Microstructure of trans-4-acryloyloxyazobenzene/methyl methacrylate copolymers by n.m.r. spectroscopy

Brar, A. S.; Thiyagarajan, Muthiah

doi:10.1016/s0032-3861(98)00123-2

Cited by 7 publications

(5 citation statements)

References 14 publications

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“…The number average molecular weight ( M n ) of poly(Azo) is about 6000 g·mol –1 . This fairly low value for a free radical polymerization is in agreement with results previously reported in the literature . The M n ’s of poly(Azo- co -AcRf6) polymers are 1000, 6000, 10 000, and 14 000 for x i Azo of 0.94, 0.79, 0.62, and 0.42, respectively.…”

Section: Resultssupporting

confidence: 92%

“…This fairly low value for a free radical polymerization is in agreement with results previously reported in the literature. 20 The M n 's of poly(Azo-co-AcRf6) polymers are 1000, 6000, 10 000, and 14 000 for x i Azo of 0.94, 0.79, 0.62, and 0.42, respectively. These low weights can be due to a solvent effect, since it has been complicated to find a common solvent of both monomers (DMF).…”

Section: Different Molar Proportions (X Imentioning

confidence: 99%

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Poly(azobenzene acrylate-co-fluorinated acrylate) Spin-Coated Films: Influence of the Composition on the Photo-Controlled Wettability

et al. 2013

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The wetting properties of spin-coated films of copolymers based on azobenzene and fluorinated units have been investigated. The copolymers, denoted as poly(Azo-co-AcRf6), have been synthesized by free-radical polymerization of different proportions of acrylate monomers bearing either an azobenzene group or a semifluorinated side chain. The UV-visible spectroscopy analysis of the different spin-coating films through a cycle of UV and visible light irradiation indicates the reversible trans-cis isomerization of azobenzene groups. Simultaneously, atomic force microscopy shows that surface roughness does not exceed 1 nm. Advancing and receding contact angles of water and diiodomethane have been measured before and after UV photoirradiation of the different surfaces. In particular, a decrease in the advancing contact angles has been observed upon trans-cis isomerization of azobenzene groups. Switching variations up to 50° have been evidenced without any introduction of surface nanoroughness. Surface free-energy evaluations have been deduced from these measurements, including dispersive and polar components. The results show that, through surface composition and UV photoirradiation, a large range of surface free-energies can be obtained, from 7 to 46 mN·m(-1).

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Section: Resultssupporting

confidence: 92%

Section: Different Molar Proportions (X Imentioning

confidence: 99%

Poly(azobenzene acrylate-co-fluorinated acrylate) Spin-Coated Films: Influence of the Composition on the Photo-Controlled Wettability

et al. 2013

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“…The 13 C( 1 H)‐NMR spectra of the A–M copolymer ( F A = 0.5) is shown in Figure 2 along with signal assignments. The assignments of aromatic carbon resonance of A‐monomeric units have been reported in previous papers 8, 9. The methyl, quaternary, and methylene carbon resonances of A‐ and M‐monomeric units were in the ranges of δ 16.9–21.6, 45.0–45.71, and 51.96–54.41 ppm, respectively.…”

Section: Resultssupporting

confidence: 65%

Stereochemical and compositional assignments oftrans-4-methacryloyloxyazobenzene-methyl methacrylate copolymers by one- and two-dimensional NMR spectroscopy

Brar

Thiyagarajan

1999

J. Appl. Polym. Sci.

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ABSTRACT:The microstructure of trans-4-methacryloyloxyazobenzene-methyl methacrylate copolymers prepared by solution polymerization process using AIBN as initiator is analyzed by one-and two-dimensional spectroscopy. Sequence distribution was calculated from the 13 C( 1 H)-NMR spectra of the copolymers. Comonomer reactivity ratios were determined using the Kelen-Tudos and the nonlinear error-in-variables methods are r A ϭ 1.14 Ϯ 0.08 and r M ϭ 0.51 Ϯ 0.03; r A ϭ 1.13 Ϯ 0.1 and r M ϭ 0.50 Ϯ 0.04, respectively. The sequence distribution of A-and M-centered triads determined from 13 C( 1 H)-NMR spectra of copolymer is in good agreement with triad concentration calculated from a statistical model. The 2-D heteronuclear single-quantum correlation and correlated spectroscopy (TOCSY) was used to analyze the complex 1 H-NMR spectrum.

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“…In microstructure studies of random copolymers of acryloyloxyazobenzene and methyl methacrylate 12 and random terpolymers of acrylonitrile, styrene, and methyl methacrylate, 13 Brar and coworkers showed that the calculated fractions of triads determined from 13 C NMR tacticity splittings were in good agreement with those calculated from the statistical model. The LDV terpolymer prepared from a 0.3:0.3:0.3 monomer feed ratio for 7 days had an M w value of approximately 100 kDa; as determined from the statisti-cal model, on average each polymer could have a maximum of eight triad LDV units.…”

Section: Resultsmentioning

confidence: 88%

Microstructural characterization of terpolymers of leucine, β‐benzyl aspartate, and valine

Wamsley¹,

Phiasivongsa²,

Jasti³

et al. 2006

J. Polym. Sci. A Polym. Chem.

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Three different characterization methods-13 C NMR spectroscopy, a terminal terpolymerization model, and a probability analysis based on the Poisson distribution-were used to determine the microstructure of random terpolymers. The methods were used to determine the amino acid sequence distribution of random terpolymers prepared from the polymerization of N-carboxyanhydrides that contained L-leucine, b-benzyl-L-aspartate, and L-valine. Poly(L-leucine-L-aspartic acid-L-valine) [poly(LDV)] was designed as a target specific substrate for the a 4 b 1 integrin that recognizes the tripeptide sequence leucine-aspartic acid-valine (LDV). The presence of the tripeptide sequence LDV within the polymer was determined to be eight LDV triad sequences on average in terpolymers of approximately 100 kDa.

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Microstructure of trans-4-acryloyloxyazobenzene/methyl methacrylate copolymers by n.m.r. spectroscopy

Cited by 7 publications

References 14 publications

Poly(azobenzene acrylate-co-fluorinated acrylate) Spin-Coated Films: Influence of the Composition on the Photo-Controlled Wettability

Poly(azobenzene acrylate-co-fluorinated acrylate) Spin-Coated Films: Influence of the Composition on the Photo-Controlled Wettability

Stereochemical and compositional assignments oftrans-4-methacryloyloxyazobenzene-methyl methacrylate copolymers by one- and two-dimensional NMR spectroscopy

Microstructural characterization of terpolymers of leucine, β‐benzyl aspartate, and valine

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