We attribute this difference to a change in the solubility parameter of the amphiphilc block. Using TEM, we show that the greatest toughening is observed when the diblock modifier forms small cylindrical micelles that are well dispersed in the PLLA matrix. This morphology is facilitated by a negative Flory-Huggins interaction parameter (χ) between PEO and PLLA. These insights suggest a new and versatile strategy for the facile and efficient toughening of brittle thermoplastics. (Graph Presented).

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Toughening Glassy Poly(lactide) with Block Copolymer Micelles

Abstract

Bibliographical note

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MRSEC IRG-2: Sustainable Nanocrystal Materials

MRSEC IRG-3: Hierarchical Multifunctional Macromolecular Materials

University of Minnesota MRSEC (DMR-1420013)

Cite this

Toughening Glassy Poly(lactide) with Block Copolymer Micelles

Abstract

Bibliographical note

How much support was provided by MRSEC?

Reporting period for MRSEC

Access

OpenUrl availability

Other files and links

Fingerprint

Projects

MRSEC IRG-2: Sustainable Nanocrystal Materials

MRSEC IRG-3: Hierarchical Multifunctional Macromolecular Materials

University of Minnesota MRSEC (DMR-1420013)

Cite this