PEEK-to-PEEK thermal bonding method for PEEK manifolds

Abstract

Methods for directly bonding two or more articles of polycthcr ether ketone (PEEK) arc provided. The method includes treating bonding surfaces on the two or more articles of PEEK. The method includes placing the treated bonding surfaces of the two or more articles of PEEK into contact with each other. The method further includes heating the two or more articles of PEEK for a pre-determined time at a pre-determined temperature between 250 °C and the melting point of the PEEK. The method additionally includes applying a pre-determined compressive load to the two or more articles of PEEK during heating. Fluid handling devices, such as manifolds and filters, formed using methods of the disclosure are also disclosed.

Description

[0001] PEEK-TO-PEEK THERMAL BONDING METHOD FOR PEEK MANIFOLDS

[0002] CROSS REFERENCE TO RELATED APPLICATIONS

[0003] This application claims priority to U.S. Patent Application No. 63 / 657,265, filed June 7, 2024, the entire contents of which are incorporated herein by reference in their entirety.

[0004] FIELD OF TECHNOLOGY

[0005] Aspects and embodiments disclosed herein are generally related to methods for directly bonding two or more articles of polyether ether ketone (PEEK), a widely used thermoplastic material in chemical and engineering applications.

[0006] SUMMARY

[0007] In accordance with an aspect, there is provided a method for directly bonding two or more articles of PEEK. The method may include treating the bonding surfaces of a first article of PEEK and a second article of PEEK. The method may include placing the treated bonding surfaces of the first article of PEEK and second article of PEEK into contact with each other. The method further may include heating the first article of PEEK and second article of PEEK for a pre-determined time to a pre-determined temperature between 250 °C and the melting point of the PEEK. The method additionally may include applying a pre-determined compressive load to the first article of PEEK and second article of PEEK before heating and / or during heating.

[0008] In some embodiments, the bonding surfaces on the first article and second article of PEEK are treated with a plasma. The plasma may be an oxidative plasma, i.e., an oxygen plasma, for cleaning the bonding surfaces and increasing surface roughness and / or surface energy. In some embodiments, argon, nitrogen, hydrogen, ammonia, air, or a mixture of thereof, may be used to generate plasma. In some embodiments, the plasma may be generated using a power in the range from about 10 W to about 1250 W, e.g., about 10 W to about 100 W, about 50 W to about 150 W, about 100 W to about 200 W, about 150 W to about 250 W, about 300 W to about 400 W, about 450 W to about 550 W, about 500 W to about 600 W, about 650 W to about 750 W, about 700 W to about 800 W, about 750 W to about 850 W, about 800 W to about 900 W, about 850 W to about 950 W, about 900 W to about 1000 W, about 950 W to about 1050 W, about 1000 W to about 1100 W, about 1050 W to about 1150 W, about 1100 W to about 1200 W, or about 1150 W to about 1250 W, e.g., about 10 W, about 15 W, about 20 W, about 25 W, about 30 W, about 35 W, about 40 W, about 45 W, about 50 W, about 55 W, or about 50 W, about 55 W, about 60 W, about 65 W, about 70 W, about 75 W, about 80 W, about 85 W, about 90 W, about 95 W, or about 100 W, about 150 W, about 200 W, about 250 W, about 300 W, about 350 W, about 400 W, about 450 W, about 500 W, about 550 W, about 600 W, about 650 W, about 700 W, about 750 W, about 800 W, about 850 W, about 900 W, about 950 W, about 1000 W, about 1050 W, about 1100 W, about 1150 W, about 1200 W, or about 1250 W.

[0009] In some embodiments, the plasma may be generated from gas with pressure in the range from 1 mTorr to 760,000 mTorr, i.e., about 760 torr or 1 atmosphere, e.g., about 1 mTorr to 10,000 mTorr, about 5,000 mTorr to about 50,000 mTorr, about 10,000 mTorr to about 100,000 mTorr, about 50,000 mTorr to about 250,000 mTorr, about 100,000 mTorr to about 400,000 mTorr, about 200,000 mTorr to about 500,000 mTorr, about 350,000 mTorr to about 600,000 mTorr, or about 500,000 mTorr to about 760,000 mTorr.

[0010] In some embodiments, the bonding surfaces of the first article and second article of PEEK may be exposed to the generated plasma for a time between 10 seconds to about 60 minutes, e.g., about 10 seconds to about 60 seconds, about 1 minute to about 10 minutes, about 5 minutes to about 15 minutes, about 10 minutes to about 20 minutes, about 15 minutes to about 25 minutes, about 20 minutes to about 30 minutes, about 25 minutes to about 35 minutes, about 30 minutes to about 40 minutes, about 35 minutes to about 45 minutes, about 40 minutes to about 50 minutes, about 45 minutes to about 55 minutes, or about 50 minutes to about 60 minutes, e.g., about 10 seconds, about 30 seconds, about 1 minute, about 1.5 minutes, about 2 minutes, about 2.5 minutes, about 3 minutes, about 3.5 minutes, about 4 minutes, about 4.5 minutes, about 5 minutes, about 5.5 minutes, about 6 minutes, about 6.5 minutes, about 7 minutes, about 7.5 minutes, about 8 minutes, about 8.5 minutes, about 9 minutes, about 9.5 minutes, or about 10 minutes, about 15 minutes, about 20 minutes, about 25 minutes, about 30 minutes, about 35 minutes, about 40 minutes, about 45 minutes, about 50 minutes, about 55 minutes, or about 60 minutes.

[0011] In some embodiments, a compressive load applied to the first article of PEEK and second article of PEEK during heating may provide for compression resulting in a change of about 0% to about 10% of an initial uncompressed dimension of the first article of PEEK and second article of PEEK, e.g., about 0% to about 3%, about 1% to about 4%, about 2% to about 5%, about 3% to about 6%, about 4% to about 7%, about 5% to about 8%, about 6% to about 9%, or about 7% to about 10%, e.g., about 0%, about 0.25%, about 0.5%, about 0.75%, about 1%, about 1.25%, about 1.5%, about 1.75%, about 2%, about 2.25%, about 2.5%, about 2.75%, about 3%, about 3.25%, about 3.5%, about 3.75%, about 4%, about 4.25%, about 4.5%, about 4.75%, about 5%, about 5.25%, about 5.5%, about 5.75%, about 6%, about 6.25%, about 6.5%, about 6.75%, about 7%, about 7.25%, about 7.5%, about 7.75%, about 8%, about 8.25%, about 8.5%, about 8.75%, about 9%, about 9.25%, about 9.5%, about 9.75%, or about 10%. The compressive load may be applied in-situ to the first article of PEEK and second article of PEEK using a source of mechanical pressure, such as a press.

[0012] In some embodiments, a compressive load applied to the first article of PEEK and second article of PEEK prior to heating provides for compression of the first article of PEEK and second article of PEEK resulting in a change of about 0% to about 10% of an initial uncompressed dimension of the first article of PEEK and second article of PEEK, e.g., about 0% to about 3%, about 1% to about 4%, about 2% to about 5%, about 3% to about 6%, about 4% to about 7%, about 5% to about 8%, about 6% to about 9%, or about 7% to about 10%, e.g., about 0%, about 0.25%, about 0.5%, about 0.75%, about 1%, about 1.25%, about 1.5%, about 1.75%, about 2%, about 2.25%, about 2.5%, about 2.75%, about 3%, about 3.25%, about 3.5%, about 3.75%, about 4%, about 4.25%, about 4.5%, about 4.75%, about 5%, about 5.25%, about 5.5%, about 5.75%, about 6%, about 6.25%, about 6.5%, about 6.75%, about 7%, about 7.25%, about 7.5%, about 7.75%, about 8%, about 8.25%, about 8.5%, about 8.75%, about 9%, about 9.25%, about 9.5%, about 9.75%, or about 10%. The compressive load may be applied to the first article of PEEK and second article of PEEK using a source of mechanical pressure, such as a press and / or a fixture.

[0013] In further embodiments, the non-bonding surfaces of the first and the second article of PEEK may be isolated, e.g., from the bearing surfaces of a press or fixture, by a separating material that can withstand the compression pressure, has a higher melting point than PEEK, and does not adhere to PEEK to facilitate removal after bonding. In some embodiments, the separating materials may be metals, e.g., aluminum, stainless steel, or titanium. In certain embodiments, the separating materials may be chemically inert, e.g., polyimide (PI), or ceramics. In some embodiments, the separating materials may be metals coated with inert coatings. In some embodiments, the first article of PEEK and second article of PEEK may be heated to a prc-dctcrmincd temperature between 250 °C and the melting point of the PEEK, such as about 250 °C to about 360 °C, e.g., about 250 °C to about 280 °C, about 270 °C to about 300 °C, about 290 °C to about 330 °C, or about 320 °C to about 360 °C, e.g., about 250 °C, about 251 °C, about 252 °C, about 253 °C, about 254 °C, about 255 °C, about 256 °C, about 257 °C, about 258 °C, about 259 °C, about 260 °C, about 261 °C, about 262 °C, about 263 °C, about 264 °C, about 265 °C, about 266 °C, about 267 °C, about 268 °C, about 269 °C, about 270 °C, about 271 °C, about 272 °C, about 273 °C, about 274 °C, about 275 °C, about 276 °C, about 277 °C, about 278 °C, about 279 °C, about 280 °C, about 281 °C, about 282 °C, about 283 °C, about 284 °C, about 285 °C, about 286 °C, about 287 °C, about 288 °C, about 289 °C, about 290 °C, about 291 °C, about 292 °C, about 293 °C, about 294 °C, about 295 °C, about 296 °C, about 297 °C, about 298 °C, about 299 °C, about 300 °C, about 301 °C, about 302 °C, about 303 °C, about 304 °C, about 305 °C, about 306 °C, about 307 °C, about 308 °C, about 309 °C, about 310 °C, about 311 °C, about 312 °C, about 313 °C, about 314 °C, about 315 °C, about 316 °C, about 317 °C, about 318 °C, about 319 °C, about 320 °C, about 321 °C, about 322 °C, about 323 °C, about 324 °C, about 325 °C, about 326 °C, about 327 °C, about 328 °C, about 329 °C, about 330 °C, about 331 °C, about 332 °C, about 333 °C, about 334 °C, about 335 °C, about 336 °C, about 337 °C, about 338 °C, about 339 °C, about 340 °C, about 341 °C, about 342 °C, about 343 °C, about 344 °C, about 345 °C, about 346 °C, about 347 °C, about 348 °C, about 349 °C, about 350 °C, or about 351 °C, about 352 °C, about 353 °C, about 354 °C, about 355 °C, about 356 °C, about 357 °C, about 358 °C, about 359 °C, or about 360 °C.

[0014] In some embodiments, heating the first article of PEEK and second article of PEEK may occur by a temperature gradient of between about 0.1 °C / min to about 120 °C / min, e.g., about 0.1 °C / min to about 1 °C / min, about 0.5 °C / min to about 5 °C / min, about 1 °C / min to about 10 °C / min, about 5 to about 20 °C / min, about 10 °C / min to about 30 °C / min, about 20 °C / min to about 50 °C / min, about 30 °C / min to about 60 °C / min, about 40 °C / min to about 70 °C / min, about 50 °C / min to about 80 °C / min, about 60 °C / min to about 90 °C / min, about 70 °C / min to about 100 °C / min, about 80 °C / min to about 110 °C / min, or about 90 °C / min to about 120 °C / min, e.g., about 0.1 °C / min, about 0.2 °C / min, about 0.3 °C / min, about 0.4 °C / min, about 0.5 °C / min, about 0.6 °C / min, about 0.7 °C / min, about 0.8 °C / min, about 0.9 °C / min, about 1 °C / min, about 1.5 °C / min, about 2 °C / min, about 2.5 °C / min, about 3 °C / min, about 3.5°C / min, about 4 °C / min, about 4.5 °C / min, about 5 °C / min, about 5.5 °C / min, about 6 °C / min, about 6.5 °C / min, about 7 °C / min, about 7.5 °C / min, about 8 °C / min, about 8.5 °C / min, about 9 °C / min, about 9.5 °C / min, about 10 °C / min, about 15 °C / min, about 20 °C / min, about 25 °C / min, about 30 °C / min, about 35 °C / min, about 40 °C / min, about 45 °C / min, about 50 °C / min, about 55 °C / min, about 60 °C / min, about 65 °C / min, about 70 °C / min, about 75 °C / min, about 80 °C / min, about 85 °C / min, about 90 °C / min, about 95 °C / min, about 100 °C / min, about 105 °C / min, about 110 °C / min, about 115 °C / min, or about 120 °C / min. In specific embodiments, the first article of PEEK and the second article of PEEK may be placed into an enclosure pre-heated to the bonding temperature.

