Positron annihilation lifetime spectroscopy of molecularly imprinted hydroxyethyl methacrylate based polymers

Djourelov, N.; Ateş, Zeliha; Güven, Olgun; Misheva, M.; Suzuki, Takenori

doi:10.1016/j.polymer.2007.03.006

Cited by 20 publications

(26 citation statements)

References 35 publications

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“…Noticeably this aspect had not been addressed in earlier investigations [22]. This is very important because the physical selectivity depends on how accurate is the porosity estimation in an MIP.…”

Section: Free Volume Distribution Resultsmentioning

confidence: 97%

“…When a positron from a radioactive source 22 Na is injected into a molecular medium such as a polymer, it interacts with the medium and loses its kinetic energy very quickly (1-2 ps) and gets thermalized. The thermalized positron may pick up an electron from the medium and annihilate as a free positron in the crystalline domains of the medium or get trapped in defects or voids present in medium before annihilation.…”

Section: Positron Annihilation Lifetime Spectroscopymentioning

confidence: 99%

“…The source-sample sandwich geometry was used for positron lifetime measurements wherein MIP samples in the form of pellets were placed on either side of the source and the resulting sandwich was held together tightly by wrapping with an aluminum foil. About 2 mm in diameter 22 Na was deposited at the centre of 1 cm 2 Kapton foil of 12.7 mm thickness was used as the source. Greater details of the experimental procedure can be found in our earlier works [26,27].…”

Section: Positron Annihilation Lifetime Spectroscopymentioning

confidence: 99%

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Synthesis and characterization of methacrylic acid-based molecular imprinted polymers by positron lifetime spectroscopy

Pasang

Ranganathaiah

2013

Polym Eng Sci

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Three molecular imprinted polymers (MIPs) were prepared with different amounts of crosslinker (ethylene glycol dimethacrylate) in methacrylic acid functional monomer. Positron lifetime spectroscopy has been used to study the variation in free volume cavities (nanosize pores) in these MIPs of different monomercrosslinker ratio. The changes in free volume cavities after the template molecule 4-chlorophenol extracted from the polymer matrix were measured. The results indicate that the optimum monomer-crosslinker ratio for this MIP is 1:5. The free volume distribution derived from CONTIN program further reveals the presence and absence of template molecules in the system. The Fourier transform infrared spectra results have been used to compliment this through the absence of stretching frequencies at 648 cm 21 and 825 cm 21 of CACl suggesting the successful extraction of the template from the MIPs. Scanning electron microscope (SEM) scans indicate the grains are of heterogeneous shape and size in agreement with earlier studies. POLYM. ENG. SCI., 54:667-674, 2014.

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Section: Free Volume Distribution Resultsmentioning

confidence: 97%

Section: Positron Annihilation Lifetime Spectroscopymentioning

confidence: 99%

Section: Positron Annihilation Lifetime Spectroscopymentioning

confidence: 99%

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Synthesis and characterization of methacrylic acid-based molecular imprinted polymers by positron lifetime spectroscopy

Pasang

Ranganathaiah

2013

Polym Eng Sci

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“…The effect of accelerated aging on polymer morphology can be determined by different techniques. PALS is a standard method used in the literature that is suitable for measuring the free‐volume radii of polymers ; it is commonly used to characterize the changes in the free volume after irradiation of the polymers .…”

Section: Methodsmentioning

confidence: 99%

“…The fourth peak, which has the longest lifetime, indicates the lifetime ( τ 4 ) and intensity ( I 4 ) of o ‐Ps in the amorphous phase of the polymer . Thus, the mean defect size in the crystalline–amorphous interphase ( R = R 3 , Table ) or the free‐volume radii of the amorphous phase ( R = R 4 , Table ) can be calculated using the empirical equation given below ,

τ_{o ‐ Ps} = 0.5 true[1 - \frac{R}{R + 0.1656} + \frac{1}{2} sin true(2 π \frac{R}{R + 0.1656} true) true]

assuming that the holes where the Positroniums are trapped and annihilated are spherical in shape.…”

Section: Methodsmentioning

confidence: 99%

Effects of thermo-fatigue loading, hydrostatic pressure, and heat aging on the free-volume and crystalline structure of polypropylene-co -ethylene random copolymer pipes

Deveci

Öner

2014

Polym Eng Sci

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Plastic pipes composed of polypropylene‐co‐ethylene random copolymers were subjected to accelerated aging by thermo‐fatigue loading (i.e., thermal cycling using hot and cold water alternately under pressure), application of hydrostatic pressure at elevated temperatures, and heat aging in an oven. The effects of these accelerated aging techniques on the molecular and crystalline structure of the material were investigated using positron annihilation lifetime spectroscopy, Fourier‐transform infrared spectroscopy, and differential scanning calorimetry. It was found that all three types of applied aging techniques decreased the size of the defects in the crystalline–amorphous interphase of the material, increased the density of these defects, and had a negligible impact on the free‐volume hole size and intensity of the amorphous phase. Thermo‐fatigue loading resulted in decreased lamellae thickness and lamellae thickness distribution; in contrast, hydrostatic pressure loading resulted in increased lamellae thickness and lamellae thickness distribution. The effect of thermo‐fatigue loading on the chemical degradation of polypropylene was more pronounced than the effects of hydrostatic pressure and heat aging. POLYM. ENG. SCI., 55:641–650, 2015. © 2014 Society of Plastics Engineers

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Crosslinking diversity on network morphology, template binding, and template transport of molecularly imprinted polymers prepared via living radical polymerization

Salian

Byrne

2013

J of Applied Polymer Sci

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The objective of this work is to study the effects of altering the chain building blocks and the reaction on template binding and transport parameters of imprinted polymer gels. The characterization of imprinted poly(diethylaminoethylmethacrylate-cohydroxyethylmethacrylate-co-polyethyleneglycol(n)dimethacrylate) polymer gels prepared via free (FRP) or living (LRP) radical polymerization with varying crosslinking monomer lengths (number of ethylene glycol repeat units of 1, 4.5, 9) and concentrations (1, 5, 10, 50%) is presented. All imprinted networks prepared via LRP exhibited significantly higher template binding affinities and capacities as well as significantly lower template diffusion coefficients compared to those prepared via FRP. Synthesizing imprinted polymers via LRP results in much smaller and relatively constant dispersities of polymer chains compared to imprinted polymers prepared via FRP. Therefore, LRP has a profound structural effect on the imprinted polymer network leading to increased homogeneity in the mesh structure which enhances the molecular imprinting effect.

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Positron annihilation lifetime spectroscopy of molecularly imprinted hydroxyethyl methacrylate based polymers

Cited by 20 publications

References 35 publications

Synthesis and characterization of methacrylic acid-based molecular imprinted polymers by positron lifetime spectroscopy

Synthesis and characterization of methacrylic acid-based molecular imprinted polymers by positron lifetime spectroscopy

Effects of thermo-fatigue loading, hydrostatic pressure, and heat aging on the free-volume and crystalline structure of polypropylene-co -ethylene random copolymer pipes

Crosslinking diversity on network morphology, template binding, and template transport of molecularly imprinted polymers prepared via living radical polymerization

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