Polymeric parts with low molecular weight poly-olefin melt additives having ultra low retention of fluids

Abstract

Disclosed herein are non-fluorinated polymer compositions including, based on the total weight of the polymer composition, greater than or equal to 0.1 wt.% and less than or equal to 20 wt.% of a low molecular weight polyolefin, the low molecular weight polyolefin being selected from a paraffin wax having a molecular weight at a value or in a range between 300 g / mol and 550 g / mol, an ultra-low molecular weight polyethylene having a molecular weight at a value or in a range between 300 g / mol and 5,000 g / mol, and a combination thereof. The polymer composition further comprises a thermoplastic polymer. The polymeric compositions may further be non-silicone compositions. Articles formed from the polymer compositions may have low fluid retention, low haze, or a combination thereof.

Description

POLYMERIC PARTS WITH LOW MOLECULAR WEIGHT POLY-OLEFIN MELT ADDITIVES HAVING ULTRA LOW RETENTION OF FLUIDSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority under 35 U.S.C. §119 of U.S. Provisional Application Serial No. 63 / 769,712 filed on March 10, 2025, U.S. Provisional Application Serial No. 63 / 650,679 filed on May 22, 2024, U.S. Provisional Application Serial No. 63 / 769,721 filed on March 10, 2025, U.S. Provisional Application Serial No. 63 / 566,611 filed on March 18, 2024, U.S. Provisional Application Serial No. 63 / 710,186 filed on October 22, 2024, and U.S. Provisional Application Serial No. 63 / 702,451 filed on October 2, 2024, the contents of each of which are relied upon and are incorporated herein by reference in their entireties.BACKGROUNDField

[0002] The present specification generally relates to non-fluorinated polymer compositions and, in particular, to non-fluorinated polymer compositions that form articles having low fluid retention.Technical Background

[0003] Polymeric parts having low fluid retention surfaces may have various applications, such as pipette tips, cell culture ware, assay plates, and liquid handling vessels, among other examples. Conventionally, fluorinated compounds or silicone compounds may be added to polymer compositions to reduce fluid retention. However, the use of fluorinated compounds may lead to increased manufacturing times, due to slow surface development of the fluorinated compound. Moreover, the use of fluorinated compounds in polymeric parts or polymeric articles is believed to have a negative impact on the environment. Silicone compounds have transparency problems, leaching problems, and solvent-resistance problems. Therefore, a continuing need exists for non-fluorinated, non-silicone polymer compositions for use in forming articles that have reduced fluid retention properties, while in some instances having similar transparency to existing fluorinated polymer compositions.SUMMARY

[0004] The present disclosure provides non-fluorinated polymeric compositions and articles formed from such compositions that have low retention properties. In some aspects of the present disclosure, some polymeric compositions and articles may further be substantially free of or free of silicone. The present disclosure further provides non-fluorinated polymeric compositions and articles that have similar transparency to articles formed from conventional fluorinated polymeric compositions available in the market and / or that are resistant to polar solvents.

[0005] Aspect 1. A first aspect is an article that comprises a low molecular weight polyolefin and a thermoplastic polymer. The low molecular weight polyolefin is present in an amount between 0.1 wt.% and 20 wt.% based on the total weight of the article and the low molecular weight polyolefin is selected from a paraffin wax additive having a molecular weight between 300 g / mol and 5,000 g / mol, an ultra-low molecular weight polyethylene additive having a molecular weight between 300 g / mol and 550 g / mol, and a combination thereof. The article is substantially free of fluorine and has low fluid retention.

[0006] Aspect 2. The article of Aspect 1, wherein the article further comprises a low haze.

[0007] Aspect 3. The article of any one of Aspects 1-2, wherein the molecular weight of the paraffin wax is greater than or equal to 300 g / mol and less than or equal to 450 g / mol and the ultra-low molecular weight polyethylene comprises a molecular weight between 500 g / mol and 3,500 g / mol.

[0008] Aspect 4. The article of any one of Aspects 1-3, wherein the article comprises, based on the total weight of the article, greater than or equal to 0.2 wt.% and less than or equal to 15 wt.% of the low molecular weight polyolefin.

[0009] Aspect 5. The article of any one of Aspects 1-4 further comprising, based on the total weight of the article, greater than 0 wt.% and less than or equal to 6 wt.% of one or more additives other than the paraffin wax or the ultra-low molecular weight polyethylene.

[0010] Aspect 6. The article of Aspect 5, wherein the one or more additives other than the paraffin wax or the ultra-low molecular weight polyethylene comprise an antioxidant, a clarifyingagent, a nucleating agent, an antistatic agent, a colorant, a radiation stability agent, and a conductive agent, or a combination thereof.

[0011] Aspect 7. The article of any one of Aspects 1-6, wherein the article comprises, based on the total weight of the polymer composition, greater than or equal to 74 wt.% and less than or equal to 99.9 wt.% of the thermoplastic polymer.

[0012] Aspect 8. The article of any one of Aspects 1-7, wherein the thermoplastic polymer comprises polypropylene, polystyrene, polymethylmethacrylate, polyvinyl chloride, polycarbonate, polysulfone, polyester, polyamide, polystyrene butadiene copolymers, hydrogenated styrenic polymers, polyurethanes, polyethylene, polymethyl pentene, polylactic acid, polybutylene succinate, polyhydroxyalkanoate, or a combination thereof.

[0013] Aspect 9. The article of Aspect 8, wherein the thermoplastic polymer comprises polypropylene or polystyrene, or a combination thereof.

[0014] Aspect 10. The article of any one Aspects 1-9, wherein the article is substantially free of silicone.

[0015] Aspect 11. The article of any one of Aspects 1-10, wherein the article is free of fluorine.

[0016] Aspect 12. The article of any one of Aspects 1-11, wherein the article is free of fluorine and silicone.

[0017] Aspect 13. The article of any one of Aspects 1-12, wherein the article comprises a first major surface and a second major surface opposite the first major surface, wherein a concentration of the low molecular weight polyolefin at the first major surface is greater than a concentration of the low molecular weight polyolefin at an approximate midpoint between the first major surface and the second major surface.

[0018] Aspect 14. The article of any one of Aspects 1-13, wherein the article comprises a pipet, a pipette tip, an assay plate, a well plate, a cell culture dish, a liquid storage vessel, a tube, a liquid receptacle, a vent filter, or a laboratory consumable.

[0019] Aspect 15. The article of any one of Aspects 1-14, wherein the article comprises a pipette tip.

[0020] Aspect 16. The article of Aspect 15, wherein the article comprises a level of fluid retention less than or equal to Level 3 as measured by a visual level of fluid retention scale.

[0021] Aspect 17. The article of Aspect 15, wherein the article comprises an amount of fluid retention of less than or equal to 6 mg per 200 pL of fluid volume in a 200 pL pipette tip after a single aspirate / dispense cycle, as measured by gravimetric testing.

[0022] Aspect 18. The article of any one of Aspects 1-17, wherein the article retains less than or equal to 3% of fluid added to the article and then dispensed.

[0023] Aspect 19. The article of any one of Aspects 1-18, wherein the article is a sterilized article.

[0024] Aspect 20. The article of any one of Aspects 1-19, wherein the article comprises a sliding angle between 5 degrees and 17 degrees.

[0025] Aspect 21. The article of any one Aspects 1-19, wherein the article comprises a water contact angle between 85 degrees and 125 degrees.

[0026] Aspect 22. A twenty-second aspect is a method of forming an article, comprising the steps of: (a) solidifying a polymer composition within a mold to form the article, and (b) removing the article from the mold. The polymer composition comprises: a low molecular weight polyolefin in a total amount at a value between 0.1 wt.% and 20 wt.%, and a thermoplastic polymer. The low molecular weight polyolefin is selected from a paraffin wax having a molecular weight between 300 g / mol and 550 g / mol, an ultra-low molecular weight polyethylene wax having a molecular weight between 300 g / mol and 5,000 g / mol, and a combination thereof. The polymer composition is substantially free of fluorine.

[0027] Aspect 23. The method of Aspect 22, wherein the polymer composition is substantially free of silicone.

[0028] Aspect 24. The method of any one of Aspects 22-23, the method further comprising injecting the polymer composition into the mold.

[0029] Aspect 25. The method of any one of Aspects 22-24, the method further comprising sterilizing the article with irradiation at a dosage between 10 kGy and 50 kGy, after removing the article from the mold.

[0030] Aspect 26. The method of Aspect 25, wherein after sterilizing the article, the article comprises a level of fluid retention of less than or equal to a Level 3, as measured with a visual level of fluid retention scale.

[0031] Aspect 27. The method of Aspect 25, wherein after sterilizing the article, the article comprises an amount of fluid retention of less than or equal to 6 mg per 200 pL of fluid volume in a 200 pL pipette tip after a single aspirate / dispense cycle, as measured by gravimetric testing.

[0032] Aspect 28. The method of Aspect 25, wherein after sterilizing the article, the article retains less than or equal to 3% of fluid added to the article and then dispensed.

[0033] Aspect 29. A twenty-ninth aspect is a non-fluorinated article, comprising a thermoplastic polymer and either a paraffin wax, an ultra-low molecular weight polyethylene, or a combination thereof. The non-fluorinated article comprises a fluid retention of less than or equal to 3% of any fluid added and then dispensed, and the non-fluorinated article is substantially free of fluorine.

[0034] Aspect 30. The non-fluorinated article of Aspect 29, wherein the non-fluorinated article is substantially free of silicone.

[0035] Aspect 31. The non-fluorinated article of any one of Aspects 29-30, wherein the non-fluorinated article further comprises low haze.

[0036] Aspect 32. The non-fluorinated article of any one of Aspects 29-31, wherein the article comprises greater than or equal to 0.1 wt.% and less than or equal to 20 wt.% of a paraffin wax, a low-molecular weight polyethylene, or a combination thereof, based on the total weight of the article.

[0037] Aspect 33. The non-fluorinated article of any one of Aspects 29-32, wherein the paraffin wax comprises a molecular weight greater than or equal to 300 g / mol and less than or equal to 550 g / mol and the ultra-low molecular weight polyethylene comprises a molecular weight greater than or equal to 300 g / mol and less than or equal to 5,000 g / mol.

[0038] Aspect 34. The non-fluorinated article of any one of Aspects 29 to 33, wherein the article has a sliding angle between 5 degrees and 17 degrees.

[0039] Aspect 35. The non-fluorinated article of any one of Aspects 29-34, wherein the article comprises, based on the total weight of the article, greater than or equal to 74 wt.% and less than or equal to 99.9 wt.% of a thermoplastic polymer.

[0040] Aspect 36. The non-fluorinated article of Aspect 35, wherein the thermoplastic polymer comprises polypropylene, polystyrene, polymethylmethacrylate, polyvinyl chloride, polycarbonate, polysulfone, polyester, polyamide, polystyrene butadiene copolymers, hydrogenated styrenic polymers, polyurethanes, polyethylene, polymethyl pentene, polylactic acid, polybutylene succinate, polyhydroxyalkanoate, or a combination thereof.

[0041] Aspect 37. The non-fluorinated article of any one of Aspects 29-36, wherein the article comprises a pipet, pipette tip, an assay plate, a well plate, a cell culture dish, a liquid storage vessel, a tube, a liquid receptacle, a vent filter, or a laboratory consumable.

[0042] Aspect 38. The non-fluorinated article of Aspect 37, wherein the article comprises a pipette tip.

[0043] Aspect 39. A thirty-ninth aspect is an article comprising: low molecular weight polyolefin an amount between 0.1 wt.% and 20 wt.% based on the total weight of the article, and a thermoplastic polymer. The low molecular weight polyolefin is selected from paraffin wax having a molecular weight between 300 g / mol and 550 g / mol, an ultra-low molecular weight polyethylene having a molecular weight between 300 g / mol and 5,000 g / mol, and a combination thereof. The article comprises a first major surface and a second major surface opposite the first major surface, wherein a concentration of the low molecular weight polyolefin at the first major surface is greater than a concentration of the low molecular weight polyolefin at an approximatemidpoint between the first major surface and the second major surface. The article is also a pipette tip and has low fluid retention.

[0044] Aspect 40. The article of Aspect 39, wherein the low fluid retention is a low percentage of fluid retention that is less than or equal to 3% of a fluid volume aspirated into the article and then dispensed.

[0045] Aspect 41. The article of Aspect 39, wherein the low fluid retention is a low level of fluid retention that is less than or equal to a Level 3 as measured by a visual level of fluid retention scale.

