The present disclosure generally relates to a device including a hydrophilic layer on a portion of an inner surface of a transparent polymer forming a body; wherein the hydrophilic layer includes a sulfonated inner surface of the transparent polymer, a silica, a silicon oxycarbide, an O2 plasma treatment of the transparent polymer, or a combination thereof. The device can be a nebulizer or a spray chamber, for example used in an inductively coupled plasma device. A method of making the device is also disclosed.
In an Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) or Inductively Coupled Plasma Mass Spectrometry (ICP-MS) sample introduction system, a sample enters a nebulizer and is broken up into a fine aerosol by pneumatic action of gas flow dispersing the liquid sample into tiny droplets. This nebulized spray is flowed into a spray chamber along with an inert gas where large and small droplets are separated out. For ICP, monodisperse droplets smaller than 10 μm are ideal, while larger droplets interfere with signal stability and intensity. For this reason, only the smallest droplets are allowed to pass through the spray chamber into the plasma, in order to efficiently atomize and finally ionize the sample's elemental components, thus achieving accurate quantitative analysis. In particular, the droplets are sorted by the design of the spray chamber and the vortex of gas flow, whereby larger droplets collide with the spray chamber walls by means of centrifugal force, leaving behind the smaller droplets to pass further into the plasma where they will be ionized by high temperature and analyzed for their elemental makeup. The larger droplets that bombarded the spray chamber surface seep down the spray chamber walls and out of the flow path so as to not interfere with the finer spray droplets.
To achieve the drainage needed to remove the larger droplets from the spray chamber surface, the surface itself must be able to wick away the solvent. Solvents such as water and alcohols drain away easier if the spray chamber surface is hydrophilic in nature. Glass, which is naturally hydrophilic, is typically used for spray chambers, which allows the drainage needed. Glass is also robust to acids that are used for ICP and is transparent, allowing users to visualize the drainage of the solution that has hit the spray chamber walls. With a hydrophilic surface like glass, the drainage is rapid, owing to less time needed to ‘wash out’ the sample before the next analysis. If the surface begins to become contaminated or loses its hydrophilicity, these wash outs are not sufficient to remove the sample residues and can cause erroneous analysis or excessively long washout times. Over time, glass spray chambers need to be cleaned or replaced, which can become costly for the users. Additionally, the production of glass spray chambers requires manual glass shaping by experienced glass technicians. This is expensive (hundreds of dollars each piece) and somewhat design limited.
Other existing materials for spray chambers, typically for specialized applications (e.g., hydrofluoric acid resistance), include fluorocarbon containing plastics, such as perfluoro-polymers (e.g. perfluoroalkoxy alkane (PFA) or polytetrafluoroethylene (PTFE)), and the inert plastic PEEK. Perfluoro-polymers are generally opaque, which prohibits visual observation of solution spraying and introduction (which is considered important by ICP-OES users). Furthermore, the perfluoro-polymers are hydrophobic, thus an expensive hydrophilic coating must be applied on the inner surface to avoid liquid beading of the spray chamber (which may interfere with the analysis and waste solution drainage).
A cost-friendly solution to manufacturing a high-performance spray chamber is desired.
The shape of glass spray chambers is limited to a combination of pre-formed (molded or extruded) parts plus minor manual modifications performed by glass blow-molding. What is needed is a device that can be cheaply made in a variety of versatile shapes without being labor or cost intensive.
Glass spray chambers will shatter when dropped from a benchtop to a floor. Additionally, glass spray chambers can crack under usage and cleaning conditions. What is needed is a device with a reasonable impact resistance at ambient use conditions. Moreover, the device should be resistant to cracks.
Features of the present disclosure are illustrated by way of example and not limited in the following figure(s), in which like numerals indicate like elements, in which:
In an aspect, there is disclosed a device including a hydrophilic layer on a portion of an inner surface of a transparent polymer forming a body; wherein the hydrophilic layer includes a sulfonated inner surface of the transparent polymer, a silica, a silicon oxycarbide, an O2 plasma treatment of the transparent polymer, or a combination thereof.
