Evident phase separation and surface segregation of hydrophobic moieties at the copolymer surface using atomic force microscopy and SFG spectroscopy

Katherine Leslee A. Cimatu; Uvinduni I. Premadasa; Tharushi D. Ambagaspitiya; Narendra M. Adhikari; Joon Hee Jang

doi:10.1016/j.jcis.2020.07.066

Evident phase separation and surface segregation of hydrophobic moieties at the copolymer surface using atomic force microscopy and SFG spectroscopy

Katherine Leslee A. Cimatu, Uvinduni I. Premadasa, Tharushi D. Ambagaspitiya, Narendra M. Adhikari, Joon Hee Jang

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

7 Scopus citations

Abstract

Hypothesis: Copolymers are developed to enhance the overall physical and chemical properties of polymers. The surface nature of a copolymer is relevant to creating efficient materials to improve adhesion and biocompatibility. We hypothesize that the improved adhesion, as a surface property, is due to phase separation, surface segregation, and the overall molecular organization of different polymer components at the copolymer surface. Experiments: The surface structure of a copolymer composed of 2-hydroxyethyl methacrylate (HEMA) monomer and 2-phenoxyethyl methacrylate (PhEMA) monomer was analyzed in comparison to the polyHEMA and polyPhEMA homopolymers using atomic force microscopy (AFM) and sum frequency generation (SFG) spectroscopy. Findings: The contrast in the phase images was due to the variance in the hydrophobic level provided by the hydroxyl and phenoxy modified monomers in the copolymer. The distribution of the adhesion values, supporting the presence of hydrophobic moieties, across the polymer surface defined the surface segregation of these two components. SFG spectra of the copolymer thin film showed combined spectral features of both polyHEMA and polyPhEMA thin films at the polymer surface. The tilt angles of the alpha-methyl group of homopolymers using the polarization intensity ratio analysis and the polarization mapping method were estimated to be in the range from 48° to 66°.

Original language	English
Pages (from-to)	645-659
Number of pages	15
Journal	Journal of Colloid and Interface Science
Volume	580
DOIs	https://doi.org/10.1016/j.jcis.2020.07.066
State	Published - Nov 15 2020
Externally published	Yes

Funding

The authors thank the National Science Foundation under Grant No. CHE-0947031 for the acquisition of the femtosecond laser. The authors would also like to thank Stephanie Chan for help during polymer synthesis. The current work was supported by the start-up fund of the Ohio University Department of Chemistry and Biochemistry and the College of Arts and Sciences. The authors would like to thank the Nanoscale and Quantum Phenomena Institute, Ohio University for their additional financial support.

Funders	Funder number
Nanoscale and Quantum Phenomena Institute
National Science Foundation	CHE-0947031
Ohio University
College of Arts and Sciences, Boston University
Chemistry and Biochemistry Department, Ohio University

Keywords

Adhesion
Atomic force microscopy
Copolymers
Force curve
Methacrylates
Phase separation
SFG spectroscopy
Surface segregation

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10.1016/j.jcis.2020.07.066

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title = "Evident phase separation and surface segregation of hydrophobic moieties at the copolymer surface using atomic force microscopy and SFG spectroscopy",

abstract = "Hypothesis: Copolymers are developed to enhance the overall physical and chemical properties of polymers. The surface nature of a copolymer is relevant to creating efficient materials to improve adhesion and biocompatibility. We hypothesize that the improved adhesion, as a surface property, is due to phase separation, surface segregation, and the overall molecular organization of different polymer components at the copolymer surface. Experiments: The surface structure of a copolymer composed of 2-hydroxyethyl methacrylate (HEMA) monomer and 2-phenoxyethyl methacrylate (PhEMA) monomer was analyzed in comparison to the polyHEMA and polyPhEMA homopolymers using atomic force microscopy (AFM) and sum frequency generation (SFG) spectroscopy. Findings: The contrast in the phase images was due to the variance in the hydrophobic level provided by the hydroxyl and phenoxy modified monomers in the copolymer. The distribution of the adhesion values, supporting the presence of hydrophobic moieties, across the polymer surface defined the surface segregation of these two components. SFG spectra of the copolymer thin film showed combined spectral features of both polyHEMA and polyPhEMA thin films at the polymer surface. The tilt angles of the alpha-methyl group of homopolymers using the polarization intensity ratio analysis and the polarization mapping method were estimated to be in the range from 48° to 66°.",

keywords = "Adhesion, Atomic force microscopy, Copolymers, Force curve, Methacrylates, Phase separation, SFG spectroscopy, Surface segregation",

author = "Cimatu, {Katherine Leslee A.} and Premadasa, {Uvinduni I.} and Ambagaspitiya, {Tharushi D.} and Adhikari, {Narendra M.} and Jang, {Joon Hee}",

