MECHANISM OF THE PHOTO-INITIATED POLYMERIZATION OF METHYL METHACRYLATE AT ZINC OXIDE SURFACES<sup>1</sup>

Kuriacose, Joseph C.; Markham, M. Clare

doi:10.1021/j100829a032

Cited by 38 publications

(24 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…of 500,000 were obtained. In a later investigation Kuriakose and Markham [247] have shown that the photo-initiator formed on the surface of zinc oxide certainly is a form of oxygen. The polymerisation process initiated on exposure to light is completed in darkness.…”

Section: Photopolymerisation In the Presence Of Metallic Oxidesmentioning

confidence: 97%

“…radiation is formed on the surface of some metallic oxides in the presence of oxygen, water or organic solvents the photolysis of which produces free hydrogen or hydroxyl radicals. A number of published papers describe the investigations of the photopolymerisation in the presence of metallic oxides such as ZnO [123][124][125]247,262,279,447,549,5501,Ti02[124,125,262,4471,Zr02[262,4471. These studies refer chiefly to the photopolymerisation of methyl methacrylate, acrylonitrile, acrylamide and vinyl acetate.…”

Section: Photopolymerisation In the Presence Of Metallic Oxidesmentioning

confidence: 99%

See 1 more Smart Citation

Photosensitized Processes in Polymer Chemistry: A Review

Rabek

1968

Photochem & Photobiology

View full text Add to dashboard Cite

Dedicated to the memory of Prof. Dr T. 1. Rabek O U T L I N E ( I ) Theoretical principles of the sensitization process. (2) Photosensitized polymerisation, graft polymerisation and cross-linking. Mercury-photosensitized reactions. Ion-pair complexes as photoinitiators. Photopolymerisation in the presence of metallic oxides. Photosensitization by chlorine, bromine and iodine compounds. Organic compounds as sensitizers. Halogenated compounds as sensitizers. Sensitizing compounds with the C=O group. Sensitizing compounds with t h e -O U g r o u p . Sensitizing compounds containing nitrogen. Sulphur containing sensitizers. Reactions photosensitized by dyes. (3) Photosensitized cis-trans isomerization of polymers. (4) Photosensitized degradation. (S) Photopolymers. (6) Photosensitizing polymers. (7) Spectral sensitization of the photoeffect in polymers. A * ( S , ) -*A(So)+hv'The time of emission decay is inversely proportional to the integrated intensity of the respective absorption band.Among various possibilities of deactivation without the participation of radiation two possibilities must be distinguished[339]:(1) Intramolecular processes.(2) Intermolecular processes. Both kinds are utilized in sensitized photochemical reactions of polymers. In the intramolecular process the energy of electron excitation is converted within the molecule into other forms of energy. When the excitation energy attains the magnitude of the energy of bond disruption, the sensitizer dissociates, thereby forming free radicals: A * ( S , ) + R 1 . + R I . + . . . + R iMany secondary reactions are promoted by radicals formed; this efl'ect depends upon the radical structure and activity [ 12,20,52 1,5321. Photosensitized processes in polymer chemistry: a reviewIn some cases a metastable triplet state is produced by the absorbed light quanta. This metastable triplet state is essential in phosphorescence and in certain processes of photosensitization, photoreduction, photodimerisation, etc. 7 A ( S 0 ) + h V + A * ( S I ) + A * ( T , )The probability of triplet state formation by direct radiative elevation of the ground state is very small, though there is a high probability of the radiationless transitions to the triplet, from the higher singlet states in solids and rigid solutions in a number of aromatic compounds.There is an important difference between the photophysical process of molecules in the n, 7r* first excited state and those of molecules in the lowest excited state r, r*. In the case of n, 7r* states in particular the natural life-time and the degree of excitation localisation are greater, and the S1 + TI energy gaps are smaller. The photochemical reactivity which is influenced in part by these factors shows distinct differences. It appears that the reactive state corresponds to the first excited singlet and the solvent participates only to the extent that it affects the relative probabilities of the several photochemical processes involved.

show abstract

Section: Photopolymerisation In the Presence Of Metallic Oxidesmentioning

confidence: 97%

Section: Photopolymerisation In the Presence Of Metallic Oxidesmentioning

confidence: 99%

Photosensitized Processes in Polymer Chemistry: A Review

Rabek

1968

Photochem & Photobiology

View full text Add to dashboard Cite

show abstract

“…[41] Upon being reduced by the photocatalytic process with ZnO, surfaceadsorbed O 2 generates superoxide radicals (•O 2 − ), which initiate the polymerization. However, Hoffman et al [42] proposed that anionic initiation may be directly prohibited by CB electrons because the reduction potential (E ared ) of MMA (−1.1 V vs NHE) is more negative than the CB energy level (E CB ) of ZnO (−0.2 V vs NHE).…”

Section: Uv Light-driven Photocatalysismentioning

confidence: 99%

“…The initial report on photocatalytic green synthesis by Markham et al used zinc oxide (ZnO) nanoparticles to realize the polymerization of methyl methacrylate (MMA) . Upon being reduced by the photocatalytic process with ZnO, surface‐adsorbed O 2 generates superoxide radicals (•O 2 − ), which initiate the polymerization.…”

Section: Conversion From Light To Chemical Energy With Various Photonmentioning

confidence: 99%

Full‐Spectrum Solar‐Light‐Activated Photocatalysts for Light–Chemical Energy Conversion

