Apparatus and method for material processing

Abstract

The invention relates to a material processing apparatus, comprising: a substantially cylindrical rotatable body configured to be received within a container; and a translation stage on which the body is mounted, configured to allow translation of the body within the container in use.

Description

[0001] APPARATUS AND METHOD FOR MATERIAL PROCESSING

[0002] TECHNICAL FIELD

[0003] The present invention relates to apparatus and methods for material processing, and in particular but not exclusively to apparatus and methods for mechanochemical material processing.

[0004] BACKGROUND

[0005] The ability to produce advanced materials with unique properties is essential to address global challenges in energy and sustainability, as well as to maintain technological progress.

[0006] Two-dimensional (2D) materials fall into the category of advanced materials that have the potential to transform existing technologies and facilitate the creation of new technologies that are not possible with materials in commercial use today.

[0007] 2D materials are a class of low-dimensional nanomaterials with atomically thin thicknesses that can result in unique and enhanced physicochemical properties compared to their bulk counterparts. The most well- know 2D material is graphene (which, for example, has an ultimate tensile strength over 300 times greater than structural steel), however, thousands more such materials exist spanning the full range of conductors, semiconductors and insulators (the building blocks of contemporary electronic devices, catalysts etc.).

[0008] These materials have been found to have a remarkable breadth of properties that has seen them used in laboratories over the past decade in applications such as wearable electronics, biosensing, photocatalytic process (such as for H2production and water treatment), photovoltaics, concrete / polymer reinforcement, battery electrodes, supercapacitors and many more.

[0009] A challenge to realising such materials in products is the limitations of material production and processing capabilities, both at laboratory and industrial scales.

[0010] Liquid phase exfoliation has been used to synthesise 2D materials, relying on mechanical forces to induce shear stresses that separate and isolate nanosheets in solution. Stable solutions are maintained through chemical means (for example, using appropriate solvents, surfactants and / or additives). However, this method is typically achieved by applying existing laboratory approaches such as ultrasonication (for example, at laboratory scale) or stirred vessels and homogenisers.

[0011] Mechanochemistry has emerged over the past decade as a potential solution to the environmental issues of toxic solvent use in many conventional chemical processes. A mechanochemical approach uses mechanical forces to induce chemical reactions and has been applied to synthesise new materials and chemicals with low or no solvent usage (for example, to produce pharmaceuticals). However, mechanochemical processing is still at the laboratory scale, and typically methods of inducing mechanical force for chemical reactions rely on implementing existing technologies used for general mixing purposes (for example, ultrasonication baths, ultrasonication probes, ball milling etc.), which have limited scalability and throughput. A significant amount of researcher time goes into material preparation, often requiring expertise in materials chemistry to ensure synthesis steps are performed and repeated correctly.

[0012] Different tools are also required depending on the mechanochemical application, for example ultrasonication for wet dilute dispersions or ball milling for dry powder processing. Experimental chemists, materials scientists can spend a significant fraction of their time (up to 50% in some cases) preparing these materials for their research, which can reduce the time available for research to focus on application of the materials (for example, the use of materials in a device or process).

[0013] At the industrial level, although graphene is now being produced commercially, the large and growing library of other 2D materials has yet to reach mainstream commercial applications. These 2D materials can require different types of mechanical force (for example, shear or impaction) and different magnitudes of mechanical force to produce, depending on the chemical bond strength and precursor material.

[0014] Existing industry processes, such as shear mixing and homogenisation, have limited adaptability to the diverse range of emerging materials, composites and ink formulations. For example, in the exfoliation of graphene, industrial homogeniser processes regularly suffer from material blockages when trying to pump solid precursor particles through microscale capillaries (around 100 pm). That also means the starting materials and concentrations must be carefully selected to mitigate that issue. Mechanochemical approaches have yet to reach mainstream industrial production and the available solutions at laboratory scale are limited in scalability and throughput.

[0015] The present invention has been devised with the foregoing in mind.

[0016] SUMMARY OF INVENTION

[0017] According to a first aspect, there is provided a material processing apparatus. The apparatus may comprise a substantially cylindrical rotatable body. The body may be configured to be received within a container. The apparatus may also comprise a translation stage on which the body is mounted. The translation stage may be configured to enable translation of the body within and / or relative to the container in use.

[0018] The apparatus may be used to process a material in a container. The material may be a liquid, a mixture of a liquid and a solid powder or particulate material, a mixture of a gas and a solid powder or particulate material, a mixture of a liquid and a gas and a solid powder or particulate material, or a solid powder or particulate material. Rotation of the body within the container may force the material towards the container walls, for example to form a thin layer or film of the material adjacent the container walls. Translation of the body may enable a narrow gap or passage to be formed between the body and the container walls for the material to pass through. Material passing through the gap may be subjected to high forces (for example, shear forces or impact forces).

[0019] The ability to control movement and positioning of the body (for example, relative positioning within a container) using the translation stage may allow the apparatus to process different types of materials whilst avoiding blockages. For example, the apparatus may process liquids, liquid-gas mixtures, liquid- gas-solid mixtures, solid-gas mixtures or solid-liquid mixtures or solid powders or particulate materials having a wide range of initial particle sizes (for example, from millimetre scale to micrometre scale) whilst avoiding blockages. Existing approaches are typically only able to process liquid and / or gases and mixtures with ultralow solid content at microscale to nanoscale particle sizes. Translation of the body may enable an initial width of the gap between the body and the container walls to be adjusted to avoid blockages when processing particles of different initial sizes. Translation of the body may also enable control and / or selection of desired processing parameters (for example, a shear rate or shear force or an impact force) using a single apparatus, for example to produce a desired final particle size, by selecting a desired final width of the gap between the body and the container walls through which the material passes. The apparatus may also enable both shear-dominant processing and impact-induced processing of a material to be carried using substantially the same apparatus, allowing a wider variety of materials to be processed.