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Evident phase separation and surface segregation of hydrophobic moieties at the copolymer surface using atomic force microscopy and SFG spectroscopy. / Cimatu, Katherine Leslee A.; Premadasa, Uvinduni I.; Ambagaspitiya, Tharushi D. et al.
In: Journal of Colloid and Interface Science, Vol. 580, 15.11.2020, p. 645-659.

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

TY - JOUR

T1 - Evident phase separation and surface segregation of hydrophobic moieties at the copolymer surface using atomic force microscopy and SFG spectroscopy

AU - Cimatu, Katherine Leslee A.

AU - Premadasa, Uvinduni I.

AU - Ambagaspitiya, Tharushi D.

AU - Adhikari, Narendra M.

AU - Jang, Joon Hee

PY - 2020/11/15

Y1 - 2020/11/15

N2 - Hypothesis: Copolymers are developed to enhance the overall physical and chemical properties of polymers. The surface nature of a copolymer is relevant to creating efficient materials to improve adhesion and biocompatibility. We hypothesize that the improved adhesion, as a surface property, is due to phase separation, surface segregation, and the overall molecular organization of different polymer components at the copolymer surface. Experiments: The surface structure of a copolymer composed of 2-hydroxyethyl methacrylate (HEMA) monomer and 2-phenoxyethyl methacrylate (PhEMA) monomer was analyzed in comparison to the polyHEMA and polyPhEMA homopolymers using atomic force microscopy (AFM) and sum frequency generation (SFG) spectroscopy. Findings: The contrast in the phase images was due to the variance in the hydrophobic level provided by the hydroxyl and phenoxy modified monomers in the copolymer. The distribution of the adhesion values, supporting the presence of hydrophobic moieties, across the polymer surface defined the surface segregation of these two components. SFG spectra of the copolymer thin film showed combined spectral features of both polyHEMA and polyPhEMA thin films at the polymer surface. The tilt angles of the alpha-methyl group of homopolymers using the polarization intensity ratio analysis and the polarization mapping method were estimated to be in the range from 48° to 66°.

AB - Hypothesis: Copolymers are developed to enhance the overall physical and chemical properties of polymers. The surface nature of a copolymer is relevant to creating efficient materials to improve adhesion and biocompatibility. We hypothesize that the improved adhesion, as a surface property, is due to phase separation, surface segregation, and the overall molecular organization of different polymer components at the copolymer surface. Experiments: The surface structure of a copolymer composed of 2-hydroxyethyl methacrylate (HEMA) monomer and 2-phenoxyethyl methacrylate (PhEMA) monomer was analyzed in comparison to the polyHEMA and polyPhEMA homopolymers using atomic force microscopy (AFM) and sum frequency generation (SFG) spectroscopy. Findings: The contrast in the phase images was due to the variance in the hydrophobic level provided by the hydroxyl and phenoxy modified monomers in the copolymer. The distribution of the adhesion values, supporting the presence of hydrophobic moieties, across the polymer surface defined the surface segregation of these two components. SFG spectra of the copolymer thin film showed combined spectral features of both polyHEMA and polyPhEMA thin films at the polymer surface. The tilt angles of the alpha-methyl group of homopolymers using the polarization intensity ratio analysis and the polarization mapping method were estimated to be in the range from 48° to 66°.

KW - Adhesion

KW - Atomic force microscopy

KW - Copolymers

KW - Force curve

KW - Methacrylates

KW - Phase separation

KW - SFG spectroscopy

KW - Surface segregation

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Evident phase separation and surface segregation of hydrophobic moieties at the copolymer surface using atomic force microscopy and SFG spectroscopy

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