[0015] In some embodiments, a compressive load may be applied to the first article of PEEK and the second article of PEEK during heating, providing for compression of the first article of PEEK and second article of PEEK that results in a change of about 0% to about 10% of an initial dimension of the first article of PEEK and second article of PEEK after any compression applied before heating, e.g., about 0% to about 3%, about 1% to about 4%, about 2% to about 5%, about 3% to about 6%, about 4% to about 7%, about 5% to about 8%, about 6% to about 9%, or about 7% to about 10%, e.g., about 0%, about 0.25%, about 0.5%, about 0.75%, about 1%, about 1.25%, about 1.5%, about 1.75%, about 2%, about 2.25%, about 2.5%, about 2.75%, about 3%, about 3.25%, about 3.5%, about 3.75%, about 4%, about 4.25%, about 4.5%, about 4.75%, about 5%, about 5.25%, about 5.5%, about 5.75%, about 6%, about 6.25%, about 6.5%, about 6.75%, about 7%, about 7.25%, about 7.5%, about 7.75%, about 8%, about 8.25%, about 8.5%, about 8.75%, about 9%, about 9.25%, about 9.5%, about 9.75%, or about 10%.

[0016] In some embodiments, a compressive load during heating may be applied indirectly by constraining the thermal expansion of the first article of PEEK and the second article of PEEK. For example, such constrained thermal expansion may be achieved by positioning the first article of PEEK and the second article of PEEK within a rigid void space constructed of a material which experiences lower thermal expansion than PEEK during heating, such as a steel press or a fixture. The application of compressive load during heating may be performed either with or without application of a compressive load before heating. In some embodiments, the total predetermined compressive load applied to the first article of PEEK and second article of PEEK during heating is a combination of the compressive load applied before heating and the compressive load applied during heating. In some embodiments, the pre-determined time for which the first article and second article of PEEK is heated is between about 0.1 hour to about 48 hours, c.g., about 0.1 hours to about 1 hour, about 0.5 hours to about 5 hours, about 1 hour to about 10 hours, about 2 hours to about 15 hours, about 3 hours to about 20 hours, about 4 hours to about 25 hours, about 5 hours to about 30 hours, about 6 hours to about 35 hours, about 7 hours to about 40 hours, about 8 hours to about 45 hours, or about 9 hours to about 48 hours, e.g., about 0.1 hours, about 0.2 hours, about 0.3 hours, about 0.4 hours, about 0.5 hours, about 0.6 hours, about 0.7 hours, about 0.8 hours, about 0.9 hours, about 1 hour, about 1.5 hours, about 2 hours, about 2.5 hours, about 3 hours, about 3.5 hours, about 4 hours, about 4.5 hours, about 5 hours, about 5.5 hours, about 6 hours, about 7 hours, about 8 hours, about 9 hours, about 10 hours, about 11 hours, about 12 hours, about 13 hours, about 14 hours, about 15 hours, about 16 hours, about 17 hours, about 18 hours, about 19 hours, about 20 hours, about 21 hours, about 22 hours, about 23 hours, about 24 hours, about 25 hours, about 26 hours, about 27 hours, about 28 hours, about 29 hours, about 30 hours, about 31 hours, about 32 hours, about 33 hours, about 34 hours, about 35 hours, about 36 hours, about 37 hours, about 38 hours, about 39 hours, about 40 hours, about 41 hours, about 42 hours, about 43 hours, about 44 hours, about 45 hours, about 46 hours, about 47 hours, or about 48 hours.

[0017] In further embodiments, following the heating of the compressed first article and second article of PEEK for the pre-determined time, the compressed and heated first article and second article of PEEK may be cooled according to a temperature gradient. The cooling temperature gradient may be between about 0.1 °C / min to about 120 °C / min, e.g., about 0.1 °C / min to about 1 °C / min, about 0.5 °C / min to about 5 °C / min, about 1 °C / min to about 10 °C / min, about 5 to about 20 °C / min, about 10 °C / min to about 30 °C / min, about 20 °C / min to about 50 °C / min, about 30 °C / min to about 60 °C / min, about 40 °C / min to about 70 °C / min, about 50 °C / min to about 80 °C / min, about 60 °C / min to about 90 °C / min, about 70 °C / min to about 100 °C / min, about 80 °C / min to about 110 °C / min, or about 90 °C / min to about 120 °C / min, e.g., about 0.1 °C / min, about 0.2 °C / min, about 0.3 °C / min, about 0.4 °C / min, about 0.5 °C / min, about 0.6 °C / min, about 0.7 °C / min, about 0.8 °C / min, about 0.9 °C / min, about 1 °C / min, about 1.1 °C / min, about 1.2 °C / min, about 1.3 °C / min, about 1.4 °C / min, about 1.5 °C / min, about 1.6 °C / min, about 1.7 °C / min, about 1.8 °C / min, about 1.9 °C / min, about 2 °C / min, about 2.1 °C / min, about 2.2 °C / min, about 2.3 °C / min, about 2.4 °C / min, about 2.5 °C / min, about 2.6 °C / min, about 2.7 °C / min, about 2.8 °C / min, about 2.9 °C / min, about 3 °C / min, about 3.1 °C / min, about 3.2 °C / min, about 3.3 °C / min, about 3.4 °C / min, about 3.5 °C / min, about 3.6 °C / min, about 3.7 °C / min, about 3.8 °C / min, about 3.9 °C / min, about 4 °C / min, about 4.1 °C / min, about 4.2 °C / min, about 4.3 °C / min, about 4.4 °C / min, about 4.5 °C / min, about 4.6 °C / min, about 4.7 °C / min, about 4.8 °C / min, about

[0018] 4.9 °C / min, about 5 °C / min, about 5.5 °C / min, about 6 °C / min, about 6.5 °C / min, about 7 °C / min, about 7.5 °C / min, about 8 °C / min, about 8.5 °C / min, about 9 °C / min, about 9.5 °C / min, about 10 °C / min, about 15 °C / min, about 20 °C / min, about 25 °C / min, about 30 °C / min, about 35 °C / min, about 40 °C / min, about 45 °C / min, about 50 °C / min, about 55 °C / min, about 60 °C / min, about 65 °C / min, about 70 °C / min, about 75 °C / min, about 80 °C / min, about 85 °C / min, about 90 °C / min, about 95 °C / min, about 100 °C / min, about 105 °C / min, about 110 °C / min, about 115 °C / min, or about 120 °C / min.

[0019] In some embodiments, a fixture containing the first article of PEEK and second article of PEEK may be taken out of a heated enclosure and put on a cooling plate immediately after the first article of PEEK and second article of PEEK have been heated at the pre-determined temperature for the pre-determined time.

[0020] In some embodiments, bonded articles produced as a result of the methods disclosed herein may have an average bonding strength of about 28 MPa.

[0021] In some embodiments, articles for bonding may be pre-formed and complimentary to form a fluid handling device after being bonded. For example, the fluid handling device may be a manifold. In certain embodiments, the fluid handling device may be a filter.

[0022] In accordance with an aspect, there is provided a manifold for directing a fluid through one or more channels therein. The manifold may include two or more articles of PEEK that have been directly bonded, e.g., using methods disclosed herein.

[0023] In some embodiments, the two or more articles of PEEK may include portions, e.g., preformed and complimentary, of the one or more channels disposed on a bonding surface of each article such that the one or more channels are formed upon bonding.

[0024] In some embodiments, the direct bonding of the two or more articles of PEEK may provide for the manifold to have a fluid containment pressure of up to about 200 bar.

[0025] In some embodiments, the one or more channels of the manifold may have a minimum diameter of between about 0.01 mm to about 10 mm, e.g., about 0.01 mm to about 0.1 mm, about 0.025 mm to about 0.25 mm, about 0.05 mm to about 0.5 mm, about 0.075 mm to about 0.75 mm, about 0. 1 mm to about 1 mm, about 0.25 mm to about 2.5 mm, about 0.5 mm to about 5 mm, about 0.75 mm to about 7.5 mm, or about 1 mm to about 10 mm, e.g., about 0.01 mm, about 0.02 mm, about 0.03 mm, about 0.04 mm, about 0.05 mm, about 0.06 mm, about 0.07 mm, about 0.08 mm, about 0.09 mm, about 0.1 mm, about 0.2 mm, about 0.3 mm, about 0.4 mm, about 0.5 mm, about 0.6 mm, about 0.7 mm, about 0.8 mm, about 0.9 mm, about 1 mm, about 1.1 mm, about 1.2 mm, about 1.3 mm, about 1.4 mm, about 1.5 mm, about 1.6 mm, about 1.7 mm, about 1.8 mm, about 1.9 mm, about 2 mm, about 2.1 mm, about 2.2 mm, about 2.3 mm, about 2.4 mm, about 2.5 mm, about 2.6 mm, about 2.7 mm, about 2.8 mm, about 2.9 mm, about 3 mm, about

[0026] 3.1 mm, about 3.2 mm, about 3.3 mm, about 3.4 mm, about 3.5 mm, about 3.6 mm, about 3.7 mm, about 3.8 mm, about 3.9 mm, about 4 mm, about 4.1 mm, about 4.2 mm, about 4.3 mm, about 4.4 mm, about 4.5 mm, about 4.6 mm, about 4.7 mm, about 4.8 mm, about 4.9 mm, about 5 mm, about 5.1 mm, about 5.2 mm, about 5.3 mm, about 5.4 mm, about 5.5 mm, about 5.6 mm, about 5.7 mm, about 5.8 mm, about 5.9 mm, about 6 mm, about 6.1 mm, about 6.2 mm, about 6.3 mm, about 6.4 mm, about 6.5 mm, about 6.6 mm, about 6.7 mm, about 6.8 mm, about 6.9 mm, about 7 mm, about 7.1 mm, about 7.2 mm, about 7.3 mm, about 7.4 mm, about 7.5 mm, about 7.6 mm, about 7.7 mm, about 7.8 mm, about 7.9 mm, about 8 mm, about 8.1 mm, about

[0027] 8.2 mm, about 8.3 mm, about 8.4 mm, about 8.5 mm, about 8.6 mm, about 8.7 mm, about 8.8 mm, about 8.9 mm, about 9 mm, about 9.1 mm, about 9.2 mm, about 9.3 mm, about 9.4 mm, about 9.5 mm, about 9.6 mm, about 9.7 mm, about 9.8 mm, about 9.9 mm, or about 10 mm. The one or more channels of the manifold may include straight channels, curved channels, serpentine channels, or channels with variable diameter or width. In any embodiment, the one or more channels of the manifold may have a rounded profile, a polygonal profile, e.g., a rectangular or triangular profile, or profile comprising a combination of two or more rounded and / or linear segments, e.g. a half-ellipse profile.

[0028] In some embodiments, the bonding interface of the manifold may have an average bonding strength of about 28 MPa upon bonding of the two or more articles of PEEK.

[0029] In accordance with an aspect, there is provided a device, such as a manifold or a filter for a fluidic flow path. The device may include two or more articles of PEEK that have been directly bonded to one another. In some embodiments, the two or more articles of PEEK may include PEEK films. In some embodiments, PEEK films have an individual thickness of 10 pm to 1000 pm. In some embodiments, the individual layers of PEEK film may have a thickness of about 10 pm to about 1000 pm, e.g., about 10 pm to about 1000 pm, about 25 pm to about 900 pm, about 50 pm to about 800 pm, about 75 pm to about 700 pm, about 100 pm to about 600 pm, about 150 pm to about 500 pm, about 200 pm to about 400 pm, or about 250 pm to about 300 pm.

[0030] In some embodiments, the individual layers of PEEK film may have a thickness of about 10 pm, about 20 pm, about 30 pm, about 40 pm, about 50 pm, about 60 pm, about 70 pm, about 80 pm, about 90 pm, about 100 pm, about 110 pm, about 120 pm, about 130 pm, about 140 pm, about 150 pm, about 160 pm, about 170 pm, about 180 pm, about 190 pm, about 200 pm, about 210 pm, about 220 pm, about 230 pm, about 240 pm, about 250 pm, about 260 pm, about 270 pm, about 280 pm, about 290 pm, about 300 pm, about 310 pm, about 320 pm, about 330 pm, about 340 pm, about 350 pm, about 360 pm, about 370 pm, about 380 pm, about 390 pm, about 400 pm, about 410 pm, about 420 pm, about 430 pm, about 440 pm, about 450 pm, about 460 pm, about 470 pm, about 480 pm, about 490 pm, about 500 pm, about 550 pm, about 520 pm, about 530 pm, about 540 pm, about 550 pm, about 560 pm, about 570 pm, about 580 pm, about 590 pm, about 600 pm, about 610 pm, about 620 pm, about 630 pm, about 640 pm, about 650 pm, about 660 pm, about 670 pm, about 680 pm, about 690 pm, about 700 pm, about 710 pm, about 720 pm, about 730 pm, about 740 pm, about 750 pm, about 760 pm, about 770 pm, about 780 pm, about 790 pm, about 800 pm, about 810 pm, about 820 pm, about 830 pm, about 840 pm, about 850 pm, about 860 pm, about 870 pm, about 880 pm, about 890 pm, about 900 pm, about 910 pm, about 920 pm, about 930 pm, about 940 pm, about 950 pm, about 960 pm, about 970 pm, about 980 pm, about 990 pm, or about 1000 pm.

