Avtar Matharu | University of York (original) (raw)
Books by Avtar Matharu
Green Chemistry Series No. 60 Print ISBN: 978-1-78262-994-8 PDF ISBN: 978-1-78801-299-7 EPUB ISBN... more Green Chemistry Series No. 60 Print ISBN: 978-1-78262-994-8 PDF ISBN: 978-1-78801-299-7 EPUB ISBN: 978-1-78801-800-5 Print
Papers by Avtar Matharu
Annual review of chemical and biomolecular engineering, 2012
In the current climate of several interrelated impending global crises, namely, climate change, c... more In the current climate of several interrelated impending global crises, namely, climate change, chemicals, energy, and oil, the impact of green chemistry with respect to chemicals and biofuels generated from within a holistic concept of a biorefinery is discussed. Green chemistry provides unique opportunities for innovation via product substitution, new feedstock generation, catalysis in aqueous media, utilization of microwaves, and scope for alternative or natural solvents. The potential of utilizing waste as a new resource and the development of integrated facilities producing multiple products from biomass is discussed under the guise of biorefineries. Biofuels are discussed in depth, as they not only provide fuel (energy) but are also a source of feedstock chemicals. In the future, the commercial success of biofuels commensurate with consumer demand will depend on the availability of new green (bio)chemical technologies capable of converting waste biomass to fuel in a context of...
Biofuels, Bioproducts and Biorefining, 2014
ABSTRACT Food waste is currently generated in significant quantities worldwide. While most of thi... more ABSTRACT Food waste is currently generated in significant quantities worldwide. While most of this has generally few uses different from landfilling or composting, advanced valorization alternatives should be developed to maximize the value derived from such an important waste source. This contribution aims to illustrate a series of examples and current valorization strategies proposed in different countries in order to tackle the food waste issue. Proposed processing schemes involve biorefinery approaches based on both chemical and biological technologies. Important legislation aspects in different countries are also presented. © 2014 Society of Chemical Industry and John Wiley & Sons, Ltd
A Sustainable Approach to the Development of Renewable Biomaterials, 2012
ABSTRACT This chapter contains sections titled: * Introduction * Porous Polysaccharides * Starbon... more ABSTRACT This chapter contains sections titled: * Introduction * Porous Polysaccharides * Starbon® Mesoporous Carbons * Summary and Future Perspectives * Acknowledgments * References
Pure and Applied Chemistry
Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals, 1999
... AVTAR MATHARU, ROBERT WILSON and CHRISSIE GROVER ... catalysed by titanium(1V) tetrachloride ... more ... AVTAR MATHARU, ROBERT WILSON and CHRISSIE GROVER ... catalysed by titanium(1V) tetrachloride to give the intermediate acyl-compounds (6 and 7). Wofff-Kishner (Huang-Minion) reduction of compounds (6 and 7) generated the corresponding alkyl-compounds (8 and ...
Liquid Crystals, 2007
ABSTRACT The synthesis, transition temperatures and structure–property relationships of a variety... more ABSTRACT The synthesis, transition temperatures and structure–property relationships of a variety of thiophene‐containing azobenzene esters derived from either 3‐(2‐thienyl)acrylic acid (series I, IV, VI, VIII, X and XII) or 3‐(3‐thienyl)acrylic acid (series II, V, VII, IX, XI and XIII) and appropriate fluoro‐ and non‐fluoro‐substituted ‘azophenols’ are reported. For comparative purposes, the non‐heterocyclic counterparts, i.e. cinnamates (series III), were also prepared and are reported. All 70 final esters are mesomorphic, exhibiting the nematic phase alone. Their mesomorphic properties are dependent on the disposition of the terminal thiophene moiety. In general, 3‐thienyl‐substitution gives thermally more stable compounds than 2‐thienyl‐substitution. The influence of mono‐ (series IV, V, VI and VII) and di‐lateral (series VIII, IX, X, XI, XII and XIII) fluoro‐substitution on mesomorphic properties is investigated in detail. Lateral fluorination lowers mesophase thermal stability and its extent is dependent on the number and disposition of the lateral fluoro‐substituents. Di‐lateral fluorination across the long molecular axis is more detrimental to mesophase thermal stability than along the long molecular axis.
Liquid Crystals, 2011
At the present time the molecular architecture of many thermotropic liquid crystals is still base... more At the present time the molecular architecture of many thermotropic liquid crystals is still based on Vorländer's century-old concept of a linear lath-like geometry [11. Vorländer, D. 1908. Kristallinisch-flüssige Substanzen , Stuttgart: Enke. ... View all references, 22. Vorländer, ...