[0020] The apparatus may further comprise a control system. The control system may be configured to control rotation and translation of the body. That may enable a pre -determined processing program or processing routine to be carried out autonomously by the apparatus, for example according to a validated processing or synthesis program which is inherently repeatable. That may minimize user input in respect of both manual operation of processing equipment and monitoring of processing progress, in turn reducing the requirement for experienced researchers in material processing and production.

[0021] The control system may be configured to rotate the body between substantially 10,000 and substantially 40,000 rpm. Rapid rotation of the body in the container may form a rotating thin film of the material on the container walls which passes through the gap between the body and the container walls.

[0022] The control system may be configurated to translate the body to control a distance between the body and a wall of the container. The distance may be selected based on a desired processing parameter (for example, a shear rate or shear force or an impact force). A smaller distance between the body and the wall of the container may result in a higher shear rate, shear force or impact force applied to the material. Additionally or alternatively, the distance may be selected to process a material whilst avoiding blockages, which may be caused by using too small a gap size.

[0023] The control system may be configurated to translate the body from a first distance (for example, a lateral distance in use) from a wall of the container (for example, a side wall of the container) to a second distance (for example, a lateral distance in use) from the wall of the container. The first distance may be greater than the second distance. Reducing a distance of the gap between the body and the container walls may accelerate a flow of the material through the gap between the body and the container walls, and / or may increase a force (for example, a shear force or an impact force) to which the material passing through the gap is subjected. The second distance may be selected based on a desired processing parameter (for example, a shear rate or shear force or an impact force).

[0024] The control system may be configured to translate the body from the first distance to the second distance substantially continuously. Alternatively, the control system may be configured to translate the body from the first position to the second position in a plurality of discrete steps.

[0025] The control system may be configured to translate the body according to a predetermined path. The predetermined path may be or comprise a circular path or a spiral path. The control system may be configured to translate the body such that a rotational direction of the circular path or the spiral path is opposite to a rotational direction of the body. That may avoid mixing dead zones within the container. That may also increase forces (for example, shear forces or impact forces) to which the material is subjected by moving in substantially the opposite direction to the material entering the gap between the body and the container walls. Alternatively, the predetermined path may be or comprise a substantially linear path, or an arbitrary path.

[0026] The control system may be configured to translate the body to induce ultrasonic waves. The control system may be configured to translate the body to induce ultrasonic waves in the material in the container. That may provide an additional processing mechanism for the material which may act in conjunction with or increase the forces (for example, shear force or impact forces) to which the material is subjected.

[0027] The control system may be configured to translate the body a distance of substantially 50pm or less, for example between substantially 1 pm and substantially 50 pm, such as substantially 10 pm, to induce the ultrasonic waves. Additionally or alternatively, the control system may be configured to translate the body at a speed of substantially 2.5 m s'1or less, for example between substantially 0.5 m s'1and substantially 2.5 m s'1, such as between substantially 1 m s'1and substantially 2.5 m s'1to induce the ultrasonic waves. Additionally or alternatively, the control system may be configured to translate the body at a frequency of between substantially 20 kHz and substantially 40 kHz to induce the ultrasonic waves.

[0028] A surface of the body may be substantially smooth. A substantially smooth surface of the body may enable shear forces to dominate in the gap between the body and the container walls, resulting in a high- shear region in the gap and enabling shear-dominant processing of the material.

[0029] A surface of the body may comprise one or more surface features. The one or more surface features may be configured to cause impact-induced processing of the material. The one or more surface features may be or comprise projections from the surface of the body. A body comprising surfaces features may mean the surface features rotate rapidly and impact particles travelling towards or entering the gap between the body and the container walls with high force and high collision frequency, resulting in a high-impact region in the gap and enabling impact-induced processing of the material. The surface features may have a height of substantially 1500 pm or smaller. Additionally or alternatively, the surface features may have an aspect ratio (defined by a height relative to a width, for example diameter, of the surface feature) between substantially 0 and substantially 0.125. The surface features may be spaced apart from one another between substantially 0.5 mm and substantially 3 mm.

[0030] The body may be releasably mounted on the translation stage. That may enable the body to be removed and replaced with an alternative substantially cylindrical rotatable body, for example to replace a body having a substantially smooth surface (for example, for use in shear-dominant processing) with a body having one or more surface features (for example, for use in impact-induced processing). That may increase utility of the apparatus and allow different materials to be processed by the same apparatus. Additionally or alternatively, that may increase an efficiency of materials processing, by reducing time between different processing steps.

[0031] The translation stage may be or comprise a three-dimensional (for example, X-Y-Z) translation stage. Alternatively, the translation stage may be or comprise a two-dimensional (for example, X and Y, X and Z or Y and Z) translation stage, or a one-dimensional (for example, X or Y) translation stage).

[0032] The apparatus may comprise a container. The container may be configured to contain material to be processed.

[0033] The apparatus may comprise a cap or cover configured to be placed over the container in use. The cap may comprise an aperture through which the cylindrical body may pass to be received within the container. The cap may comprise a pleated or concertina structure. That may enable a position of the aperture to change under an applied force, which may enable the cylindrical body to be translated within the container without restriction from the cap.

[0034] According a second aspect, there is provided a material processing method. The method may comprise rotating a substantially cylindrical body in a container containing a material. The method may also comprise translating the body within and / or relative to the container.

