Imperial College London

PROFESSOR CHARLOTTE K. WILLIAMS

Faculty of Natural SciencesDepartment of Chemistry

Visiting Professor
 
 
 
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Contact

 

+44 (0)20 7594 5790c.k.williams Website

 
 
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Location

 

317 RCS1ChemistrySouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

170 results found

Montrikittiphant T, Tang M, Lee K-Y, Williams CK, Bismarck Aet al., 2014, Bacterial Cellulose Nanopaper as Reinforcement for Polylactide Composites: Renewable Thermoplastic NanoPaPreg, MACROMOLECULAR RAPID COMMUNICATIONS, Vol: 35, Pages: 1640-1645, ISSN: 1022-1336

Journal article

Montrikittiphant T, Tang M, Lee KY, Williams CK, Bismarck Aet al., 2014, Macromol. Rapid commun. 19/2014., Macromol Rapid Commun, Vol: 35

Frontispiece: A Werkstoffverbund (laminated composite) manufacturing concept is used to produce high performance renewable bacterial cellulose (BC) nanopaper reinforced thermoplastic laminates. The mechanical performance of the resulting BC-reinforced thermoplastic laminates is found to be dependent on the tensile performance of the reinforcing BC nanopaper. Further details can be found in the article by T. Montrikittiphant, M. Tang, K.-Y. Lee,* C. K. Williams, and A. Bismarck* on page 1640.

Journal article

Weiner J, Brown NJ, Shaffer MSP, Williams CKet al., 2014, Colloidal ZnO/Cu hybrid nanocatalysts for CO2 hydrogenation to methanol, 248th National Meeting of the American-Chemical-Society (ACS), Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727

Conference paper

Saini PK, Romain C, Williams CK, 2014, Dinuclear metal catalysts: Improved performance of heterodinuclear mixed catalysts for CO2-epoxide copolymerization, 248th National Meeting of the American-Chemical-Society (ACS), Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727

Conference paper

Romain C, Williams CK, 2014, Chemoselective polymerization control: From mixed monomer feedstock to copolymers, 248th National Meeting of the American-Chemical-Society (ACS), Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727

Conference paper

Williams CK, Bakewell C, Long N, Auffrant Aet al., 2014, Stereoblock polylactide: New, highly active, and iso-selective catalysts based on group 3/lanthanide phosphasalen complexes, 248th National Meeting of the American-Chemical-Society (ACS), Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727

Conference paper

Saini PK, Romain C, Zhu Y, Williams CKet al., 2014, Di-magnesium and zinc catalysts for the copolymerization of phthalic anhydride and cyclohexene oxide, Polymer Chemistry, Vol: 5, Pages: 6068-6075, ISSN: 1759-9962

Two new homogeneous dinuclear catalysts for the ring-opening copolymerization of phthalic anhydride (PA)/cyclohexene oxide (CHO) and the terpolymerization of phthalic anhydride (PA)/cyclohexene oxide (CHO)/carbon dioxide (CO2) are reported. The catalysts are a di-magnesium (1) and a di-zinc complex (2), both are coordinated by the same macrocyclic ancillary ligand. Both catalysts show good polymerization control and activity (TOF = 97 (1) and 24 (2) h−1), with the di-magnesium complex (1) being approximately four times faster compared to the di-zinc (2) analogue. Their relative reactivity is closely related to that observed for well documented chromium salen/porphyrin catalysts. However, these results represent the first example of a well-defined magnesium catalyst which may be advantageous in terms of obviating use of co-catalysts, low cost, lack of colour and redox chemistry.

Journal article

Bakewell C, White AJP, Long NJ, Williams CKet al., 2014, Metal-Size Influence in Iso-Selective Lactide Polymerization, Angewandte Chemie-International Edition, Vol: 53, Pages: 9226-9230, ISSN: 1521-3773

Iso-selective initiators for the ring-opening polymerization (ROP) of rac-lactide are rare outside of Group 13. We describe the first examples of highly iso-selective lutetium initiators. The phosphasalen lutetium ethoxide complex shows excellent iso-selectivity, with a Pi value of 0.81–0.84 at 298 K, excellent rates, and high degrees of polymerization control. Conversely, the corresponding La derivative exhibits moderate heteroselectivity (Ps=0.74, 298 K). Thus, the choice of metal center is shown to be crucial in determining the level and mode of stereocontrol. The relative order of rates for the series of complexes is inversely related to metallic covalent radius: that is, La>Y>Lu.

Journal article

Saini PK, Romain C, Williams CK, 2014, Dinuclear metal catalysts: improved performance of heterodinuclear mixed catalysts for CO2-epoxide copolymerization, Chemical Communications, Vol: 50, Pages: 4164-4167, ISSN: 1364-548X

Some of the most active catalysts for carbon dioxide and epoxide copolymerization are dinuclear metal complexes. Whilst efficient homodinuclear catalysts are known, until now heterodinuclear catalysts remain unreported. Here, a facile, in situ route to a catalyst system comprising a mixture of homo- and heteronuclear Zn–Mg complexes is presented. This catalyst system shows excellent polymerization control and exhibits significantly higher activity than the homodinuclear catalysts alone or in combination.