Green Chem., 2015
A systematic study of the synthesis and characterization of epoxy thermosets derived from ELO cur... more A systematic study of the synthesis and characterization of epoxy thermosets derived from ELO cured with different DCAs in the presence of DMAP at 160 °C for 1 h.
ACS Sustainable Chemistry & Engineering, 2014
ABSTRACT The drive toward sustainable practices and principles across the supply chain has led to... more ABSTRACT The drive toward sustainable practices and principles across the supply chain has led to an upsurge in renewable materials. Epoxy resins are used in a wide range of applications in various fields, such as coatings, adhesives, castings, modeling compounds, impregnation materials, high-performance composites, insulating materials, and encapsulating and packaging materials for electronic devices. In order to achieve the desired properties, uncured epoxy resins must be converted to hard, infusible, thermoset networks in the presence of a variety of curing agents, also known as hardeners. This paper reviews recent advances in the development of curing agents from renewable materials. Attention is given to modified plant oils, biobased acids and anhydrides, amines and their derivatives, biobased phenols, rosin acids, and terpenes and lignin as biobased curing agents for primarily epoxy resin or biobased epoxy resin systems.
Green Chem., 2015
Editorial article to accompany the Green Chemistry themed issue “Elemental Recovery and Sustainab... more Editorial article to accompany the Green Chemistry themed issue “Elemental Recovery and Sustainability”.
RSC Advances, 2014
Bio-based thermoset composites comprising epoxidised linseed oil (ELO), a bio-derived diacid cros... more Bio-based thermoset composites comprising epoxidised linseed oil (ELO), a bio-derived diacid crosslinker (Pripol 1009) and starch are reported.
RSC Advances, 2011
ABSTRACT Considerable mineralogical changes occur during the combustion of biomass such as wheat ... more ABSTRACT Considerable mineralogical changes occur during the combustion of biomass such as wheat straw, which lead to variation in the physical, chemical and textural properties of the ashes formed. Mineralogical and chemical changes occur above combustion temperatures of 500 °C causing reductions in the solubility of potassium, chloride, silica and sulfate. This can be directly correlated to the evaporation of KCl, dissociation of K2SO4, softening of silica and formation of alkali silicates. Calciumextraction increased above combustion temperatures of 700 °C due to the decomposition of CaCO3. We have discovered, for the first time, that the inherent alkali in unleached wheat straw is sufficient to solubilise up to 30% of the silica in the ash at room temperature. This could be used to produce potassium silicate solution as a new valuable by-product of wheat straw combustion. It was also found that incomplete combustion at high temperatures, following leaching of ashes can lead to the formation of porous activated carbons and inorganic materials, demonstrating yet another valuable use for this waste material.
Journal of Materials Chemistry C, 2013
ABSTRACT The ability of suitably derived prop-2-enoates from 3-(thiophen-2-yl)- and 3-(thiophen-3... more ABSTRACT The ability of suitably derived prop-2-enoates from 3-(thiophen-2-yl)- and 3-(thiophen-3-yl)-prop-2-enoic acid and appropriately fluorinated and non-fluorinated 4-[(4-alkoxyphenyl)diazenyl]phenols to promote excellent photoalignment of a bulk commercial nematic liquid crystal is reported. The performed study showed that the photoalignment of the liquid crystal is influenced by the number and disposition of fluoro-substituents and the position of attachment of the terminal thiophene moiety, either 2- or 3-substituted, in the molecular structure of the alignment material. Inclusion of a lateral fluoro-substituent(s) induces an excellent photoalignment whereas the non-fluorinated counterpart tends to give an unsatisfactory alignment. 3-Substituted thiophenes give a better photoalignment than their 2-substituted isomeric counterparts. A prototype display, which contains an alignment layer made from one of the proposed materials, possessing good alignment ability, is presented in order to demonstrate the application potential of these materials in LCDs.
Advanced Materials Research, 2014
The photoalignment properties of thin films made from several azo-containing thiophene-based acry... more The photoalignment properties of thin films made from several azo-containing thiophene-based acrylate with respect to the commercially available nematic liquid crystal (MLC 6873-100; ε>o) is reported. As observed, the photoalignment ability of these films is influenced by the number and disposition of fluoro-substituents and the position of attachment of the terminal thiophene moiety. Inclusion of a lateral fluoro-substituent (s) provides excellent photo alignment ability whereas the non-fluorinated counterpart tends to give unsatisfactory alignment quality. The performed study showed also that 2-substituted thiophenes give better photoalignment quality.