[0035] The method of the second aspect may comprise one or more features corresponding to features of the apparatus of the first aspect.

[0036] The method may comprise rotating the body between substantially 10,000 rpm and substantially 40,000 rpm. The method may comprise translating the body from a first distance (for example, a lateral distance) from a wall of the container (for example, a side wall of the container) to a second distance (for example, a lateral distance) from the wall of the container. The first distance may be greater than the second distance.

[0037] The method may comprise translating the body from the first distance to the second distance substantially continuously. Alternative, the method may comprise translating the body from the first distance to the second distance in a plurality of discrete steps.

[0038] The method may comprise translating the body according to a predetermined path. The predetermined path may be or comprise a circular path or a spiral path. The method may comprise translating the body such that a rotational direction of the circular path or the spiral path is opposite to a rotational direction of the body. Alternatively, the predetermined path may be or comprise a substantially linear path, or an arbitrary path.

[0039] The method may comprise translating the body to induce ultrasonic waves. The method may comprise translating the body to induce ultrasonic waves in the material in the container.

[0040] The method may comprise translating the body by a distance of substantially 50pm or less, for example between substantially 1 pm and substantially 50 pm, such as substantially 10 pm, to induce the ultrasonic waves. Additionally or alternatively, the method may comprise translating the body at a speed of substantially 2.5 m s'1or less, for example between substantially 0.5 m s'1and substantially 2.5 m s'1, such as between substantially 1 m s'1and substantially 2.5 m s'1to induce the ultrasonic waves. Additionally or alternatively, the method may comprise translating the body at a frequency of between substantially 20 kHz and substantially 40 kHz to induce the ultrasonic waves.

[0041] A surface of the body may be substantially smooth.

[0042] A surface of the body may comprise one or more surface features. The one or more surface features may be configured to cause impact-induced processing of the material. The one or more surface features may be or comprise projections from the surface of the body.

[0043] The body may be releasably mounted on the translation stage. The method may comprise replacing a first body with a second, different body. The second body may be different from the first body to provide a different processing mechanism (for example, to provide impact-induced processing in place of sheardominant processing).

[0044] According to a third aspect, there is provided a material processing system. The system may comprise the apparatus of the first aspect. The system may be configured to carry out the method of the second aspect. The system may comprise a plurality of substantially cylindrical bodies. Each body may be configured to be received within a container. The system may also comprise a translation stage on which each body is mountable. The translation stage may be configured to enable translation of the body within and / or relative to the container in use.

[0045] The system of the third aspect may comprise one of more features from or corresponding to features of the apparatus of the first aspect and / or the method of the second aspect.

[0046] Each body may be removably mountable to the translation stage.

[0047] The system may comprise a control system. The control system may be configured to control rotation and translation of each body when mounted on the translation stage.

[0048] The system may be configured to automatically connect and release each body from the translation stage. The control system may be configured to select a body to be mounted to the translation stage. The control system may be configured to control an attachment mechanism to connect and / or release the selected body from the translation stage. The attachment mechanism may be or comprise a collet mechanism or a clamp mechanism.

[0049] Optional features of any of the above aspects may be combined with the features of any other aspect, in any combination. For example, features described in connection with the apparatus of the first aspect may have corresponding features definable with respect to the method of the second aspect or the system of the third aspect, and vice versa, and these embodiments are specifically envisaged. Features which are described in the context of separate aspects and embodiments of the invention may be used together and / or be interchangeable wherever possible. Similarly, where features are described in the context of a single embodiment for brevity, those features may also be provided separately or in any suitable subcombination.

[0050] BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0052] FIG. 1 shows an embodiment of a material processing apparatus comprising a substantially cylindrical rotatable body, in accordance with the present invention;

[0053] FIGs. 2 A, 2B and 2C show operation of the apparatus shown in FIG. 1;

[0054] FIGs. 3A and 3B show shear-dominant processing and impact-induced processing during operation of the apparatus shown in FIG. 1, depending on a surface texture of the cylindrical body;

[0055] FIGs. 4 A, 4B, 4C and 4D show variation of a distance between the cylindrical body and a wall of a container as a function of time during operation; FIGs. 5A, 5B and 5C show another embodiment of a material processing apparatus comprising a substantially cylindrical rotatable body, in accordance with the present invention;

[0056] FIG. 6 shows an embodiment of a material processing method, in accordance with the present invention;

[0057] FIGs. 7A, 7B and 7C show experimental results of graphene nanosheets and h-BN nanosheets produced using the apparatus shown in FIGs. 5A, 5B and 5C in accordance with the method shown in FIG. 6;

[0058] FIG. 8 shows an embodiment of a material processing system comprising a substantially cylindrical rotatable body, in accordance with the present invention; and

[0059] FIG. 9 shows another embodiment of material processing system comprising a substantially cylindrical rotatable body, in accordance with the present invention.

[0060] Like reference numerals in different Figures may represent like elements.

[0061] DETAILED DESCRIPTION

[0062] Figure 1 shows a material processing apparatus 10 in accordance with an embodiment of the present invention.

[0063] The apparatus 10 comprises a substantially cylindrical rotatable body 15. The cylindrical body 10 is configured to be received within a container 20. The apparatus 10 also comprises a translation stage 25 on which the cylindrical body 15 is mounted. The translation stage 25 is configured to enable translation of the cylindrical body 15 relative to the container in use. In the embodiment shown, the translation stage 25 comprises an X-Y-Z translation stage configured to allow translation in three dimensions (for example, laterally in X and Y directions and vertically in an X direction). However, that is not essential, and the translation stage 25 may be configured to allow translations in two dimensions (for example, laterally in X and Y directions, or laterally in an X or Y direction and vertically in a Z direction) or one dimension (for example, laterally in an X or Y direction).