Journal article

Duran B, Hartig E, Draper E, Snyder R, DeGanga C, Williams CK, Haaf Met al., 2014, Tri- and tetra-dentate quinolide organometallic catalysts for stereocontrolled rac-lactide polymerization, 247th National Spring Meeting of the American-Chemical-Society (ACS), Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727

Conference paper

Brown NJ, Harris JE, Yin X, Silverwood I, White AJP, Kazarian SG, Hellgardt K, Shaffer MSP, Williams CKet al., 2014, Mononuclear phenolate diamine zinc hydride complexes and their Reactions with CO2, Organometallics, Vol: 33, Pages: 1112-1119, ISSN: 1520-6041

The synthesis, characterization, and zinc coordination chemistry of the three proligands 2-tert-butyl-4-[tert-butyl (1)/methoxy (2)/nitro (3)]-6-{[(2′-dimethylaminoethyl)methylamino]methyl}phenol are described. Each of the ligands was reacted with diethylzinc to yield zinc ethyl complexes 4–6; these complexes were subsequently reacted with phenylsilanol to yield zinc siloxide complexes 7–9. Finally, the zinc siloxide complexes were reacted with phenylsilane to produce the three new zinc hydride complexes 10–12. The new complexes 4–12 have been fully characterized by NMR spectroscopy, mass spectrometry, and elemental analyses. The structures of the zinc hydride complexes have been probed using VT-NMR spectroscopy and X-ray diffraction experiments. These data indicate that the complexes exhibit mononuclear structures at 298 K, both in the solid state and in solution (d8-toluene). At 203 K, the NMR signals broaden, consistent with an equilibrium between the mononuclear and dinuclear bis(μ-hydrido) complexes. All three zinc hydride complexes react rapidly and quantitatively with carbon dioxide, at 298 K and 1 bar of pressure over 20 min, to form the new zinc formate complexes 13–15. The zinc formate complexes have been analyzed by NMR spectroscopy and VT-NMR studies, which reveal a temperature-dependent monomer–dimer equilibrium that is dominated by the mononuclear species at 298 K.

Journal article

Romain C, Williams CK, 2014, Chemoselective Polymerization Control: From Mixed-Monomer Feedstock to Copolymers, Angewandte Chemie-International Edition, Vol: 53, Pages: 1607-1610, ISSN: 1521-3773

Journal article

Silverwood IP, Keyworth CW, Brown NJ, Shaffer MSP, Williams CK, Hellgardt K, Kelsall GH, Kazarian SGet al., 2014, An Attenuated Total Reflection Fourier Transform Infrared (ATR FT-IR) Spectroscopic Study of Gas Adsorption on Colloidal Stearate-Capped ZnO Catalyst Substrate, APPLIED SPECTROSCOPY, Vol: 68, Pages: 88-94, ISSN: 0003-7028

Journal article

Bakewell C, White AJP, Long NJ, Williams CKet al., 2013, 8-quinolinolato gallium complexes: iso-selective initiators for rac-lactide polymerization, Inorganic Chemistry, Vol: 52, Pages: 12561-12567, ISSN: 1520-510X

The synthesis and characterization of a series of 8-quinolinolato gallium complexes is presented, and the complexes are analogous to a series of aluminum complexes previously reported. The complexes have been shown to be active initiators for the ring-opening polymerization of rac-lactide. High degrees of polymerization control are demonstrated, as exemplified by the linear evolution of molecular weight as the polymerization progresses, narrow polydispersity indices, and molecular weights corresponding to those predicted on the basis of initiator concentration. Some of the initiators show iso-selective polymerization of rac-lactide, with Pi = 0.70. The polymerization rates have been monitored, and the pseudo first-order rate constants are compared to those of analogous aluminum compounds. The 8-quinolinolato gallium initiators show rates approximately 3 times higher than those of the series of aluminum compounds, while maintaining equivalently high iso-selectivity (Pi = 0.70) and polymerization control.

Journal article

Tang M, Purcell M, Steele JAM, Lee K-Y, McCullen S, Shakesheff KM, Bismarck A, Stevens MM, Howdle SM, Williams CKet al., 2013, Porous Copolymers of epsilon-Caprolactone as Scaffolds for Tissue Engineering, MACROMOLECULES, Vol: 46, Pages: 8136-8143, ISSN: 0024-9297

Journal article

Brown NJ, Weiner J, Shaffer MSP, Williams CKet al., 2013, Tuneable ZnOCu catalyst system for CO2 hydrogenation to methanol, 245th National Meeting of the American-Chemical-Society (ACS), Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727

Conference paper

Bakewell CM, Thi-Phuong-Anh C, Haaf M, Williams CK, Long NJ, Auffrant A, Platel RHet al., 2013, Bis(quinolinolato)aluminium ethyl and yttrium phosphasalen complexes: New iso-selective initiators for rac-lactide ring-opening polymerisation, 245th National Spring Meeting of the American-Chemical-Society (ACS), Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727