Biofuels, Bioproducts and Biorefining, 2014
Food waste is currently generated in signifi cant quantities worldwide. While most of this has ge... more Food waste is currently generated in signifi cant quantities worldwide. While most of this has generally few uses different from landfi lling or composting, advanced valorization alternatives should be developed to maximize the value derived from such an important waste source. This contribution aims to illustrate a series of examples and current valorization strategies proposed in different countries in order to tackle the food waste issue. Proposed processing schemes involve biorefi nery approaches based on both chemical and biological technologies. Important legislation aspects in different countries are also presented.
Photochemistry and Photophysics of Polymer Materials, 2010
... The spiropyran-merocyanine photochro-mic switch relies on UV-induced (approximately 360nm) ph... more ... The spiropyran-merocyanine photochro-mic switch relies on UV-induced (approximately 360nm) photolysis of the spiro-carbonoxygen (CspiroO) bond in spiropyran (colorless closed form) to generate the intensely colored open form, merocyanine. ...
ChemInform, 2008
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Pure and Applied Chemistry, 2000
ABSTRACT
Plant and Soil, 2012
Background D-amino acids are far less abundant in nature than L-amino acids. Both L-and D-amino a... more Background D-amino acids are far less abundant in nature than L-amino acids. Both L-and D-amino acids enter soil from different sources including plant, animal and microbial biomass, antibiotics, faeces and synthetic insecticides. Moreover, D-amino acids appear in soil due to abiotic or biotic racemization of Lamino acids. Both L-and D-amino acids occur as bound in soil organic matter and as "free" amino acids dissolved in soil solution or exchangeably bound to soil colloids. D-amino acids are mineralized at slower rates compared to the corresponding L-enantiomers. Plants have a capacity to directly take up "free" Damino acids by their roots but their ability to utilize them is low and thus D-amino acids inhibit plant growth.
Green Chemistry Series No. 60 Print ISBN: 978-1-78262-994-8 PDF ISBN: 978-1-78801-299-7 EPUB ISBN... more Green Chemistry Series No. 60 Print ISBN: 978-1-78262-994-8 PDF ISBN: 978-1-78801-299-7 EPUB ISBN: 978-1-78801-800-5 Print
Annual review of chemical and biomolecular engineering, 2012
In the current climate of several interrelated impending global crises, namely, climate change, c... more In the current climate of several interrelated impending global crises, namely, climate change, chemicals, energy, and oil, the impact of green chemistry with respect to chemicals and biofuels generated from within a holistic concept of a biorefinery is discussed. Green chemistry provides unique opportunities for innovation via product substitution, new feedstock generation, catalysis in aqueous media, utilization of microwaves, and scope for alternative or natural solvents. The potential of utilizing waste as a new resource and the development of integrated facilities producing multiple products from biomass is discussed under the guise of biorefineries. Biofuels are discussed in depth, as they not only provide fuel (energy) but are also a source of feedstock chemicals. In the future, the commercial success of biofuels commensurate with consumer demand will depend on the availability of new green (bio)chemical technologies capable of converting waste biomass to fuel in a context of...
Biofuels, Bioproducts and Biorefining, 2014
ABSTRACT Food waste is currently generated in significant quantities worldwide. While most of thi... more ABSTRACT Food waste is currently generated in significant quantities worldwide. While most of this has generally few uses different from landfilling or composting, advanced valorization alternatives should be developed to maximize the value derived from such an important waste source. This contribution aims to illustrate a series of examples and current valorization strategies proposed in different countries in order to tackle the food waste issue. Proposed processing schemes involve biorefinery approaches based on both chemical and biological technologies. Important legislation aspects in different countries are also presented. © 2014 Society of Chemical Industry and John Wiley & Sons, Ltd
A Sustainable Approach to the Development of Renewable Biomaterials, 2012
ABSTRACT This chapter contains sections titled: * Introduction * Porous Polysaccharides * Starbon... more ABSTRACT This chapter contains sections titled: * Introduction * Porous Polysaccharides * Starbon® Mesoporous Carbons * Summary and Future Perspectives * Acknowledgments * References
Pure and Applied Chemistry
Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals, 1999
... AVTAR MATHARU, ROBERT WILSON and CHRISSIE GROVER ... catalysed by titanium(1V) tetrachloride ... more ... AVTAR MATHARU, ROBERT WILSON and CHRISSIE GROVER ... catalysed by titanium(1V) tetrachloride to give the intermediate acyl-compounds (6 and 7). Wofff-Kishner (Huang-Minion) reduction of compounds (6 and 7) generated the corresponding alkyl-compounds (8 and ...