[0064] The apparatus 10 also comprises a control system 30 to control rotation and translation of the cylindrical body 15. In the embodiment shown, the control system 30 comprises a processor, a motor for rotating the cylindrical body and at least one actuator for adjusting a spatial position of the cylindrical body 15 on the translation stage 25. The processor is in communication with the motor and the at least one actuator to control rotation and translation of the cylindrical body 15 during processing, for example in accordance with a predetermined program and / or in response to user input during processing. Figures 2A, 2B and 2C show the operation of the apparatus 10 in more detail. The container 20 contains a material M to be processed. The material M may be a liquid, a mixture of a liquid and a solid powder or particulate material, or a solid powder or particulate material. The cylindrical body 15 is received within the container 20 and rotated about its longitudinal axis (the axis running parallel to the cylindrical outer surface of the cylindrical body 15). The cylindrical body 15 is rotated at a speed coi within the container 20. In the embodiment shown, the speed coi is between 10,000 rpm and 40,000 rpm, although that is not essential, and any suitable rotational speed may alternatively be used. Rotation of the cylindrical body 15 within the container 20 forces the material M towards the container walls and forms a rotating thin film F of the material M on the container walls, as shown in Figures 2B and 2C. The rotating thin film of the material M forms a vortex surrounding a void V in the container 20. In the embodiment shown, the cylindrical body 15 is translated a lateral distance R2 from a central axis of the container 20 towards a wall of the container 20, creating a narrow gap W between the body 15 and the wall of the container 20 for the material M to pass through. The reduction of the distance between the cylindrical body 15 and the wall of the container 20 accelerates the flow of the material M in the thin film through the gap W. A high mechanical force zone Z is therefore created at or near the narrow gap W, with the material M subjected to high mechanical forces as it passes through the gap W. The mechanical forces may be sufficiently high to enable mechanochemical processing of the material M to take place. The cm rotation of the cylindrical body 15 amplifies a speed of the flow in the thin film vortex around the container 20 in the area A which in turn feeds back into the high force zone Z. It will also be appreciated the cylindrical body 5 may be initially positioned within the container 20 at a distance from the wall of the container 20 corresponding to a desired with of the gap W, rather than translated from an initial position along the central axis of the container 20 (which may be done either in discrete steps or in a substantially continuous motion).

[0065] In the embodiment shown, a global void is formed in the material M in the container 20 when the cylindrical body 15 is rotated within the container 20, the global void surrounding by the rotating thin film F of the material M on the container walls. Depending on one or more factors such as a relative size (for example, diameter) of the cylindrical body 15 relative to the container 20, and / or a viscosity of the material M, a global void substantially spanning the container 20 (bar the presence of the thin film F of material M) may not be formed. Instead, a local void may be formed around the location of the cylindrical body 15. A thin film F of material M is still formed in the narrow gap W between the body 15 and the wall of the container 20 as the cylindrical body 15 is translated towards the wall of the container. The same processing mechanism as described above therefore takes place, because the processing predominantly takes place in the thin film F formed between the cylindrical body 15 and the wall of the container. The rotation of the cylindrical body 15 and the presence of the void (local rather than global) still encourages material M to circulate around the container and back into the high force zone Z.

[0066] In the embodiment shown in Figures 2A to 2C, the cylindrical body 15 has a substantially smooth cylindrical outer surface S. The apparatus 10 is therefore configured to provide shear-dominant processing of the material M. With a smooth outer surface, shear stresses dominate in the narrow gap W forming a high shear zone Z, as shown in Figure 3A. The shear rate or velocity gradient across the gap W is shown in Figure 3A. The flow speed Uw of the thin film of the material M adjacent the wall of the container 20 is substantially 0, increasing to a maximum speed of Ui adjacent the cylindrical body 15. The speed Ui can be approximated as corRi, where Ri is the radius of the cylindrical body 15.

[0067] In the embodiment shown, the cylindrical body 15 is made from or comprises stainless steel. However, it will be appreciated the cylindrical body 15 may alternatively be made from any suitable material. For example, for applications requiring high abrasion resistance during processing, the cylindrical body 15 may be made from or comprise tungsten carbide, high speed steel, stainless steel etc. For applications requiring high chemical resistance during processing, the cylindrical body 15 may be made from or comprise a polymeric material such as PEEK (poly ether ether ketone) or PTFE (polytetrafluoroethylene). The cylindrical body 15 may additionally or alternatively be made from or comprise a catalyst material for chemical reactions, such as copper.

[0068] Figure 3B shows another material processing apparatus 10’ in accordance with an embodiment of the present invention. The apparatus 10’ is substantially similar to the apparatus 10 described with respect to Figures 1, 2A to 2C and 3A, with like reference numerals indicating like elements.

[0069] In the embodiment shown, the apparatus 10’ comprises a substantially cylindrical rotatable body 15’. The cylindrical body 15’ comprises a featured cylindrical outer surface S’ rather than a substantially smooth cylindrical outer surface. The featured surface S’ comprises a plurality of projections 15’A extending from the cylindrical outer surface of the cylindrical body 15’. In the embodiment shown, the projections 15’A are substantially pointed, although that it essential. As the cylindrical body 15’ rotates, the projections 15’A rotate rapidly and impact oncoming material M with high force and high collision frequency. The material M is also forced towards the wall of the container 20 by that action, producing a high impact zone Z’ that extends across a full width of the thin film of the material M in the gap W.