[0031] In some embodiments, the two or more articles of PEEK may include bulk PEEK layers. In some embodiments, such bulk PEEK layers may have individual thicknesses that can vary, e.g., thicknesses from about 1 mm to about 500 mm, e.g., about 1 mm, about 2 mm, about 3 mm, about 4 mm, about 5 mm, about 6 mm, about 7 mm, about 8 mm, about 9 mm, 10 mm, about 11 mm, about 12 mm, about 13 mm, about 14 mm, about 15 mm, about 16 mm, about 17 mm, about 18 mm, about 19 mm, about 20 mm, about 21 mm, about 22 mm, about 23 mm, about 24 mm, about 25 mm, about 26 mm, about 27 mm, about 28 mm, about 29 mm, about 30 mm, about 31 mm, about 32 mm, about 33 mm, about 34 mm, about 35 mm, about 36 mm, about 37 mm, about 38 mm, about 39 mm, about 40 mm, about 41 mm, about 42 mm, about 43 mm, about 44 mm, about 45 mm, about 46 mm, about 47 mm, about 48 mm, about 49 mm, about 50 mm, about 51 mm, about 52 mm, about 53 mm, about 54 mm, about 55 mm, about 56 mm, about 57 mm, about 58 mm, about 59 mm, about 60 mm, about 61 mm, about 62 mm, about 63 mm, about 64 mm, about 65 mm, about 66 mm, about 67 mm, about 68 mm, about 69 mm, about 70 mm, about 71 mm, about 72 mm, about 73 mm, about 74 mm, about 75 mm, about 76 mm, about 77 mm, about 78 mm, about 79 mm, about 80 mm, about 81 mm, about 82 mm, about 83 mm, about 84 mm, about 85 mm, about 86 mm, about 87 mm, about 88 mm, about 89 mm, about 90 mm, about 91 mm, about 92 mm, about 93 mm, about 94 mm, about 95 mm, about 96 mm, about 97 mm, about 98 mm, about 99 mm, about 100 mm, about 110 mm, about 120 mm, about 130 mm, about 140 mm, about 150 mm, about 160 mm, about 170 mm, about 180 mm, about 190 mm, about 200 mm, about 210 mm, about 220 mm, about 230 mm, about 240 mm, about 250 mm, about 260 mm, about 270 mm, about 280 mm, about 290 mm, about 300 mm, about 310 mm, about 320 mm, about 330 mm, about 340 mm, about 350 mm, about 360 mm, about 370 mm, about 380 mm, about 390 mm, about 400 mm, about 410 mm, about 420 mm, about 430 mm, about 440 mm, about 450 mm, about 460 mm, about 470 mm, about 480 mm, about 490 mm, or about 500 mm.

[0032] In accordance with an aspect, there is provided a method for directly bonding two or more articles of PEEK. The method may include treating bonding surfaces on a first article of PEEK and a second article of PEEK. The method may include placing the treated bonding surfaces of the first article of PEEK and second article of PEEK into contact with each other. The method further may include heating the first article of PEEK and second article of PEEK for a pre-determined time at a temperature between about 250 °C and the melting point of the PEEK.

[0033] In further embodiments, the method may include applying a pre-determined compressive load to the first article of PEEK and second article of PEEK during heating.

[0034] In accordance with an aspect, there is provided a method for directly bonding two or more articles of PEEK. The method may include treating bonding surfaces on a first article of PEEK and a second article of PEEK. The method may include placing the treated bonding surfaces of the first article of PEEK and second article of PEEK into contact with each other. The method further may include applying a pre-determined compressive load to the first article of PEEK and second article of PEEK. The method additionally may include heating the compressed first article and second article of PEEK for a pre-determined time at a temperature between about 250 °C and the melting point of the PEEK. In accordance with an aspect, there is provided a method for directly bonding two or more articles of PEEK. The method may include treating bonding surfaces on a first article of PEEK and a second article of PEEK. The method may include placing the treated bonding surfaces of the first article of PEEK and second article of PEEK into contact with each other. The method further may include applying a compressive load to the first article of PEEK and second article of PEEK. The method further may include heating the first article of PEEK and second article of PEEK for a pre-determined time at a temperature between about 250 °C and the melting point of the PEEK. The method further may include applying an additional compressive load to the first article of PEEK and second article of PEEK during heating, such that the total pre-determined compressive load applied to the first article of PEEK and second article of PEEK during heating is a combination of the compressive load applied before heating and the additional compressive load applied during heating.

[0035] In some embodiments, the materials from which the PEEK articles are made may include virgin PEEK material of various trade names produced by various vendors, derivatives of such virgin PEEK materials which include non-PEEK additives, composite materials which include such virgin PEEK materials or derivatives, and / or any combination thereof. In some embodiments, such composite materials may include, e.g., glass-filled PEEK, carbon-filled PEEK, carbon fiber-filled PEEK, or bearing grade PEEK.

[0036] BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings are not drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in the various figures may be represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. In the drawings:

[0038] FIG. 1 illustrates a flow chart of a method of bonding two or more articles of PEEK, according to an embodiment;

[0039] FIG. 2 illustrates a schematic of bonding two or more articles of PEEK with directly applied compressive load in situ;

[0040] FIG. 3 illustrates a fixture used to bond two or more articles of PEEK with a locked-in compressive load applied before heating; FIG. 4 shows images of a vice used to bond two PEEK blocks, before and after compressive load being applied to the PEEK blocks via clamping;

[0041] FIG. 5 illustrates a fixture used to bond two or more articles of PEEK with spacers of predetermined compression distance. As illustrated, the pre-determined compressive load during heating was achieved indirectly by constraining the thermal expansion of the contacted articles of PEEK during heating in the void space between the bonding plates, the height of which was set by the spacers;

[0042] FIG. 6 illustrates a methodology by which two or more stacked PEEK articles may be independently bonded at the same time by using a non-bonding separator between each PEEK article;

[0043] FIG. 7 illustrates images of the non-bonding surfaces of PEEK before and after bonding;

[0044] FIGS. 8A-8B illustrate an example of creating channels in a PEEK part by the bonding of two PEEK articles. FIG. 8 A shows a first PEEK article with preformed features prior to bonding. FIG. 8B shows vertical cross sections through the resulting part after this first PEEK article was bonded to a second PEEK article, which was flat and featureless. These cross sections reveal the channels that were formed inside the part;

[0045] FIGS. 9A-9B are images of a bonded PEEK cross, made by bonding two articles of PEEK over a 5x5 mm2area, before and after tensile-pull testing. FIG. 9A is a photograph before pull testing of the cross, which was bonded by methods disclosed herein, but under conditions that were sub-optimal for maximizing bond strength. FIG. 9B illustrates the broken cross after tensile-pull testing, showing breakage at the bonding interface and little material transferred from one article to the other;

[0046] FIG. 10 illustrates the tensile-pull testing results of the bonded PEEK cross illustrated in FIGS. 9A-9B;

[0047] FIGS. 11A-11B are images of a bonded PEEK cross, made by bonding two articles of PEEK over a 5x5 mm2area, before and after tensile-pull testing. FIG. 11 A is a photograph before pull testing of the cross, which was bonded by methods disclosed herein, under conditions that were more optimal for maximizing bond strength compared to those used to bond the cross in FIG. 9A. FIG. 11B illustrates the broken cross after tensile -pull testing, showing breakage at the bonding interface with a large portion of material transferred from one PEEK article to the other; FIG. 12 illustrates the tensile-pull testing results of the bonded PEEK cross illustrated in FIGS. 11A-11B;

[0048] FIGS. 13A-13B are images of a cross machined out of solid PEEK, before and after tensile-pull testing. This cross was made to the same dimensions as the bonded crosses in FIG. 9A and FIG. 11 A. FIG. 13A is a photograph of the solid PEEK cross before tensile-pull testing, after being subjected to a similar heating cycle to that used to bond the crosses in FIG. 9A and FIG. 11 A. FIG. 13B illustrates the broken cross after pull testing, showing material transfer from one part to the other across the entire joint area;

[0049] FIG. 14 illustrates the tensile-pull testing results of the solid PEEK cross illustrated in FIGS. 13A-13B;

[0050] FIGS. 15A-15B are side (FIG. 15A) and top (FIG. 15B) photographs of two bonded coupons of PEEK;

[0051] FIG. 16 illustrates the tensile-pull test setup for measuring the shear bonding strength of the two bonded coupons of PEEK illustrated in FIGS. 15A-15B; and

[0052] FIG. 17 illustrates the tensile-pull testing results of the two bonded coupons of PEEK illustrated in FIGS. 15A-15B. The vertical axis displays the average shear stress on the bonding interface, but ultimate failure occurred in the bulk of one of the initial PEEK coupons rather than at the bonding interface;

[0053] FIG. 18 shows three PEEK articles with dimensions. These articles were prepared for bonding in the illustrated orientation by methods disclosed herein;

[0054] FIG. 19A illustrates pre-heating compression of a PEEK stack made from the three articles shown in FIG. 18; FIG. 19B illustrates the resulting part after bonding of the PEEK stack shown in FIG. 19A;

[0055] FIG. 20 illustrates the tensile-pull test setup for measuring the bonding strength of the bonded three-article PEEK part of FIG. 19B;

[0056] FIG. 21 illustrates the tensile-pull testing results of the bonded three-article PEEK part for the setup shown in FIG. 20;

[0057] FIG. 22 shows photographs from different perspectives of the broken three-article PEEK part after failure at the end of the tensile-pull test in FIG. 21. The bonded part failed in the bulk of the center PEEK article rather than at either of the two bonding interfaces; and FIGS. 23A-23C illustrate the formation of filters made from multiple layers of PEEK films that have been thermally bonded by methods disclosed herein. FIG. 23A illustrates the shapes of the individual PEEK film layers. FIG. 23B illustrates the bonding of the stacked PEEK films. FIG. 23C illustrates the resultant filters.

[0058] DETAILED DESCRIPTION

[0059] Conventional connections for fluidic components and devices used in the chemical analysis industry, e.g., pumps, valves, and flow sensors, is typically achieved using large bundles or clusters of suitable lengths of tubing terminating in appropriate fittings. The large number of connections between sources of fluid, sample station, sensors, and analytical equipment require substantial lengths of tubing, which makes installation, maintenance, and troubleshooting cumbersome and error-prone.

[0060] There has been a recent trend in the chemical analysis industry to shift away from the traditional bundles or clusters of tubing and move towards integrated fluidic-handling manifolds. Integrated manifolds with internal fluid channels and external connections ports can provide a robust and reliable solution for connecting and managing large numbers of fluidic components. Manifolds are used to reduce connection complexity and leakage risks and overall provide for more facile installation, troubleshooting and servicing. At present, fluid handling manifolds with integrated fluid channels are generally made from polymers such as poly(methyl methacrylate) (PMMA, i.e., acrylic), polyetherimide (PEI, i.e., ULTEM®), or polytetrafluoroethylene (PTFE, i.e., TEFLON®). While these materials are suitable for many applications, these materials lack sufficient mechanical strength or chemical resistance for certain analysis applications.

[0061] Many application-specific fluid handling elements, e.g. filters, microfluidic devices, micro-LCs, and mixers, have disadvantages in their manufacturing processes which can limit the achievable flow geometries and / or require the parts to be made from a material which is unsuitable for some applications. These, and related constraints may result in undesirably high production costs, cause suboptimal performance of the produced parts, or even preclude some applications entirely. Depending on the application, fluid handling elements may have special requirements regarding the material presented in the flow path. Certain material classes, e.g. metals, polymers, or ceramics, or specific types thereof, may be more ideal than others when considering factors such as chemical compatibility or contaminant leeching. Filters, such as solvent filters and inline filters, are generally produced using a sintering process where a monodisperse granulate or powder is pressed into a desired shape under the influence of pressure and heat. Under appropriate, i.e., material- specific, conditions, the applied pressure and heat cause the particles to sinter together and form a stable structure. Though the exact arrangement of sintered particles is random, the resulting structure may be regarded stochastically as yielding a uniform pore size provided that the individual particle volumes are sufficiently small relative to the volume of the part. Having a uniform pore structure is often undesirable for filter applications, however, due to faster clogging and inability to recover performance via back flushing.

