Tacticity determination of poly(methyl methacrylate) (PMMA) by high‐resolution NMR

White, A. J.; Filisko, Frank E.

doi:10.1002/pol.1982.130201003

Cited by 39 publications

(38 citation statements)

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“…The 1 H NMR spectrum contains signals attributed to CH 3 (0.8-1.1 ppm), CH 2 (1.7-2.2 ppm), and OCH 3 (3.5-3.8 ppm) protons, which is in accordance to results published in the literature [33,34].…”

Section: Characteristics Of Neat Pmmasupporting

confidence: 90%

Nano-Mechanical Properties of Modified Poly(Methyl Methacrylate) Films Studied by Atomic Force Microscopy

Kaczmarek

Gałka

2010

Tribol Lett

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Atomic force microscopy (AFM) has been used to study the effect of various photoinitiators doped into poly(methyl methacrylate) (PMMA) on the mechanical properties of PMMA films at the nanometer scale. Pure and modified PMMA films (containing four different photoinitiators) were exposed to a mercury vapor lamp in air atmosphere. Force-distance curves for hardness, Young modulus, and adhesion forces were obtained using different AFM modes (tapping or contact-mode) and different tips (diamond or silicon nitride). The results revealed that the added photoinitiators slightly changed the nanomechanical properties of PMMA as a result of alterations in the photochemical reactions and physical processes occurring in the studied systems. tert-Butyl peroxybenzoate had the most efficient effect on the measured parameters in UV-irradiated PMMA, whereas benzoyl peroxide was less active. The mechanism of the observed processes is discussed.

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Section: Characteristics Of Neat Pmmasupporting

confidence: 90%

Nano-Mechanical Properties of Modified Poly(Methyl Methacrylate) Films Studied by Atomic Force Microscopy

Kaczmarek

Gałka

2010

Tribol Lett

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“…PMMA tacticity was determined using proton NMR ( Figure S1 in Supporting Information), while the tacticity of d 5 -PMMA cannot be determined by measuring the proton NMR spectra of ester-methyl groups. 32 Sapphire prisms were used for the SFG experiments. Before spincoating, the prisms were sonicated for 20 min in chloroform (99.9%, certified ACS, Fisher Scientific) and 20 min in toluene (99.5%, AR ACS, Avantor Performance Materials).…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Molecular Structure of Poly(methyl methacrylate) Surface II: Effect of Stereoregularity Examined through All-Atom Molecular Dynamics

et al. 2014

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The chemical composition and molecular structure of polymeric surfaces are important in understanding wetting, adhesion, and friction. Here, we combine interfacesensitive sum frequency generation spectroscopy (SFG), allatom molecular dynamics (MD) simulations, and ab initio calculations to understand the composition and the orientation of chemical groups on poly(methyl methacrylate) (PMMA) surface as a function of tacticity and temperature. The SFG spectral features for isotactic and syndiotactic PMMA surfaces are similar, and the dominant peak in the spectra corresponds to the ester-methyl groups. The SFG spectra for solid and melt states are very similar for both syndiotactic and isotactic PMMA. In comparison, the MD simulation results show that both the ester-methyl and the α-methyl groups of syndiotactic-PMMA are ordered and tilted toward the surface normal. For the isotactic-PMMA, the α-methyl groups are less ordered compared to their ester-methyl groups. The backbone methylene groups have a broad angular distribution and are disordered, independent of tacticity and temperature. We have compared the SFG results with theoretical spectra calculated using MD simulations and ab initio calculations. Our analysis shows that the weaker intensity of α-methyl groups in SFG spectra is due to a combination of smaller molecular hyperpolarizability, lower ordering, and lower surface number density. This work highlights the importance of combining SFG spectroscopy with MD simulations and ab initio calculations in understanding polymer surfaces. ■ INTRODUCTIONOne of the simplest and still commonly used technique to characterize surfaces of polymers is the measurement of water contact angle. Although this is a very simple technique to judge the wettability of surfaces, it lacks molecular level sensitivity to identify the chemical composition and molecular structure of surfaces. In addition, the rearrangement of molecules at the surface after exposure to water complicates the interpretation of contact angle results. 1 X-ray photoelectron spectroscopy (XPS), a vacuum-based technique, provides excellent information regarding the elemental composition present at the surfaces. However, to identify different hydrocarbon groups (or bondings) is not trivial and relies on subtle shifts of carbon binding energies in the high-resolution XPS analysis. 2 Attenuated-total-reflectance infrared can be used to pick up molecular fingerprints, but this technique samples a much thicker layer than the surface region that affects wetting, surface energy, and friction. 3 In the past two decades, surface-sensitive infrared−visible sum frequency generation spectroscopy (SFG) has been used to study polymer surfaces, 4−7 polymer/liquid interfaces, 7−11 polymer/metal or metal oxide interfaces, 5,12−15 and polymer/polymer interfaces. 12,16−19 SFG is a second-order nonlinear optical technique, and under electric dipole approximation, the SFG signal is only generated by the ordered molecules at surfaces or interfaces and the contribution from ...