Wang

Sang

et al. 2017

Advanced Energy Materials

222

113

View full text Add to dashboard Cite

photocatalysis based on semiconductors represents another route for light energy conversion. This route endows the direct conversion of light energy into oxidation and reduction energy via charge carriers (electrons and holes) generated in the semiconductors. For instance, the photocatalytic degradation of harmful and toxic organic substances, dyes, and chemicals has been considered to be a suitable candidate for removing organic pollution from water, [5][6][7][8] where photooxidation dominates the degradation of the organic molecules. The full process of photocatalytic water splitting into H 2 and O 2 is believed to be promising for generating renewable and green energy, [9,10] and the process includes the photoreduction and photooxidation of water, respectively. The photocatalytic reduction of CO 2 can convert solar energy into chemical energy, stored as CH 4 , CO, CH 3 OH, etc. [11][12][13] These processes can help reduce the pressure of the global warming crisis and supply usable renewable energy. Due to the precise control of photocatalytic reduction and oxidation, photocatalytic molecular synthesis has also attracted much interest, which provides a sustainable pathway for green synthesis. [14][15][16] For an efficient photocatalytic process, solar light harvesting and a redox process based on photogenerated charge carriers are essential steps. Solar light harvesting consists of light absorption and charge carrier excitation steps, which can be expressed as the light utilization efficiency. The efficiency determines the total energy converted from solar light and is mostly determined by the band structure of the semiconductor applied to the photocatalytic process.The photocatalytic process has been extensively studied by examining the response of photocatalysts to UV light, due to its relatively high photonic energy. As is well known, UV light energy amounts to no more than 5% of the solar light energy. Visible light and near-infrared (NIR) light contain approximately 90% of the solar light energy. To utilize solar light in order to solve the environmental and energy crisis, visible light and NIR-light-activated photocatalysts are essential. For decades, many studies have focused on expanding the range over which a photocatalyst can utilize the solar light spectrum. In addition, there are several good reviews summarizing recent progress on UV-vis-light-activated photocatalysts, as well as strategies to improve the photocatalytic efficiency. [17][18][19][20] As is well known, the photonic energy of visible light is low, and that of NIR light is even lower. Photoinduced redox requires an initial amount of energy to activate the process; however, NIR photonic energy may be too low to realize photoinduced The realization of light-chemical energy conversion using solar light is an ideal goal in renewable energy studies. Many reports are concerned with extracting energy from solar light and the use/storage of the converted energy. Due to the progress in solar light absorption with various photocatalysts, the vari...

show abstract

“…The used radical polymerization mechanism requires a time interval of approximately two hours to reach complete polymerization. After the generation of the polymerization seed, zinc oxide can support a propagation reaction [47], leading to a polymerization yield improved by 4% ( Figure 4). In contrast to this, iron seems to quench the initiator, probably by redox-reactions, resulting in a polymerization yield decreased by 22% compared to an unloaded microgel.…”

Section: Polymerisation Yield and Microgel Morphologymentioning

confidence: 99%

Water-based, surfactant-free cytocompatible nanoparticle-microgel-composite biomaterials – rational design by laser synthesis, processing into fiber pads and impact on cell proliferation

et al. 2017

View full text Add to dashboard Cite

Abstract:This work highlights the laser-based aqueous synthesis and processing of nanocomposites, composed of zinc or iron nanoparticles embedded in a N-Vinylcaprolactam microgel matrix, with potential applicability as ion releasing fiber pads for wound healing. An in situ laser process for microgel synthesis is developed and optimized for high embedded nanoparticle yields, evaluating influences of laser repetition rate and monomer concentration. The impact of the nanoparticles on polymerization was increased by embedded zinc oxide nanoparticles, and reduced in the presence of iron oxide. Furthermore, TEM images verified that the nanoparticles were homogeneously embedded into the polymer matrix. The nanoparticle-loaded microgels were thermally stable up to 429°C, which ensures that the composites maintain their integrity after heat sterilization and during rapid prototyping by thermal polymer processing. The general suitability of the hydrogels as active biomaterial for wound healing was assessed in toxicity, cell proliferation and migration assays using human dermal fibroblasts and keratinocytes, where cytocompatibility was verified, while the proliferation was affected by the gel alone as well as the embedded nanoparticles. The hydrogels were processed to suit their use as a biomaterial for wound coverages via electrospinning resulting in a centimeter scale fully cytocompatible fiber pad with the nanoparticle-filled microgel capsules supported on the fiber's surface.

show abstract

MECHANISM OF THE PHOTO-INITIATED POLYMERIZATION OF METHYL METHACRYLATE AT ZINC OXIDE SURFACES¹

Cited by 38 publications

References 3 publications

Photosensitized Processes in Polymer Chemistry: A Review

Photosensitized Processes in Polymer Chemistry: A Review

Full‐Spectrum Solar‐Light‐Activated Photocatalysts for Light–Chemical Energy Conversion

Water-based, surfactant-free cytocompatible nanoparticle-microgel-composite biomaterials – rational design by laser synthesis, processing into fiber pads and impact on cell proliferation

Contact Info

Product

Resources

About

MECHANISM OF THE PHOTO-INITIATED POLYMERIZATION OF METHYL METHACRYLATE AT ZINC OXIDE SURFACES1

Cited by 38 publications

References 3 publications

Photosensitized Processes in Polymer Chemistry: A Review

Photosensitized Processes in Polymer Chemistry: A Review

Full‐Spectrum Solar‐Light‐Activated Photocatalysts for Light–Chemical Energy Conversion

Water-based, surfactant-free cytocompatible nanoparticle-microgel-composite biomaterials – rational design by laser synthesis, processing into fiber pads and impact on cell proliferation

Contact Info

Product

Resources

About

MECHANISM OF THE PHOTO-INITIATED POLYMERIZATION OF METHYL METHACRYLATE AT ZINC OXIDE SURFACES¹