In another aspect, there is disclosed a method of making a device, comprising: forming the device by mold manufacturing or injection molding a transparent polymer; and chemically modifying a portion of an inner surface of the device to render the portion hydrophilic.
Additional features and advantages of various embodiments will be set forth, in part, in the description that follows, and will, in part, be apparent from the description, or can be learned by the practice of various embodiments. The objectives and other advantages of various embodiments will be realized and attained by means of the elements and combinations particularly pointed out in the description herein.
For simplicity and illustrative purposes, the present disclosure is described by referring mainly to an example thereof. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. It will be readily apparent however, that the present disclosure may be practiced without limitation to these specific details. In other instances, some methods and structures have not been described in detail so as not to unnecessarily obscure the present disclosure.
Additionally, the elements depicted in the accompanying figures may include additional components and some of the components described in those figures may be removed and/or modified without departing from scopes of the present disclosure. Further, the elements depicted in the figures may not be drawn to scale and thus, the elements may have sizes and/or configurations that differ from those shown in the figures.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are intended to provide an explanation of various embodiments of the present teachings. In its broad and varied embodiments, disclosed herein is a device including a hydrophilic layer on a portion of an inner surface of a transparent polymer forming a body; wherein the hydrophilic layer includes a sulfonated (or chemically modified) inner surface of the transparent polymer, a silica, a silicon oxycarbide, an O2 plasma treatment of the transparent polymer, or a combination thereof.
The device disclosed herein can be shaped and prepared in a cost efficient manner. In this manner, the device can be disposable and/or reusable. The device can be transparent or nearly transparent to enable visualization of the contents of device and a process of solution nebulization. Additionally, the device can be durable to solvents used in Inductively Coupled Plasma processes in order to increase a lifespan of the device. Solutions used in Inductively Coupled Plasma processes can be inhibited from beading on an inner surface of the device. In particular, a hydrophilic layer on a portion of the inner surface of the device can enable the fluid droplets to flatten, coalesce, and/or drain, thereby inhibiting beading. In particular, the hydrophilic layer enables the spray chamber to be hydrophilic, withstand a low pH environment, and/or to be fabricated from clear plastics in a more cost efficient manner.
The device can be a nebulizer (as shown in
A nebulizer can include concentric and parallel paths. A spray chamber can include cyclonic (single and double pass) and Scott types.
The device can be a body including one or more inlets and one or more outlets. The body can include an outer surface and an inner surface. The body can be formed of a transparent material. In an aspect, the transparent material can be any transparent material whose surface is or can be modified or coated to yield a hydrophilic layer. The transparent material can be a transparent polymer. Non-limiting examples of transparent polymers for use in the device include polystyrene, polyethylene terephthalate with glycol modification, polyethylene terephthalate, cyclic olefin polymers, polycarbonate, and the like. Commercially available examples of a cyclic olefin polymer include ZEONOR® 1020 and ZEONOR® 790 from Zeon Corporation, Japan. The transparent polymer can be polystyrene.
The body of the device can be formed by additive processing, such as three-dimensional printing, or injection molding capabilities. These fabrication methods can enable a variety of modifications to a body, such as a spray chamber, design, shape, and/or size.
The device, including an inner surface thereof, can be formed of the transparent polymer. A portion of the inner surface of the device can be modified, surface treated, or coated to yield a hydrophilic layer. By “a portion” is understood to mean at least 1% of the inner surface of the device, such as from about 5% to about 100%; for example from about 50% to about 99%; and as a further example, from about 75% to about 95%, including subranges and endpoints therebetween.
The hydrophilic layer can be any coating, surface treatment, and/or surface modification that can render a portion of the inner surface of the transparent polymer hydrophilic or substantially hydrophilic. For example, the hydrophilic layer can inhibit the formation of liquid beads on the portion of the inner surface of the transparent polymer. Non-limiting examples of a hydrophilic layer includes a sulfonated (carboxylated, aminated, hydroxylated or other chemical moieties that can impart a hydrophilic character) inner surface of the transparent polymer, a silica, a silicon oxycarbide, an O2 plasma treatment of the transparent polymer, or a combination thereof.
