Gareth J. Price

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Organization: University of Bath , England

Department: Department of Chemistry

Title: (PhD)

TOPICS

Organic Chemistry

Polymer

Block Copolymer Atom Transfer Radical Polymerization

Chemicals
References

Sonochemical production of nanoparticle metal oxides for potential use in dentistry

Co-reporter:James Stubbing, Judith Brown, Gareth J. Price

Ultrasonics Sonochemistry 2017 Volume 35(Part B) pp:646-654

Publication Date(Web):March 2017

DOI:10.1016/j.ultsonch.2016.04.036

•Ultrasonic dental instruments produce sufficiently intense sound fields to perform sonochemistry.•Zinc and copper oxides have been produced sonochemically using benign reagents.•Reactions have been performed under conditions simulating dental surgery.Two types of ultrasonic instruments used in dentistry have been compared with a sonochemical horn for the production of copper oxide and zinc oxide nanoparticles. The nanoparticles can be produced from benign reagents using dental instruments as the source of sonochemical enhancement. The process has been operated in resin models of teeth in a preliminary exploration of the potential of the method for enhancing procedures such as root canal surgery. The technique is potentially useful but further work is needed for a full assessment of using in-situ generated nanoparticles as an aid to disinfection during some types of dental surgery.

The Structures of Uncommon Cationic N-alkenyl Purine and Pyrimidine Bases

Co-reporter:Gabriele Kociok-Köhn;Kieran C. Molloy;Douglas R. G. Smith

Journal of Heterocyclic Chemistry 2016 Volume 53( Issue 1) pp:64-68

Publication Date(Web):

DOI:10.1002/jhet.2300

The structures of 1,3 bis-(allyl)cytosinium bromide (1), 7,9 bis-(allyl)adeninium bromide hydrate (2) and 3-(butenyl)adeninium bromide (3) have been determined. 1 is dimeric via N―H…Br hydrogen bonds, which further associate into ribbons via weaker C―H…Br interactions. 2 is also dimeric, now from N―H…N hydrogen bonds, which build up further through a complex array of hydrogen bonds involving both the anion and water of crystallization (O―H…N, O―H…Br, C―H…Br). 3 does not dimerise but forms polymeric sheets via a series of N―H…N, C―H…N and C―H…Br hydrogen bonds.

Thymine-functionalised siloxanes: Model compounds and polymers

Co-reporter:Douglas R.G. Smith, Gabriele Kociok-Köhn, Kieran C. Molloy, Gareth J. Price, Rhys D. Short

Journal of Organometallic Chemistry 2015 Volume 778() pp:29-34

Publication Date(Web):15 February 2015

DOI:10.1016/j.jorganchem.2014.12.007

•Organosiloxanes functionalised with thymine have been prepared using a novel, efficient method.•Condensation of α-amino-ω-alkylsilanes or amino-functionalised siloxanes with thymine aldehydes gave high molecular weight polymers.•Variation in thymine loading led to a range of material properties from highly viscous fluids to brittle solids.A novel, efficient synthetic method for the production of organosiloxane polymers functionalised with pendant DNA bases, typified by thymine, is reported. A condensation reaction between an α-amino-ω-alkylsilane or an amino-functionalised siloxane with aldehyde-functionalised thymine gave polymers in higher overall yields than the methods previously reported. Variation in the loading of thymine led to a range of material properties from a highly viscous fluid at 0.2% functionalization to a hard, brittle solid at 20% loading due to hydrogen bonding interactions.Organosiloxane polymers functionalised with a pendant DNA base, thymine, have been prepared in high yield by condensation of amino-functionalised siloxanes with aldehyde-functionalised thymine.

Biomimetic polyorganosiloxanes: model compounds for new materials

Co-reporter:Gabriele Kociok-Köhn, Mary F. Mahon, Kieran C. Molloy, Gareth J. Price, Timothy J. Prior and Douglas R. G. Smith