[0046] Aspect 42. The article of Aspect 39, wherein the low fluid retention is a low amount of fluid retention that is less than or equal to 6 mg per 200 pL of fluid volume in a 200 pL pipette tip after a single aspirate / dispense cycle, as measured by gravimetric testing.

[0047] It is to be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the various embodiments, and are incorporated into and constitute a part of this specification. The drawings illustrate the various embodiments described herein, and together with the description serve to explain the principles and operations of the claimed subject matter.BRIEF DESCRIPTION OF THE DRAWINGS

[0048] FIG. 1 is a schematic of an article comprising a polymer composition, according to one or more embodiments of the present disclosure.

[0049] FIG. 2 is a photographic scale of levels of fluid retention in articles formed into pipette tips from polymeric compositions, according to one or more embodiments of the present disclosure.

[0050] FIG. 3 is a photographic scale of levels of haze identified in articles made from polymeric compositions, according to one or more embodiments of the present disclosure.

[0051] FIG. 4A is a photograph of the fluid retention in eight pipette tips formed from 100 wt.% polypropylene TP1, according to one or more embodiments of the present disclosure.

[0052] FIG. 4B is a photograph of the fluid retention in eight pipette tips formed from 99.5 wt.% polypropylene TP1 and 0.5 wt.% paraffin wax (PW), according to one or more embodiments of the present disclosure.

[0053] FIG. 4C is a photograph of the fluid retention in eight pipette tips formed from 99 wt.% polypropylene TP1 and 1 wt.% paraffin wax (PW), according to one or more embodiments of the present disclosure.

[0054] FIG. 4D is a photograph of the fluid retention in eight pipette tips formed from 98 wt.% polypropylene TP1 and 2 wt.% paraffin wax (PW), according to one or more embodiments of the present disclosure.

[0055] FIG. 5A is a photograph of the fluid retention in eight pipette tips formed from 100 wt.% polypropylene TP2, according to one or more embodiments of the present disclosure.

[0056] FIG. 5B is a photograph of the fluid retention in eight pipette tips formed from 98 wt.% polypropylene TP2 and 2 wt.% of a fluorinated additive, according to one or more embodiments of the present disclosure.

[0057] FIG. 5C is a photograph of the fluid retention in eight pipette tips formed from 99.5 wt.% polypropylene TP2 and 0.5 wt.% paraffin wax (PW), according to one or more embodiments of the present disclosure.

[0058] FIG. 5D is a photograph of the fluid retention in eight pipette tips formed from 99 wt.% polypropylene TP2 and 1 wt.% paraffin wax (PW), according to one or more embodiments of the present disclosure.

[0059] FIG. 5E is a photograph of the fluid retention in eight pipette tips formed from 98 wt.% polypropylene TP2 and 2 wt.% paraffin wax (PW), according to one or more embodiments of the present disclosure.

[0060] FIG. 6A is a photograph of the fluid retention in eight pipette tips formed from 98 wt.% polypropylene TP1 and 2 wt.% paraffin wax (PW), according to one or more embodiments of the present disclosure.

[0061] FIG. 6B is a photograph of the fluid retention in eight pipette tips formed from 98 wt.% polypropylene TP2 and 2 wt.% paraffin wax (PW), according to one or more embodiments of the present disclosure.

[0062] FIG. 6C is a photograph of the fluid retention in eight pipette tips formed from 98 wt.% polypropylene TP3 and 2 wt.% paraffin wax (PW), according to one or more embodiments of the present disclosure.

[0063] FIG. 6D is a is a photograph of the fluid retention in eight pipette tips formed from 98 wt.% polypropylene TP4 and 2 wt.% paraffin wax (PW), according to one or more embodiments of the present disclosure.

[0064] FIG. 7A are photographs of the fluid retention in eight pipette tips formed from 98 wt.% polypropylene TP1 and 2 wt.% paraffin wax post-molding (left photo) and after gamma irradiation with a 20 kGy irradiation dosage and then 14 days in an oven at 55° C (right photo), according to one or more embodiments of the present disclosure.

[0065] FIG. 7B are photographs of the fluid retention in eight pipette tips formed from 98 wt.% polypropylene TP3 and 2 wt.% paraffin wax post-molding (left photo) and after gamma irradiation with a 20 kGy irradiation dosage and then 14 days in an oven at 55° C (right photo), according to one or more embodiments of the present disclosure.

[0066] FIG. 8A is a photograph of the fluid retention in eight pipette tips formed from 100 wt.% polypropylene TP1, according to one or more embodiments of the present disclosure.

[0067] FIG. 8B is a photograph of the fluid retention in eight pipette tips formed from 98 wt.% polypropylene TP1 and 2 wt.% of paraffin wax (PW), according to one or more embodiments of the present disclosure.

[0068] FIG. 8C is a photograph of the fluid retention in eight pipette tips formed from 98 wt.% polypropylene TP1 and 2 wt.% of polyethylene wax PEI, according to one or more embodiments of the present disclosure.

[0069] FIG. 8D is a photograph of the fluid retention in eight pipette tips formed from 98 wt.% polypropylene TP1 and 2 wt.% of polyethylene wax PE2, according to one or more embodiments of the present disclosure.DETAILED DESCRIPTION

[0070] The various aspects and embodiments will now be fully described herein. These aspects and embodiments may, however, be embodied in many different forms and should not be construed as limiting; rather, these embodiments are provided so the disclosure will be thorough and complete, and will fully convey the scope of the present subject matter to those skilled in the art. All publications, patents and patent applications cited herein, whether supra or infra, are hereby incorporated by reference in their entirety.

[0071] Modifications of the disclosure will occur to those skilled in the art and to those who make or use the disclosure. Therefore, it is understood that the embodiments shown in the drawings and described above are merely for illustrative purposes and not intended to limit the scope of the disclosure, which is defined by the following claims, as interpreted according to the principles of patent law, including the doctrine of equivalents.A. Definitions

[0072] Unless defined otherwise, all terms and phrases used herein include the meanings that the terms and phrases have attained in the art, unless the contrary is clearly indicated or clearly apparent from the context in which the term or phrase is used. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, particular methods and materials are now described.

[0073] Unless otherwise stated, the use of individual numerical values are stated as approximations as though the values were preceded by the word “about” or “approximately.” Similarly, the numerical values in the various ranges specified in this application, unless expresslyindicated otherwise, are stated as approximations as though the minimum and maximum values within the stated ranges were both preceded by the word “about” or “approximately.” In this manner, variations above and below the stated ranges can be used to achieve substantially the same results as values within the ranges. As used herein, the terms “about” and “approximately” when referring to a numerical value shall have their plain and ordinary meanings to a person of ordinary skill in the art to which the disclosed subject matter is most closely related or the art relevant to the range or element at issue. The amount of broadening from the strict numerical boundary depends upon many factors. For example, some of the factors which may be considered include the criticality of the element and / or the effect a given amount of variation will have on the performance of the claimed subject matter, as well as other considerations known to those of skill in the art. As used herein, the use of differing amounts of significant digits for different numerical values is not meant to limit how the use of the words “about” or “approximately” will serve to broaden a particular numerical value or range. Thus, as a general matter, “about” or “approximately” broaden the numerical value. Also, the disclosure of ranges is intended as a continuous range including every value between the minimum and maximum values plus the broadening of the range afforded by the use of the term “about” or “approximately.” Consequently, recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, and each separate value is incorporated into the specification as if it were individually recited herein.

[0074] As used herein, the term “and / or,” when used in a list of two or more items, means that any one of the listed items can be employed by itself, or any combination of two or more of the listed items can be employed. For example, if a composition is described as containing components A, B, and / or C, the composition can contain A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B, and C in combination.

[0075] As used herein, “has,” “have,” “having,” “include,” “including,” “comprise,” “comprising” or the like are used in their open-ended sense, and generally mean “including, but not limited to.”

[0076] “Optional” or “optionally” means that the subsequently described element, component or circumstance may or may not occur, so that the description includes instances where the element, component, or circumstance occurs and instances where it does not.

[0077] As used herein the terms “the,” “a,” or “an,” mean “at least one,” and should not be limited to “only one” unless explicitly indicated to the contrary. Thus, for example, reference to “a component” includes embodiments having two or more such components unless the context clearly indicates otherwise.

[0078] The term “substantially free,” when used to describe the amount and / or absence of a particular component in a composition and the resultant article, means that the component is not intentionally added to the composition and the resultant article. However, the composition and the resultant article may contain traces of the component as a contaminant or trace amounts of less than 0.05 weight percent (wt.%).

[0079] The term “free,” when used to describe the amount and / or absence of a particular component in a composition and the resultant articles, means that the component is not present in the article.

[0080] In this document, relational terms, such as first and second, top and bottom, and the like, are used solely to distinguish one entity or action from another entity or action, without necessarily requiring or implying any actual such relationship or order between such entities or actions.

[0081] All scientific and technical terms used herein have meanings commonly used in the art unless otherwise specified. The definitions provided herein are to facilitate understanding of certain terms used frequently herein and are not meant to limit the scope of the present disclosure.B. Introduction

[0082] Commercially available low fluid retention polymer parts, such as pipette tips and PCR tubes widely employ fluorinated melt additives and, in some cases, polydimethylsiloxane (PDMS) silicones to create low fluid retention surfaces in laboratory plasticwares. However, fluoromolecules are the subject of increasing regulation in US and Europe. PDMS-based materials oftenhave poor solvent resistance, teachability (contamination of biological fluids) and poor miscibility with polyolefins, and they produce hazy (non-transparent) parts. Hence, there is a need for alternative polymeric compositions that have low fluid retention and are transparent without the problems encountered with currently available formulations.

[0083] Although the resin industry has been trying to solve the problem of a non-fluorinated polymeric composition that produces polymeric parts or articles with low fluid retention and low haze, the industry has been unable to find a solution. The present disclosure provides a solution in the form of a non-fluorinated polyolefin composition that comprises a low molecular weight polyolefin, which provides excellent low fluid retention along with sufficient clarity (transparency) to be useful to a number of applications, including applications with biological matter.Polymeric Compositions

[0084] Polymeric compositions that are substantially free of fluorine are provided from which polymeric parts (articles) may be formed that have low fluid retention properties. The polymer compositions of the present disclosure comprise a thermoplastic polymer and a nonfluorinated ultra-low molecular weight polyethylene additive, a non-fluorinated paraffin wax additive, or a combination thereof. Both ultra-low molecular weight polyethylene and paraffin wax additives are low molecular weight poly-olefins. However, paraffin wax is derived from crude oil whereas the ultra-low molecular weight polyethylene is formed from polymerization of ethylene. The polymer composition may be further be substantially free of or free of silicone.

[0085] Embodiments of the polymer compositions described herein may comprise, based on a total weight of the polymer composition, greater than or equal to 0.1 wt.% and less than or equal to 20 wt.% of a low molecular weight polyolefin, wherein the low molecular weight polyolefin is an ultra-low molecular weight polyethylene additive, a paraffin wax additive, or a combination thereof. When a combination of an ultra-low molecular weight polyethylene and paraffin wax is used, the maximum total weight of the two components together is greater than or equal to 1 wt.% and less than or equal to 20 wt.% based on the total weight of the polymer composition. It should also be understood that the polymer composition may comprise an ultralow molecular weight polyethylene additive, a paraffin wax additive, or a combination thereof may be at any value or in any range between 0.1% wt.% and 20 wt.%, based on the total weight of thepolymer composition. For example, without limitation, the polymer compositions may comprise a low molecular weight polyolefin that is an ultra-low molecular weight polyethylene additive, a paraffin wax additive, or a combination thereof in an amount, in an amount based on the total weight of the polymer composition of greater than or equal to 0.1 wt.% and less than or equal to 20 wt.%, greater than or equal to 0.25 wt.% and less than or equal to 20 wt.%, greater than or equal to 1 wt.% and less than or equal to 20 wt.%, greater than or equal to 3 wt.% and less than or equal to 20 wt.%, greater than or equal to 5 wt.% and less than or equal to 20 wt.%, greater than or equal to 7 wt.% and less than or equal to 20 wt.%, greater than or equal to 9 wt.% and less than or equal to 20 wt.%, greater than or equal to 11 wt.% and less than or equal to 20 wt.%, greater than or equal to 13 wt.% and less than or equal to 20 wt.%, greater than or equal to 15 wt.% and less than or equal to 20 wt.%, greater than or equal to 17 wt.% and less than or equal to 20 wt.%, greater than or equal to 19 wt.% and less than or equal to 20 wt.%, greater than or equal to 0.1 wt.% and less than or equal to 18 wt.%, greater than or equal to 0.1 wt.% and less than or equal to 16 wt.%, greater than or equal to 0.1 wt.% and less than or equal to 14 wt.%, greater than or equal to 0.1 wt.% and less than or equal to 12 wt.%, greater than or equal to 0.1 wt.% and less than or equal to 10 wt.%, greater than or equal to 0.1 wt.% and less than or equal to 8 wt.%, greater than or equal to 0.1 wt.% and less than or equal to 6 wt.%, greater than or equal to 0.1 wt.% and less than or equal to 4 wt.%, greater than or equal to 0.1 wt.% and less than or equal to 2 wt.%, greater than or equal to 0.1 wt.% and less than or equal to 1 wt.%, or at any value or in any range or combination of ranges formed from these endpoints. In some embodiments, the polymer composition may comprise greater than or equal to 0.25 wt.% and less than or equal to 5 wt.% of an ultra-low molecular weight polyethylene additive, a paraffin wax additive, or a combination thereof. In some embodiments, the polymer composition may comprise greater than or equal to 1 wt.% and less than or equal to 7 wt.% of an ultra-low molecular weight polyethylene additive, a paraffin wax additive, or a combination thereof. In one embodiment, the polymer composition may comprise greater than or equal to 0.4 wt.% and less than or equal to 5 wt.% of an ultra-low molecular weight polyethylene additive, a paraffin wax additive, or a combination thereof.