Conference paper

Bakewell C, Thi-Phuong-Anh C, Le Goff XF, Long NJ, Auffrant A, Williams CKet al., 2013, Yttrium Phosphasalen Initiators for rac-Lactide Polymerization, ORGANOMETALLICS, Vol: 32, Pages: 1475-1483, ISSN: 0276-7333

Journal article

Donaghey JE, Sohn E-H, Ashraf RS, Anthopoulos TD, Watkins SE, Song K, Williams CK, McCulloch Iet al., 2013, Pyrroloindacenodithiophene polymers: the effect of molecular structure on OFET performance, POLYMER CHEMISTRY, Vol: 4, Pages: 3537-3544, ISSN: 1759-9954

Journal article

Brown NJ, Weiner J, Hellgardt K, Shaffer MSP, Williams CKet al., 2013, Phosphinate stabilised ZnO and Cu colloidal nanocatalysts for CO2 hydrogenation to methanol, CHEMICAL COMMUNICATIONS, Vol: 49, Pages: 11074-11076, ISSN: 1359-7345

Journal article

Lee KY, Montrikittiphant T, Tang M, Williams CK, Bismarck Aet al., 2013, Carbohydrate derived co-poly(lactide) as compatibiliser for bacterial cellulose reinforced polylactide nanocomposites, Pages: 2842-2843

Conference paper

Bakewell C, Thi-Phuong-Anh C, Long N, Le Goff XF, Auffrant A, Williams CKet al., 2012, Yttrium Phosphasalen Initiators for rac-Lactide Polymerization: Excellent Rates and High Iso-Selectivities, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, Vol: 134, Pages: 20577-20580, ISSN: 0002-7863

Journal article

Kember MR, Williams CK, 2012, Efficient Magnesium Catalysts for the Copolymerization of Epoxides and CO2; Using Water to Synthesize Polycarbonate Polyols, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, Vol: 134, Pages: 15676-15679, ISSN: 0002-7863

Journal article

Lee K, Tang M, Williams CK, Bismarck Aet al., 2012, Carbohydrate derived copoly(lactide) as the compatibilizer for bacterial cellulose reinforced polylactide nanocomposites, Composites Science and Technology, Vol: 72, Pages: 1646-1650, ISSN: 0266-3538

A novel, entirely bio-derived polylactide carbohydrate copolymer (RP1) is used as a compatibilizer, to produce bacterial cellulose (BC) poly(l-lactide) (PLLA) nanocomposites with improved mechanical properties. Contact angle measurements of RP1 droplets on single BC nanofibres proved that it has a higher affinity towards BC than PLLA. RP1 has a comparable Young’s modulus, but lower tensile strength, than PLLA. When RP1 was blended with PLLA at a concentration of 5 wt%, the tensile modulus and strength of the resulting polymer blend decreased from 4.08 GPa and 63.1, respectively, for PLLA to 3.75 GPa and 56.1 MPa. A composite of BC and PLLA (with 5 wt% RP1 and 5 wt% BC) has a higher Young’s modulus and tensile strength, compared to either pure PLLA or PLLA–BC nanocomposites.

Journal article

Buchard A, Jutz F, Kember MR, White AJP, Rzepa HS, Williams CKet al., 2012, Experimental and Computational Investigation of the Mechanism of Carbon Dioxide/Cyclohexene Oxide Copolymerization Using a Dizinc Catalyst, MACROMOLECULES, Vol: 45, Pages: 6781-6795, ISSN: 0024-9297

Journal article

Orchard KL, Shaffer MSP, Williams CK, 2012, Organometallic Route to Surface-Modified ZnO Nanoparticles Suitable for In Situ Nanocomposite Synthesis: Bound Carboxylate Stoichiometry Controls Particle Size or Surface Coverage, CHEMISTRY OF MATERIALS, Vol: 24, Pages: 2443-2448, ISSN: 0897-4756

Journal article

Bakewell C, Platel RH, Cary SK, Hubbard SM, Roaf JM, Levine AC, White AJP, Long NJ, Haaf M, Williams CKet al., 2012, Bis(8-quinolinolato)aluminum ethyl complexes: Iso-Selective Initiators for rac-Lactide Polymerization, ORGANOMETALLICS, Vol: 31, Pages: 4729-4736, ISSN: 0276-7333

Journal article

Naro YR, Haaf MP, Williams CK, Bakewell CMet al., 2012, Zinc quinolide catalysts for the stereoselective polymerization of lactide, 11th International Biorelated Polymer Symposium / 243rd National Spring Meeting of the American-Chemical-Society (ACS), Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727

Conference paper

Hubbard SM, Haaf MP, Williams CK, Bakewell CMet al., 2012, Isotactic polylactic acid (PLA) formation with chiral aluminum hydroxyquinolate catalysts, 11th International Biorelated Polymer Symposium / 243rd National Spring Meeting of the American-Chemical-Society (ACS), Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727

Conference paper

Thi-Phuong-Anh C, Buchard A, Le Goff XF, Auffrant A, Williams CKet al., 2012, Phosphasalen Yttrium Complexes: Highly Active and Stereoselective Initiators for Lactide Polymerization, INORGANIC CHEMISTRY, Vol: 51, Pages: 2157-2169, ISSN: 0020-1669

Journal article

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