Dalton Transactions 2014 vol. 43(Issue 21) pp:7734-7746

Publication Date(Web):04 Apr 2014

DOI:10.1039/C4DT00554F

The chemistry of N-organosilylalkyl-substituted heterocyclic bases (thymine, adenine and cytosine) is described, covering the structures of model compounds, the synthesis of substituted oligo-siloxanes and a preliminary report of the synthesis of a poly(organosiloxane) with pendant N-alkyl(heterocycle) functionalities. N-Alkenylthymines CH2CH(CH2)nT (T = thymine, n = 1 (1), 2 (2), 3 (3)) have been prepared and 2 hydrosilylated to form PhMe2Si(CH2)4T (5). Alternatively, 5 was prepared by reaction of PhMe2Si(CH2)4Br (6) with (O,O-SiMe3)2T, a method which has also been used to prepare PhMe2Si(CH2)4A (7) and PhMe2Si(CH2)4C (8) (A = adenine, C = cytosine). Model di- and tri-siloxanes [Br(CH2)4(Me)2Si]2O (10), Me3SiOSi(Me)2(CH2)4Br (11), PhMe2SiOSi(Me)2(CH2)4Br (12) and (Me3SiO)2(Me)Si(CH2)4Br (13) have been prepared by hydrosilylation of H2CC(H)(CH2)4Br with an appropriate hydrosiloxane and used to prepare Me3SiO(Me)2Si(CH2)4T (14), Me3SiO(Me)2Si(CH2)4A (15) (both from 11), and (Me3SiO)2(Me)Si(CH2)4T (16), (Me3SiO)2(Me)Si(CH2)4A (17) (both from 13). 10 reacts with thymine to give a mixture of the pyrimidocyclophane cyclo-T-N,N-[(CH2)4(Me)2Si]2O (19) and [T(CH2)4Si(Me)2]2O (20), while cytosine reacts similarly to form cyclo-C-N,N-[(CH2)4(Me)2Si]2O (21; as an imine) and [C(CH2)4Si(Me)2]2O (22); adenine only generates [A(CH2)4Si(Me)2]2O (18) in an analogous synthesis. Using a related protocol, polymeric {[MeSi(O)(CH2)4Br]2[Me2SiO]98}n (23) has been converted to {[MeSi(O)(CH2)4T]2[Me2SiO]98}n (24) and {[MeSi(O)(CH2)4A]2[Me2SiO]98}n (25). The structures of 4, 5, 8, 19 and 21, along with a 2:1 adduct of 5 with Ni(dithiobiuret)2 (9) are reported.

Encapsulation and release of aqueous components from sonochemically produced protein microspheres

Co-reporter:Emily K. Skinner and Gareth J. Price

Chemical Communications 2012 vol. 48(Issue 74) pp:9260-9262

Publication Date(Web):02 Aug 2012

DOI:10.1039/C2CC34926D

Aqueous solutions of salts or dyes have been contained in sonochemically produced lysozyme microspheres by encapsulating an inverse emulsion in tetradecane. Release can be triggered by chemically disrupting crosslinking in the protein shell or by mechanical disruption using high intensity ultrasound.

Room temperature sonochemical initiation of thiol-ene reactions

Co-reporter:Emily K. Skinner, Fraeya M. Whiffin and Gareth J. Price

Chemical Communications 2012 vol. 48(Issue 54) pp:6800-6802

Publication Date(Web):14 May 2012

DOI:10.1039/C2CC32457A

Thiol-ene ‘click’ reactions have been initiated for a range of primary alkenes using ultrasound in both toluene and water. The method is particularly effective in aqueous solutions in the presence of air.

Ultrasound promoted Wurtz coupling of alkyl bromides and dibromides

Co-reporter:Daniel VandenBurg, Gareth J. Price

Ultrasonics Sonochemistry 2012 Volume 19(Issue 1) pp:5-8

Publication Date(Web):January 2012

DOI:10.1016/j.ultsonch.2011.06.002

Sonochemically enhanced Wurtz coupling using lithium metal has been investigated for a number of isomeric alkyl bromides under a variety conditions. The products result from direct coupling of short lived radicals formed at the metal surface rather than the secondary radicals which can be formed during coupling of aromatic halides and thus give rise to a single major product. Coupling has been extended to dibrominated aryl and alkyl compounds as well as showing that aryl–alkyl coupling is possible. Dibrominated alkyls were found to give low molecular weight oligomers although no reaction occurred for 1,2-isomers. The growth of oligomers in THF may be solubility limited. A simple model is proposed to explain these findings.Highlights► Wurtz coupling using lithium metal of alkyl bromides. ► Single products formed from short lived radicals, unlike aromatic bromides. ► 1,2-Dibromides do not couple. ► 1,3- and 1,4-Dibromides couple to give oligomers.