In an aspect, the transparent polymer can be a polystyrene. The polystyrene can be chemically modified as shown below to yield a hydrophilic layer, which is a sulfonated inner surface of the transparent polymer.
In another aspect, the device can be formed of a transparent polymer, such as polyethylene terephthalate with glycol modification or polyethylene terephthalate. A hydrophilic layer of silica or silicon oxycarbide can be deposited on a portion of an inner surface of the transparent polymer using conventional deposition processes, such as plasma enhanced chemical vapor deposition (PECVD). For example, a gas feed of oxygen:hexamethyldisiloxane (HDMSO) 3:1, as a further example, of 12:1, can be applied to the portion of the inner surface.
In another aspect, the device can be formed of a transparent polymer, such as cyclic olefin polymer. A portion of an inner surface of the transparent polymer can be surface modified using an O2 plasma treatment to yield a hydrophilic layer on the portion of the inner surface. The O2 plasma treatment can be performed at 500 W for 5 minutes at 400 mTorr oxygen.
The device can be a spray chamber including polyethylene glycol. A portion of an inner surface of the spray chamber can include a hydrophilic layer of silica. The hydrophilic layer of silica can be formed using atomic layer deposition. A first precursor, such as a silicon source, can be used to react to an inner surface of the body of the device to form a monolayer. A second precursor, such as an oxygen source, can be dosed in a manner to react with the monolayer to form a single fully reacted monolayer, which is a complete cycle. The cycle can be repeated several times to control a thickness of a hydrophilic layer formed of multiple fully reacted monolayers.
There is disclosed herein a method of making a device, comprising forming the device by mold manufacturing or injection molding a transparent polymer; and chemically modifying a portion of an inner surface of the device to render the portion hydrophilic. The step of forming the device can further include molding two halves of the device separately; and joining the two halves together to form the device of transparent polymer. The step of chemically modifying can further include immersing the formed device of transparent polymer into a sulfuric acid bath.
In an alternative aspect, a method of making a device can comprise forming the device by mold manufacturing or injection molding a transparent polymer; and chemically modifying a portion of a surface of the device to render the portion hydrophilic. The step of forming the device can further include molding two halves of the device separately. The step of chemically modifying can further include immersing the formed device of transparent polymer into a sulfuric acid bath. The method can include, after the step of chemically modifying, joining the two halves together to form the device.
With regard to the method steps of chemically modifying discussed above, the step of chemically modifying can include application of sulfuric acid for a period of time ranging from about 1 minute to about 1 hour, at a temperature ranging from about −5° C. to less than about 80° C. The sulfuric acid can have a concentration of at least 96%. The sulfuric acid can be a fuming sulfuric acid with from about 0.01% to about 20% free SO3. In this manner, the step of chemical modification can include sulfonation of the portion of the inner surface of the device.
There is disclosed herein a method of making a device, comprising forming the device by mold manufacturing or injection molding a transparent polymer; and chemically modifying a portion of an inner surface of the device to render the portion hydrophilic. The step of forming the device can further include molding two halves of the device separately. The step of chemically modifying can further include plasma enhanced chemical vapor deposited silica or silicon oxycarbide of the molded two halves of the device; and immersing the coated, molded two halves of the device into a solution for chemical stability of surface hydrophilicity. The method can include, after the step of chemically modifying, joining the two halves together to form the device of coated transparent polymer.
There is disclosed herein a method of making a device, comprising forming the device by mold manufacturing or injection molding a transparent polymer; and chemically modifying a portion of a surface of the device to render the portion hydrophilic. The step of forming the device can further include molding two halves of the device separately. The step of chemically modifying can further include plasma enhanced chemical vapor deposited silica or silicon oxycarbide of the molded two halves of the device. The method can include, after the step of chemically modifying, joining the two halves together to form the device of coated transparent polymer. The device including the coated transparent polymer can be immersed into a solution for chemical stability of surface hydrophilicity.
There is disclosed herein a method of making a device, comprising forming the device by mold manufacturing or injection molding a transparent polymer; and chemically modifying a portion of a surface of the device to render the portion hydrophilic. The step of forming the device can further include molding two halves of the device separately. The step of chemically modifying can further include O2 plasma treatment of the molded two halves of the device; and immersing the coated, molded two halves of the device into a solution, such as nitric acid, or a cleaning solution. The method can include, after the step of chemically modifying, joining the two halves together to form the device of coated transparent polymer.