[0070] In that way, substantially the same apparatus 10, 10’ may be used to provide both shear-dominant processing and impact-induced processing depending on a surface texture of the cylindrical body 15, 15’. The apparatus 10, 10’ may otherwise in a substantially identical way yet provide distinctly different processing behaviour depending on a surface texture of the cylindrical body 15, 15’. A cylindrical body 15’ may be provided by disposing a cylindrical sleeve having surface features over a cylindrical body 15. The cylindrical sleeve having surface features may be removably connectable to the cylindrical body 15 to easily change between the smooth cylindrical body 15 and the featured cylindrical body 15’.

[0071] In the embodiment shown, the projections 15’A of the featured surface S’ each have a height or projection distance (from the cylindrical outer surface of the cylindrical body 15’) of approximately 700 pm and have an aspect ratio (defined by height relative to diameter) of approximately 0.05. The projections 15’A are spaced approximately 1.5 mm apart from one another on the cylindrical outer surface of the cylindrical body 15’. However, the projections 15’A may have any suitable height or projection distance, for example substantially 1500 pm or smaller. The projections 15’A may also have any suitable aspect ratio (defined by height relative to diameter), for example between substantially 0 (that is, a substantially smooth surface with no projections) and substantially 0.125. The projections 15’ A may be spaced apart from one another any suitable distance, for example between substantially 0.5 mm and substantially 3 mm apart. The spacing between adjacent projections 15’A may be between the two closest points of the adjacent projections 15’A. In the embodiment shown, the projections 15’A comprise a substantially pointed or pyramidal shape, although that is not essential and any suitable shape may alternatively be used (for example, cylindrical, rounded lobes, substantially spherical or ball-shaped etc.).

[0072] As shown in Figures 2A to 2C, 3 A and 3B, the cylindrical body 15, 15’ is also translated to follow a path within the container 20, 20’ as the cylindrical body 15, 15’ rotates. In the embodiments shown, the path is substantially circular having a radius R2, and the cylindrical body 15, 15’ is translated along the path at a rotational speed CO2. The rotational direction of the circular path along which the cylindrical body 15, 15’ is translated is opposite or counter to the rotational direction of the cylindrical body 15, 15’ itself, to avoid mixing dead zones in the container 20, 20’, and may also increase a magnitude of the forces to which the material M is subjected in the high force zone Z, Z’. However, it will be appreciated that is not essential, and the rotational directional of the circular path of the cylindrical body 15, 15’ may be the same as the rotational direction of the cylindrical body 15, 15’ itself. The rotational speed C02 of the circular path may be between substantially 10 rpm and substantially 1000 rpm, for example between substantially 20 rpm and substantially 700 rpm. Alternatively, the cylindrical body 15, 15’ may be translated in substantially a single lateral direction in the container 20, 20’ (for example, in a substantially straight line) rather than in a circular path. Alternatively, the cylindrical body 15, 15’ may not be translated to follow a path within the container 20, 20’ and may rotate in a substantially fixed position within the container 20, 20’.

[0073] Figures 4A and 4B show operation of the apparatus 10 in which the radius R2 of the circular path of the cylindrical body 15 is varied as a function of time. As shown in Figure 4 A, at time ti the cylindrical body 15 may initially follow a circular path having a first radius R2(ti), the first radius R2(ti) defining a first gap W(ti) between the cylindrical body 15 and the wall of the container 20. At time t2, the radius of the circular path is increased to a second radius R2 2) larger than the first radius R2 1) in a discrete step (as depicted by the step shown in the plot of gap size W(m) as a function of time t in Figure 4B). The second radius R2(t2) defines a second gap W(tz) between the cylindrical body 15 and the wall of the container 20, the second gap W(tz) smaller than the first gap W(ti). At time ts, the radius of the circular path is increased again to a third radius R2 3) larger than the second radius R2(t2) in a discrete step. The third radius R2(ts) defines a third gap W(ts) between the cylindrical body 15 and the wall of the container 20, the third gap W(ts) smaller than the second gap W(t2). By varying the size of the gap W, the apparatus 10 can be used to process materials M having different particle sizes, for example from millimetre scale (as shown at time ti in Figures 4A and 4B) to micrometre scale (at shown at time ts in Figures 4A and 4B), whilst avoiding blockages caused by using a gap size which is inappropriately small for the particle size of the material M. Varying the width of the gap W allows tuneable mechanical force to be applied on-the-fly during processing. Varying the width of the gap W as a function of time may also allow processing to gradually reduce particle sizes until a target gap width (for example, a micrometre scale gap W) and / or a target processing parameter (such as shear rate, shear force or impact force) is achieved. In Figures 4A and 4B, the radius R2 of the circular path of the cylindrical body 15 (and therefore the size of the gap W) is varied in discrete steps. However, it will be appreciated the radius R2 of the path of the cylindrical body 15 may be varied substantially continuously as a function of time to follow a substantially spiral path, as shown in Figures 4C and 4D (Figure 4D shows the continuous variation overlaid over the discrete variation in time of Figures 4A and 4B). It will also be appreciated the apparatus 10’ may equally be operated in a similar manner to vary the radius R2 of the path of the cylindrical body 15’ within the container 20’, either in discrete steps or substantially continuously. The cylindrical body 15, 15’ may alternatively be translated within the container 20, 20’ to follow an arbitrary path (for example, a non-circular or non-spiral path). The arbitrary path may be a predetermined path, although that is not essential. However, it will be appreciated the radius R2 of the path of the cylindrical body 15, 15’ may not be varied as a function of time during operation of the apparatus 10, 10’.