Composition of Calcium Carbonate Polymorphs Precipitated Using Ultrasound

Co-reporter:Gareth J. Price, Mary F. Mahon, James Shannon, and Crispin Cooper

Crystal Growth & Design 2011 Volume 11(Issue 1) pp:39-44

Publication Date(Web):November 17, 2010

DOI:10.1021/cg901240n

The precipitation of calcium carbonate (CaCO3) from saturated solutions prepared using calcium chloride and sodium hydrogen carbonate under the influence of ultrasound (20 kHz, intensity ranging from 1.5−18.5 W cm−2) has been studied. For short reaction times or treatment at low intensity, precipitates containing up to 90% vaterite were recovered; longer (>30 min) times or higher intensities yielded up to 100% calcite. Changes in the crystal sizes were noted. The results are consistent with the literature model of CaCO3 crystallization by the initial formation of vaterite followed by a dissolution−recrystallization process. Although a complete explanation cannot be offered, the results help to explain some of the apparently conflicting information previously published on this topic.

Cavitation occurrence around ultrasonic dental scalers

Co-reporter:Bernhard Felver, David C. King, Simon C. Lea, Gareth J. Price, A. Damien Walmsley

Ultrasonics Sonochemistry 2009 Volume 16(Issue 5) pp:692-697

Publication Date(Web):June 2009

DOI:10.1016/j.ultsonch.2008.11.002

Ultrasonic scalers are used in dentistry to remove calculus and other contaminants from teeth. One mechanism which may assist in the cleaning is cavitation generated in cooling water around the scaler. The vibratory motion of three designs of scaler tip in a water bath has been characterised by laser vibrometry, and compared with the spatial distribution of cavitation around the scaler tips observed using sonochemiluminescence from a luminol solution. The type of cavitation was confirmed by acoustic emission analysed by a ‘Cavimeter’ supplied by NPL. A node/antinode vibration pattern was observed, with the maximum displacement of each type of tip occurring at the free end. High levels of cavitation activity occurred in areas surrounding the vibration antinodes, although minimal levels were observed at the free end of the tip. There was also good correlation between vibration amplitude and sonochemiluminescence at other points along the scaler tip. ‘Cavimeter’ analysis correlated well with luminol observations, suggesting the presence of primarily transient cavitation.

Synthesis and modification of silicon-containing polymers using ultrasound

Co-reporter:Gareth J Price

Polymer International 2009 Volume 58( Issue 3) pp:290-295

Publication Date(Web):

DOI:10.1002/pi.2525

Abstract

The application of high-intensity ultrasound to silicon backbone polymers, particularly polydimethylsiloxane and polyorganosilanes, is described. There are advantages in using ultrasound in both modifying the molecular weights or end-group structures of preformed polymers and accelerating the course of polymerization reactions. Copyright © 2009 Society of Chemical Industry

Ultrasonic intensification of ozone and electrochemical destruction of 1,3-dinitrobenzene and 2,4-dinitrotoluene

Co-reporter:V.O. Abramov, O.V. Abramov, A.E. Gekhman, V.M. Kuznetsov, G.J. Price

Ultrasonics Sonochemistry 2006 Volume 13(Issue 4) pp:303-307

Publication Date(Web):May 2006

DOI:10.1016/j.ultsonch.2005.04.007

The removal of nitroaromatics from polluted water is difficult due to their high stability to conventional treatment methods. This paper presents a method for the destruction of 1,3-dinitrobenzene and 2,4-dinitrotoluene in aqueous solutions. The compounds are shown to be stable to reaction with ozone, even under ultrasonic activation. The use of ultrasound enhances the rate of electrochemical reduction but the overall rate of reaction is still slow. However, the simultaneous application of ultrasound and ozonation to the electrochemical reaction allows virtually complete destruction of the compounds in short times. The effect is attributed to the ultrasonic enhancement of the electrochemical process giving intermediates that are susceptible to ozone oxidation. While further analytical work is needed to deduce the exact contributions of the various possible degradation mechanisms, the work demonstrates the synergies that can be gained by using combined techniques for the destruction of these difficult compounds.

Vapour sorption studies of polymer-solution thermodynamics using a piezoelectric quartz crystal microbalance

Co-reporter:Gareth J Price;Dawn A Haddon;Anthony Bainbridge;Jill M Buley

Polymer International 2006 Volume 55(Issue 7) pp:

Publication Date(Web):16 MAY 2006

DOI:10.1002/pi.2062

A quartz crystal microbalance was used as the basis of a vapour sorption apparatus to measure thermodynamic interaction parameters of polystyrene, poly(4-chlorostyrene) and poly(methyl methacrylate) with a number of solvents. The apparatus was shown to give rapid and reliable results by comparison with literature results for poly(dimethyl siloxane). Measurements of activity coefficients and Flory–Huggins interaction parameters were correlated with the solution behaviour of the components and revealed some hitherto unreported effects of the solution concentration in polar systems. Copyright © 2006 Society of Chemical Industry