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“…Tacticities were estimated by α-CH 3 peaks of PMMA. 8 These were assigned to be isotactic, atactic and syndiotactic conformations at 1.31-1.16, 1.11-0.95, and 0.95-0.72 ppms, respectively. Table I shows the tacticities in PMMA prepared under 29 × 10 4 g and 1 g. It was confirmed that the isotactic conformations in the centrifugal samples were higher than those in the controlled samples which were obtained under 1 g. It indicates that strong gravity field increases the isotacticity.…”

Section: Effect Of Initiator Concentrationmentioning

confidence: 99%

“…The tacticities of PMMA were determined by these spectra in CDCl 3 with 0.03% TMS as described by White and Filisco. 8 SEC was performed on a Waters 966 chromatograph equipped with Tosoh column Super HM-M (6 mm i.d. × 150 mm) using tetrahydrofuran (THF) as an eluent at room temperature.…”

Section: Measurementsmentioning

confidence: 99%

Enhancement of Isotacticity in Bulk Radical Polymerization of Poly(methyl methacrylate) under Strong Gravity Field

Nishihara

Teramoto

Sakurai

et al. 2003

Polym J

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KEY WORDSPoly(Methyl Methacrylate)(PMMA) / Centrifugation / Strong Gravity Field / Tacticity / 1 H NMR spectroscopy / Isotacticity / Stereoregular polymers are one of the most important materials in industry due to its thermostability, stiffness and chemical resistance. Stereoregular polymers have been prepared by polymerization with metal catalysts such as Ziegler-Natta catalysts. They have been extensively studied by the polymerization with Grignard reagents, alkylaluminum and alkyllithium. 1 On the other hand, control of stereoregularity without metal catalysts should be valuable. For this purpose, it has been reported the polymerizations of methacrylates having bulky side chains. 2 However, this idea provides limitation of chemical structures in monomers and then may be less applicable to extend.In this study, we aim to increase stereoregularity in free radical bulk polymerization of general-purpose monomers without special metal catalyst. Therefore, we focused on the polymerization under strong gravity field over 10 5 g although there has been a few reports under gravity field of 10 4 g level 3 and their research aims are not related to stereoregularity. 3,4 Fortunately, one of the authors has established the sedimentation theory under mega gravity field 5 and also developed the centrifugal apparatus generated over 10 6 g. 6 This gravity field can induce the sedimentation of metal atoms in solid-solution system alloy. 7 If monomers have a deviated center of gravity and are exposed to strong gravity field, the polymerization may proceed with molecular orientation of the monomers. In this study, methyl methacrylate was used as a monomer. The tacticity of the resultant poly(methyl methacrylate) (PMMA) was measured by 1 H NMR spectroscopy. † To whom correspondence should be addressed.

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Tacticity determination of poly(methyl methacrylate) (PMMA) by high‐resolution NMR

Cited by 39 publications

References 2 publications

Nano-Mechanical Properties of Modified Poly(Methyl Methacrylate) Films Studied by Atomic Force Microscopy

Nano-Mechanical Properties of Modified Poly(Methyl Methacrylate) Films Studied by Atomic Force Microscopy

Molecular Structure of Poly(methyl methacrylate) Surface II: Effect of Stereoregularity Examined through All-Atom Molecular Dynamics

Enhancement of Isotacticity in Bulk Radical Polymerization of Poly(methyl methacrylate) under Strong Gravity Field

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