There is disclosed herein a method of making a device, comprising forming the device by mold manufacturing or injection molding a transparent polymer; and chemically modifying a portion of a surface of the device to render the portion hydrophilic. The step of forming the device can further include molding two halves of the device separately. The step of chemically modifying can further include O2 plasma treatment of the molded two halves of the device. The method can include, after the step of chemically modifying, joining the two halves together to form the device of coated transparent polymer. The device including the coated transparent polymer can be immersed into a solution, such as nitric acid or a cleaning solution.
A method of making a device, can also comprise, forming a device by additive processing or injection molding a transparent polymer; and providing a hydrophilic layer on a portion of an inner surface of the device. Providing for the hydrophilic layer can include reacting a first precursor, such as a silicon source, to the portion of the inner surface of the device to form a monolayer; and reacting a second precursor, such as an oxygen source, to the monolayer to form a fully reacted monolayer in a cycle. The method can include repeating the cycle one or more times to control a thickness of the hydrophilic layer.
With regard to the methods of making the device described above, it should be noted that that the step of chemically modifying a portion of an inner surface of the transparent polymer does not reduce the transparency of the transparent polymer. Additionally, the hydrophobic portion (such as a hydrophilic layer) of the device can be durable over ambient room temperature (for example, ranging from about 10° C. to about 35° C., and as a further example from about 15° C. to about 30° C., including subranges, and end points therein). A person of ordinary skill in the art would understand that durability can be determined demonstrated as shown in
For example, the hydrophilic portion of the device can be durable against solvents including 20% aqua regia, dilute hydrochloric acid, nitric acid, or combinations thereof.
The surface hydrophilicity of a device including sulfonated polystyrene, freshly prepared (New Sample 1) and stored under ambient room temperature for 12 weeks (12 weeks air), is shown in
The coupon provided a flat surface for characterizing the extent or depth of any surface modifications and was representative of the coating on the inner surfaces of the device, such as a nebulizer or a spray chamber.
The performance of untreated (left) and chemically modified (right) transparent polymer (polystyrene) in a pseudo spray chamber was tested. As shown in
The surface hydrophilicity of sulfonated polystyrene, freshly prepared (New Sample 2) was stored with continuous 20% aqua regia contact for up to 14 days, as shown in
An actual plasma enhanced chemical vapor deposition (PECVD) silica coating exhibited insufficient hydrophilicity, which led to beading of a sprayed solution in the device and having a static water contact angle of about 45° to about 65°. If a silicon oxycarbide was targeted, the hydrophobicity issue was worse (e.g., having a static water contact angle of about 60° to about 1100).
A device containing a transparent polymer with an activated high surface hydrophilicity silica (or silicon oxycarbide) was formed. Thierry plasma using a kilohertz plasma PECVD tool with a gas feed of hexamethyldisiloxane:O2=3:1 was used. The coating was characterized by X-ray photoelectron spectroscopy (XPS) with ˜1-2%, ˜32% Si, ˜65% O. The surface (<20 nm) was found to be ˜19% C, ˜24% Si, ˜57% O.
The device exhibited a static water contact angle of 60°-70° following PECVD deposition of the silica. It was then immersed in a solution containing 2% commercially available “RBS-25 solution” in deionized water (20-30 minutes) to activate the hydrophilicity followed by deionized water rinsing. The device was characterized by static water contact angle of ˜15°. XPS characterization showed little change on the elemental composition of the surface by RBS solution treatment.
Additionally, the PECVD silica (or silicon oxycarbide) coated transparent polymer was durable against continuous 20% aqua regia contact. In particular, a coated coupon was contacted with ICP-OES solvent for 25 days.
ICP-OES spray chambers are often cleaned with aggressive (highly alkaline and/or oxidative) cleaning solution under sonication. Many inorganic oxide-coated plastics fail under this condition. The coated transparent polymer was preserved for tens of cleaning cycles under non- or low-etching cleaning methods.