Potassium selective quartz crystal microbalance chemical sensors using functionalized copolymer coatings

Co-reporter:Gareth J. Price, Philip L. Drake

Sensors and Actuators B: Chemical 2006 Volume 114(Issue 1) pp:466-472

Publication Date(Web):30 March 2006

DOI:10.1016/j.snb.2005.05.034

Quartz crystal microbalance sensors that specifically detect K+ ions have been developed using copolymers based on poly(acrylic acid) and functionalised with crown ethers to provide selectivity. The coatings selectively absorb K+ over other Group I ions such as Li+ and Na+. Sensors have been used in both batch and flow modes with detection limits in the region of 0.1–0.2 ppm for K+(aq) with a linear range extending to over 1000 ppm. The sensors perform at least as well as other recently developed methodologies although further optimisation should significantly improve this performance.

Surface modification of calcium carbonates studied by inverse gas chromatography and the effect on mechanical properties of filled polypropylene

Co-reporter:Gareth J Price;Deeba M Ansari

Polymer International 2004 Volume 53(Issue 4) pp:

Publication Date(Web):8 MAR 2004

DOI:10.1002/pi.1392

Inverse gas chromatography (IGC) has been used to characterize the surfaces of a pure calcitic calcium carbonate as well as samples that had been treated with sodium polyacrylate and/or stearic acid. The dispersive components of the surface free energy for the pure material agreed well with related literature data. Polar contributions to the surface interactions with a range of probes were determined. The results show that the surface treatments reduced the polarities of the surfaces and that modification with stearic acid produced a non-polar, low-energy surface. Some mechanical properties of the polypropylene composites containing the modified calcium carbonates were found to correlate well with the filler surface energies. Copyright © 2004 Society of Chemical Industry

Recent developments in sonochemical polymerisation

Co-reporter:Gareth J. Price

Ultrasonics Sonochemistry 2003 Volume 10(4–5) pp:277-283

Publication Date(Web):July 2003

DOI:10.1016/S1350-4177(02)00156-6

High intensity ultrasound has been applied to two classes of step-growth polymerisation. The ring-opening polymerisation of cyclic lactones to polyesters was accelerated under 20 kHz ultrasound but, in the case of δ-valerolactone, sonication also promoted a depolymerisation reaction so that the molecular weight fell during later stages of the reaction. Sonication was also applied to the preparation of polyurethanes from a number of diisocyanates and diols. In all cases, the sonochemical reactions proceeded faster in the early stages and led to higher molecular weight polymers. The effect of changing the ultrasound intensity is discussed and some speculation as to the mechanisms of the reaction enhancements is given.

An inverse gas chromatography study of calcination and surface modification of kaolinite clays

Co-reporter:Gareth J. Price and Deeba M. Ansari

Physical Chemistry Chemical Physics 2003 vol. 5(Issue 24) pp:5552-5557

Publication Date(Web):03 Nov 2003

DOI:10.1039/B309641F

Inverse gas chromatography, IGC, has been used to investigate the surface properties of a kaolinite clay. Changes in enthalpies of adsorption for a range of probes and in the surface energies of the clays have been measured and the effect of calcination of the native clay as well as of coating with an aminopropylsilane coupling agent have been determined. The surface energy of the clay was lowered by calcination and further considerably reduced on coating with the silane. From the retention of polar probes, information on the accessibility of surface sites to the probes and on the acid–base character of the surface was measured. Two commonly used methods for quantifying these specific interactions are compared and yield similar results. The hydrated clay became less porous and less acidic after calcination while coating with the silane conferred a largely, though not exclusively, basic character.

Correlation of the material properties of calcium carbonate filled polypropylene with the filler surface energies

Co-reporter:Gareth J. Price;Deeba M. Ansari;Deeba M. Ansari

Journal of Applied Polymer Science 2003 Volume 88(Issue 8) pp:1951-1955

Publication Date(Web):5 MAR 2003

DOI:10.1002/app.11877

The physical and mechanical properties of polypropylene (PP) were measured and compared with those of PP composites filled with calcium carbonate modified with sodium polyacrylate, stearic acid, or both. The variations in the mechanical properties showed a high degree of correlation with the surface energies of the fillers, as determined by inverse gas chromatography. The results confirmed the usefulness of inverse gas chromatography for characterizing the compatibility of polymer–filler combinations. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1951–1955, 2003

Inverse gas chromatography study of the thermodynamic behaviour of thermotropic low molar mass and polymeric liquid crystals

Co-reporter:Gareth J. Price and Ian M. Shillcock

Physical Chemistry Chemical Physics 2002 vol. 4(Issue 21) pp:5307-5316

Publication Date(Web):26 Sep 2002

DOI:10.1039/B202173K

We report measurements of activity coefficients and derived excess partial molar enthalpies and entropies of mixing for 17 hydrocarbon probes in three low molar mass liquid crystals as well as a polymeric version containing the same mesogenic group. Values were obtained in the isotropic liquids and in N, SmA, SmC, and N* mesophases. The results are interpreted in terms of a qualitative, descriptive model accounting for the various contributions to the energetics and the entropic effects of probe–LC interactions. The behaviour of the LC polymer was found to be determined largely by the interactions with the mesogen while the polymer backbone had a relatively minor effect.

