Compositional distribution characterization of poly(methyl methacrylate)-graft-polydimethylsiloxane copolymers

Timothy C. Schunk, Timothy Edward Long

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

Graft copolymers prepared by radical polymerization of a low-molecular-mass monomer with a macromonomer display heterogeneity in both molecular mass and chemical composition. The characterization of these joint distributions by a single technique [e.g., size-exclusion chromatography (SEC)] is hindered by the effects of both variables on the separation mechanism. Separation emphasizing chemical composition heterogeneity can be efficiently performed by gradient elution high-performance liquid chromatography (HPLC) combining precipitation and adsorption retention. Comparison of Fourier transform IR and evaporative light-scattering detection indicated decreasing polydimethylsiloxane (PDMS) macromonomer incorporation corresponding to increasing retention time for a poly(methyl methacrylate) (PMMA)-graft-PDMS copolymer. More detailed information was obtained by multidetector SEC of composition fractions from gradient elution HPLC. SEC separation in an isorefractive solvent for PDMS (tetrahydrofuran) with low-angle laser-light scattering, differential viscometry, and differential refractive index detection allowed determination of the molecular mass of both the whole copolymer and that of the PMMA backbone for each HPLC fraction. Comparison with an independent SEC determination of the PDMS macromonomer molecular mass allowed estimation of the number of pendant PDMS chains per graft copolymer molecule across the HPLC chromatogram. Results indicated a relatively constant incorporation of the number of PDMS side chains with increasing PMMA backbone molecular mass, leading to a relative decrease in weight fraction PDMS incorporation with increasing molecular mass of the whole graft copolymer molecule.

Original languageEnglish
Pages (from-to)221-232
Number of pages12
JournalJournal of Chromatography A
Volume692
Issue number1-2
DOIs
Publication statusPublished - 1995 Feb 10
Externally publishedYes

Fingerprint

Polymethyl Methacrylate
Grafts
Molecular mass
Copolymers
Size exclusion chromatography
Transplants
High performance liquid chromatography
Gel Chromatography
Graft copolymers
High Pressure Liquid Chromatography
Light scattering
Chemical analysis
Light
Refractometry
Molecules
Viscosity measurement
Fourier Analysis
Free radical polymerization
baysilon
Polymerization

ASJC Scopus subject areas

  • Analytical Chemistry
  • Biochemistry
  • Organic Chemistry

Cite this

Compositional distribution characterization of poly(methyl methacrylate)-graft-polydimethylsiloxane copolymers. / Schunk, Timothy C.; Long, Timothy Edward.

In: Journal of Chromatography A, Vol. 692, No. 1-2, 10.02.1995, p. 221-232.

Research output: Contribution to journalArticle

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