[0086] If the amount of ultra-low molecular weight polyethylene additive or paraffin wax additive in the polymer composition is too low, for example less than 0.1 wt.%, then articles formed from the polymer composition may not exhibit the desired low fluid retention properties. Additionally, minimizing the amount of the ultra-low molecular weight polyolefin additive and / orparaffin wax additive, such as in amounts less than or equal to 20 wt.%, may be cost effective. If the amount of ultra-low molecular weight polyethylene additive or paraffin wax additive in the polymer composition is too high, the articles formed from the polymer composition may have decreased mechanical strength, which is undesired. Further, if the amount of ultra-low molecular weight polyethylene additive or paraffin wax additive in the polymer composition is too high, the articles formed from the polymer composition may experience decreased friction causing low grip strength, which is undesirable for articles that need to be attached to devices (for example, pipette tips with low grip strength will not stay attached to a pipettor).

[0087] According to embodiments, the ultra-low molecular weight polyethylene may have a molecular weight greater than or equal to 300 g / mol and less than or equal to 5,000 g / mol. As used herein, “molecular weight” refers to weight average molecular weight. In some embodiments, the ultra-low molecular weight polyethylene may have a molecular weight greater than or equal to 300 g / mol and less than or equal to 4,500 g / mol, greater than or equal to 300 g / mol and less than or equal to 4,000 g / mol, greater than or equal to 300 g / mol and less than or equal to 3,500 g / mol, greater than or equal to 300 g / mol and less than or equal to 3,000 g / mol, greater than or equal to 300 g / mol and less than or equal to 2,500 g / mol, greater than or equal to 300 g / mol and less than or equal to 2,000 g / mol, greater than or equal to 300 g / mol and less than or equal to 1,500 g / mol, greater than or equal to 300 g / mol and less than or equal to 1,000 g / mol, greater than or equal to 500 g / mol and less than or equal to 5,000 g / mol, greater than or equal to 1,000 g / mol and less than or equal to 5,000 g / mol, greater than or equal to 1,500 g / mol and less than or equal to 5,000 g / mol, greater than or equal to 2,000 g / mol and less than or equal to 5,000 g / mol, greater than or equal to 2,500 g / mol and less than or equal to 5,000 g / mol, greater than or equal to 3,000 g / mol and less than or equal to 5,000 g / mol, greater than or equal to 3,500 g / mol and less than or equal to 5,000 g / mol, greater than or equal to 4,000 g / mol and less than or equal to 5,000 g / mol, greater than or equal to 4,500 g / mol and less than or equal to 5,000 g / mol, greater than or equal to 500 g / mol and less than or equal to 3,500 g / mol, or in any other range or at any value between 300 g / mol and 5,000 g / mol. In one specific embodiment, the ultra-low molecular weight polyethylene may have a molecular weight greater than or equal to 750 g / mol and less than or equal to 3,000 g / mol.

[0088] In one or more embodiments, the ultra-low molecular weight polyethylene may comprise between C21 and C357 carbon atoms, or at any value or in any range therebetween. Inembodiments, the ultra-low molecular weight polyethylene may comprise between C21 and C300 carbons, between C21 and C250 carbons, between C21 and C200 carbons, between C21 and C150 carbons, between C21 and C100 carbons, between C21 and C50 carbons, between C50 and C357 carbons, between C100 and C357 carbons, between C150 and C357 carbons, between C200 and C357 carbons, between C250 and C357 carbons, between C300 and C357 carbons, between C35 and C285 carbons, or between C35 and C215 carbons, or at any value or in any range between any of the foregoing ranges. For example, in one specific embodiment, the ultra-low molecular weight polyethylene may comprise between C35 and C250 carbons.

[0089] According to embodiments, the paraffin wax may have a molecular weight greater than or equal to 300 g / mol and less than or equal to 550 g / mol. In some embodiments, the paraffin wax may have a molecular weight greater than or equal to 300 g / mol and less than or equal to 500 g / mol, greater than or equal to 300 g / mol and less than or equal to 450 g / mol, greater than or equal to 300 g / mol and less than or equal to 400 g / mol, greater than or equal to 300 g / mol and less than or equal to 350 g / mol, greater than or equal to 350 g / mol and less than or equal to 550 g / mol, greater than or equal to 400 g / mol and less than or equal to 550 g / mol, greater than or equal to 450 g / mol and less than or equal to 550 g / mol, greater than or equal to 500 g / mol and less than or equal to 550 g / mol, or greater than or equal to 350 g / mol and less than or equal to 500 g / mol, or greater than or equal to 350 g / mol and less than or equal to 450 g / mol, or greater than or equal to 400 g / mol and less than or equal to 500 g / mol, or in any other range or at any value between 300 g / mol and 550 g / mol. In one specific embodiment, the paraffin wax may have a molecular weight greater than or equal to 300 g / mol and less than or equal to 475 g / mol.

[0090] In one or more embodiments, the paraffin wax may comprise between Ci6 and C35 carbons, or at any value or in any range therebetween. In embodiments, the paraffin wax may comprise between Ci6 and C30 carbons, between Ci6 and C25 carbons, between Ci6 and C20 carbons, between C20 and C35 carbons, between C25 and C35 carbons, between C30 and C35 carbons, between C17 and C34 carbons, or between C20 and C30 carbons, or at any value or in any range between the foregoing ranges. For example, in one specific embodiment, the paraffin wax may comprise between Cis and C32 carbons.

[0091] The size of the low molecular weight polyolefin may affect the properties of the low molecular weight polyolefin with the thermoplastic polymer used in the polymer composition. If the molecular weight of the low molecular weight polyolefin is too great, then the low molecular weight polyolefin may be too compatible with the thermoplastic polymer and may not migrate to the surface of the formed part.

[0092] The thermoplastic polymer included in the polymer compositions described herein is not necessarily limited. For example, the thermoplastic polymer may be selected based on the intended use of the article formed from the polymer composition. In embodiments, the thermoplastic polymer comprises polypropylene, polystyrene, polymethylmethacrylate, polyvinyl chloride, polycarbonate, polysulfone, polyester, polyamide, polystyrene butadiene copolymers, hydrogenated styrene polymers, polyurethanes, polyethylene, polymethyl pentene, polylactic acid, polybutylene succinate, polyhydroxyalkanoates, or a combination thereof. In some embodiments, the thermoplastic polymer may comprise a propylene homopolymer or a propylene ethylene copolymer. In some embodiments, the thermoplastic polymer may comprise polypropylene. In some embodiments, the thermoplastic polymer is a bio-based polymer, such as polysaccharides, polylactide, polybutylene succinate, polyhydroxyalkanoates, and poly(dihydrofuran), among others known to those of ordinary skill in the art.

[0093] In some embodiments, the thermoplastic polymer may have a melt flow index (MFI), also known as melt flow rate, greater than or equal to 1 g / 10 min. and less than or equal to 100 g / 10 min. For example, the thermoplastic polymer may have a melt flow rate greater than or equal to 1 g / 10 min. and less than or equal to 100 g / 10 min., greater than or equal to 10 g / 10 min. and less than or equal to 100 g / 10 min., greater than or equal to 20 g / 10 min. and less than or equal to 100 g / 10 min., greater than or equal to 30 g / 10 min. and less than or equal to 100 g / 10 min., greater than or equal to 40 g / 10 min. and less than or equal to 100 g / 10 min., greater than or equal to 50 g / 10 min. and less than or equal to 100 g / 10 min., greater than or equal to 60 g / 10 min. and less than or equal to 100 g / 10 min., greater than or equal to 70 g / 10 min. and less than or equal to 100 g / 10 min., greater than or equal to 80 g / 10 min. and less than or equal to 100 g / 10 min., greater than or equal to 90 g / 10 min. and less than or equal to 100 g / 10 min., greater than or equal to 1 g / 10 min. and less than or equal to 90 g / 10 min., greater than or equal to 1 g / 10 min. and less than or equal to 80 g / 10 min., greater than or equal to 1 g / 10 min. and less than or equal to 70 g / 10 min.,greater than or equal to 1 g / 10 min. and less than or equal to 60 g / 10 min., greater than or equal to 1 g / 10 min. and less than or equal to 50 g / 10 min., greater than or equal to 1 g / 10 min. and less than or equal to 40 g / 10 min., greater than or equal to 1 g / 10 min. and less than or equal to 30 g / 10 min., greater than or equal to 1 g / 10 min. and less than or equal to 20 g / 10 min., greater than or equal to 1 g / 10 min. and less than or equal to 10 g / 10 min., or any range or combination of ranges formed from these endpoints. In one specific embodiment, the thermoplastic polymer may have a melt flow rate greater than or equal to 5 g / 10 min. and less than or equal to 40 g / 10 min. As described herein, “melt flow rate” may be measured according to ASTM D1238. Without intending to be bound by theory, polymers having melt flow rates greater than or equal to 1 g / 10 min. and less than or equal to 100 g / 10 min. may relatively easily fill parts having thin walls and long flow paths while maintaining desirable physical properties.

[0094] In embodiments, the polymer composition may comprise, based on the total weight of the polymer composition, greater than or equal to 74 wt.% and less than or equal to 99.9 wt.% of the thermoplastic polymer. For example, without limitation, the polymer composition may comprise thermoplastic polymer in an amount, based on the total weight of the polymer composition, greater than or equal to 74 wt.% and less than or equal to 99.9 wt.%, greater than or equal to 80 wt.% and less than or equal to 99.9 wt.%, greater than or equal to 85 wt.% and less than or equal to 99.9 wt.%, greater than or equal to 90 wt.% and less than or equal to 99.9 wt.%, greater than or equal to 95 wt.% and less than or equal to 99.9 wt.%, greater than or equal to 74 wt.% and less than or equal to 95 wt.%, greater than or equal to 74 wt.% and less than or equal to 90 wt.%, greater than or equal to 74 wt.% and less than or equal to 85 wt.%, greater than or equal to 74 wt.% and less than or equal to 80 wt.%, or any range or combination of ranges formed from these endpoints.

[0095] In some embodiments, the polymer composition with an ultra-low molecular weight polyethylene, a paraffin wax, or a combination thereof may further comprise one or more additional additives. The additional additives that may be included in the polymer composition are not necessarily limited. In embodiments, the additional additives may comprise antioxidants, clarifying agents, nucleating agents, antistatic agents, colorants, radiation stability agents, and conductive agents. Antioxidants may be included in the polymer composition to prevent degradation of the polymers. Some embodiments of the polymer composition include multipleantioxidants. Clarifying agents and nucleating agents may improve the clarity of articles formed from the polymer composition. Without intending to be bound by theory, clarifying agents and nucleating agents may initiate the growth of crystalline phases of crystalline polymers, such as polypropylene. Increasing the number of relatively small crystalline structures in the article may reduce the light scattered by the crystalline phases improving the clarity of articles formed from the polymer composition. Antistatic agents may reduce the resistivity of the polymer composition to provide static protection. Colorants may be included in the polymer composition to impart color to articles formed from the polymer composition. Suitable colorants may be selected for use in transparent, translucent, or opaque articles. Radiation stability agents may be included in the polymer composition to reduce the effects of irradiation on the polymer composition. For example, radiation stability agents may reduce discoloration, such as yellowing, that may occur in some polymer compositions. Radiation stability agents may also reduce the effect of radiation on the mechanical properties of articles formed from the polymer composition. Conductive agents may be included in the polymer composition to improve the electrical conductivity of the polymer composition. Conductive agents may include, for example, carbon black and carbon fibers. Some conductive agents, such as carbon black, may also impart color to the polymer composition and articles formed from the polymer composition.