The effect of high-intensity ultrasound on the ring-opening polymerisation of cyclic lactones

Co-reporter:Gareth J. Price, Emma J. Lenz, Christopher W.G. Ansell

European Polymer Journal 2002 Volume 38(Issue 9) pp:1753-1760

Publication Date(Web):September 2002

DOI:10.1016/S0014-3057(02)00056-3

High-intensity ultrasound has been applied to the ring-opening polymerisation of δ-valerolactone and ε-caprolactone catalysed by dibutyl tin dilaurate. Sonication was found to accelerate the polymerisation. In the case of δ-valerolactone, sonication also promoted a depolymerisation reaction so that the molecular weight fell during later stages of the reaction. Co-polymers of the two monomers were synthesised and the use of ultrasound led to preferential incorporation of ε-caprolactone into the material, probably due to degradation of the valerolactone sequences.

The effect of high intensity ultrasound on the synthesis of some polyurethanes

Co-reporter:Gareth J. Price, Emma J. Lenz, Christopher W.G. Ansell

European Polymer Journal 2002 Volume 38(Issue 8) pp:1531-1536

Publication Date(Web):August 2002

DOI:10.1016/S0014-3057(02)00039-3

High intensity ultrasound has been applied to the preparation of polyurethanes from a number of diisocyanates and diols. In all cases, the sonochemical reactions proceeded faster in the early stages and led to higher molecular weight polymers. The effect of changing the ultrasound intensity is discussed and some speculation as to the mechanism of the reaction enhancement is given.

Crown-ether containing copolymers as selective membranes for quartz crystal microbalance chemical sensors

Co-reporter:Philip L Drake;Gareth J Price

Polymer International 2000 Volume 49(Issue 9) pp:

Publication Date(Web):31 AUG 2000

DOI:10.1002/1097-0126(200009)49:9<926::AID-PI378>3.0.CO;2-H

Novel chemical sensors have been developed based on piezoelectric quartz resonators coated with chemically engineered copolymer resins. These have been employed for the selective detection in aqueous solution of K⁺ over other Group I ions such as Li⁺ and Na⁺.

A quartz crystal microbalance, QCM, operating with 10 MHz, AT-cut piezoelectric crystals and Au electrodes, forms the basis of the sensor set-up where the frequency changes indicate a change in absorbed mass of the species of interest. The copolymer coating was designed to chelate specific ions from solution introducing selectivity to the sensor response. Acrylic acid polymers crosslinked with ethylene glycol dimethacrylate (EGDMA) and substituted with 18-crown-6 and the 15-crown-5 rings were synthesized and coated onto the crystal. The sensor was employed in a flow injection analysis (FIA) set-up. The detection limit of the developed sensor is estimated at 0.4 ppm for , although further optimization should significantly reduce this value.

Surface modification of poly(vinyl chloride) using high intensity ultrasound

Co-reporter:Gareth J Price;Andrew A Clifton

Polymer International 1999 Volume 48(Issue 11) pp:

Publication Date(Web):14 OCT 1999

DOI:10.1002/(SICI)1097-0126(199911)48:11<1141::AID-PI278>3.0.CO;2-Q

The use of high intensity ultrasound to promote a number of reactions at the surface of solid poly(vinyl chloride) is reported. Substitution reactions involving a range of compounds, including dyes, can rapidly be carried out from aqueous solution under labile conditions. Sonochemically enhanced treatment with strong aqueous base produces dehydrochlorination even at room temperature to produce a thin layer of conjugated material at the surface which can then be grafted with a number of compounds. Some speculation as to the mechanistic features of the process as well as its potential utility is made.

Room temperature sonochemical initiation of thiol-ene reactions

Co-reporter:Emily K. Skinner, Fraeya M. Whiffin and Gareth J. Price

Chemical Communications 2012 - vol. 48(Issue 54) pp:NaN6802-6802

Publication Date(Web):2012/05/14