[0062] One method for producing fluidic handling systems, e.g., microfluidic devices, micro- LCs, filters, and mixers, is by bonding together multiple layers or films of a material. Complex 3D flow path structures can be achieved in this way by appropriately aligning much simpler channel / through-hole features in each discreet layer. For any material which cannot be 3D printed, many complex internal flow geometries are only achievable by this approach. There are established methods of applying such manufacturing processes for many materials, including metals, e.g. metal microfluidics, and certain polymers, e.g., poly[methyl methacrylate] and polyetherimide. Metal microfluidics allows for bonding of multiple (> 3) thin layers (<1 mm) to either form low-profile parts and / or reduce the amount of material required to create a given flow path.

[0063] Polyether ether ketone (PEEK) is recognized and widely used as a bio-inert material with high chemical resistance and good mechanical strength. For example, PEEK tubing and fittings are used in inline auto dilution systems for inductively coupled plasma-mass spectrometry / optical emission spectroscopy (ICP-MS / OES). Compared to other polymers commonly used for commercial manifolds, e.g., PMMA, PEI, and PTFE, it is substantially more difficult to achieve strong self-bonding of PEEK due to its higher melting point and lower surface energy. Laser or ultrasonic welding of multiple pieces of PEEK generally produces bonding strengths of less than 1 MPa in the finished fluid handling components, making manifolds produced through these routes unsuitable for containing even low fluidic pressures, far lower than the pressures required for most chemical analysis methods. Stronger bonding of multiple pieces of PEEK can be achieved by using heat-curing epoxy adhesives; however, this has the disadvantage of introducing a second, foreign material to the finished fluid handling component that may reduce the final chemical resistance of the bonded structures or limit operating temperature and / or pressure. It is an object of the present disclosure to provide for methods of directly bonding two or more pieces of PEEK without the use of adhesives or welding that provide for non-chemically inert, weaker joints.

[0064] Disclosed herein are methods for the direct thermal bonding of two or more articles of PEEK. As disclosed herein, the bonding surfaces of the two or more articles of PEEK are pretreated using one or more physical or chemical treatments to enhance surface roughness and surface energy such that a more stable bond is formed. The pretreated bonding surfaces are mated under a compressive load such that, once the mated articles of PEEK are heated to a high temperature between 250 °C and the melting point of the PEEK, diffusion bonding occurs at the mating point. It is an object of the methods disclosed herein to produce parts, e.g., fluid handling parts, e.g., manifolds, filters, in-line mixers, and distribution plates, that have a bonding strength close to 28 MPa or higher and a comparable chemical resistance to unbonded, bulk PEEK material.

[0065] In accordance with an aspect, there is provided a method for directly bonding two or more articles of PEEK. The method may include treating bonding surfaces on a first article of PEEK and a second article of PEEK. The method may include placing the treated bonding surfaces of the first article of PEEK and second article of PEEK into contact with each other. The method further may include heating the first article and second article of PEEK for a predetermined time at a temperature between 250 °C and the melting point of the PEEK. The method additionally may include applying a pre-determined compressive load to the first article and second article of PEEK during heating.

[0066] FIG. 1 illustrates a method according to an embodiment of this disclosure. In FIG. 1, method 100 bonding directly bonding two or more articles of PEEK includes step 102 of treating the bonding surfaces on a first and a second article of PEEK. Following treatment of the bonding surfaces of the first article of PEEK and the second article of PEEK, the bonding surfaces of the first article of PEEK and the second article of PEEK are placed into contact with each other at step 104. The bonding surfaces of the first article of PEEK and the second article of PEEK are heated to a temperature between 250 °C and the melting point of the PEEK and are heated for a pre-determined amount of time at step 106 to allow diffusion bonding to occur between the bonding surfaces of the first article of PEEK and the second article of PEEK. During heating, the first and the second article of PEEK are compressed by a pre-determined compressive load at step 108. Once bonded, the PEEK article can be cooled along a temperature gradient at optional step 110 in the dashed box in FIG. 1.

[0067] In some embodiments, the bonding surfaces on the first article of PEEK and second article of PEEK are treated with a plasma. PEEK is a material with a low surface energy, meaning that the surface is difficult to adhere to and is not readily wet by liquids such as water, i.e., exhibits large contact angles. The application of a plasma to the surface of PEEK generally increases the surface energy, wettability, adhesiveness, and roughness by altering the molecular structure of the PEEK surface. The plasma may be an oxidative plasma, i.e., an oxygen plasma, for cleaning the bonding surfaces and increasing surface energy, surface roughness, and / or wettability. Oxygen plasmas increase the number of hydroxyl, i.e., -OH, and -CO- groups on the PEEK surface, increasing the surface energy of PEEK. Other plasmas, e.g., argon, nitrogen, hydrogen, air, and / or ammonia, may be used as well to tune the characteristics of the resultant PEEK articles. A variety of combinations of plasma power, gas pressure and time in wide ranges could effectively modify PEEK bonding surfaces and improve bonding strength. For example, the plasma power could range from about 10 W to about 1250 W, e.g., about 10 W to about 100 W, about 50 W to about 150 W, about 100 W to about 200 W, about 150 W to about 250 W, about 300 W to about 400 W, about 450 W to about 550 W, about 500 W to about 600 W, about 650 W to about 750 W, about 700 W to about 800 W, about 750 W to about 850 W, about 800 W to about 900 W, about 850 W to about 950 W, about 900 W to about 1000 W, about 950 W to about 1050 W, about 1000 W to about 1100 W, about 1050 W to about 1150 W, about 1100 W to about 1200 W, or about 1150 W to about 1250 W, e.g., about 10 W, about 15 W, about 20 W, about 25 W, about 30 W, about 35 W, about 40 W, about 45 W, about 50 W, about 55 W, or about 50 W, about 55 W, about 60 W, about 65 W, about 70 W, about 75 W, about 80 W, about 85 W, about 90 W, about 95 W, or about 100 W, about 150 W, about 200 W, about 250 W, about 300 W, about 350 W, about 400 W, about 450 W, about 500 W, about 550 W, about 600 W, about 650 W, about 700 W, about 750 W, about 800 W, about 850 W, about 900 W, about 950 W, about 1000 W, about 1050 W, about 1100 W, about 1150 W, about 1200 W, or about 1250 W. The pressure of the gas used to generate the plasma could range from 1 mTorr to 760,000 mTorr, i.e., about 760 torr or 1 atmosphere, e.g., about 1 mTorr to 10,000 mTorr, about 5,000 mTorr to about 50,000 mTorr, about 10,000 mTorr to about 100,000 mTorr, about 50,000 mTorr to about 250,000 mTorr, about 100,000 mTorr to about 400,000 mTorr, about 200,000 mTorr to about 500,000 mTorr, about 350,000 mTorr to about 600,000 mTorr, or about 500,000 mTorr to about 760,000 mTorr.

[0068] The plasma treatment time, i.e., the exposure time for the bonding surfaces, is for a time between about 10 seconds to about 60 minutes, e.g., about 10 seconds to 60 seconds, about 1 minute to about 10 minutes, about 5 minutes to about 15 minutes, about 10 minutes to about 20 minutes, about 15 minutes to about 25 minutes, about 20 minutes to about 30 minutes, about 25 minutes to about 35 minutes, about 30 minutes to about 40 minutes, about 35 minutes to about 45 minutes, about 40 minutes to about 50 minutes, about 45 minutes to about 55 minutes, or about 50 minutes to about 60 minutes, e.g., about 10 seconds, about 30 seconds, about 1 minute, about 1.5 minutes, about 2 minutes, about 2.5 minutes, about 3 minutes, about 3.5 minutes, about 4 minutes, about 4.5 minutes, about 5 minutes, about 5.5 minutes, about 6 minutes, about 6.5 minutes, about 7 minutes, about 7.5 minutes, about 8 minutes, about 8.5 minutes, about 9 minutes, about 9.5 minutes, or about 10 minutes, about 15 minutes, about 20 minutes, about 25 minutes, about 30 minutes, about 35 minutes, about 40 minutes, about 45 minutes, about 50 minutes, about 55 minutes, or about 60 minutes.

[0069] The two or more articles of PEEK being directly bonded can be in any form factor. In some embodiments, the two or more articles of PEEK can be PEEK blocks, cylinders, or other PEEK parts having sufficient thickness and / or mass for an intended purpose. For example, PEEK block can be used to form manifolds with channels for directing fluids as a block has sufficient thickness to accept the formation of the corresponding parts of the channels when pressed together. As another example, the two or more articles of PEEK can be PEEK films. As disclosed herein, films or layers of a material can be used in a stack arrangement to form fluid handling devices. Individual layers of PEEK film can be shaped or cut with precision forming methods, e.g., laser cutting, mechanical die cutting, or lithographic patterning and etching, to form a desired shape or other internal structures, e.g., channels, when the two or more PEEK films are bonded together. For example, the individual layers of PEEK film can be shaped to have complimentary structural features such that when pressed together and bonded, a desired shape is achieved.

[0070] The individual layers of PEEK film can be of any suitable thickness for the intended application. In some embodiments, the individual layers of PEEK film may have a thickness of about 10 pm to about 1000 pm, e.g., about 10 pm to about 1000 pm, about 25 pm to about 900 m, about 50 pm to about 800 pm, about 75 pm to about 700 pm, about 100 pm to about 600 pm, about 150 pm to about 500 pm, about 200 pm to about 400 pm, or about 250 pm to about 300 pm.

[0071] In some embodiments, the two or more articles of PEEK include bulk PEEK layers. In some embodiments, such bulk PEEK layers can have individual thicknesses that vary, e.g., thicknesses from about 1 mm to about 500 mm, e.g., about 1 mm, about 2 mm, about 3 mm, about 4 mm, about 5 mm, about 6 mm, about 7 mm, about 8 mm, about 9 mm, 10 mm, about 11 mm, about 12 mm, about 13 mm, about 14 mm, about 15 mm, about 16 mm, about 17 mm, about 18 mm, about 19 mm, about 20 mm, about 21 mm, about 22 mm, about 23 mm, about 24 mm, about 25 mm, about 26 mm, about 27 mm, about 28 mm, about 29 mm, about 30 mm, about 31 mm, about 32 mm, about 33 mm, about 34 mm, about 35 mm, about 36 mm, about 37 mm, about 38 mm, about 39 mm, about 40 mm, about 41 mm, about 42 mm, about 43 mm, about 44 mm, about 45 mm, about 46 mm, about 47 mm, about 48 mm, about 49 mm, about 50 mm, about 51 mm, about 52 mm, about 53 mm, about 54 mm, about 55 mm, about 56 mm, about 57 mm, about 58 mm, about 59 mm, about 60 mm, about 61 mm, about 62 mm, about 63 mm, about 64 mm, about 65 mm, about 66 mm, about 67 mm, about 68 mm, about 69 mm, about 70 mm, about 71 mm, about 72 mm, about 73 mm, about 74 mm, about 75 mm, about 76 mm, about 77 mm, about 78 mm, about 79 mm, about 80 mm, about 81 mm, about 82 mm, about 83 mm, about 84 mm, about 85 mm, about 86 mm, about 87 mm, about 88 mm, about 89 mm, about 90 mm, about 91 mm, about 92 mm, about 93 mm, about 94 mm, about 95 mm, about 96 mm, about 97 mm, about 98 mm, about 99 mm, about 100 mm, about 110 mm, about 120 mm, about 130 mm, about 140 mm, about 150 mm, about 160 mm, about 170 mm, about 180 mm, about 190 mm, about 200 mm, about 210 mm, about 220 mm, about 230 mm, about 240 mm, about 250 mm, about 260 mm, about 270 mm, about 280 mm, about 290 mm, about 300 mm, about 310 mm, about 320 mm, about 330 mm, about 340 mm, about 350 mm, about 360 mm, about 370 mm, about 380 mm, about 390 mm, about 400 mm, about 410 mm, about 420 mm, about 430 mm, about 440 mm, about 450 mm, about 460 mm, about 470 mm, about 480 mm, about 490 mm, or about 500 mm.

[0072] In some embodiments, the individual layers of PEEK film may have a thickness of about 10 pm, about 20 pm, about 30 pm, about 40 pm, about 50 pm, about 60 pm, about 70 pm, about 80 pm, about 90 pm, about 100 pm, about 110 pm, about 120 pm, about 130 pm, about 140 pm, about 150 pm, about 160 pm, about 170 pm, about 180 pm, about 190 pm, about 200 pm, about 210 pm, about 220 pm, about 230 pm, about 240 pm, about 250 pm, about 260 pm, about 270 pm, about 280 pm, about 290 pm, about 300 pm, about 310 pm, about 320 pm, about 330 pm, about 340 pm, about 350 pm, about 360 pm, about 370 pm, about 380 pm, about 390 pm, about 400 pm, about 410 pm, about 420 pm, about 430 pm, about 440 pm, about 450 pm, about 460 pm, about 470 pm, about 480 pm, about 490 pm, about 500 pm, about 550 pm, about 520 pm, about 530 pm, about 540 pm, about 550 pm, about 560 pm, about 570 pm, about 580 pm, about 590 pm, about 600 pm, about 610 pm, about 620 pm, about 630 pm, about 640 pm, about 650 pm, about 660 pm, about 670 pm, about 680 pm, about 690 pm, about 700 pm, about 710 pm, about 720 pm, about 730 pm, about 740 pm, about 750 pm, about 760 pm, about 770 pm, about 780 pm, about 790 pm, about 800 pm, about 810 pm, about 820 pm, about 830 pm, about 840 pm, about 850 pm, about 860 pm, about 870 pm, about 880 pm, about 890 pm, about 900 pm, about 910 pm, about 920 pm, about 930 pm, about 940 pm, about 950 pm, about 960 pm, about 970 pm, about 980 pm, about 990 pm, or about 1000 pm.