[0074] The translation of the cylindrical body 15, 15’ described above with respect to Figures 2A to 2C, 3A, 3B and 4A to 4C is in reference to lateral translation (in the X and Y directions) within the container 20, 20’. The cylindrical body 15, 15’ may also be translated vertically (in the Z direction) within the container 20, 20’, either separately from or in combination with the lateral translation. For example, as shown in Figure 2A, the cylindrical body 15, 15’ may translated vertically a distance d. The translation over the distance d may be a high speed (for example, between substantially 0.5 m s'1and substantially 5 m s'1, such as between substantially 1 m s'1and substantially 2.5 m s'1), low amplitude (for example, between substantially 1 pm and substantially 50pm, such as substantially 10 pm) translation to induce ultrasonic waves in the material M as the cylindrical body 15, 15’ rotates. Such vertical translation may be superimposed on the lateral translation path of the cylindrical body 15, 15’ within the container 20, 20’.

[0075] Figures 5 A to 5C shows another material processing apparatus 110 in accordance with an embodiment of the present invention. The apparatus 110 is substantially similar to the apparatus 10, 10’ described with respect to Figures 1 to 4D, with like reference numerals indicating like elements.

[0076] The apparatus 110 comprises a substantially cylindrical rotatable body 115 configured to be received within a container 120. The apparatus 110 also comprises a translation stage 125 on which the cylindrical body 115 is mounted. The translation stage 125 is an X-Y-Z translation stage configured to allow translation in an X direction along the X-stage 125A, in a Y direction along the Y-stage 125B and in a Z direction along the Z-stage 125C. The apparatus 110 also comprises a control system 130 to control rotation and translation of the cylindrical body 115. The control system 130 comprises a processor 130A, a motor 130B for rotating the cylindrical body 115, and actuators (not shown) for adjusting a spatial position of the cylindrical body 115 along the respective X-stage 125A, Y-stage 125B and Z-stage 125C of the translation stage 125. The processor 130A is in communication with the motor 130B and the actuators to control rotation and translation of the cylindrical body 115 during processing. The cylindrical body 115 is removably mounted to the translation stage 125. In the embodiment shown, the cylindrical body 115 is removably mounted to the translation stage 125 via an attachment mechanism (such as a collet or clamp mechanism) configured to receive at least a part of the cylindrical body 115 (for example, a projection extending from the cylindrical body 115 having a narrower diameter than the main cylindrical body 115 as shown in Figures 1, 2A and 2B, although that is not essential). The attachment mechanism may be manually operated or may be operated automatically by the control system 130 to connect and release the cylindrical body 115 to and from the translation stage 125.

[0077] In the embodiment shown, the apparatus 110 comprises a cap 135 configured to be placed over the container 120. The cap 135 comprises an aperture 135A through which the cylindrical body 115 can pass such that the cylindrical body 115 can be received within the container 120. The cap 135 comprises a concertina or pleated structure to allow the cylindrical body 115 to be translated within the container 120 without restriction, whilst inhibiting or preventing material from exiting the container 120 during processing. The pleats of the cap 135 are configured to fold relative to one another to allow the cap 135 to compress or extend in different areas. That allows the cap 135 to accommodate translation of the cylindrical body 115 within the container 120 by causing compression and / or extension of the pleats under force applied by the apparatus 110 during translation. The cap 135 is made from thermoplastic polyurethane in the embodiment shown, although any suitable flexible material or structure may alternatively be used.

[0078] Figure 6 shows a material processing method 200 in accordance with an embodiment of the present invention. The method 200 may be carried out using, and is described with respect to, the apparatus 110 shown in Figures 5A to 5C. Operation of the apparatus 110 in accordance with the method 200 may enable the apparatus 110 to autonomously carry out a predetermined processing or synthesis program.

[0079] Step 205 of the method 200 optionally comprises locating the cylindrical body 115 in the container 120. Initially the cylindrical body 115 may be located at a start or rest position on the translation stage 125 (for example, an origin point with respect to coordinates used by the processor 130A to control a position of the cylindrical body 115 on the translation stage 125). Upon starting a processing program, the control system 130 moves the cylindrical body 115 to be received within the container 120 (for example, by translating the cylindrical body 115 laterally to a position above the container 120, then translating the cylindrical body 115 vertically to pass through the aperture 135A in the cap 135 to be received within the container 120).

[0080] Step 210 of the method 200 comprises rotating the cylindrical body 115 in the container 120. Step 215 of the method 200 comprises translating the cylindrical body 115 in the container 120. The control system 130 controls rotation and translation of the cylindrical body 115 to process the material within the container 120, according to the processing program.

[0081] Figures 7A, 7B and 7C show results for processing of graphite powder and hexagonal boron nitride (h- BN) powder respectively using the apparatus 110 described with respect to Figures 5A to 5C, in accordance with the method 200 described with respect to Figure 6. The predetermined processing program used to process the graphite powder and h-BN powder was caried out using the following parameters: coi = 17000 rpm; CO2 = 20 rpm; Ri = 8 mm; W = 5 mm. The graphite powder and h-BN powder was mixed into an aqueous surfactant solution consisting of a mixture of Sodium Cholate in de-ionised water (2 g-L’1). No ultrasonic waves were induced or utilised during processing. The processing was carried out using the cylindrical body 15’ having a featured surface S’ comprising projections 15’A as described with respect to Figure 3B. The processing was carried out for 15 minutes.