Liquid Crystals, 2007
ABSTRACT The synthesis, transition temperatures and structure–property relationships of a variety... more ABSTRACT The synthesis, transition temperatures and structure–property relationships of a variety of thiophene‐containing azobenzene esters derived from either 3‐(2‐thienyl)acrylic acid (series I, IV, VI, VIII, X and XII) or 3‐(3‐thienyl)acrylic acid (series II, V, VII, IX, XI and XIII) and appropriate fluoro‐ and non‐fluoro‐substituted ‘azophenols’ are reported. For comparative purposes, the non‐heterocyclic counterparts, i.e. cinnamates (series III), were also prepared and are reported. All 70 final esters are mesomorphic, exhibiting the nematic phase alone. Their mesomorphic properties are dependent on the disposition of the terminal thiophene moiety. In general, 3‐thienyl‐substitution gives thermally more stable compounds than 2‐thienyl‐substitution. The influence of mono‐ (series IV, V, VI and VII) and di‐lateral (series VIII, IX, X, XI, XII and XIII) fluoro‐substitution on mesomorphic properties is investigated in detail. Lateral fluorination lowers mesophase thermal stability and its extent is dependent on the number and disposition of the lateral fluoro‐substituents. Di‐lateral fluorination across the long molecular axis is more detrimental to mesophase thermal stability than along the long molecular axis.
Liquid Crystals, 2011
At the present time the molecular architecture of many thermotropic liquid crystals is still base... more At the present time the molecular architecture of many thermotropic liquid crystals is still based on Vorländer's century-old concept of a linear lath-like geometry [11. Vorländer, D. 1908. Kristallinisch-flüssige Substanzen , Stuttgart: Enke. ... View all references, 22. Vorländer, ...
Green Chem., 2015
A systematic study of the synthesis and characterization of epoxy thermosets derived from ELO cur... more A systematic study of the synthesis and characterization of epoxy thermosets derived from ELO cured with different DCAs in the presence of DMAP at 160 °C for 1 h.
ACS Sustainable Chemistry & Engineering, 2014
ABSTRACT The drive toward sustainable practices and principles across the supply chain has led to... more ABSTRACT The drive toward sustainable practices and principles across the supply chain has led to an upsurge in renewable materials. Epoxy resins are used in a wide range of applications in various fields, such as coatings, adhesives, castings, modeling compounds, impregnation materials, high-performance composites, insulating materials, and encapsulating and packaging materials for electronic devices. In order to achieve the desired properties, uncured epoxy resins must be converted to hard, infusible, thermoset networks in the presence of a variety of curing agents, also known as hardeners. This paper reviews recent advances in the development of curing agents from renewable materials. Attention is given to modified plant oils, biobased acids and anhydrides, amines and their derivatives, biobased phenols, rosin acids, and terpenes and lignin as biobased curing agents for primarily epoxy resin or biobased epoxy resin systems.
Green Chem., 2015
Editorial article to accompany the Green Chemistry themed issue “Elemental Recovery and Sustainab... more Editorial article to accompany the Green Chemistry themed issue “Elemental Recovery and Sustainability”.
RSC Advances, 2014
Bio-based thermoset composites comprising epoxidised linseed oil (ELO), a bio-derived diacid cros... more Bio-based thermoset composites comprising epoxidised linseed oil (ELO), a bio-derived diacid crosslinker (Pripol 1009) and starch are reported.
RSC Advances, 2011
ABSTRACT Considerable mineralogical changes occur during the combustion of biomass such as wheat ... more ABSTRACT Considerable mineralogical changes occur during the combustion of biomass such as wheat straw, which lead to variation in the physical, chemical and textural properties of the ashes formed. Mineralogical and chemical changes occur above combustion temperatures of 500 °C causing reductions in the solubility of potassium, chloride, silica and sulfate. This can be directly correlated to the evaporation of KCl, dissociation of K2SO4, softening of silica and formation of alkali silicates. Calciumextraction increased above combustion temperatures of 700 °C due to the decomposition of CaCO3. We have discovered, for the first time, that the inherent alkali in unleached wheat straw is sufficient to solubilise up to 30% of the silica in the ash at room temperature. This could be used to produce potassium silicate solution as a new valuable by-product of wheat straw combustion. It was also found that incomplete combustion at high temperatures, following leaching of ashes can lead to the formation of porous activated carbons and inorganic materials, demonstrating yet another valuable use for this waste material.