A PECVD silica coated transparent polymer (polyethylene terephthalate with glycol modification—PETG) coupon was contacted with ICP-OES solvent followed by sonication in spray chamber cleaning solutions. The number of equivalent cleaning cycles were calculated by durability divided by the time required to erase the hydrophobic effect of A-solv contact (30 minutes for Extran MA02, 3 hours for Triton X-100. The results are shown in Table 1. The results indicated that at least tens of cleaning cycles can be performed before failure of the hydrophilicity.
An O2 plasma treatment was applied using a kilohertz plasma PECVD tool with a gas feed of oxygen:hexamethyldisiloxane=12:1 was used. 20 minutes in activation solution a hydrophilic surface was present.
500 W, 5 minutes at 400 m Torr oxygen provided performance for the O2 plasma treatment of a cyclic olefin polymer. For the chemical stabilization of the surface hydrophilicity, the surface was immersed in 10% HNO3 solution for 1-2 hours at room temperature, followed by rinsing with water and air drying was provided for performance. A concentrated (e.g., 70% nitric acid) or a stronger oxidizer (e.g., 5% ammonium persulfate) did not provide performance. Without the chemical stabilization, the surface reverted to its characteristics prior to the O2 plasma treatment within 1-4 weeks of storage in air and ambient conditions. As shown in
The performance of untreated (
As shown in
The performance of untreated (
The hydrophilic layer of SiO2 (i.e., a coating) was made using a vapor phase deposition process, such as Atomic Layer Deposition (ALD). ALD is a vapor deposition method used to make thin films in a sequential layer-by-layer growth method. For ALD, parts and substrates are first put under vacuum and/or a chamber of inert atmosphere. To make a hydrophilic layer of SiO2 using ALD, a 1st precursor vapor was exposed into the vacuum chamber with the substrates to be coated. The first silicon source precursor, Orthrus obtained from Air Liquide. This precursor allowed for a low temperature SiO2 coating to be made, which is beneficial for coating plastics that would otherwise deform or melt in SiO2 ALD recipes that require higher temperatures. This precursor was used as received and heated in a dual stage heating jacket set at 50° C. on the lower stage and 55° C. on the higher stage.
This precursor reacted to the substrate surface, but not itself, thus forming a monolayer of precursor that was bound to the substrate. Excess or unreacted vapors were purged away with an inert gas and a 2nd precursor was dosed into the chamber. This 2nd precursor, or co-reactant, was chosen to react with the already-bound 1st precursor, but not to itself. Ozone, O3, was used as the oxygen source precursor. Ozone was synthesized from oxygen using a Savannah ozone generator attached to the ALD vacuum chamber tool (Savannah S300, Veeco). The chamber temperature during the ALD was performed at 50-70° C.
After exposure to the ozone, excess or unreacted vapors were purged from the chamber resulting in a single fully reacted monolayer on all surfaces within the vacuum chamber, and thus completing one full ‘cycle’ of ALD. Each cycle of ALD resulted in a new reacted monolayer on the substrate surface and was used to control the thickness of film deposited. Because ALD is a vapor process with precursors separated by inert gas purging steps, thin films of very even thicknesses (high conformality) can be made into very narrow trenches, bores, or other complicated substrate features, such as the insides of spray chambers.
Prior to the SiO2 deposition, the plastic spray chamber substrates were loaded into the ALD chamber and allowed a 1-5 hour pump-down and warmup time to remove moisture and gas from the spray chamber samples. After warmup, ozone was pulsed into the chamber to activate the plastic surface, enabling the SiO2 precursors to chemically adhere. This was done with a 0.2 s pulse of ozone (˜100 mg/L concentration) into the non-purging ALD chamber and held for 5 minutes before purging with N2 for 20 s. This sequence was repeated 12 or more times for a total of 60 minutes of ozone pretreatment of the plastic.