[0073] PEEK-to-PEEK bonding normally requires high compressive pressure to be applied during the diffusion bonding process to achieve high strength. Such pressures may be applied during heating, i.e., in situ, in a diffusion bonder as illustrated in FIG. 2, either in a constant pressure mode or a constant displacement / spacing mode. In some embodiments, a compressive load applied in-situ to the first article of PEEK and second article of PEEK provides for compression resulting in a change of about 0% to about 10% of an initial uncompressed dimension of the first article of PEEK and second article of PEEK, e.g., about 0% to about 3%, about 1% to about 4%, about 2% to about 5%, about 3% to about 6%, about 4% to about 7%, about 5% to about 8%, about 6% to about 9%, or about 7% to about 10%, e.g., about 0%, about 0.25%, about 0.5%, about 0.75%, about 1%, about 1.25%, about 1.5%, about 1.75%, about 2%, about 2.25%, about 2.5%, about 2.75%, about 3%, about 3.25%, about 3.5%, about 3.75%, about 4%, about 4.25%, about 4.5%, about 4.75%, about 5%, about 5.25%, about 5.5%, about 5.75%, about 6%, about 6.25%, about 6.5%, about 6.75%, about 7%, about 7.25%, about 7.5%, about 7.75%, about 8%, about 8.25%, about 8.5%, about 8.75%, about 9%, about 9.25%, about 9.5%, about 9.75%, or about 10%.

[0074] In some embodiments, a constant displacement of about 0% to 10% of an initial uncompressed dimension of the first article of PEEK and second article of PEEK, e.g., about 0% to about 3%, about 1 % to about 4%, about 2% to about 5%, about 3% to about 6%, about 4% to about 7%, about 5% to about 8%, about 6% to about 9%, or about 7% to about 10%, c.g., about 0%, about 0.25%, about 0.5%, about 0.75%, about 1%, about 1.25%, about 1.5%, about 1.75%, about 2%, about 2.25%, about 2.5%, about 2.75%, about 3%, about 3.25%, about 3.5%, about 3.75%, about 4%, about 4.25%, about 4.5%, about 4.75%, about 5%, about 5.25%, about 5.5%, about 5.75%, about 6%, about 6.25%, about 6.5%, about 6.75%, about 7%, about 7.25%, about 7.5%, about 7.75%, about 8%, about 8.25%, about 8.5%, about 8.75%, about 9%, about 9.25%, about 9.5%, about 9.75%, or about 10%, is held during heating.

[0075] As disclosed herein, a compressive load may also be applied to the contacting bonding surfaces on the first article of PEEK and second article of PEEK before heating to cause compression, i.e., a compressive displacement, of the first article of PEEK and second article of PEEK. The compressive displacement of the first article of PEEK and second article of PEEK can be locked in by tightening the nuts of the press, shown in FIG. 3, and the entire fixture assembly can be placed and heated in an oven to bond the PEEK. Without wishing to be bound by any particular theory, additional compressive load may be applied to the first article and second article of PEEK during heating, e.g., by using mechanical force or by constraining the thermal expansion of the PEEK as it heats. For example, the first article and second article of PEEK can be secured together in a fixture that permits application of a compressive force, e.g., a vice (illustrated in FIG. 4), mechanical press, hydraulic press, or the like to one or both of the non-bonding surfaces. Upon compression in this manner, the distance compressed can be measured, starting from the known distance of the total uncompressed thickness of the first article of PEEK and second article of PEEK being bonded, and the compressed distance fixed using methods known in the art. Alternatively, such compressive displacement could be either “positive” or “negative” by using an appropriately sized spacer or spacers to set the compression distance. When spacers are used in the fixture holding the first article of PEEK and second article of PEEK, such as illustrated in FIG. 5, the spacers can either be shorter or taller than the total uncompressed thickness of the first article of PEEK and second article of PEEK. If the spacers are shorter, the pre-heating compressive displacement is “positive” when the top bonding plate stops on the spacers, so there is an initial compressive load / pressure applied to the first article of PEEK and second article of PEEK before heating. Thermal expansion mismatch between the PEEK articles and the fixture during heating will produce additional compressive pressure to the initial compressive load generated by the positive pre-heating compressive displacement. Conversely, the pre-heating compressive displacement is “negative” if the spacers are taller than the initial uncompressed thickness of the first article of PEEK and second article of PEEK. In this case, the pre-heating compressive load is zero. The same effect of thermal expansion mismatch between the bonding plates and the first article of PEEK and second article of PEEK during heating can still produce compressive pressure, however, and facilitate PEEK bonding. Thus, the total pre-determined compressive load applied to the first article of PEEK and second article of PEEK during heating will be a combination of the compressive load applied before heating, if any, and any additional compressive load applied during heating.

[0076] In some embodiments, a compressive load applied before heating to the first article and the second article of PEEK provides for compression to at least one of the first article and the second article of PEEK of about 0% to about 10% of an initial uncompressed dimension of the first article of PEEK and second article of PEEK, e.g., about 0% to about 3%, about 1% to about 4%, about 2% to about 5%, about 3% to about 6%, about 4% to about 7%, about 5% to about 8%, about 6% to about 9%, or about 7% to about 10%, e.g., about 0%, about 0.25%, about 0.5%, about 0.75%, about 1%, about 1.25%, about 1.5%, about 1.75%, about 2%, about 2.25%, about 2.5%, about 2.75%, about 3%, about 3.25%, about 3.5%, about 3.75%, about 4%, about 4.25%, about 4.5%, about 4.75%, about 5%, about 5.25%, about 5.5%, about 5.75%, about 6%, about 6.25%, about 6.5%, about 6.75%, about 7%, about 7.25%, about 7.5%, about 7.75%, about 8%, about 8.25%, about 8.5%, about 8.75%, about 9%, about 9.25%, about 9.5%, about 9.75%, or about 10%.

[0077] In some embodiments, additional compressive load applied to the first article of PEEK and the second article of PEEK during heating provides for additional compression to at least one of the first article of PEEK and the second article of PEEK of about 0% to about 10% of an initial dimension of the first article of PEEK and second article of PEEK after any compression applied before heating, e.g., about 0% to about 3%, about 1% to about 4%, about 2% to about 5%, about 3% to about 6%, about 4% to about 7%, about 5% to about 8%, about 6% to about 9%, or about 7% to about 10%, e.g., about 0%, about 0.25%, about 0.5%, about 0.75%, about 1%, about 1.25%, about 1.5%, about 1.75%, about 2%, about 2.25%, about 2.5%, about 2.75%, about 3%, about 3.25%, about 3.5%, about 3.75%, about 4%, about 4.25%, about 4.5%, about 4.75%, about 5%, about 5.25%, about 5.5%, about 5.75%, about 6%, about 6.25%, about 6.5%, about 6.75%, about 7%, about 7.25%, about 7.5%, about 7.75%, about 8%, about 8.25%, about 8.5%, about 8.75%, about 9%, about 9.25%, about 9.5%, about 9.75%, or about 10%. The compressive load(s) may be applied to the first article of PEEK and the second article of PEEK using a source of mechanical pressure, such as a vice, mechanical press, hydraulic press, fixturing, or other similar devices.

[0078] When the first article of PEEK and second article of PEEK are compressed in a fixture and heated between 250 °C and the melting point of the PEEK, the PEEK may begin to adhere to the fixture material, causing difficulty when separating or even irreversible damage to the PEEK articles after bonding. To prevent this type of adhesion, a separator layer or barrier layer is disposed between the non-bonding surfaces of the first article of PEEK and second article of PEEK and the bearing surfaces of the fixture holding the first article of PEEK and second article of PEEK in position. The separators may be of a variety of materials, including aluminum and stainless steel sheets or foils, polyimide (PI) sheets, or ceramics. Suitable separator materials are those that can withstand compressive pressures, have a higher melting point than PEEK, and do not adhere to PEEK or can be easily separated from the PEEK after bonding. Some applications may require bonded PEEK articles which are free of metals, in which case a non-metallic or otherwise suitably inert separator material may be required. One non-limiting example of an inert separator material useful for methods disclosed herein is polyimide (PI). PI is a high- temperature compatible, highly inert, and physically robust polymer that can act as a separator layer or barrier for PEEK diffusion bonding. Other materials similar in properties to PI that would be useful for a separator layer or barrier for PEEK diffusion bonding are within the scope of this disclosure. Alternatively, metal separators coated with inert coatings may prevent metal contaminates from passing on to the bonded PEEK manifolds.

[0079] The published PEEK glass transition temperature is between 143 °C to 162 °C, but most commercially available PEEK materials are rated for a maximum continuous operating temperature of about 250 °C. The published melting point of PEEK is between 343 °C and 353 °C. Effective diffusion bonding of treated PEEK requires a temperature higher than 250 °C, but below the melting point. In some embodiments, the compressed first article and second article of PEEK may be heated to a temperature of at least 250 °C, such as from about 250 °C to about 360 °C, e.g., about 250 °C to about 280 °C, about 270 °C to about 300 °C, about 290 °C to about 330 °C, or about 320 °C to about 360 °C, e.g., about 250 °C, about 251 °C, about 252 °C, about 253 °C, about 254 °C, about 255 °C, about 256 °C, about 257 °C, about 258 °C, about 259 °C, about 260 °C, about 261 °C, about 262 °C, about 263 °C, about 264 °C, about 265 °C, about 266 °C, about 267 °C, about 268 °C, about 269 °C, about 270 °C, about 271 °C, about 272 °C, about 273 °C, about 274 °C, about 275 °C, about 276 °C, about 277 °C, about 278 °C, about 279 °C, about 280 °C, about 281 °C, about 282 °C, about 283 °C, about 284 °C, about 285 °C, about 286 °C, about 287 °C, about 288 °C, about 289 °C, about 290 °C, about 291 °C, about 292 °C, about 293 °C, about 294 °C, about 295 °C, about 296 °C, about 297 °C, about 298 °C, about 299 °C, about 300 °C, about 301 °C, about 302 °C, about 303 °C, about 304 °C, about 305 °C, about 306 °C, about 307 °C, about 308 °C, about 309 °C, about 310 °C, about 311 °C, about 312 °C, about 313 °C, about 314 °C, about 315 °C, about 316 °C, about 317 °C, about 318 °C, about 319 °C, about 320 °C, about 321 °C, about 322 °C, about 323 °C, about 324 °C, about 325 °C, about 326 °C, about 327 °C, about 328 °C, about 329 °C, about 330 °C, about 331 °C, about 332 °C, about 333 °C, about 334 °C, about 335 °C, about 336 °C, about 337 °C, about 338 °C, about 339 °C, about 340 °C, about 341 °C, about 342 °C, about 343 °C, about 344 °C, about 345 °C, about 346 °C, about 347 °C, about 348 °C, about 349 °C, about 350 °C, or about 351 °C, about 352 °C, about 353 °C, about 354 °C, about 355 °C, about 356 °C, about 357 °C, about 358 °C, about 359 °C, or about 360 °C. The heating of the PEEK can occur in any heated enclosure that provides for accurate temperature control. For example, the heating can occur in a furnace, oven, refractory chamber, or other suitable enclosure.

[0080] In some embodiments, heating the compressed first article of PEEK and second article of PEEK may occur by a temperature gradient. The temperature gradient will bring the temperature of the oven or other heated enclosure from room temperature up to the bonding temperature, e.g., as disclosed herein, then hold at the bonding temperature for the predetermined amount of time.