[0096] In embodiments where the polymer composition further comprises one or more additives other than ultra-low molecular weight polyethylene or paraffin wax, the polymer composition may comprise, based on the total weight of the polymer composition, greater than 0 wt.% and less than or equal to 6 wt.% of the one or more of these additional additives. For example, the polymer composition may comprise the one or more additives other than ultra-low molecular weight polyethylene or paraffin wax in an amount greater than 0 wt.% and less than or equal to 6 wt.%, greater than or equal to 0.5 wt.% and less than or equal to 6 wt.%, greater than or equal to 1 wt.% and less than or equal to 6 wt.%, greater than or equal to 1.5 wt.% and less than or equal to 6 wt.%, greater than or equal to 2 wt.% and less than or equal to 6 wt.%, greater than or equal to 2.5 wt.% and less than or equal to 6 wt.%, greater than or equal to 3 wt.% and less than or equal to 6 wt.%, greater than or equal to 3.5 wt.% and less than or equal to 6 wt.%, greater than or equal to 4 wt.% and less than or equal to 6 wt.%, greater than or equal to 4.5 wt.% and less than or equal to 6 wt.%, greater than or equal to 5 wt.% and less than or equal to 6 wt.%, greater than or equal to 5.5 wt.% and less than or equal to 6 wt.%, greater than 0 wt.% and less than or equal to 5.5wt.%, greater than 0 wt.% and less than or equal to 5.0 wt.%, greater than 0 wt.% and less than or equal to 4.5 wt.%, greater than 0 wt.% and less than or equal to 4 wt.%, greater than 0 wt.% and less than or equal to 3.5 wt.%, greater than 0 wt.% and less than or equal to 3 wt.%, greater than 0 wt.% and less than or equal to 2.5 wt.%, greater than 0 wt.% and less than or equal to 2 wt.%, greater than 0 wt.% and less than or equal to 1.5 wt.%, greater than 0 wt.% and less than or equal to 1 wt.%, greater than 0 wt.% and less than or equal to 0.5 wt.%, or in any range or at any value that is greater than or equal to 0 wt.% and less than or equal to 6 wt.%. In embodiments, the polymer composition may be free or substantially free of additional additives.

[0097] In one or more embodiments, the polymer composition may be free or substantially free of fluorine. For example, the ultra-low molecular weight polyethylene, the paraffin wax, or a combination thereof, may be free from any moieties or functionalities comprising fluorine. Likewise, the thermoplastic polymer and / or any additional additives may be free from any moieties or functionalities comprising fluorine. In embodiments where the polymer composition comprises one or more additional additives, the additives may each be free or substantially free from fluorine. Without intending to be bound by theory, articles formed from polymer compositions that are free or substantially free of fluorine may have reduced manufacturing times relative to articles formed from polymer compositions comprising fluorinated compounds. Furthermore, fluorinated compound in articles formed from polymer compositions that are used to handle biological samples may contaminate the biological samples. Using polymer compositions that are free from fluorine to form such articles may reduce the likelihood of such samples being contaminated with fluorinated compounds. Additionally, in certain industries, it may be desirable to avoid fluorinated compounds due to their potential environmental impact.

[0098] In one or more embodiments, the polymer composition may be free or substantially free of silicone. For example, the ultra-low molecular weight polyethylene, the paraffin wax, or a combination thereof, may be free from any moieties or functionalities comprising silicone. Likewise, the thermoplastic polymer and / or any additives may be free from any moieties or functionalities comprising silicone. In embodiments where the polymer composition comprises one or more additives other than ultra-low molecular weight polyethylene or paraffin wax, these additional additives may each be free or substantially free from silicone.Articles Formed from the Polymeric Compositions

[0099] The polymeric parts (articles) formed from polymeric compositions of the present disclosure have low fluid retention surfaces and / or surfaces with low binding to biological matter. The articles comprising the polymer composition are not necessarily limited. They may have various applications for biological matter. In one or more embodiments, an article may comprise a pipette tip, a pipet (e.g., serological pipets and other transfer pipets), a tube such as polymerase chain reaction (“PCR”) tubes and centrifuge tubes, a tube rack, a storage vessel, a plate and / or well for cell culture (e.g., well plates for two-dimensional or three-dimensional cell cultures), an assay plate (e.g., PCR plates), a liquid handling vessel, a liquid storage vessel, a vent filters or other bioreactor components, a packaging container, or a laboratory consumable, among other examples. As described herein, a “laboratory consumable” refers to any item for laboratory use that is replaced regularly after it is used or after it wears down. In some embodiments, the article comprises a pipette tip, a PCR tube, a pipette rack, a pipet, a well plate, a plate, a vent filter, or a storage vessel.

[0100] Embodiments of the polymer compositions described herein may be used to form various articles. Such articles may comprise the polymer compositions previously described. In some embodiments, the articles may be formed from the polymer compositions. In some embodiments, the articles may consist essentially of the polymer composition.

[0101] Referring now to FIG. 1, an article 100 comprising a polymer composition as described herein may comprise a first major surface 110 and a second major surface 120. The second major surface 120 may be opposite the first major surface 110. It should be noted that the shape of the article is not necessarily limited to the structure depicted in FIG. 1. Articles comprising the polymer composition may have any suitable form or shape. For example, the polymer composition may be shaped to form any of the articles described hereinabove.

[0102] In one or more embodiments of an article made from the polymer compositions described herein, a concentration of the ultra-low molecular weight polyethylene, the paraffin wax, or a combination thereof at the first major surface 110 of article 100 may be greater than a concentration of the ultra-low molecular weight polyethylene, the paraffin wax, or a combination thereof at a midpoint 130 between the first major surface 110 and the second major surface 120 ofthe article 100. Likewise, in one or more embodiments, the concentration of the ultra-low molecular weight polyethylene, the paraffin wax, or a combination thereof at the second major surface 120 of the article 100 may be greater than a concentration of the ultra-low molecular weight polyethylene, the paraffin wax, or a combination thereof at the midpoint 130 between the first major surface 110 and the second major surface 120 of the article 100. This difference in concentration of the low molecular weight polyolefin between the surfaces of the article and the middle of the article may be achieved in several ways. For example, during manufacturing processes, the low molecular weight polyolefin may separate from the thermoplastic polymer and migrate to the surface (blooming) of the article formed from the polymer composition. Once the article is formed, the concentration of the low molecular weight polyolefin may be greater on the surface of the article. Without intending to be bound by theory, increasing the concentration of the low molecular weight polyolefin on the surface of an article may improve the fluid retention properties of the article; specifically, reducing the fluid retention of the article.

[0103] In one or more embodiments, a concentration of ultra-low molecular weight polyethylene or the paraffin wax at a depth from 0 nm to 10 nm from the first major surface 110 of the article 100 may be greater than its concentration at a midpoint 130 between the first major surface 110 and the second major surface 120 of the article 100. In such embodiments, the midpoint 130 between the first major surface 110 and the second major surface 120 is greater than 10 nm from the first major surface. In one or more embodiments, the concentration of the ultra-low molecular weight polyethylene or the paraffin wax at a depth from 0 nm to 10 nm from the first major surface 110 of the article 100 may be 2, 3, 5, 10, 15 or even 20 times greater than its concentration at a midpoint 130 between the first major surface 110 and the second major surface 120 of the article 100. Likewise, in one or more embodiments, the concentration of ultra-low molecular weight polyethylene or the paraffin wax at a depth from 0 nm to 10 nm from the second major surface 120 of the article 100 may be greater than its concentration at the midpoint 130 between the first major surface 110 and the second major surface 120 of the article 100. In such embodiments, the midpoint 130 between the first major surface 110 and the second major surface 120 is greater than 10 nm. In one or more embodiments, the concentration of ultra-low molecular weight polyethylene or the paraffin wax at a depth from 0 nm to 10 nm from the second major surface 120 of the article 100 may be 2, 3, 5, 10, 15 or even 20 times greater than its concentration at a midpoint 130 between the second major surface 120 and the second major surface 120 of thearticle 100. The concentration of ultra-low molecular weight polyethylene or the paraffin wax at a depth from 0 nm to 10 nm may be measured by x-ray photoelectron spectroscopy.

[0104] The article formed from the polymeric compositions described herein may have low fluid retention. An article that has “low fluid retention” as used herein is an article that has one or more of a low level, a low amount, or a low percentage of fluid retained in the article after aspirating and then dispensing a volume of fluid from the article. How levels of fluid retention, amounts of fluid retention, and percentages of fluid retention are determined along with what levels, amounts and percentages are considered “low” are now described in more detail.

[0105] Starting with a low level of fluid retention, an article formed from the polymeric compositions described herein may have a low level of fluid retention. The level of fluid retention of an article is determined by visual inspection with comparison to a standard. In one or more embodiments, the article may comprise a fluid retention level of less than or equal to a Level 3 on the below described fluid retention scale. As described herein, the “level of fluid retention” for an article in the form of a pipette tip is measured by the following method. A 200 pL pipette tip formed from a polymeric composition is attached to a manual pipettor. 200 pL of McCormick® green food coloring dye (or an equivalent) is drawn (aspirated) into the pipette tip. The dye is then dispensed from the pipette tip. Each round of aspirating and dispensing is considered an aspirate / dispense cycle. The pipette tip is then visually inspected against the fluid retention scale shown in FIG. 2 and assigned the level number it closest matches to. If the pipettor is a multichannel pipettor with multiple pipette tips being observed, and more than one level is present across the pipette tips, both levels are listed. For example, if the visual observation shows that with an 8-channel multi-channel pipettor shows that three tips match Level 1 and five tips match Level 2, the Level for that set of eight pipette tips is Level 1-2. An article that has a low level of fluid retention refers to an article having Level 3, Level 2, Level 1, Level 0, or a combination thereof, referring to the scale shown in FIG. 2.

[0106] It should be understood that the level of fluid retention of a pipette tip may be measured after any given aspirate / dispense cycle. In the Examples section of the present disclosure, the pipette tip is subjected to five aspirate / dispense cycles. The level of fluid retentionof a pipete tip may be measured after any one of the first, second, third, fourth, fifth, sixth, seventh, or any subsequent aspirate / dispense cycles.

[0107] Referring to FIG. 2, a Level 0 score is present when no visible fluid retention is present in the pipette tip and corresponds to no fluid retention in the tip. A Level 1 score is present when the total visible fluid retention in the pipete tip is less than or equal to 1 mm of fluid drag on the surface. As used herein, “fluid drag” refers to the length that a fluid droplet extends along a surface as measured by its greatest length. A Level 2 score is present when the total visible fluid retention in the pipete tip is greater than 1 mm and less than or equal to 2 mm. A Level 3 score is present when the total visible fluid retention in the pipette tip is greater than 2 mm and less than or equal to 4 mm. A Level 4 score is present when the total visible fluid retention in the pipete tip is greater than 4 mm and less than or equal to 5 mm. A Level 5 score is present when the total visible fluid retention in the pipete tip is greater than 5 mm.

[0108] An article having a low level of fluid retention has a level of fluid retention that is less than or equal to a Level 3 as measured by the visual level of fluid retention scale shown in FIG. 2. In some embodiments, the level of fluid retention of an article (including pipete tips) formed from the polymer compositions described herein may be less than or equal to Level 3, Level 2-3, Level 2, Level 1-2, or Level 1 after a single aspirating / dispensing cycle. In some embodiments, the level of fluid retention may be less than or equal to Level 3, Level 2-3, Level 2, Level 1-2, or Level 1 after two aspirating / dispensing cycles. In some embodiments, the level of fluid retention may be less than or equal to Level 3, Level 2-3, Level 2, Level 1-2, or Level 1 after two aspirating / dispensing cycles. In some embodiments, the level of fluid retention may be less than or equal to Level 3, Level 2-3, Level 2, Level 1-2, or Level 1 after three aspirating / dispensing cycles. In some embodiments, the level of fluid retention may be less than or equal to Level 3, Level 2-3, Level 2, Level 1-2, or Level 1 after a four aspirating / dispensing cycles. In some embodiments, the level of fluid retention may be less than or equal to Level 3, Level 2-3, Level 2, Level 1-2, or Level 1 after five aspirating / dispensing cycles.