[0082] Figures 7A, 7B and 7C show nanosheets of less than ten atomic layers of both graphene and h-BN were produced using the processing program described above. Figure 7A shows the extinction profile derived from UV-vis spectroscopy measurements obtained after processing of the graphite powder according to the processing program described above. The measurements show an extinction peak at = 267 nm which is indicative of the electronic conjugation of graphene. The inset image in Figure 7A shows the graphene nanosheets dissolved in the solvent (the aqueous surfactant solution described above). Figures 7B 1 shows the extinction profile derived from UV-vis spectroscopy measurements (using PerkinElmer Lambda 365) obtained after processing the h-BN powder according to the processing program described above. Figure 7B2 shows the second derivative of the absorbance profile derived from UV-vis spectroscopy measurements obtained after processing the h-BN powder according to the processing program described above. Figure 7B2 indicates a bandgap of Ebg= 6. 14 eV which agrees with the literature for few atomic layer h-BN nanosheets. The inset image in Figure 7B 1 shows the h-BN nanosheets dissolved in the solvent. Figure 7C shows a particle size distribution for graphite particles before and after processing. The initial particle size distribution of the graphite particles prior to processing has a relatively narrow peak centred around 650 pm. The final particle size distribution of the graphite particles after processing is much broader and exhibits a distinct upper size cut-off substantially corresponding to the amplitude of the surface features on the cylindrical body 115 (approx. 700 pm). The graphite particles were allowed to sediment out of the processed mixture and then recovered, while the graphene nanosheets formed during processing remained in dispersion due to their size. A size of the recovered graphite particles was measuring using a laser diffraction particle size analyzer (Malvern Mastersizer)

[0083] Figure 8 shows a material processing system 300 in accordance with an embodiment of the present invention. In the embodiment shown, the material processing system 300 comprises the apparatus 110 described with respect to Figures 5A, 5B and 5C above.

[0084] The system 300 is shown performing automated materials processing or synthesis in Figure 8. The system 300 is a single digital materials processing platform performing batch processing or synthesis on a m x n array of samples. The array of samples comprises a plurality of containers each containing a material (for example, a precursor material) to be processed. The system 300 comprises a translation stage 125 and a control system 130 as described above with respect to the apparatus 110. The system 300 also comprises a plurality of cylindrical bodies 115A-115E. The cylindrical body 115A comprises a featured cylindrical outer surface as described above with respect to the cylindrical body 15’ of Figure 3B. The cylindrical bodies 115B-115D also comprise featured cylindrical outer surfaces. The cylindrical body 115E comprises a substantially smooth cylindrical outer surface as describe above with respect to Figures 1, 2A to 2C and 3A. The control system 130 operates the other components of the system 300 to automatically run through predetermined processing or synthesis programs for each of the m x n samples. In the embodiment shown, the processing or synthesis status of each sample is shown green if completed, yellow if in progress and hatched if still to be completed. For example, the sample in column 1, row 2 of the array is currently undergoing impact-induced processing using cylindrical body 115A, and subsequently will be subjected to shear-dominant process using cylindrical body 115E. The system 300 is configured to automatically change between the different cylindrical bodies 115A-115E as required. For example, as described above with respect to Figures 5A, 5B and 5C, each cylindrical body 115A-115E is removably mountable to the translation stage 125 via an attachment mechanism. The control system 130 is configured to automatically operate the attachment mechanism to connect and release each cylindrical body 115 to and from the translation stage 125 as required, for example as determined by the processing program for a particular sample. When not in use the cylindrical bodies 115A-115E may be held in a support or rack, for example each cylindrical body 115A-115E placed at a distinct location having a known position in the coordinate system of the translation stage 125 to enable the control system 130 to translate the attachment mechanism to the cylindrical bodies 115A-115E for connection and release. The attachment mechanism (for example, a collet or clamp mechanism) may be pneumatically controlled for connection and release of the cylindrical bodies 115A-115E. The control system 130 may be configured to control pneumatic control of the attachment mechanism. The control system 130 may be configured to automatically translate a currently attached cylindrical body (for example, cylindrical body 115A) to its distinct location on the support or rack, operate the attachment mechanism to release the currently attached cylindrical body 115A, translate the attachment mechanism to a different cylindrical body (for example, cylindrical body 115B), operate the attachment mechanism to connect to the new cylindrical body 115B, and then continue processing using the system 300. Such automated pneumatic tool changeover systems are known and have been implemented, for example, in CNC milling machines. The system 300 also comprises a device cleaning station 340 to minimize or prevent contamination between samples. In the embodiment shown, the cylindrical body in use is moved from sample to sample without cleaning between samples (for example, following the path of cylindrical body 115A shown in blue line). That may be appropriate where each sample consists of the same material M and the different cylindrical bodies 115A-115E are used to apply different processing mechanisms (such as shear-dominant processing or impact-induced processing) or different processing parameters (for example, different rotational speeds or device paths for optimising the hydrodynamic conditions of the processing). In such cases, contamination may not be a concern. However, if one or more samples consist of a different material M to other samples and a single cylindrical body is to be used to process samples consisting of different materials M, the processing program may include cleaning the cylindrical body at the device cleaning station 340 in between samples. The control system 130 may control translation of the cylindrical body to the location of the cleaning station 340. The cleaning station 340 may be or comprise a tank of de-ionised water. However, depending on the material M of one or more samples, the cleaning station may be or comprise a different cleaning fluid (for example, a water / alcohol mixture or a different solvent). The cleaning station 340 may comprise an ultrasonic bath, although that is not essential because the control system 130 may control rotation of the cylindrical body in the tank to perform a self-cleaning operation. The cleaning station 340 may comprise a recirculation loop to either filter the cleaning fluid and return the filtered cleaning fluid to the tank, or replace the cleaning fluid in the tank.