[0081] In some embodiments, the temperature gradient for heating the compressed first article and second article of PEEK is between about 0.1 °C / min to about 120 °C / min, e.g., about 0.1 °C / min to about 1 °C / min, about 0.5 °C / min to about 5 °C / min, about 1 °C / min to about 10 °C / min, about 5 to about 20 °C / min, about 10 °C / min to about 30 °C / min, about 20 °C / min to about 50 °C / min, about 30 °C / min to about 60 °C / min, about 40 °C / min to about 70 °C / min, about 50 °C / min to about 80 °C / min, about 60 °C / min to about 90 °C / min, about 70 °C / min to about 100 °C / min, about 80 °C / min to about 110 °C / min, or about 90 °C / min to about 120 °C / min, e.g., about 0.1 °C / min, about 0.2 °C / min, about 0.3 °C / min, about 0.4 °C / min, about 0.5 °C / min, about 0.6 °C / min, about 0.7 °C / min, about 0.8 °C / min, about 0.9 °C / min, about 1 °C / min, about 1 .5 °C / min, about 2 °C / min, about 2.5 °C / min, about 3 °C / min, about 3.5°C / min, about 4 °C / min, about 4.5 °C / min, about 5 °C / min, about 5.5 °C / min, about 6 °C / min, about 6.5 °C / min, about 7 °C / min, about 7.5 °C / min, about 8 °C / min, about 8.5 °C / min, about 9 °C / min, about 9.5 °C / min, about 10 °C / min, about 15 °C / min, about 20 °C / min, about 25 °C / min, about 30 °C / min, about 35 °C / min, about 40 °C / min, about 45 °C / min, about 50 °C / min, about 55 °C / min, about 60 °C / min, about 65 °C / min, about 70 °C / min, about 75 °C / min, about 80 °C / min, about 85 °C / min, about 90 °C / min, about 95 °C / min, about 100 °C / min, about 105 °C / min, about 110 °C / min, about 115 °C / min, or about 120 °C / min. In specific embodiments, the fixture with the first article of PEEK and second article of PEEK may be placed into an enclosure pre-heated to the bonding temperature.

[0082] Similarly to the temperature gradient used to bring the oven or other heated enclosure and the compressed first article of PEEK and second article of PEEK up to the bonding temperature, the bonded PEEK article is generally cooled back down to room temperature using a cooling gradient. The cooling temperature gradient is between about 0.1 °C / min to about 120 °C / min, e.g., about 0.1 °C / min to about 1 °C / min, about 0.5 °C / min to about 5 °C / min, about 1 °C / min to about 10 °C / min, about 5 to about 20 °C / min, about 10 °C / min to about 30 °C / min, about 20 °C / min to about 50 °C / min, about 30 °C / min to about 60 °C / min, about 40 °C / min to about 70 °C / min, about 50 °C / min to about 80 °C / min, about 60 °C / min to about 90 °C / min, about 70 °C / min to about 100 °C / min, about 80 °C / min to about 110 °C / min, or about 90 °C / min to about 120 °C / min, e.g., about 0.1 °C / min, about 0.2 °C / min, about 0.3 °C / min, about 0.4 °C / min, about 0.5 °C / min, about 0.6 °C / min, about 0.7 °C / min, about 0.8 °C / min, about 0.9 °C / min, about 1 °C / min, about 1.5 °C / min, about 2 °C / min, about 2.5 °C / min, about 3 °C / min, about 3.5°C / min, about 4 °C / min, about 4.5 °C / min, about 5 °C / min, about 5.5 °C / min, about 6 °C / min, about 6.5 °C / min, about 7 °C / min, about 7.5 °C / min, about 8 °C / min, about 8.5 °C / min, about 9 °C / min, about 9.5 °C / min, about 10 °C / min, about 15 °C / min, about 20 °C / min, about 25 °C / min, about 30 °C / min, about 35 °C / min, about 40 °C / min, about 45 °C / min, about 50 °C / min, about 55 °C / min, about 60 °C / min, about 65 °C / min, about 70 °C / min, about 75 °C / min, about 80 °C / min, about 85 °C / min, about 90 °C / min, about 95 °C / min, about 100 °C / min, about 105 °C / min, about 110 °C / min, about 115 °C / min, or about 120 °C / min. In some embodiments, the fixture with the first article of PEEK and second article of PEEK may be taken out of a heated enclosure and put on a cooling plate right after the bonding time ends.

[0083] In further embodiments, the diffusion reaction of the first article of PEEK and second article of PEEK can be quenched to control the resulting bonding strength.

[0084] In some embodiments, the pre-determined time for which the first article and second article of PEEK is heated is between about 0.1 hour to about 48 hours, e.g., about 0.1 hours to about 1 hour, about 0.5 hours to about 5 hours, about 1 hour to about 10 hours, about 2 hours to about 15 hours, about 3 hours to about 20 hours, about 4 hours to about 25 hours, about 5 hours to about 30 hours, about 6 hours to about 35 hours, about 7 hours to about 40 hours, about 8 hours to about 45 hours, or about 9 hours to about 48 hours, e.g., about 0.1 hours, about 0.2 hours, about 0.3 hours, about 0.4 hours, about 0.5 hours, about 0.6 hours, about 0.7 hours, about 0.8 hours, about 0.9 hours, about 1 hour, about 1.5 hours, about 2 hours, about 2.5 hours, about 3 hours, about 3.5 hours, about 4 hours, about 4.5 hours, about 5 hours, about 5.5 hours, about 6 hours, about 7 hours, about 8 hours, about 9 hours, about 10 hours, about 11 hours, about 12 hours, about 13 hours, about 14 hours, about 15 hours, about 16 hours, about 17 hours, about 18 hours, about 19 hours, about 20 hours, about 21 hours, about 22 hours, about 23 hours, about 24 hours, about 25 hours, about 26 hours, about 27 hours, about 28 hours, about 29 hours, about 30 hours, about 31 hours, about 32 hours, about 33 hours, about 34 hours, about 35 hours, about 36 hours, about 37 hours, about 38 hours, about 39 hours, about 40 hours, about 41 hours, about 42 hours, about 43 hours, about 44 hours, about 45 hours, about 46 hours, about 47 hours, or about 48 hours.

[0085] In some embodiments, PEEK-to-PEEK bonding interfaces produced as a result of the methods disclosed herein have a bonding strength between about 5 MPa and about 28 MPa, e.g., about 5 MPa to about 8 MPa, about 7 MPa to about 11 MPa, about 10 MPa to about 13 MPa, about 11 MPa to about 15 MPa, about 12 MPa to about 17 MPa, about 14 MPa to about 18 MPa, about 15 MPa to about 19 MPa, about 16 MPa to about 20 MPa, about 18 MPa to about 22 MPa, about 20 MPa to about 24MPa, about 22 MPa to about 26 MPa, or about 24 MPa to about 28 MPa. In some embodiments, a PEEK manifold when bonded may have an average bonding strength of about 10 MPa, about 11 MPa, about 12 MPa, about 13 MPa, about 14 MPa, about 15 MPa, about 16 MPa, about 17 MPa, about 18 MPa, about 19 MPa, about 20 MPa, about 21 MPa, about 22 MPa, about 23 MPa, about 24 MPa, about 25 MPa, about 26 MPa, about 27 MPa, or about 28 MPa. In specific embodiments, bonded PEEK articles produced using the methods disclosed herein have a bonding strength of about 28 MPa.

[0086] In some embodiments, bonded articles produced as a result of the methods disclosed herein may exhibit and average bonding strength that exceeds 28 MPa, e.g., an average bonding strength of between about 28 MPa and about 80 MPa upon bonding of the two or more articles of PEEK. For example, bonded articles produced as a result of the methods disclosed herein may have an average bonding strength of about 28 MPa to about 33 MPa, about 30 MPa to about 35 MPa, about 32 MPa to about 37 MPa, about 35 MPa to about 40 MPa, about 37 MPa to about 42 MPa, about 40 MPa to about 45 MPa, about 44 MPa to about 48 MPa, about 46 MPa to about 50 MPa, about 48 MPa to about 52 MPa, about 50 MPa to about 54 MPa, about 52 MPa to about 56

[0087] MPa, about 55 MPa to about 60 MPa, about 57 MPa to about 62 MPa, about 60 MPa to about 65

[0088] MPa, about 62 MPa to about 67 MPa, about 65 MPa to about 70 MPa, about 67 MPa to about 72

[0089] MPa, about 70 MPa to about 75 MPa, about 72 MPa to about 77 MPa, or about 75 MPa to about

[0090] 80 MPa.

[0091] In some embodiments, bonded articles produced as a result of the methods disclosed herein may have an average bonding strength of about 28 MPa, about 29 MPa, about 30 MPa, about 31 MPa, about 32 MPa, about 33 MPa, about 34 MPa, about 35 MPa, about 36 MPa, about 37 MPa, about 38 MPa, about 39 MPa, about 40 MPa, about 41 MPa, about 42 MPa, about 43 MPa, about 44 MPa, about 45 MPa, about 46 MPa, about 47 MPa, about 48 MPa, about 49 MPa, about 50 MPa, about 51 MPa, about 52 MPa, about 53 MPa, about 54 MPa, about 55 MPa, about 56 MPa, about 57 MPa, about 58 MPa, about 59 MPa, or about 60 MPa, about 61 MPa, about 62 MPa, about 63 MPa, about 64 MPa, about 65 MPa, about 66 MPa, about 67 MPa, about 68 MPa, about 69 MPa, about 70 MPa, about 71 MPa, about 72 MPa, about 73 MPa, about 74 MPa, about 75 MPa, about 76 MPa, about 77 MPa, about 78 MPa, about 79 MPa, or about 80 MPa.

[0092] In some embodiments, articles for bonding may be pre-formed and complimentary to form a fluid handling device. For example, the fluid handling device may be a manifold, filter, in-line mixer, fluid distribution plate, or any other fluid handling device. This disclosure is in no way limited by the type of fluid handling device produced using two or more PEEK articles bonded using methods of this disclosure.

[0093] In accordance with an aspect, there is provided a method for directly bonding two or more articles of PEEK. The method includes treating bonding surfaces on a first article of PEEK and a second article of PEEK. The method includes placing the treated bonding surfaces of the first article of PEEK and second article of PEEK into contact with each other. The method further includes heating the first article of PEEK and second article of PEEK for a predetermined time at a temperature between 250 °C and the melting point of the PEEK.

[0094] In further embodiments, the method includes applying a pre-determined compressive load to the first article of PEEK and second article of PEEK during heating.

[0095] In accordance with an aspect, there is provided a method for directly bonding two or more articles of PEEK. The method includes treating bonding surfaces on a first article of PEEK and a second article of PEEK. The method includes placing the treated bonding surfaces of the first article of PEEK and second article of PEEK into contact with each other. The method further includes applying a pre-determined compressive load to the first article of PEEK and second article of PEEK. The method additionally includes heating the compressed first article of PEEK and second article of PEEK for a pre-determined time between 250 °C and the melting point of the PEEK.

[0096] In accordance with an aspect, there is provided a method for directly bonding two or more articles of PEEK. The method includes treating bonding surfaces on a first article of PEEK and a second article of PEEK. The method includes placing the treated bonding surfaces of the first article of PEEK and second article of PEEK into contact with each other. The method further includes heating the first article of PEEK and second article of PEEK for a predetermined time at a temperature between 250 °C and the melting point of the PEEK. The method further includes applying a pre-determined compressive load to the first article of PEEK and second article of PEEK during heating.

[0097] In accordance with an aspect, there is provided a manifold for directing a fluid through one or more channels therein. The manifold includes two or more articles of PEEK that have been directly bonded, e.g., diffusion bonding, e.g., thermally bonded using methods disclosed herein.

[0098] In some embodiments, the two or more articles of PEEK include portions, e.g., preformed and complimentary portions, of the one or more channels disposed on a bonding surface of each article such that the one or more channels are formed upon bonding. For example, the first article of PEEK can include one half of the one or more channels formed, i.e., cut, milled, or pressed, into the bonding surface and the second article of PEEK can include the other half of the one or more channels formed, i.e., cut, milled, or pressed, into its bonding surface. Alternatively, the second article of PEEK can present a flat surface such that a half-channel geometry is created upon bonding with the first article of PEEK. Once the first article of PEEK and second article of PEEK are mated and bonded, the full dimensions of the one or more channels in the manifold are formed.

[0099] In some embodiments, the direct bonding of the two or more articles of PEEK may provide for the manifold to have a fluid containment pressure of about 200 bar.