[0109] As described herein, the “amount of fluid retention” for a pipette tip is measured by the following method using gravimetric testing. A solution may be formed by adding 50 wt.% of glycerol, 40 wt.% McCormick® green food dye (or equivalent), and 10 wt.% deionized water.An article formed from a polymer composition is weighed for mass using a mass balance scale having at least three decimal places and the measurement is recorded as the pre-cycle mass. The pipette tip is added to a pipettor and then a single cycle of drawing up the described solution (aspirating) and then dispensing it is performed. The pipette tip is then removed from the pipettor and re-weighed, and the measurement is recorded as the post-cycle mass. The pre-cycle mass is subtracted from the post-cycle mass and the difference in mass is the amount of fluid retained by the tip. Pipette tips formed from the polymer compositions described herein that have a gravimetric testing amount less than or equal to 6 mg per 200 pL volume of the described solution in a 200 pL pipette tip after a single aspirating dispensing cycle are considered to have a low amount of fluid retention.

[0110] In some embodiments, the amount of fluid retention in a 200 pL pipette tip formed from the polymer compositions described herein is less than or equal to 10 mg, 9 mg, 8 mg, 7 mg, 6 mg, 5 mg, 4 mg, 3 mg, 2 mg, 1.9 mg, 1.8 mg, 1.7 mg, 1.6 mg, 1.5 mg, 1.4 mg, 1.3 mg, 1.2 mg, 1.1 mg, 1.0 mg, 0.9 mg, 0.8 mg, 0.7 mg, 0.6 mg, 0.5 mg, 0.4 mg, 0.3 mg, 0.2 mg, or 0.1 mg per 200 pL volume of a solution comprising 50 wt.% of glycerol, 40 wt.% McCormick® green food dye (or equivalent), and 10 wt.% deionized water, after a single aspirate / dispense cycle, as measured with gravimetric testing. In one specific embodiment, the amount of fluid retention in a 200 pL pipette tip formed from the polymer compositions described herein is less than or equal to 6.0 mg per 200 pL of a solution comprising 50 wt.% of glycerol, 40 wt.% McCormick® green food dye (or equivalent), and 10 wt.% deionized water, after a single aspirating dispensing cycle, as measured with gravimetric testing.

[0111] The amount of fluid retention of an article comprising a polymer composition may be greater than 7% less than a similar article lacking the low molecular weight polyolefin that is an ultra-low molecular weight polyethylene, a paraffin wax, or a combination thereof. As described herein, a “similar article lacking the low molecular weight polyolefin” refers to an article that is identical to the article comprising the polymer composition in both structure and composition, except that any low-molecular weight polyethylene and paraffin content of the polymer composition is replaced with the thermoplastic polymer in the “similar article lacking the low molecular weight polyolefin.” In some embodiments, the amount of fluid retention of an article comprising the polymer composition described herein may be greater than 7%, 10%, 15%,20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, or even 85% less than a similar article lacking the low molecular weight polyolefin. In some embodiments, the amount of fluid retention of a pipette tip comprising the polymer composition described herein may be greater than 7%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, or even 85% less than a similar pipette tip lacking the low molecular weight polyolefin after the first aspirate / dispense cycle. In some embodiments, the amount of fluid retention of a pipette tip comprising the polymer composition described herein may be greater than 7%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, or even 85% less than a similar pipette tip lacking the low molecular weight polyolefin after the second aspirate / dispense cycle. In some embodiments, the amount of fluid retention of a pipette tip comprising the polymer composition described herein may be greater than 7%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, or even 85% less than a similar pipette tip lacking the low molecular weight polyolefin after the third aspirate / dispense cycle.

[0112] In some embodiments, an article formed from a polymeric composition comprising an ultra-low molecular weight polyethylene and / or a paraffin wax as described herein may retain less than or equal to 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.9%, 0.8%, 0.7%, 0.6%, 0.5%, 0.4%, 0.3%, 0.2%, 0.1%, or even less, of a fluid that is aspirated or added to the article and then dispensed (or decanted). In one embodiment, an article formed from a polymeric composition comprising an ultra-low molecular weight polyethylene and / or a paraffin wax as described herein may retain less than or equal to 10% of a fluid that is aspirated or added to the article and then dispensed (or decanted). In another embodiment, an article formed from a polymeric composition comprising an ultra-low molecular weight polyethylene and / or a paraffin wax as described herein may retain less than or equal to 5% of a fluid that is aspirated or added to the article and then dispensed (or decanted). In another embodiment, an article formed from a polymeric composition comprising an ultra-low molecular weight polyethylene and / or a paraffin wax as described herein may retain less than or equal to 1% of a fluid that is aspirated or added to the article and then dispensed (or decanted). In yet another embodiment, an article formed from a polymeric composition comprising an ultra-low molecular weight polyethylene and / or a paraffin wax as described herein may retain less than or equal to 0.5% of a fluid that is aspirated or added to the article and then dispensed (or decanted). An article having a low percentage of fluid retention retains less than or equal to about 3% of a fluid that is aspirated and then dispensed from the article.

[0113] The percentage of fluid retained in an article may be based on the amount of fluid retained by an article. When the article is a pipette tip, the amount of fluid retained in the pipette tip may be determined as described earlier. The total mass of the fluid aspirated into the pipette tip may be determined as follows. An empty 200 pL pipette tip may be weighed on a mass balance scale that has at least three decimal places and the resultant value for the mass is recorded as the mass of the empty pipette tip. Then, 200 pL of a solution comprising 50 wt.% of glycerol, 40 wt.% McCormick® green food dye (or equivalent), and 10 wt.% deionized water is aspirated into the pipette tip. The filled pipette tip is then re-weighed and the resultant value for the mass is recorded as the filled mass of the pipette tip. The empty mass of pipette tip is subtracted from the filled mass of the pipette tip, and the difference is the amount of fluid aspirated into the pipette tip. The percentage of fluid retained, is then calculated by dividing the amount of fluid retained as described earlier by the amount of fluid aspirated into the pipette tip and then multiplying the resultant value by 100%. For example, if the amount of fluid retained after a single aspiration / dispense cycle is 1 mg (0.001 g), and the amount of fluid aspirated into the pipette tip was 220 mg (0.220 g), then the percentage of fluid retained would be 0.5%.

[0114] An article formed from the polymeric compositions described herein may have level of haze (transparency). The level of haze of an article is determined by visual inspection with comparison to a standard. In one or more embodiments, the article may comprise a level of haze of less than or equal to a Level 3 on the below described visual haze scale. As described herein, the “level of haze” for an article is measured by the following method. An article (e.g. a 200 pL pipette tip) formed from a polymeric composition is molded and allowed to cool. The article is then visually inspected against the visual haze scale shown in FIG. 3 and assigned the level number it closest matches to. If the article is between two levels on the visual haze scale shown in FIG. 3, both levels are listed. For example, if the visual observation shows has a haze that matches between Level 1 and Level 2, the Level for that article is Level 1-2. An article that has a low level of haze (i.e., a low haze) refers to an article having Level 3, Level 2, Level 1, of Level 0 or a combination thereof, referring to the scale shown in FIG. 3. In some embodiments, an post-molded article (including pipette tips) formed from the polymer compositions described herein may have low haze as determined by the visual level of haze scale shown in FIG. 3, meaning the article has lessthan or equal to a Level 3, a Level 2-3, a Level 2, a Level 1-2, a Level 1, a Level 0-1, or a Level 0 as determined by visual comparison to the level of haze scale shown in FIG. 3.

[0115] The articles may be sterilized after they have been formed from one of the polymeric compositions described herein. Sterilization techniques include gamma irradiation, e- beam irradiation, x-ray irradiation, and ethylene oxide, among others known to those of ordinary skill in the art. High energy irradiation (including gamma, e-beam, and x-ray) can alter the properties of the surface of articles such that an article that has low fluid retention pre-sterilization may not have low fluid retention post-sterilization. High energy irradiation (including gamma, e- beam, and x-ray) can also alter the properties of the surface of articles such that an article that has low haze pre-sterilization may not have low haze post-sterilization.

[0116] In some embodiments, the dosage for irradiation (gamma, x-ray, or e-beam) is greater than or equal to 15 kGy and less than or equal to 50 kGy, or any range or value between these two endpoints. In one embodiment, the dosage for irradiation is greater than or equal to 15 kGy and less than or equal to 45 kGy, greater than or equal to 15 kGy and less than or equal to 40 kGy, greater than or equal to 15 kGy and less than or equal to 35 kGy, greater than or equal to 15 kGy and less than or equal to 30 kGy, greater than or equal to 15 kGy and less than or equal to 25 kGy, greater than or equal to 15 kGy and less than or equal to 25 kGy, greater than or equal to 15 kGy and less than or equal to 20 kGy, greater than or equal to 20 kGy and less than or equal to 50 kGy, greater than or equal to 25 kGy and less than or equal to 50 kGy, greater than or equal to 30 kGy and less than or equal to 50 kGy, greater than or equal to 35 kGy and less than or equal to 50 kGy, greater than or equal to 40 kGy and less than or equal to 50 kGy, greater than or equal to 45 kGy and less than or equal to 50 kGy, greater than or equal to 20 kGy and less than or equal to 45 kGy, greater than or equal to 20 kGy and less than or equal to 40 kGy, greater than or equal to 20 kGy and less than or equal to 35 kGy, greater than or equal to 20 kGy and less than or equal to 30 kGy. In one specific embodiment, the irradiation is gamma irradiation, and the dosage is greater than or equal to 17.5 kGy and less than or equal to 30 kGy, or greater than equal to 17.5 kGy and less than or equal to 22.5 kGy. In one specific embodiment, the irradiation is gamma irradiation, and the dosage is about 20 kGy.

[0117] In some embodiments, an article formed from a polymeric composition as described herein has low fluid retention after sterilization with a dosage of high-energy irradiation (gamma, x-ray, or e-beam) that is greater than or equal to 15 kGy and less than or equal to 50 kGy dosage, or at any range or value therebetween. The low fluid retention may be one or more of a low level of fluid retention, a low amount of fluid retention, or a low percentage of fluid retention. In one embodiment, an article formed from a polymeric composition as described herein has low fluid retention after sterilization with a dosage of high-energy irradiation (gamma, x-ray, or e- beam) greater than or equal to 17.5 kGy and less than or equal to 30 kGy, or at any range or value therebetween. In one specific embodiment, an article formed from a polymeric composition as described herein has low fluid retention after sterilization with a dosage of gamma irradiation of about 20 kGy.

[0118] An article can also be tested for its fluid retention properties after aging it to aid in determination of how well the article maintains its low retention or low haze properties with time and exposure to heat. Aging can be simulated by putting an article (sterilized or unsterilized) in an oven at 55 °C for a period of time (e.g., 3 days, 14 days). The aged articles can then be tested for their properties such as their level, amount, or percentage of fluid retention, or for their haze level.

[0119] In some embodiments, an article formed from a polymeric composition described herein has low fluid retention after high-energy irradiation (gamma, x-rays, or e-beam) with a dosage greater than or equal to 15 kGy and less than or equal to 35 kGy, and spending about 1 day, 2 days, 3 days, 4 days, 5 days, 6 days, 7 days, 14 days, 21 days, 28 days, or more, in an oven at 55 °C. In some embodiments, an article formed from a polymeric composition described herein has low fluid retention after high-energy irradiation (gamma, x-rays, or e-beam) with a dosage greater than or equal to 10 kGy and less than or equal to 30 kGy, and spending about 1 day, 2 days, 3 days, 4 days, 5 days, 6 days, 7 days, 14 days, 21 days, 28 days, or more, in an oven at 55 °C. In one specific embodiment, an article formed from a polymeric composition described herein has low fluid retention after high-energy irradiation (gamma, x-rays, or e-beam) with a dosage of about 20 kGy, and spending about 1 day, 2 days, 3 days, 4 days, 5 days, 6 days, 7 days, 14 days, 21 days, 28 days, or more, in an oven at 55 °C.