Journal of Materials Chemistry C, 2013
ABSTRACT The ability of suitably derived prop-2-enoates from 3-(thiophen-2-yl)- and 3-(thiophen-3... more ABSTRACT The ability of suitably derived prop-2-enoates from 3-(thiophen-2-yl)- and 3-(thiophen-3-yl)-prop-2-enoic acid and appropriately fluorinated and non-fluorinated 4-[(4-alkoxyphenyl)diazenyl]phenols to promote excellent photoalignment of a bulk commercial nematic liquid crystal is reported. The performed study showed that the photoalignment of the liquid crystal is influenced by the number and disposition of fluoro-substituents and the position of attachment of the terminal thiophene moiety, either 2- or 3-substituted, in the molecular structure of the alignment material. Inclusion of a lateral fluoro-substituent(s) induces an excellent photoalignment whereas the non-fluorinated counterpart tends to give an unsatisfactory alignment. 3-Substituted thiophenes give a better photoalignment than their 2-substituted isomeric counterparts. A prototype display, which contains an alignment layer made from one of the proposed materials, possessing good alignment ability, is presented in order to demonstrate the application potential of these materials in LCDs.
Advanced Materials Research, 2014
The photoalignment properties of thin films made from several azo-containing thiophene-based acry... more The photoalignment properties of thin films made from several azo-containing thiophene-based acrylate with respect to the commercially available nematic liquid crystal (MLC 6873-100; ε>o) is reported. As observed, the photoalignment ability of these films is influenced by the number and disposition of fluoro-substituents and the position of attachment of the terminal thiophene moiety. Inclusion of a lateral fluoro-substituent (s) provides excellent photo alignment ability whereas the non-fluorinated counterpart tends to give unsatisfactory alignment quality. The performed study showed also that 2-substituted thiophenes give better photoalignment quality.
Biofuels, Bioproducts and Biorefining, 2014
Food waste is currently generated in signifi cant quantities worldwide. While most of this has ge... more Food waste is currently generated in signifi cant quantities worldwide. While most of this has generally few uses different from landfi lling or composting, advanced valorization alternatives should be developed to maximize the value derived from such an important waste source. This contribution aims to illustrate a series of examples and current valorization strategies proposed in different countries in order to tackle the food waste issue. Proposed processing schemes involve biorefi nery approaches based on both chemical and biological technologies. Important legislation aspects in different countries are also presented.
Photochemistry and Photophysics of Polymer Materials, 2010
... The spiropyran-merocyanine photochro-mic switch relies on UV-induced (approximately 360nm) ph... more ... The spiropyran-merocyanine photochro-mic switch relies on UV-induced (approximately 360nm) photolysis of the spiro-carbonoxygen (CspiroO) bond in spiropyran (colorless closed form) to generate the intensely colored open form, merocyanine. ...
ChemInform, 2008
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Pure and Applied Chemistry, 2000
ABSTRACT
Plant and Soil, 2012
Background D-amino acids are far less abundant in nature than L-amino acids. Both L-and D-amino a... more Background D-amino acids are far less abundant in nature than L-amino acids. Both L-and D-amino acids enter soil from different sources including plant, animal and microbial biomass, antibiotics, faeces and synthetic insecticides. Moreover, D-amino acids appear in soil due to abiotic or biotic racemization of Lamino acids. Both L-and D-amino acids occur as bound in soil organic matter and as "free" amino acids dissolved in soil solution or exchangeably bound to soil colloids. D-amino acids are mineralized at slower rates compared to the corresponding L-enantiomers. Plants have a capacity to directly take up "free" Damino acids by their roots but their ability to utilize them is low and thus D-amino acids inhibit plant growth.
Optics Letters, 2003
Polarization holographic and surface-relief gratings have been recorded in an amorphous azobenzen... more Polarization holographic and surface-relief gratings have been recorded in an amorphous azobenzene polyester by use of a frequency-doubled argon-ion laser beam at 257 nm. Higher excited states of azobenzene in the trans and cis configurations contribute to the formation of a diffraction grating in this experiment. A combination of right and left circularly polarized writing beams has been found to give the highest diffraction efficiency. The contributions to the total phase difference that arise from anisotropy and surface relief have been separated experimentally, and it is shown that the surface-relief grating contributes a larger phase difference than that which is due to anisotropy.