[0100] In some embodiments, the one or more channels of the manifold have a minimum diameter of between about 0.01 mm to about 10 mm, e.g., e.g., about 0.01 mm to about 0.1 mm, about 0.025 mm to about 0.25 mm, about 0.05 mm to about 0.5 mm, about 0.075 mm to about 0.75 mm, about 0.1 mm to about 1 mm, about 0.25 mm to about 2.5 mm, about 0.5 mm to about 5 mm, about 0.75 mm to about 7.5 mm, or about 1 mm to about 10 mm, e.g., about 0.01 mm, about 0.02 mm, about 0.03 mm, about 0.04 mm, about 0.05 mm, about 0.06 mm, about 0.07 mm, about 0.08 mm, about 0.09 mm, about 0.1 mm, about 0.2 mm, about 0.3 mm, about 0.4 mm, about 0.5 mm, about 0.6 mm, about 0.7 mm, about 0.8 mm, about 0.9 mm, about 1 mm, about

[0101] 1.1 mm, about 1.2 mm, about 1.3 mm, about 1.4 mm, about 1.5 mm, about 1.6 mm, about 1.7 mm, about 1.8 mm, about 1.9 mm, about 2 mm, about 2.1 mm, about 2.2 mm, about 2.3 mm, about 2.4 mm, about 2.5 mm, about 2.6 mm, about 2.7 mm, about 2.8 mm, about 2.9 mm, about 3 mm, about 3.1 mm, about 3.2 mm, about 3.3 mm, about 3.4 mm, about 3.5 mm, about 3.6 mm, about 3.7 mm, about 3.8 mm, about 3.9 mm, about 4 mm, about 4.1 mm, about 4.2 mm, about 4.3 mm, about 4.4 mm, about 4.5 mm, about 4.6 mm, about 4.7 mm, about 4.8 mm, about 4.9 mm, about 5 mm, about 5.1 mm, about 5.2 mm, about 5.3 mm, about 5.4 mm, about 5.5 mm, about 5.6 mm, about 5.7 mm, about 5.8 mm, about 5.9 mm, about 6 mm, about 6.1 mm, about

[0102] 6.2 mm, about 6.3 mm, about 6.4 mm, about 6.5 mm, about 6.6 mm, about 6.7 mm, about 6.8 mm, about 6.9 mm, about 7 mm, about 7.1 mm, about 7.2 mm, about 7.3 mm, about 7.4 mm, about 7.5 mm, about 7.6 mm, about 7.7 mm, about 7.8 mm, about 7.9 mm, about 8 mm, about 8.1 mm, about 8.2 mm, about 8.3 mm, about 8.4 mm, about 8.5 mm, about 8.6 mm, about 8.7 mm, about 8.8 mm, about 8.9 mm, about 9 mm, about 9.1 mm, about 9.2 mm, about 9.3 mm, about 9.4 mm, about 9.5 mm, about 9.6 mm, about 9.7 mm, about 9.8 mm, about 9.9 mm, or about 10 mm. The one or more channels of the manifold can have any suitable shape for directing fluids. Examples of channel shapes include, but arc not limited to, straight channels, curved channels, serpentine channels, or channels with a variable diameter or width. The one or more channels can be in a single plane of a manifold, such as in X-Y plane. Alternatively, or in addition, the one or more channels can be formed in two or more planes of the manifold, e.g., X- Y plane with changes in one or both of the X-Z or Y-Z planes, i.e., within the thickness, of the manifold.

[0103] In any embodiment of a manifold disclosed herein, the one or more channels of the manifold have any suitable profile for directing fluids. Non-limiting examples of channel profiles include, but is not limited to, rounded profile, rectangular profile, triangular profile, trapezoidal profile, or any other suitable shape. In some embodiment, the one or more channels of the manifold may have a rounded profile or a rectangular profile. This disclosure is not limited by the profile shape of the one or more channels.

[0104] In some embodiments, the manifold when bonded may have an average bonding strength that exceeds 28 MPa, e.g., an average bonding strength of between about 28 MPa and about 80 MPa upon bonding of the two or more articles of PEEK to form the manifold. For example, manifolds produced as a result of the methods disclosed herein may have an average bonding strength of about 28 MPa to about 33 MPa, about 30 MPa to about 35 MPa, about 32 MPa to about 37 MPa, about 35 MPa to about 40 MPa, about 37 MPa to about 42 MPa, about 40 MPa to about 45 MPa, about 44 MPa to about 48 MPa, about 46 MPa to about 50 MPa, about 48 MPa to about 52 MPa, about 50 MPa to about 54 MPa, about 52 MPa to about 56 MPa, about 55 MPa to about 60 MPa, about 57 MPa to about 62 MPa, about 60 MPa to about 65 MPa, about 62 MPa to about 67 MPa, about 65 MPa to about 70 MPa, about 67 MPa to about 72 MPa, about 70 MPa to about 75 MPa, about 72 MPa to about 77 MPa, or about 75 MPa to about 80 MPa.

[0105] In some embodiments, manifolds produced as a result of the methods disclosed herein may have an average bonding strength of about 28 MPa, about 29 MPa, about 30 MPa, about 31 MPa, about 32 MPa, about 33 MPa, about 34 MPa, about 35 MPa, about 36 MPa, about 37 MPa, about 38 MPa, about 39 MPa, about 40 MPa, about 41 MPa, about 42 MPa, about 43 MPa, about 44 MPa, about 45 MPa, about 46 MPa, about 47 MPa, about 48 MPa, about 49 MPa, about 50 MPa, about 51 MPa, about 52 MPa, about 53 MPa, about 54 MPa, about 55 MPa, about 56 MPa, about 57 MPa, about 58 MPa, about 59 MPa, or about 60 MPa, about 61 MPa, about 62 MPa, about 63 MPa, about 64 MPa, about 65 MPa, about 66 MPa, about 67 MPa, about 68 MPa, about 69 MPa, about 70 MPa, about 71 MPa, about 72 MPa, about 73 MPa, about 74 MPa, about 75 MPa, about 76 MPa, about 77 MPa, about 78 MPa, about 79 MPa, or about 80 MPa.

[0106] In some embodiments, the PEEK materials may include virgin PEEK material of various trade names produced by various vendors, derivatives of such virgin PEEK materials which include non-PEEK additives, composite materials which include such virgin PEEK materials or derivatives, and / or any combination thereof. In some embodiments, such composite materials may include, e.g., glass-filled PEEK, carbon-filled PEEK, carbon fiber-filled PEEK, or bearing grade PEEK.

[0107] EXAMPLES

[0108] The function and advantages of these and other embodiments can be better understood from the following examples. These examples are intended to be illustrative in nature and are not considered to be in any way limiting the scope of the invention.

[0109] Example 1 - Overview of PEEK-to-PEEK Thermal Bonding

[0110] In this example, an overview of the methods disclosed herein, e.g., PEEK-to-PEEK thermal bonding, is explored. The method disclosed in this example includes pretreatment of the PEEK articles to be bonded, pre-compression of the PEEK articles before heating, heating the compressed articles, and mechanical testing of the resultant bonded PEEK parts.

[0111] PEEK is an inert material with low surface energy, which makes PEEK-to-PEEK selfbonding challenging. Oxygen plasma treatment of the bonding surfaces of the PEEK was used to increase the surface energy and wettability of the PEEK to improve its ability to self-bond. Other commonly used gases, such as nitrogen, argon, hydrogen, or their mixtures may also be used in plasma activation of a PEEK surface. Surface modification using PEEK etchants, such as permanganic acid, chromium sulfuric acid, and concentrated sulfuric acid, and dichlorobenzene, have shown to improve PEEK bonding strength.

[0112] PEEK-to-PEEK bonding generally requires high compressive pressure to be applied during the diffusion bonding process to achieve high strength. Such pressures could be applied in situ in a diffusion bonder, either in a constant pressure mode or a constant displacement / spacing mode. Alternatively, individual PEEK articles stacked together may be pre-compressed and / or physically constrained with a bonding fixture design. FIG. 3 illustrates a schematic of a setup used to bond two articles of plasma-prctrcatcd PEEK blocks using precompression in a fixture. In FIG. 3, the top article of PEEK includes channels cut into its surface such that the finished part would be able to pass fluids. The two articles of PEEK were held between the top and bottom plates of a press and pre-heating compression was applied by securing the corners of the press plates using threaded rods and nuts. FIG. 4 is a simplified example of this method where a vice is used to clamp / pre-compress two PEEK strips together in a cross shape. The complete assembly was then heated in an oven to bond the PEEK strips. FIG. 5 illustrates a methodology in which spacers were used to control the width of the void space restricting PEEK thermal expansion during heating for generating compressive load to the stacked PEEK articles. The pre-heating compressive displacement was pre-determined and controlled by stopping the application of downward force on the metal spacers in FIG. 5. The comer nuts were tightened after reaching the pre-determined compressive displacement. With spacers taller than the uncompressed PEEK stack, there is no compressive load on the PEEK stack prior to heating. Instead, compressive load is generated during heating when thermal expansion of the PEEK articles is restricted by the bonding plates. With spacers shorter than the uncompressed PEEK stack, there would be compressive load applied to PEEK prior to heating and additional compressive load generated by the thermal expansion effect during heating.

[0113] In FIGS. 2 to 5, separators were used above the upper PEEK article and below the lower PEEK article during bonding to prevent adherence of the PEEK to the metal bonding plates of the press. Two or more independent PEEK parts could also be bonded separately in a single stack by including additional such separators at the interface between each part, as illustrated in FIG. 6. As illustrated in FIG. 6, there are two independent PEEK manifolds stacked on top of each other separated by a spacer. The first PEEK manifold has two PEEK articles (labeled as 1 and 2 in FIG. 6) and the second PEEK manifold as two PEEK articles (labeled as 3 and 4 in FIG. 6). PEEK articles 1 and 2 may be the same as PEEK articles 3 and 4, i.e., two identical manifolds being formed simultaneously. In other cases, PEEK articles 1 and 2 may be different than PEEK articles 3 and 4, i.e., two different manifolds, e.g., different internal channels, being formed simultaneously. This disclosure is in no way limited by the types of PEEK articles being formed in processes where more than one article is prepared by methods disclosed herein. The separators may be made from a variety of materials, including aluminum or stainless steel sheets or foils, polyimide (PI) sheets, or ceramics that are non-binding to PEEK and easily removed or peeled off after bonding. Separating sheets with smooth surfaces may reduce the roughness of the PEEK outer surfaces after bonding. For some applications requiring no metal contamination on the bonded PEEK part, inert materials like PI, ceramics, or metal sheets covered with inert coatings may be preferable as separators.

[0114] Polyimide (PI) is a high-temperature compatible, inert, and physically robust polymer that has been shown not to react or bond to PEEK or the metal bonding plates of the press, nor introduce contaminates to the PEEK parts. As illustrated in FIG. 7, the use of smooth PI sheets as separators reduced the surface roughness of the exterior surfaces of the PEEK parts from pre- to post-bonding. As further illustrated in FIG. 7, optical surface profiles are shown at right which were measured at the locations marked by the “X” on each image of the example PEEK manifold shown on the left. The post-bonding exterior PEEK showed a significant change in surface texture compared to the pre-bonding exterior PEEK, showing a significant reduction in surface roughness after bonding.

[0115] PEEK bonding was conducted at a temperature above its maximum continuous operating temperature, typically in the range of 250 °C to nearly the PEEK melting temperature. PEEK melts and recrystallizes over a relatively narrow temperature range, with a published melting point between 343 °C and 353 °C. FIGS. 8A-8B illustrate a PEEK manifold before and after bonding. FIG. 8A shows one half of the PEEK manifold before bonding with the channels milled into the bonding surface. FIG. 8B shows cross sections cut through the fully bonded PEEK manifold with the channels visible and no indication of a separation line between the two halves of the manifold.

[0116] Chemical resistance tests with commonly used strong acids were performed on diffusion- bonded PEEK blocks for a total exposure time of 1 month. No difference was observed in the chemical resistance of the bonded PEEK material compared to the as-received PEEK material.

[0117] Example 2 - PEEK-to-PEEK Thermal Bonding Bond Strength Test

[0118] In this example, methods of this disclosure for bonding PEEK articles were used to thermally bond PEEK and test the resulting bond strength.

[0119] The first set of samples for this experiment included two PEEK blocks having approximate dimensions of 5.0 x 25.0 x 3.0 mm3and 5.0 x 25.0 x 10.0 mm3, respectively. The two PEEK blocks were plasma treated and bonded into a cross using methods disclosed herein, but under conditions that were not optimized for maximizing bond strength. The cross piece was then tensile-pull tested in the direction perpendicular to the bonding interface using an Instron machine. FIG. 9A is the sideview image of the bonded PEEK cross before the pull test, and FIG. 9B shows the two PEEK blocks pulled apart. As illustrated, there was little material transfer at the bonding interface. The bonding test results are illustrated in FIG. 10, which shows the first breakage point occurred at 40 kgf, i.e., 16 MPa average stress on the 5.0 x 5.0 mm2bonding interface.

[0120] The second set of samples for this experiment included two PEEK blocks having similar dimensions of 5.0 x 25.0 x 3.0 mm3and 5.0 x 25.0 x 10.0 mm3, respectively. The two PEEK blocks were plasma treated and bonded into a cross using methods disclosed herein, under conditions that were more optimized for maximizing bond strength compared to those used to bond the cross in FIG. 9A. The cross piece was then tensile-pull tested in the direction perpendicular to the bonding interface using an Instron machine. FIG. 11 A illustrates a side image of the bonded PEEK cross before the pull test, and FIG. 11B shows the two PEEK blocks pulled apart. There was a large portion of PEEK material transferred from the thinner PEEK block to the thicker PEEK block at the bonding interface, unlike in FIG. 9B, indicating higher bonding strength of the blocks in FIG. 11A compared to those in FIG. 9A. The bonding test results for the blocks in FIG. 11 are illustrated in FIG. 12, which shows the first breakage point occurred at 71 kgf, i.e., 28 MPa average stress on the 5.0 x 5.0 mm2bonding interface. This confirmed that the conditions used to bond the cross in FIG. 11A produced a stronger bonding joint than those used to bond the cross in FIG. 9A.