[0120] In some embodiments, an article formed from a polymeric composition as described herein after sterilization with a dosage of high-energy irradiation (gamma, x-ray, or e- beam) of between 15 kGy and 50 kGy has low fluid retention (one or more of a low level, low amount, or low percentage of fluid retention). In some embodiments, an article formed from a polymeric composition as described herein after sterilization with dosage of high-energy irradiation of between 15 kGy and 50 kGy has a percentage of fluid retention of less than or equal to 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, or 1%. In some embodiments, an article formed from a polymeric composition as described herein after sterilization with a dosage of high-energy irradiation (gamma, x-ray, or e-beam) of between 15 kGy and 50 kGy has a lower fluid retention after equilibrating in an oven at 55 °C for at least 3 days than the same article without equilibrating in an oven at 55 °C.

[0121] In some embodiments, an article formed from a polymeric composition as described herein has low haze after sterilization with a dosage of high-energy irradiation (gamma, x-ray, or e-beam) that is greater than or equal to 15 kGy and less than or equal to 35 kGy dosage, or at any range or value therebetween. In one embodiment, an article formed from a polymeric composition as described herein has low haze after sterilization with a dosage of high-energy irradiation (gamma, x-ray, or e-beam) greater than or equal to 17.5 kGy and less than or equal to 30 kGy, or at any range or value therebetween. In one specific embodiment, an article formed from a polymeric composition as described herein has low haze after sterilization with a dosage of gamma irradiation of about 20 kGy. In some embodiments, an article formed from a polymeric composition described herein has low haze after high-energy irradiation (gamma, x-rays, or e- beam) with a dosage greater than or equal to 15 kGy and less than or equal to 35 kGy, and spending about 1 day, 2 days, 3 days, 4 days, 5 days, 6 days, 7 days, 14 days, 21 days, 28 days, or more, in an oven at 55 °C. In some embodiments, an article formed from a polymeric composition described herein has low haze after high-energy irradiation (gamma, x-rays, or e-beam) with a dosage greater than or equal to 10 kGy and less than or equal to 30 kGy, and spending about 1 day, 2 days, 3 days, 4 days, 5 days, 6 days, 7 days, 14 days, 21 days, 28 days, or more, in an oven at 55 °C. In one specific embodiment, an article formed from a polymeric composition described herein has low haze retention after high-energy irradiation (gamma, x-rays, or e-beam) with a dosage of about 20 kGy, and spending about 1 day, 2 days, 3 days, 4 days, 5 days, 6 days, 7 days, 14 days, 21 days, 28 days, or more, in an oven at 55 °C.

[0122] The articles formed from the polymeric compositions described herein have certain surface characteristics, such as wettability and a sliding angle (“SA”). The wettability can be characterized with a surface wettability test by measuring the water contact angle (“WCA”) using a goniometer (such as a KRUSS goniometer, model #DSA30) equipped with a liquid dispenser, charge coupled device camera, and image-processing software that analyzes drop shape. A sessile drop method is employed to measure the static contact angles using a drop of deionized water (volume of ~5 pL) at room temperature (~24-25°C). In some embodiments, an article formed from a polymeric composition described has a water contact angle between 85° and 125°, or any range or value between 85° and 125°. In some embodiments, an article formed from a polymeric composition described herein has a water contact angle between 85° and 120°, between 85° and 115°, between 85° and 110°, between 85° and 105°, between 85° and 100°, between 85° and 95°, between 85° and 105°, between 90° and 125°, between 95° and 125°, between 100° and 125°, between 105° and 125°, between 110° and 125°, between 115° and 125°, between 120° and 125°, between 90° and 120°, between 90° and 115°, between 95° and 115°, or between 90° and 110°. In one specific embodiment, an article formed from a polymeric composition described herein has a water contact angle between 85° and 115°

[0123] A sliding angle is a measurement related to the slipperiness of the surface. A sliding angle is the angle that a 50 pL drop of deionized water on a flat sample (in this disclosure, a flat article made from a polymeric composition herein) begins to slide down as the sample is tilted. An article formed from a polymeric composition described herein has a sliding angle between 5° and 17°, or in any range or value between 5° and 17°. In some embodiments, an article formed from a polymeric composition described herein has a sliding angle between 5° and 17°, 5° to 16°, from 5° to 15°, from 5° to 14°, from 5° to 13°, from 5° to 12°, from 5° to 11°, from 5° to 10°, from 6° to 17°, from 7° to 17°, from 8° to 17°, from 9° to 17°, from 10° to 17°, from 11 ° to 17°, or from 12° to 17°. In one specific embodiment, an article formed from a polymeric composition described herein has a sliding angle from 7° to 17°.

[0124] The articles formed from the polymeric compositions described herein have low fluid retention without sterilization, low fluid retention after gamma irradiation, low retention after aging, or a combination thereof. The articles may further have low haze. These properties may bedesirable for the articles formed from the polymer compositions described herein. For example, in one specific embodiment, an article without sterilization (the post-molding stage) that is formed from the polymeric compositions described herein comprises a level of fluid retention less than or equal to Level 2. This article may further have low haze. In another specific embodiment, an article sterilization with gamma irradiation that is formed from the polymeric compositions described herein comprises a level of fluid retention less than or equal to Level 2. This article may further have low haze. In another specific embodiment, a sterilized article formed from a polymeric composition described herein comprises an amount of fluid retention less than or equal to 2 mg of fluid per 200 pL of fluid volume. This article may have low haze. In yet another specific embodiment, an unsterilized article formed from a polymeric composition described herein comprises an amount of fluid retention less than or equal to 2 mg of fluid per 200 pL of fluid volume. This article may have low haze. In one embodiment, an unsterilized article formed from a polymeric composition described herein comprises a level fluid retention less than or equal to Level 2 and comprises an amount fluid retention less than or equal to 2 mg per 200 pL of fluid volume. This article may further have low haze. In another embodiment, a sterilized article formed from polymeric composition described herein comprises a level fluid retention less than or equal to Level 2 and comprises an amount of fluid retention less than or equal to 2 mg per 200 pL of fluid volume. This article may further have low haze.

[0125] According to embodiments, a non-fluorinated article includes articles formed from a polymer composition of the present disclosure. In some embodiments, the non-fluorinated article has a level of fluid retention less than or equal to a Level 3 as measured by a visual level of fluid retention scale and is free of fluorine. These articles may further have low haze and / or be substantially free of silicone. In some embodiments, a non-fluorinated article has an amount of fluid retention of less than or equal to 6 mg per 200 pL of fluid volume as measured by gravimetric testing and is free of fluorine. This article may further have low haze and / or be substantially free of silicone. In some embodiments, a non-fluorinated article has a level of fluid retention of less than or equal to a Level 3 as measured by a visual level of fluid retention scale and is substantially free of fluorine. This article may further have low haze and / or be substantially free of silicone. In some embodiments, a non-fluorinated article has an amount of fluid retention of less than or equal to 6 mg per 200 pL of fluid volume as measured by gravimetric testing and is substantially free offluorine. This article may further have low haze and / or be substantially free of silicone. In some embodiments, a non-fluorinated article has a level of fluid retention less than or equal to a Level 2 as measured by a visual level of fluid retention scale and is free of fluorine. This article may have low haze.

[0126] In some embodiments, a non-fluorinated, non-silicone article has an amount of fluid retention of less than or equal to 2 mg per 200 pL of fluid volume as measured by gravimetric testing and is free of fluorine and silicone. This article may have low haze. In some embodiments, a non-fluorinated, non-silicone article has an amount of fluid retention of less than or equal to a Level 2 as measured by a visual level of fluid retention scale and is substantially free of fluorine and silicone. In some embodiments, the non-fluorinated, non-silicone article has an amount of fluid retention of less than or equal to a 2 mg per 200 pL of fluid volume as measured by gravimetric testing and is substantially free of fluorine and silicone. This article may have low haze.Methods of Making Articles

[0127] According to other aspects of the present disclosure, a method for forming an article including a polymer composition may comprise solidifying the polymer composition within a mold to form an article and removing the article from the mold.

[0128] Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order, nor that with any apparatus specific orientations be required. Accordingly, where a method claim does not actually recite an order to be followed by its steps, or that any apparatus claim does not actually recite an order or orientation to individual components, or it is not otherwise specifically stated in the claims or description that the steps are to be limited to a specific order, or that a specific order or orientation to components of an apparatus is not recited, it is in no way intended that an order or orientation be inferred, in any respect. This holds for any possible non-express basis for interpretation, including: matters of logic with respect to arrangement of steps, operational flow, order of components, or orientation of components; plain meaning derived from grammatical organization or punctuation, and; the number or type of embodiments described in the specification.

[0129] The polymer compositions used to form the articles described herein may be described as comprising an ultra-low molecular weight polyethylene additive and a thermoplastic polymer, comprising a paraffin wax additive and a thermoplastic polymer, or comprising an ultralow molecular weight polyethylene additive, a paraffin wax additive, and a thermoplastic polymer. The articles formed from the polymer compositions described herein are non-fluorinated articles having low fluid retention and / or low binding of biological matter. As used herein, a “nonfluorinated article” is an article formed from a polymer composition that is free or substantially free of fluorine. The articles formed from the polymer compositions described herein may further be non-silicone articles having low fluid retention. As used herein, a “non-silicone article” is an article formed from a polymer composition that is free or substantially free of silicone.

[0130] Specifically, the polymer compositions disclosed herein comprise an ultra-low molecular weight polyethylene comprising a specified molecular weight (e.g., greater than or equal to 300 g / mol and less than or equal to 5,000 g / mol) or a specified number of carbon atoms (e.g., greater than or equal to C21 and less than or equal to C357), a paraffin wax comprising a specified molecular weight (e.g., greater than or equal to 300 g / mol and less than or equal to 550 g / mol) or number of carbons (e.g., greater than or equal to 18 carbons and less than or equal to 32 carbons), or a combination thereof, which results in an article having low amount of fluid retention (e.g., less than or equal to 6 mg / 200 pL fluid in a 200 pL pipette tip) and / or low level of fluid retention (less than or equal to Level 3). The specified molecular weight and chemistry within the low molecular weight polyolefins described herein may ensure separation of the low molecular weight polyolefin from the thermoplastic polymer and migration of the low molecular weight polyolefin towards the surface of the polymeric part or article being formed during manufacturing. The increased low molecular weight polyolefin content on or near the article (polymeric part) surface may result in the article having low fluid retention. The polymer composition may undergo surface development during manufacturing, such that the low molecular weight polyolefin migrates to the surface of the article formed from the polymer composition. This may contribute to the lower fluid retention properties of articles formed from the polymer composition.

[0131] Methods for forming articles comprising the polymer composition are not necessarily limited. In some embodiments, articles comprising the polymer composition may be formed by injection molding, blowmolding, extrusion, compression molding, or any other suitableprocesses. In some embodiments, methods for forming an article comprising the polymer composition may comprise the steps of solidifying a polymer composition within a mold to form an article comprising the polymer composition and removing the article from the mold. The polymer composition may be processed at a sufficient temperature and for a sufficient amount of time to ensure surface development of low molecular weight polyolefins included in the polymer composition.

[0132] In one or more embodiments, the polymer composition may be disposed into the mold. In such embodiments, the polymer composition is formed outside the mold and before it is disposed into the mold. The polymer composition may be formed by mixing the ultra-low molecular weight polyethylene, the paraffin wax, or a combination thereof with the thermoplastic polymer, and optionally, one or more additives, each of which are previously described. The polymer composition may then be disposed into the mold, and solidified within the mold to form an article comprising the polymer composition. In some embodiments, the polymer composition may be disposed into the mold in a single step. In such embodiments, the low molecular weight polyolefin may undergo surface development and move toward the surface of the article as the polymer composition is disposed into the mold and solidifies within the mold to form the article.

[0133] In some embodiments, the polymer composition may be formed within the mold. In such embodiments, at least a portion of the mold may be coated with the ultra-low molecular weight polyethylene, the paraffin wax, or a combination thereof, followed by disposing the thermoplastic polymer into the mold to form the polymer composition. Any optional additional additives present in the polymer composition may be present in the ultra-low molecular weight polyethylene, the paraffin wax, or the thermoplastic polymer, or in a combination thereof. The polymer composition may then be solidified within the mold to form the article. In such embodiments, surface development of the low molecular weight polyolefin may be minimal, as the low molecular weight polyolefin is positioned near the eventual surface of the article when the polymer composition is formed within the mold.EXAMPLES

[0134] The embodiments described herein will be further clarified by the following examples.Example 1Polymer Compositions

[0135] Polymer compositions comprising thermoplastic polymers and low molecular weight polyolefins were formed by blending thermoplastic polymers (“TP”) and either a paraffin wax (“PW”) or a conventional fluorinated melt additive (“FLA”). The thermoplastic polymers, the paraffin wax, and the fluorinated melt additives used in this Example are listed in Table 1.

