Abstracts Book - IMRC 2018

• SB1-O008
DETERMINATION OF RADICAL REACTIVITY RATIOS OF
FLUOROPHILIC MONOMERS AND N,N-DIMETHYLACRYLAMIDE IN
RADICAL COPOLYMERIZATIONS BY IN-SITU QUANTITATIVE 1 H-
NMR SPECTROSCOPY
Coleen Pugh 1 , Dibyendu Debnath 1 , Jessi Baughman 2 , Sujay Datta 3
1
University of Akron, Polymer Science, United States. 2 University of Akron, Chemistry, United
States. 3 University of Akron, Statistics, United States.
A model system of styrene (St) and methyl methacrylate (MMA) were
copolymerized in an NMR tube at 60 ËšC using 2,2-azobisisobutyronitrile as the
initiator and pyridazine as an internal standard to optimize an in-situ 1 H NMR
spectroscopic method for determining reactivity ratios by generating data at
hundreds of instantaneous comonomer compositions (1 to 95 mol% St) starting
with only nine initial comonomer compositions. The radical reactivity ratios of
styrene (rSt = 0.697 ± 0.010) and methyl methacrylate (rMMA = 0.491 ± 0.007) were
determined by non-linear least squares fitting of a Mayo-Lewis plot of the
instantaneous copolymer composition as a function of the comonomer feed
composition using the terminal model and MINITAB statistical software, in which
the copolymer composition was calculated by assuming that all comonomer
consumed was converted to copolymer without side reactions; the results were
consistent with accepted literature values for the terminal and implicit
penultimate models. After correcting for changes in the “lock” value during the
copolymerization (because of solids formed in the sealed NMR tube), the same
technique was used to determine the reactivity ratios of 2-(Nethylperfluorooctanesulfonamido)ethyl
acrylate (FOSA; rFOSA = 1.624 ± 0.048)
and 2-(N-ethylperfluorooctanesulfonamido)ethyl methacrylate (FOSM; rFOSM =
2.876 ± 0.083) in their radical copolymerizations with N,N-dimethylacrylamide
(DMA; rDMA = 1.126 ± 0.031 with FOSA; rDMA = 0.859 ± 0.026 with
FOSM). Therefore, under living conditions, the FOSA/DMA copolymerizations
produce blocky copolymers, and the FOSM/DMA copolymerizations produce
gradient copolymers. Such copolymers form tough physical hydrogels.
Acknowledgment: To the National Science Foundation for support of this
research through CHE-1112326, and The University of Akron Magnetic
Resonance Center for the donation of NMR time.
Keywords: radical reactivity ratios, in-situ NMR spectroscopy, physical hydrogel
Presenting authors email: cpugh@uakron.edu