O'HARE GROUP

1. AMO-LDH

We report the synthesis and characterisation of a new family of layered double hydroxides entitled Aqueous Miscible Organic Layered Double Hydroxide (AMO-LDH). AMO-LDHs have the chemical composition [Mz+1−xM′y+x(OH)2]a+(Xn)a/r·bH2c(AMO-solvent) wherein M and M′ are metal cations, z = 1 or 2; y = 3 or 4, 0 < x < 1, b = 0–10, c = 0–10, X is an anion, r is 1–3 and a = z(1 − x) + xy − 2. The role of the AMO-solvents such as acetone (A) or methanol (M) in the LDH synthesis is discussed. The distinguishing features between AMO, and conventional or commercial LDHs are investigated using X-ray diffraction, infrared spectroscopy, electron microscopy, thermal analysis, adsorption and powder density studies. These experiments show that AMO-LDHs are highly dispersed and exhibit significantly higher surface areas and lower powder densities than conventional or commercially available LDHs. AMO-LDHs can exhibit N2 BET surface areas in excess of 301 m2 g−1 compared to 13 m2 g−1 for the equivalent LDHs prepared by co-precipitation in water. The Zn2Al–borate LDH exhibits a pore volume of 2.15 cm3 g−1 which is 2534 times higher than the equivalent conventionally prepared LDH.

 

Unique Technical Advance (UTA)

1. Rosette (flower-like) morphology

2. High surface density, (100-430 m2 g–1)*

3. High porosity,  (1.5-2.2 cm3 g–1) *

4. Multi-pore size range

5. Dispersible in hydrocarbon solvents

6. Generally applicable across all LDHs

7. Precursors to high surface area mixed metal oxides*

8. Particles with OAN up to 350*

 

2. AIM-LDH

Post synthesis treatment of Layered Double Hydroxides (LDHs) with aqueous immiscible solvents (AIM solvents) yields highly dispersible, high surface area materials (up to 377 m2g−1). The effect of solvent functional groups and structure, initial LDH particle morphology along with parameters such as dispersion time, and solvent recycling properties of AIM-LDHs are explored. The strength of the hydrogen bonding interactions that a given solvent can offer appears a crucial factor for the effectiveness of the treatment.

 

3. LDH@Core Hybrids

New 3D Hierarchical Structures

           

  

 

 

4. LDH Nanosheets

        

Unique Technical Advance (UTA)

1. Platelet morphology

2. High Aspect ratio:  10-350

3. Generally applicable across all LDHs

4. Scaleable using non-toxic chemistry

 

5. AMO-LDH as supports or slurry phase olefin polymerisation

We report the synthesis of solid catalysts based on a zirconocene supported on either silica@AMO-LDH or zeolite@AMO-LDH for the slurry phase polymerisation of ethylene. The hybrid catalysts demonstrate synergistic effects in which the polymerisation activity is up to three times higher than the zirconocene supported on analogous single phase silica or zeolite supports. We present here a simple method for the synthesis of core–shell SiO2@LDH (LDH: layered double hydroxide) particles using an in situ co-precipitation method without any pretreatment. The LDH composition, the overall particle size and morphology can be tuned giving new opportunities for the development of novel sorbents and catalyst systems.

 

6. Barrier coatings (H2O, O2, UV, antimicrobial)

One of the major challenges in the circular economy relating to food packaging is the elimination of metallised film which is currently the industry standard approach to achieve the necessary gas barrier performance. Here, we report the synthesis of high aspect ratio 2D non-toxic layered double hydroxide (LDH) nanosheet dispersions using a non-toxic exfoliation method in aqueous amino acid solution. High O2 and water vapour barrier coating films can be prepared using food safe liquid dispersions through a bar coating process. The oxygen transmission rate (OTR) of 12 μm PET coated film can be reduced from 133.5 cc·m−2·day−1 to below the instrument detection limit (<0.005 cc·m−2·day−1). The water vapour transmission rate (WVTR) of the PET film can be reduced from 8.99 g·m−2·day−1 to 0.04 g·m−2·day−1 after coating. Most importantly, these coated films are also transparent and mechanically robust, making them suitable for flexible food packing while also offering new recycling opportunities.

 

Recent publications:

High gas barrier coating using non-toxic nanosheet dispersions for flwxible food packaging film. J. Yu, K. Ruengkajorn, D.-G. Crivoi, C. Chen, J.-C. Buffet and D. O’Hare, Nat. Commun., (2019), 10, 1-18.

Bifunctional acid-base mesoporous silica@aqueous miscible organic-layered double hydroxides, H. Suo, H. Duan, C. Chen, J.-C. Buffet and D. O'Hare, RSC Adv., (2019), 9, 3749-3754. 

Solvothermal synthesis MgAl-LDH nanosheets, K. CermeljK. RuengkajornJ.-C. BuffetD. O’Hare, J. Energy Chem., (2019), 35, 88-94. 

Aqueous immiscible layered double hydroxides – AIM-LDHs, K. Ruengkajorn, C. M. R. Wright, N. H. Rees, J.-C. Buffet and D. O’Hare, Mater. Chem. Front.(2018).

Water adsorbancy of high surface area layered double hydroxides (AMO-LDHs), C. Chen, K. Ruenkajorn, J.-C. Buffet and D. O’Hare, RSC Adv.(2018), 8, 34650-34655.

Metallocene supported core@LDH catalysts for slurry phase ethylene polymerisation, J.-C. Buffet, C. F. H. Byles, R. Felton, C. Chen and D. O’Hare, Chem. Commun., (2016), 52, 4076-4079

Core-shell zeolite@aqueous miscible organic-layered double hydroxide, C. Chen, C. F. H. Byles, J.-C. Buffet, N. H. Rees, Y. Wu and D. O’Hare, Chem. Sci., (2016), 7, 1457-1461

Rapid, efficient phase pure synthesis of Ca2AlNO3 layered double hydroxide, M. Yang, E. Tuckley, J.-C. Buffet, D. O'Hare, J. Mater. Chem. A, (2016), 4, 500-504

Tuneable Ultra High Specific Surface Area Mg/Al-CO3 Layered Double Hydroxides, C. Chen, A.Wangriya, J.-C. Buffet, and D. O’Hare, Dalton Transactions, (2015), 44, 16392-16398.

Core-Shell SiO2@LDHs with Tuneable Size, Composition and Morphology, C. Chen, R. Felton, J-C. Buffet and D. O’Hare, Chem Commun., (2015), 51, 3462 - 3465,

Synthesis and Characterisation of Layered Double Hydroxide Dispersions in Organic Solvents, M. Yang, O. McDermott, J-C. Buffet, D. O'Hare, RSC Adv., (2014), 4 (93), 51676 – 51682

Synthesis and Characterisation of Aqueous Miscible Organic-Layered Double Hydroxides, C. Chen, M. Yang, Q. Wang, J-C. Buffet and D. O’Hare, J. Mater Chem., A., (2014), (36), 15102 – 15110