[0136] Table 1

[0137] From these ingredients, three control compositions were created with either 100 wt.% polypropylene homopolymer TP1, 100 wt.% polypropylene homopolymer TP2, or 98 wt.% polypropylene homopolymer TP2 and 2 wt.% POLR. Compositions were also created with either 0.5 wt.%, 1.0 wt.%, or 2.0 wt.% paraffin wax, and either 99.5 wt.%, 99 wt.%, or 98 wt.%, polypropylene homopolymer TP2 respectively. Compositions were also created with either 0.5 wt.%, 1.0 wt.%, or 2.0 wt.% paraffin wax, and either 99.5 wt.%, 99 wt.%, or 98 wt.%polypropylene homopolymer TP1 respectively. The compositions used are summarized below in Table 2.

[0138] Table 2

[0139] None of the compositions in Table 2 have silicone, they are non-silicone compositions. Controls 1-2 and Compositions 1-6 are non-fluorinated compositions. Control 3 is a fluorinated composition. The compositions were formed into 200 pL pipette tips by disposing each polymeric composition into a mold and then solidifying the composition in the mold.Level of Fluid Retention of Pipette Tips Comprising Paraffin Wax

[0140] The level of fluid retention of pipette tips formed from the controls and from polymer compositions 1-6 were analyzed by the following process. McCormick® green food coloring at 100% strength (i.e., undiluted) was poured into a clean reservoir. Eight 200 pL pipette tips were loaded onto a manual multi-channel pipette. The eight pipette tips were formed from the polymeric compositions of Controls 1-3 and Compositions 1-6 respectively. After the pipette tips were loaded onto the pipette, 200 pL of the green dye was aspirated from the reservoir and subsequently dispensed back into the reservoir. The aspirating / dispensing process was repeated four more times, for a total of five cycles. For Control 3, the test was performed 5 days after tips were made. The pipette tips were then photographed while still on the multi-channel pipette. The photographs are shown in FIGS. 4-5. Each photograph was visually compared to the levels shown in FIG. 2 to determine the corresponding level of the fluid retention. Table 3 provides the level of fluid retention for each of Controls 1-3 and Compositions 1-6. If some of the eight tips on themulti-channel pipettor had one level of fluid retention but others had a different level, both levels were noted, as is reflected in Table 3.

[0141] Table 3

[0142] As shown in Table 3, the pipette tips formed from the polymer compositions of compositions 1-3 and 6 post-molding (pre-gamma irradiation) had reduced levels of fluid retention over the pipette tips formed from the Controls 1-2 polymer compositions. Compositions 4-5 (comprising 0.5 wt.% and 1.0 wt.% paraffin wax respectively with the remainder polypropylene TP2) had more fluid drag than control 2 (100 wt.% TP2). Pipette tips from Compositions 3 and 6 (each comprising 2.0 wt.% paraffin wax) had similar levels of fluid retention to the pipette tips to control 3 (comprising fluorinated additive). Control 3 and Compositions 3 and 6 had low levels of fluid retention post-molding.Amount of Fluid Retention of Pipette Tips Comprising Paraffin Wax

[0143] The amount of fluid retention of 200 L pipette tips formed from polymerCompositions 1-6 and Controls 1-3 were analyzed by the following process.

[0144] 200 pL pipette tips were formed from the polymeric compositions of Controls 1-3 and Compositions 1-6 respectively. A solution of 50 w.% glycerol, 40 w.% McCormick® Green food dye and 10 w.% deionized water was prepared. Each tip was weighed on a mass balance scale to determine its mass in milligrams. The pipette tips were then placed on an 8-tip multi-channel pipettor until all eight channels of the pipettor had a tip. The solution containing the food dye was aspirated into the tips using the multi-channel pipettor and then the solution was dispensed. Each tip was then reweighed on the scale to determine its post-cycle mass. The entire process was replicated two additional times with new tips formed from the same polymeric composition, creating a total of three replicated tests for a single polymeric composition.

[0145] This process was repeated for each of Controls 1-3 and Compositions 1-6. The results of gravimetric testing for the pipette tips formed from polymeric compositions Controls 1- 3 and Compositions 1-6 respectively are shown in Table 4.

[0146] Table 4

[0147] As shown in Table 4, the post-molded (pre-gamma irradiation) pipette tips formed from the polymer compositions of Compositions 1-6 comprising paraffin wax had reduced amounts of fluid retention over the pipette tips formed from the Controls 1-2 polymer compositions. Control 3 and Compositions 3 and 6 had low amounts of fluid retention at the postmolding stage, and some of the tips from Compositions 2 and 5 had low amounts of fluid retention.Example 2Surface Characteristics of Articles Comprising Paraffin Wax

[0148] 200 pL pipete tips were formed from compositions with 1.5 wt.%, 2 wt.%, or 2.5 wt.% paraffin wax and polypropylene TP1, from compositions with 2 wt.% POLR (fluorinated additive) and TP1, or from 100 wt.% TP1 as described below in Tables 5-6. These pipette tips were investigated for characteristics at their surfaces. The pipette tips were not irradiated or aged. The sliding angle for each pipete tip was determined by measuring the angle at which a 50 pL drop of de-ionized water began to slide off a flat surface made of each of the polymeric compositions when the surfaces were tilted from horizontal. The results are shown in Table 5.

[0149] Table 5

[0150] The sliding angle was, on average, highest for pipete tips made from 100% polypropylene TP1, and lowest for the composition comprising 2.5 wt.% paraffin wax.

[0151] The water contact angle was also determined for 200 pL pipete tips formed from each of the same compositions. The pipete tips were not irradiated or aged. The water contact angle for each pipete tip was determined using a KRUSS goniometer (model #DSA30) equipped with a (manual) liquid dispenser, charge coupled device camera, and image-processing software for drop shape. A sessile drop method was employed with deionized water (volume of ~5-6 pL) at room temperature (~24-25°C) to determine the water contact angle. The average contact angle was determined from 4-5 measurements performed at different locations on the same sample. The results are shown in Table 6.

[0152] Table 6

[0153] The water contact angle for the compositions in Table 6 are lowest for 100% polypropylene TP1, and highest for the composition comprising 2 wt.% POLR (fluorinated additive). The compositions comprising the paraffin wax have water contact angles higher than 100 wt.% TP1 but on average less than the composition comprising 2 wt.% POLR. On average, greater amounts of paraffin wax added to the composition produced higher water contact angle values. All the compositions had water contact angles that indicate the surfaces were hydrophobic.Example 3Effect of Thermoplastic Polymer Choice with Paraffin Wax

[0154] 200 pL pipette tips were formed from 2.0 wt.% paraffin wax and one of four different polypropylenes, as shown in Tables 7-8. The level of fluid retention and the amount of fluid retention was determined for the tips in the same manner as described in the previous examples.

[0155] Table 7

[0156] FIG. 6A-6D shows photographs of the fluid retention of tips formed from Composition 1-4 post molding. The level of fluid retention was then determined by comparing the tips to the level of fluid retention scale shown in FIG. 2 using visual observation, and the results are summarized in Table 8.

[0157] Table 8

[0158] The determination of the amount of fluid retention was performed for each of the compositions using gravimetric testing as described in Example 1. The average values for the results of the gravimetric testing are shown in Table 9

[0159] Table 9

[0160] Tips made from all four compositions had low amounts of fluid retention. The lowest amounts of fluid retention were with polypropylene homopolymers (Compositions 1-3). Composition 4, which used a random copolymer as the thermoplastic polymer, had more than double the amount of fluid retention compared to the polypropylene homopolymers, but it still had a low level of fluid retention.Example 4Sterilized Pipette Tips Comprising Paraffin Wax

[0161] 200 pL pipette tips formed from Control 1 (100 wt.% TP1), Composition 1 (98 wt.% TP1 and 2 wt.% paraffin wax (PW)), and Composition 2 (98 wt.% TP3 and 2 wt.% PW), were formed. A subset of the pipette tips for each type were then subjected to gamma irradiation at a 20 kGy dosage and then left to sit in an oven for 14 days at 55 °C. After formation but before sterilization with high-energy irradiation (e.g., gamma irradiation) or aging in an oven 14 days at 55 °C, the tips are in the “post-molding” stage. After sterilization with gamma irradiation but before aging tips in an oven for 14 days at 55 °C, the tips are in the “post-gamma” stage. After the tips have been gamma irradiated and left to sit in an oven for 14 days at 55 °C, the tips are in the “post-oven” stage.

[0162] For Compositions 1-2, both pre-sterilized tips (i.e., post-molded tips) and tips that were sterilized and then aged were subjected to testing to determine the level of fluid retention using the process described in Example 1. Photographs of the fluid retained in the tips at the postmolding stage and after the aging process are shown in FIGS 7A-7B. FIG. 7A shows that low levels of fluid are obtained in the tips comprising 98 wt.% TP1 and 2 wt.% paraffin wax both at the post-molding stage (FIG. 7A, figure on the left) and after sterilization and aging (FIG. 7A,figure on the right). FIG. 7B shows that low levels of fluid are retained (if any at all) in the tips comprising 98 wt.% TP3 and 2 wt.% paraffin both at the post-molding stage (FIG. 7B, figure on the left) and after sterilization and aging (FIG. 7B, figure on the right).

[0163] For Control 1 and Compositions 1-2, both pre-sterilized tips (i.e., post-molded tips), tips that were sterilized (post-gamma tips), and tips that were aged in an oven for 14 days at 55 °C were subjected to testing to determine the amount of fluid retention using the process described in Example 1. A total of three replicas were performed for each of the compositions at each stage. The average amount of fluid retention for each tip type (i.e., Control 1, Compositions 1-2) at the post-molding stage, after the sterilization step (i.e., post-gamma), and then after the aging step (i. e. , post-oven) is shown in Table 10.

[0164] Table 10

[0165] As shown in Table 10, the pipette tips formed from the polymer compositions of Compositions 1-2 at the post-molding stage showed reduced amounts of fluid retention over the pipette tips formed from the Control 1 polymer compositions. Compositions 1-2 showed similar amounts and both compositions demonstrated low amounts of fluid retention both before and after sterilization but were lowest at the stages after sterilization. Control 1 did not have low amounts of fluid retention at any stage tested.Example 5Pipette Tips Comprising Different Types of Ultra-Low MW Polyethylene Waxes

[0166] 200 pL pipette tips formed from Control 1 (100 wt.% TP 1), and compositions of different types of ultra-low molecular weight polyethylene (polyethylene waxes) in different amounts were formed as described in Tables 11-12.

[0167] Table 11

[0168] Table 12

[0169] For Control 1 and Compositions 1, 4, and 7, pipette tips at the post-molding stage (unsterilized and not aged) were subjected to testing to determine the level of fluid retention using the process described in Example 1. Photographs of the fluid retained in the tips at the postmolding stage for Control 1 and Compositions 1, 4, and 7 are shown in FIGS. 8A-8D. The level of fluid retention was determined based on visual observation in comparison to the level of fluid retention scale shown in FIG. 2. The levels of fluid retention for Control 1 and Compositions 1, 4, and 7 are provided in Table 13.

[0170] Table 13

[0171] Low levels of fluid retention were found for the tips comprising 98 wt.% TP1 and 2 wt.% paraffin wax (FIG. 8B), and the tips comprising 98 wt.% TP1 and 2 wt.% PE2 (FIG. 8D). Control 1 (100% polypropylene TP1) had high levels of fluid retention (FIG. 8A). All of the compositions comprising either paraffin wax (PW) or one of the ultra-low molecular weight polyethylenes (polyethylene waxes PEI and PE2) had lower levels of fluid retention than the composition comprising 100% polypropylene TP1.

[0172] Pipete tips formed from Control 1 and Compositions 1-7 were tested for the amount of fluid retention post-molding (no sterilization or aging) with the process described in Example 1. A total of three replicas were performed for each of the compositions. The average amount of fluid retention for each tip type (i.e., Control 1, Compositions 1-7) at the post-molding stage is shown in Table 14.