[0121] The third sample for this experiment was a PEEK cross piece, machined out of solid PEEK material, that has the same 5.0 x 5.0 mm2cross area as the samples in FIG. 9A and FIG. 11 A. The solid PEEK cross went through the same bonding thermal cycle of samples 1 and 2. The solid cross was then tensile-pull tested in the same direction as the bonded cross samples in FIG. 9A and FIG. 11A using an Instron machine. FIG. 13A illustrates the side image of the solid PEEK cross before the pull test, and FIG. 13B shows the two PEEK pieces after the solid cross was pulled apart. The bonding test results are illustrated in FIG. 14, which showed the first breakage point occurred around 204 kgf, i.e., 80 MPa average stress on the 5.0 x 5.0 mm2joint area. Based on the results of the tensile-pull testing, the average bonding strength of the sample in FIG. 11A was about one third that of the bulk strength of the solid PEEK cross.

[0122] The fourth set of samples for this experiment included two PEEK coupons having approximate dimensions of 1.0 x 2.0 x 0.3 cm3. The bonding interfaces of each PEEK sample were sanded by hand using 30 pm grit sandpaper. Each PEEK sample was then plasma treated, clamped together in a vice, and bonded using similar conditions to the first 3 samples above. The resulting bonded PEEK sample is illustrated in FIG. 15A and 15B. The bonded PEEK sample was tensile-pull tested by securing the overhanging part of each end of the sample in the upper and lower clamps of an Instron machine as illustrated in FIG. 16. The test geometry was such that the stress applied to the bonding interface in this example was a shear stress. The bonding test results are illustrated in FIG. 17, where the bonded PEEK sample failed at an applied tensile force corresponding to an average shear stress on the PEEK-to-PEEK bonding interface of about 14 MPa. The inset picture of the broken sample showed that the bonded PEEK sample did not break at the bonding interface, however, but rather in the bulk of one of the initial coupons. Based on the cross-section of the broken area, this failure corresponded to a bulk failure at about 52 MPa. Since failure did not occur at the bonding interface, the test demonstrated that the average shear bond strength was greater than 14 MPa.

[0123] Example 3 - PEEK-to-PEEK Multi-Stack Thermal Bonding

[0124] In this example, methods of this disclosure for bonding a stack of PEEK articles are explored. For this example, the tested stack of PEEK articles includes three separate articles stacked such that there are two separate bonding interfaces.

[0125] For this experiment, three similarly sized articles of PEEK (labeled “A,” “B,” and “C” in FIG. 18 with their respective dimensions) were chosen such that, once bonded, the bonding geometry more closely resembled that of an actual fluidic manifold rather than the “cross” geometry shown in Examples 1 and 2. For the three articles, two separate oxygen plasma pretreatment steps were performed. The first oxygen plasma treatment step included: 1) article A at the A / B bonding interface; 2) article B at the A / B bonding interface; and 3) article C at the B / C bonding interface. The second oxygen plasma treatment step included treating article B at the B / C bonding interface. As illustrated in FIG. 19A, the three articles were stacked A-B-C and compressed in a vice before being placed into the oven. The resultant thrcc-articlc PEEK part after bonding is illustrated in FIG. 19B. The bonding strength of the bonded three-article PEEK part was measured using the pull-test setup on an Instron machine shown in FIG. 20. The results of the pull testing are illustrated in the graph of FIG. 21 and images of the broken multi- stack PEEK article are shown in FIG. 22. The data of load versus pulling extension in FIG. 21 revealed that there were four discrete breakage points as the multi-stack PEEK article was pulled apart. The first break occurred at about 742 N, i.e., 11 MPa average stress on the bonding interfaces, corresponding to the dashed line in FIG. 21, which was also the maximum load before the bonded three-article PEEK part fully broke. The images in FIG. 22 indicated that a crack corresponding to the first break was initiated at a comer of the bonding interface, but then propagated through the article B bulk.

[0126] Example 4 - PEEK-to-PEEK Thermal Bonding of Films

[0127] In this example, methods of this disclosure for bonding PEEK articles are explored. For this example, three filters with different characteristic structure sizes were manufactured from layers of thermally bonded PEEK film.

[0128] The filters manufactured from the PEEK film are illustrated in FIGS. 23A-23C. A laser cutting system was used to cut various through-sheet features in 127 pm thick PEEK film. The geometry was designed such that the final parts were formed from nine total layers of stacked PEEK film. The characteristic structures in each filter were a grill-like pattern of through-cuts consisting of parallel slits. For this example, each filter was made using a constant slit width for all nine layers. The slit widths were 100 pm, 75 pm, and 50 pm. In principle, a filter with a pore size gradient could have been made by using a different slit width for each layer within a single part.

[0129] To form the filters, the nine layers of PEEK film were stacked in an A / B sequence with 90° rotations between each sheet. This arrangement ensured the pattern of parallel slits in each layer were rotated 90° relative to the adjacent layer(s). To bond the nine layers, the stacked layers were compressed in a fixture and placed into an oven for bonding. The resultant parts are illustrated in FIG. 23B-23C. After bonding, each of the three circular filters were cut out of the surrounding “frame” present in FIG. 23B. Based on initial optical analysis of the parts, the laser- cut features remained largely intact through the bonding process, though some partial collapse of the pore structure in the 50 pm part was observed. Further development of the process will allow for improved stability of fluidic structures in this size range.

[0130] The phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. As used herein, the term “plurality” refers to two or more items or components. The terms “comprising,” “including,” “carrying,” “having,” “containing,” and “involving,” whether in the written description or the claims and the like, are open-ended terms, i.e., to mean “including but not limited to.” Thus, the use of such terms is meant to encompass the items listed thereafter, and equivalents thereof, as well as additional items. Only the transitional phrases “consisting of’ and “consisting essentially of,” are closed or semi-closed transitional phrases, respectively, with respect to the claims. Use of ordinal terms such as “first,” “second,” “third,” and the like in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having a same name (but for use of the ordinal term) to distinguish the claim elements.

[0131] Having thus described several aspects of at least one embodiment, it is to be appreciated various alterations, modifications, and improvements will readily occur to those skilled in the art. Any feature described in any embodiment may be included in or substituted for any feature of any other embodiment. Such alterations, modifications, and improvements are intended to be part of this disclosure and are intended to be within the scope of the invention. Accordingly, the foregoing description and drawings are by way of example only.

[0132] Those skilled in the art should appreciate that the parameters and configurations described herein are exemplary and that actual parameters and / or configurations will depend on the specific application in which the disclosed methods and materials are used. Those skilled in the art should also recognize or be able to ascertain, using no more than routine experimentation, equivalents to the specific embodiments disclosed.

[0133] What is claimed is:

Claims

CLAIMS1. A method for directly bonding two or more articles of polycthcr ether ketone (PEEK), comprising: treating bonding surfaces on a first article and a second article of PEEK; placing the treated bonding surfaces of the first article of PEEK and second article of PEEK into contact with each other; heating the first article and second article of PEEK for a pre-determined time at a temperature of between about 250 °C and the melting point of PEEK; and applying a pre-determined compressive load to the first article of PEEK and second article of PEEK during heating.

2. The method of claim 1, wherein the bonding surfaces on the first article of PEEK and second article of PEEK are treated with a plasma.

3. The method of claim 2, wherein the gas used in the plasma is Ch, No, Ar, H2, air, NH3, or a mixture of thereof.

4. The method of claim 1, wherein the bonding surfaces on the first article and second article of PEEK are treated with solvents.

5. The method of claim 4, wherein the solvents can etch PEEK.

6. The method of claim 1, further comprising applying a compressive load prior to heating, the compressive load providing compression of the first article of PEEK and second article of PEEK resulting in a change of about 0% to about 10% of an initial uncompressed dimension of the first article of PEEK and second article of PEEK.

7. The method of claim 6, wherein the compressive load is applied using a fixture or press.

8. The method of claim 1, wherein compressive load is applied during heating providing for compression of the first article of PEEK and second article of PEEK resulting in a change ofabout 0% to about 10% of an initial uncompressed dimension of the first article of PEEK and second article of PEEK.

9. The method of claim 8, wherein the compressive load is applied indirectly by constraining the ability of the first article of PEEK and second article of PEEK to thermally expand during heating.

10. The method of claim 7, wherein non-bonding surfaces of the first article of PEEK and second article of PEEK are isolated from a bearing surface of the fixture or press by a separator material.

11. The method of claim 10, wherein separator material includes inert materials.

12. The method of claim 11 wherein inert materials may include polyimide, ceramics, or metals with inert coatings.

13. The method of claim 12, wherein heating the first article of PEEK and second article of PEEK to the pre-determined temperature occurs by a temperature gradient of between about 0.1 °C / min to about 120 °C / min.

14. The method of claim 13, further comprising, following the heating, cooling the first article and second article of PEEK to room temperature according to a temperature gradient.

15. The method of claim 14, wherein the cooling temperature gradient is from about 0.1 °C / min to 120 °C / min.

16. The method of claim 1, wherein the predetermined time is between about 0.1 hour to about 48 hours.

17. The method of claim 1, wherein the PEEK may include virgin PEEK, PEEK derivatives, PEEK composites, and combinations thereof18. The method of claim 1 , further comprising bonding a plurality of PEEK units each unit comprising two or more articles of PEEK, wherein each PEEK unit of the plurality of PEEK units is separated from an adjacent PEEK unit with a separator material.

19. The method of claim 1, wherein the PEEK articles may include PEEK films of individual thickness between 10 pm to 1000 pm.

20. The method of claim 1, wherein the PEEK articles may include bulk PEEK materials having individual thickness of about 1 mm to about 500 mm.

21. The method of claim 1, wherein the articles are preformed and complimentary to form a fluid handling device.

22. The method of claim 21, wherein the fluid handling device is a manifold.

23. The method of claim 21, wherein the fluid handling device is a filter.

24. A manifold for directing a fluid through one or more channels therein, the manifold comprising two or more articles of PEEK that have been directly bonded to one another.

25. The manifold of claim 24, wherein one or more of the two or more articles of PEEK comprise portions of the one or more channels disposed on a bonding surface of each article such that the one or more channels are formed upon bonding.

26. The manifold of claim 25, wherein the one or more channels of the manifold have a width or diameter of about 0.01 mm to about 10 mm.

27. The manifold of claim 26, wherein the one or more channels of the manifold include straight channels, curved channels, serpentine channels, or channels with variable width or diameter.

28. The manifold of claim 27, wherein the one or more channels of the manifold have a rounded profile, a triangular profile, a rectangular profile, a polygonal profile, or a half-ellipse profile.

29. A filter for a fluidic flow path, the filter comprising two or more articles of PEEK that have been directly bonded to one another.

30. The filter of claim 29, wherein the two or more articles of PEEK comprise PEEK films.

31. The filter of claim 30, wherein the PEEK films have an individual thickness of 10 pm to 1000 pm.

32. A method for directly bonding two or more articles of polyether ether ketone (PEEK), comprising: treating the bonding surfaces on a first and a second article of PEEK; placing the treated bonding surfaces of the first article of PEEK and second article ofPEEK into contact with each other; and heating the first article of PEEK and second article of PEEK for a pre-determined time at a temperature between 250 °C and the melting point of the PEEK.

33. The method of claim 32, further comprising applying a pre-determined compressive load to the first article and second article of PEEK during heating.

34. A method for directly bonding two or more articles of polyether ether ketone (PEEK), comprising: treating bonding surfaces on a first article of PEEK and a second article of PEEK; placing the treated bonding surfaces of the first article of PEEK and second article of PEEK into contact with each other; applying a pre-determined compressive load to the first article of PEEK and second article of PEEK; and heating the compressed first article of PEEK and second article of PEEK for a predetermined time at a temperature between 250 °C and the melting point of the PEEK.

35. A method for directly bonding two or more articles of polycthcr ether ketone (PEEK), comprising: treating bonding surfaces on a first article of PEEK and a second article of PEEK; placing the treated bonding surfaces of the first article of PEEK and second article ofPEEK into contact with each other; applying a compressive load to the first article of PEEK and second article of PEEK; heating the first article of PEEK and second article of PEEK for a pre-determined time at a temperature between 250 °C and the melting point of the PEEK; and applying an additional compressive load to the first article of PEEK and second article ofPEEK during heating, such that the total pre-determined compressive load applied to the first article of PEEK and second article of PEEK during heating is a combination of the compressive load applied before heating and the additional compressive load applied during heating.

Images