After the ozone pretreatment ALD cycling began as follows: the first step of the cycle was a 0.2 s pulse of the Orthrus precursor into the vacuum chamber without any active pumping. The precursor remained in the chamber to react for 90 seconds and was then purged out with high nitrogen flow and pumping for 65 seconds. Once the chamber was purged, ozone (˜100 mg/L concentration) was dosed into the chamber for 0.2 seconds with no active pumping. The ozone remained in the chamber to react for 300 seconds and was purged away with high nitrogen flow and active pumping for 75 seconds. This sequence was repeated for approximately 225 cycles, resulting in 50-55 nm of film deposition on the substrates, as measured by ellipsometry on silicon wafer samples. Note the long exposure time for ozone was used to maximize the combustion reaction of the growing surface, which can be difficult at these relatively low temperatures, resulting in a better SiO2 film.
Once the SiO2 film deposition was completed, a final ozone activation step was performed to ensure the SiO2 film was fully reacted and maximized the hydrophilicity of the final film. This was done by dosing ozone for a 0.2 second pulse without active pumping and held for 5 minutes. After purging for 20 seconds, these steps were repeated for 24 or more cycles totaling 120 or more minutes of ozone exposure. The full recipe took approximately 48 hours to complete.
After the deposition process, sample substrates of silicon run alongside the spray chambers during the deposition were used to test the SiO2 deposited film thickness using ellipsometry. These substrates along with sample plastic coupons were also used to test the hydrophilicity of the final film using water contact angle (WCA) measurement, as shown in
Preliminary experiments of SiO2 coated PET spray chambers with ICP-OES have shown the sensitivity, precision, and washout tests were within a passing metric when the spray chambers were cleaned in a 2% RBS-25 solution.
As noted, the experiments in
The durability of the SiO2 coated spray chambers against strong acid (ICP-OES solvent) and cleaning solution is a metric for users. Two separate tests were developed to evaluate the adhesion, cracking, and hydrophilicity of the SiO2 coating of the film after exposure to acidic conditions similar to the ICP-OES environment as well as cleaning solutions that could be used to reactivate the initial working conditions of the spray chambers.
The durability test was done using PET coupon samples that were ALD SiO2 coated alongside the PET spray chambers. The PET coupons allowed for easier optical microscopy to evaluate the stability of the coating. In these experiments, PET coupons were submerged into a solution of 5% HNO3 or 20% aqua regia with light stirring. Samples were stirred in the solution for a given number of days then taken out and cleaned for 90+ minutes in either 5% Extran MA02 or 15% Citranox solutions before optical microscopy imaging. Shown in
SiO2 coated PET spray chambers were tested using ICP-OES spraying parameters by nebulizing 5% HNO3 (1.0 mL/min) into the spray chamber from a peristaltic pump along with house N2 (0.7 L/min). The spray chamber was placed at the bottom of an acid drain sink and blue food-colored water went through for a visual analysis of water beading on the spray chamber inner surface. For safety concerns, the spray chamber was covered with a beaker to trap the nebulized droplets from escaping the sink, and the sink was completely covered with a transparent acrylic cover when not being inspected.
Using this spray chamber setup, long-term testing was done in conditions similar to real use. After spraying 5% HNO3 for several days through the nebulizer and SiO2 coated PET spray chamber setup, visual inspection of water beading done by temporarily switching to a blue colored water solution. The results are shown in
From the foregoing description, those skilled in the art can appreciate that the present teachings can be implemented in a variety of forms. Therefore, while these teachings have been described in connection with particular embodiments and examples thereof, the true scope of the present teachings should not be so limited. Various changes and modifications can be made without departing from the scope of the teachings herein.
This scope disclosure is to be broadly construed. It is intended that this disclosure disclose equivalents, means, systems and methods to achieve the devices, activities and mechanical actions disclosed herein. For each device, article, method, mean, mechanical element or mechanism disclosed, it is intended that this disclosure also encompass in its disclosure and teaches equivalents, means, systems and methods for practicing the many aspects, mechanisms and devices disclosed herein. The claims of this application are likewise to be broadly construed. The description of the inventions herein in their many embodiments is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.
The present application claims priority to U.S. Provisional Application No. 63/350,800, filed Jun. 9, 2022, the entire disclosure of which is hereby incorporated by reference.
Number | Date | Country | |
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63350800 | Jun 2022 | US |