[0173] Table 14

[0174] As shown in Table 14, the pipette tips formed from the polymer compositions comprising 1% or more of a polyethylene wax (Compositions 3-4 and 6-7) or a paraffin wax (Composition 1) had low amounts of fluid retention. All of the polymer compositions comprising either polyethylene wax or paraffin wax had lower amounts of fluid retention than the composition with 100 wt.% polypropylene TP1.Surface Characteristics

[0175] 200 pL pipette tips formed from Control 1 (100 wt.% TP 1), and compositions of different types of ultra-low molecular weight polyethylene (polyethylene waxes) in different amounts were formed as described in Tables 15-16.

[0176] Table 15

[0177] Table 16

[0178] The sliding angle for each pipette tip composition was determined by measuring the angle at which a 50 pL drop of de-ionized water began to slide off a flat surface made of each of the polymeric compositions when the surfaces were tilted from horizontal. The results of the sliding angle test are shown in Table 17.

[0179] Table 17

[0180] The sliding angle was, on average, between 9.6 and 18.8 degrees for all of the compositions.

[0181] The water contact angle was also determined for 200 pL pipette tips formed from each of the compositions in Tables 15-16. The pipette tips were not irradiated. The water contact angle for each pipette tip was determined as described in Example 2. The results are shown in Table 18.

[0182] Table 18

[0183] The water contact angle for the compositions in Table 6 are highest for the composition comprising 2 wt.% paraffin wax. The compositions comprising polyethylene waxes range on average from 101.1 degrees to 108.5 degrees. All the compositions had water contact angles that indicate the surfaces were hydrophobic.Example 6Sterilized Pipette Tips Comprising Ultra-low Molecular Weight Polyethylene

[0184] 200 pL pipette tips formed from Control 1 (100 wt.% TP2), and compositions of different types of ultra-low molecular weight polyethylene (polyethylene waxes) in different amounts were formed as described in Tables 19-20.

[0185] Table 19

[0186] Table 20

[0187] The pipette tips were sterilized with gamma irradiation at a dosage of 20 kGy and then the post-gamma amount of fluid retention was determined using the same procedure as described in Example 1 for the post-molding stage, except that a total of four pipette tips of each composition type was tested. The results are provided in Table 21.

[0188] Table 21

[0189] Low amounts of fluid retention were found for the tips comprising 2 wt.% paraffin wax (PW) with either polypropylene homopolymer TP1 or polypropylene homopolymer TP4, and the composition comprising 2 wt.% PE2 an TP1. All of the compositions comprising either paraffin wax (PW) or one of the ultra-low molecular weight polyethylenes (polyethylene waxes PEI and PE2) had lower levels of fluid retention than the composition comprising 100% polypropylene TP1.

[0190] The present disclosure is directed to various embodiments of polymer compositions and articles formed from the polymer composition. The polymer compositions may comprise a thermoplastic polymer and either a paraffin wax or an ultra-low molecular weight polyethylene (a polyethylene wax), or a combination thereof. The paraffin wax may have a molecular weight greater than or equal to 300 g / mol and less than or equal to 550 g / mol. The ultra-low molecular weight polyethylene may have a molecular weight greater than or equal to 300 g / mol and less than or equal to 5,000 g / mol. The specified molecular weight of the paraffin wax and / or ultra-low molecular polyethylene, may lead to compatibility with the thermoplastic polymer, decreasing haze and ensuring separation from the thermoplastic polymer and surface development during manufacturing, leading to low fluid retention. The articles formed from the polymer composition may be free or substantially free from fluorinated compounds while having a low fluid retention. The articles formed from the polymer composition may further be free or substantially free from silicone compounds while having a low fluid retention. Articles formed from the polymer composition may retain low fluid retention properties after exposure to solvents, such as isopropanol, ethanol, and dimethyl sulfoxide (DMSO).

[0191] It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments described herein without departing from the spirit and scope of the claimed subject matter. Thus, it is intended that the specification cover the modifications and variations of the various embodiments described herein provided such modification and variations come within the scope of the appended claims and their equivalents.

Claims

CLAIMS1. An article, comprising: a low molecular weight polyolefin in an amount between 0.1 wt.% and 20 wt.% based on the total weight of the article, wherein the low molecular weight polyolefin is selected from the group consisting of a paraffin wax additive having a molecular weight between 300 g / mol and 5,000 g / mol, an ultra-low molecular weight polyethylene additive having a molecular weight between 300 g / mol and 550 g / mol, and a combination thereof; and a thermoplastic polymer; wherein the article is substantially free of fluorine; and wherein the article comprises low fluid retention.

2. The article of claim 1 , wherein the article further comprises a low haze.

3. The article of any one of claims 1-2, wherein the molecular weight of the paraffin wax is greater than or equal to 300 g / mol and less than or equal to 450 g / mol and the ultra-low molecular weight polyethylene comprises a molecular weight between 500 g / mol and 3,500 g / mol.

4. The article of any one of claims 1-3, wherein the article comprises, based on the total weight of the article, greater than or equal to 0.2 wt.% and less than or equal to 15 wt.% of the low molecular weight polyolefin.

5. The article of any one of claims 1-4 further comprising, based on the total weight of the article, greater than 0 wt.% and less than or equal to 6 wt.% of one or more additives other than the paraffin wax or the ultra-low molecular weight polyethylene.

6. The article of claim 5, wherein the one or more additives other than the paraffin wax or the ultra-low molecular weight polyethylene comprise an antioxidant, a clarifying agent, a nucleating agent, an antistatic agent, a colorant, a radiation stability agent, and a conductive agent, or a combination thereof.

7. The article of any one of claims 1-6, wherein the article comprises, based on the total weight of the polymer composition, greater than or equal to 74 wt.% and less than or equal to 99.9 wt.% of the thermoplastic polymer.

8. The article of any one of claims 1-7, wherein the thermoplastic polymer comprises polypropylene, polystyrene, polymethylmethacrylate, polyvinyl chloride, polycarbonate, polysulfone, polyester, polyamide, polystyrene butadiene copolymers, hydrogenated styrenic polymers, polyurethanes, polyethylene, polymethyl pentene, polylactic acid, polybutylene succinate, polyhydroxyalkanoate, or a combination thereof.

9. The article of claim 8, wherein the thermoplastic polymer comprises polypropylene or polystyrene, or a combination thereof.

10. The article of any one of claims 1 -9, wherein the article is substantially free of silicone.

11. The article of any one of claims 1-10, wherein the article is free of fluorine.

12. The article of any one of claims 1-11, wherein the article is free of fluorine and silicone.

13. The article of any one of claims 1-12, wherein the article comprises a first major surface and a second major surface opposite the first major surface, wherein a concentration of the low molecular weight polyolefin at the first major surface is greater than a concentration of the low molecular weight polyolefin at an approximate midpoint between the first major surface and the second major surface.

14. The article of any one of claims 1-13, wherein the article comprises a pipet, a pipette tip, an assay plate, a well plate, a cell culture dish, a liquid storage vessel, a tube, a liquid receptacle, a vent filter, or a laboratory consumable.

15. The article of any one of claims 1-14, wherein the article comprises a pipette tip.

16. The article of claim 15, wherein the article comprises a level of fluid retention less than or equal to Level 3 as measured by a visual level of fluid retention scale.

17. The article of claim 15, wherein the article comprises an amount of fluid retention of less than or equal to 6 mg per 200 pL of fluid volume in a 200 pL pipette tip after a single aspirate / dispense cycle, as measured by gravimetric testing.

18. The article of any one of claims 1-17, wherein the article retains less than or equal to 3% of fluid added to the article and then dispensed.

19. The article of any one of claims 1-18, wherein the article is a sterilized article.

20. The article of any one of claims 1-19, wherein the article comprises a sliding angle between 5 degrees and 17 degrees.

21. The article of any one of claims 1-19, wherein the article comprises a water contact angle between 85 degrees and 125 degrees.

22. A method of forming an article, comprising the steps of:(a) solidifying a polymer composition within a mold to form the article, the polymer composition comprising: a low molecular weight polyolefin in a total amount at a value between 0.1 wt.% and 20 wt.%, wherein the low molecular weight polyolefin is selected from the group consisting of a paraffin wax having a molecular weight between 300 g / mol and 550 g / mol, an ultra-low molecular weight polyethylene wax having a molecular weight between 300 g / mol and 5,000 g / mol, and a combination thereof; and a thermoplastic polymer; wherein the polymer composition is substantially free of fluorine; and(b) removing the article from the mold.

23. The method of claim 22, wherein the polymer composition is substantially free of silicone.

24. The method of any one of claims 22-23, the method further comprising injecting the polymer composition into the mold.

25. The method of any one of claims 22-24, the method further comprising sterilizing the article with irradiation at a dosage between 10 kGy and 50 kGy, after removing the article from the mold.

26. The method of claim 25, wherein after sterilizing the article, the article comprises a level of fluid retention of less than or equal to a Level 3, as measured with a visual level of fluid retention scale.

27. The method of claim 25, wherein after sterilizing the article, the article comprises an amount of fluid retention of less than or equal to 6 mg per 200 pL of fluid volume in a 200 pL pipette tip after a single aspirate / dispense cycle, as measured by gravimetric testing.

28. The method of claim 25, wherein after sterilizing the article, the article retains less than or equal to 3% of fluid added to the article and then dispensed.

29. A non-fluorinated article, comprising a thermoplastic polymer and either a paraffin wax, an ultra-low molecular weight polyethylene, or a combination thereof, wherein the non-fluorinated article comprises a fluid retention of less than or equal to 3% of any fluid added and then dispensed, and wherein the non-fluorinated article is substantially free of fluorine.

30. The non-fluorinated article of claim 29, wherein the non-fluorinated article is substantially free of silicone.

31. The non-fluorinated article of any one of claims 29-30, wherein the non-fluorinated article further comprises low haze.

32. The non-fluorinated article of any one of claims 29-31, wherein the article comprises greater than or equal to 0.1 wt.% and less than or equal to 20 wt.% of a paraffin wax, a low- molecular weight polyethylene, or a combination thereof, based on the total weight of the article.

33. The non-fluorinated article of any one of claims 29-32, wherein the paraffin wax comprises a molecular weight greater than or equal to 300 g / mol and less than or equal to 550 g / mol and the ultra-low molecular weight polyethylene comprises a molecular weight greater than or equal to 300 g / mol and less than or equal to 5,000 g / mol.

34. The non-fluorinated article of any one of claims 29 to 33, wherein the article has a sliding angle between 5 degrees and 17 degrees.

35. The non-fluorinated article of any one of claims 29-34, wherein the article comprises, based on the total weight of the article, greater than or equal to 74 wt.% and less than or equal to 99.9 wt.% of a thermoplastic polymer.

36. The non-fluorinated article of claim 35, wherein the thermoplastic polymer comprises polypropylene, polystyrene, polymethylmethacrylate, polyvinyl chloride, polycarbonate, polysulfone, polyester, polyamide, polystyrene butadiene copolymers, hydrogenated styrenic polymers, polyurethanes, polyethylene, polymethyl pentene, polylactic acid, polybutylene succinate, polyhydroxyalkanoate, or a combination thereof.

37. The non-fluorinated article of any one of claims 29-36, wherein the article comprises a pipet, pipette tip, an assay plate, a well plate, a cell culture dish, a liquid storage vessel, a tube, a liquid receptacle, a vent filter, or a laboratory consumable.

38. The non-fluorinated article of claim 37, wherein the article comprises a pipette tip.

39. An article, comprising: a low molecular weight polyolefin an amount between 0.1 wt.% and 20 wt.% based on the total weight of the article, wherein the low molecular weight polyolefin is selected from the groupconsisting of paraffin wax having a molecular weight between 300 g / mol and 550 g / mol, an ultralow molecular weight polyethylene having a molecular weight between 300 g / mol and 5,000 g / mol, and a combination thereof; and a thermoplastic polymer; wherein the article comprises a first major surface and a second major surface opposite the first major surface, wherein a concentration of the low molecular weight polyolefin at the first major surface is greater than a concentration of the low molecular weight polyolefin at an approximate midpoint between the first major surface and the second major surface; and wherein the article is a pipette tip, and wherein the article has low fluid retention.

40. The article of claim 39, wherein the low fluid retention is a low percentage of fluid retention that is less than or equal to 3% of a fluid volume aspirated into the article and then dispensed.

41. The article of claim 39, wherein the low fluid retention is a low level of fluid retention that is less than or equal to a Level 3 as measured by a visual level of fluid retention scale.

42. The article of claim 39, wherein the low fluid retention is a low amount of fluid retention that is less than or equal to 6 mg per 200 pL of fluid volume in a 200 pL pipette tip after a single aspirate / dispense cycle, as measured by gravimetric testing.

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