[0085] The control system 130 may be configured to run a different processing or synthesis program for each sample, although that is not essential. The different processing or synthesis program may be carried out by using different cylindrical bodies 115A-115E to process the material M of each sample, and / or by using different processing parameters to process the material M of each sample (for example, rotational speed, device path, gap width, ultrasonic waves etc.). In the embodiment show, cylindrical bodies 115A- 115D have substantially identical featured outer surfaces S’, and are primarily provided to avoid contamination between samples. Alternatively, however, each of the cylindrical bodies 115A-115D may have a different featured outer surface S’, for example providing intermediate positions between impact- induced processing (cylindrical body 115A) and shear-dominant processing (cylindrical body 115E), to provide increase flexibility in processing the material M of each sample. A processing program for a sample may incorporate any number of combinations of different cylindrical bodies using different processing parameters.

[0086] The system 300 may provide automated processing and synthesis with enhanced flexibility, for example with respect to different processing mechanisms (such as shear-dominant processing and impact-induced processing) and variable processing parameters for each processing mechanism. That may allow a large number of different samples to be processed using different processing mechanisms and processing parameters using a single system 300. The development of processing or synthesis programs may be guided or determined by computational material design, with the programs then carried out automatically using the system 300. The outcome of the processing of the processing or synthesis may then provide additional information which can be used in further computational iterations, and so on. This may enable the system 300 to both efficiently test and inform data-driven computational materials research and discovery, which may accelerate the production of advanced materials at an industrial scale.

[0087] Figure 9 shows use of the apparatus 10, 10’, 110 or the system 300 in a materials production system. An open container 420 containing material is provided. In the embodiment shown, the material is a precursor material from which a final product may be synthesised by processing using the apparatus 10, 10’, 110 or the system 300. The cylindrical body 15 (or 15’, 115) is inserted into the container 420, and then rotated and translated substantially as described above with respect to Figures 1 to 6 and 8. Processing of the precursor material directly in the container 420 may enable may increase efficiency by removing the need to separately process the precursor material and then transfer the final product to a container 420 (for example, for storage or shipping). The inset image in Figure 9 shows a prototype test carried out on a 100 mL HDPE bottle, showing direct in-bottle processing of a precursor material to synthesise a final product can be achieved using the apparatus 10, 10’, 110 or the system 300. In the embodiment shown, a plurality of containers 420 are transported along a conveyor belt 445. As the containers 420 are transported the cylindrical body 15 is inserted into the container 420 and processed as described above. Once processed, the container 420 containing the final product continues along the production line, for example to capping and final packaging. The apparatus 10, 10’, 110 or the system 300 may therefore enable a high-throughput materials production line which is capable of being used to process (for example, mechanochemically process) a wide variety of different materials, due to its ability to flexibly apply different processing mechanisms (such as shear-dominant processing and impact-induced processing) with a wide variety of processing parameters.

[0088] From reading the present disclosure, other variations and modifications will be apparent to the skilled person. Such variations and modifications may involve equivalent and other features which are already known in the art of materials processing devices, in particular mechanochemical material processing devices, and which may be used instead of, or in addition to, features already described herein.

[0089] Although the appended claims are directed to particular combinations of features, it should be understood that the scope of the disclosure of the present invention also includes any novel feature or any novel combination of features disclosed herein either explicitly or implicitly or any generalisation thereof, whether or not it relates to the same invention as presently claimed in any claim and whether or not it mitigates any or all of the same technical problems as does the present invention.

[0090] Features which are described in the context of separate embodiments may also be provided in combination in a single embodiment. Conversely, various features which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination. The applicant hereby gives notice that new claims may be formulated to such features and / or combinations of such features during the prosecution of the present application or of any further application derived therefrom.

[0091] For the sake of completeness, it is also stated that the term "comprising" does not exclude other elements or steps, the term "a" or "an" does not exclude a plurality, and any reference signs in the claims shall not be construed as limiting the scope of the claims.

Claims

CLAIMS1. A material processing apparatus, comprising: a substantially cylindrical rotatable body configured to be received within a container; a translation stage on which the body is mounted, configured to allow translation of the body within the container in use.

2. The apparatus of claim 1, further comprising a control system configured to control rotation and translation of the body.

3. The apparatus of claim 2, wherein the control system is configured to rotate the body between substantially 10,000 rpm and substantially 40,000 rpm.

4. The apparatus of claim 2 or of claim 3, wherein the control system is configurated to translate the body from a first position at a first distance from a wall of the container to a second position at a second distance from the wall of the container, wherein the first distance is greater than the second distance.

5. The apparatus of claim 4, wherein the control system is configured to: i) translate the body from the first position to the second position substantially continuously; or i) translate the body from the first position to the second position in a plurality of discrete steps.

6. The apparatus of any of claims 2 to 5, wherein the control system is configured to translate the body according to a predetermined path.

7. The apparatus of claim 6, wherein the predetermined path comprises a circular path or a spiral path.

8. The apparatus of claim 7, wherein the control system is configured to translate the body such that a rotational direction of the circular path or the spiral path is opposite to a rotational direction of the body.

9. The apparatus of any of claims 2 to 8, wherein the control system is configured to translate the body to induce ultrasonic waves.

10. The apparatus of claim 7, wherein the control system is configured to translate the body a distance of substantially 50 pm or less at a speed of substantially 2.5 m s'1or less to induce the ultrasonic waves.

11. The apparatus of any of claims 1 to 10, wherein a surface of the body is substantially smooth.

12. The apparatus of any of claims 1 to 10, wherein a surface of the body comprises one or more surface features, optionally one or more projections.

13. The apparatus of any preceding claim, wherein the body is releasably mounted on the translation stage.

14. A material processing method, comprising: rotating a substantially cylindrical body in a container containing a material; and translating the body within the container.

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