uide to Hydrophobic Polymers and Hydrophobic Surfaces: Wetting Models, Evaluation Metrics, and Task-Oriented Material Selection (including Tables 1–3)

I.Hydrophobicity Framework: Meaning and a Metrics System

1.1 Background: An Overview of Hydrophobic Polymers

Hydrophobic polymers are not niche materials—they form the “base color” of our everyday plastic world. A large number of common polymers are chemically low-polarity and low–surface-energy, and therefore naturally show poor water wettability, weak compatibility with water, and pronounced interfacial behavior. This creates both value (water resistance, anti-fouling, barrier performance, corrosion resistance, processability) and headaches (difficult bonding, difficult coating/printing, easy pinning by contamination, interfacial instability).

1.2 “Hydrophobicity” Is Not a Single Word: It Has at Least Three Layers of Meaning

1. Molecular scale (why nonpolar segments aggregate in water): IUPAC’s definition of hydrophobicity emphasizes that it arises from water’s tendency to exclude nonpolar molecules, causing nonpolar fragments to “associate/aggregate” in water.

2. Interfacial scale (whether a surface is wetted): What we most often call a “hydrophobic surface” usually means a water droplet tends to “bead up” rather than spread on the surface (the contact-angle concept).

3. Bulk scale (whether water can enter the material): Many reliability problems are not about whether a droplet “sticks,” but whether water vapor/liquid water enters the material over time, leading to swelling, dimensional change, and performance drift. ISO 62 explicitly notes that plastics exposed to water can show dimensional changes (e.g., swelling), extraction of soluble components, and other property changes. Moreover, “moisture uptake (humidity) / immersion / boiling-water exposure” can trigger different material responses; when making comparisons, the exposure conditions must be stated clearly (ISO 62 also emphasizes differences among exposure methods).

1.3 Metrics System

The table below aligns the three layers of meaning with key metrics and commonly used standards.

Level	The real question you want to answer	Core metric(s)	Typical standard(s)/method(s)	Common misuse reminder
Molecular scale (hydrophobic effect)	Why do nonpolar segments tend to aggregate/phase-separate in water?	Conceptual level: definitions of hydrophobicity / hydrophobic interactions	IUPAC definitions of hydrophobicity / hydrophobic interactions for “concept anchoring”	The hydrophobic effect explains why molecules in water tend to “cluster”; contact angle addresses whether a droplet spreads on a solid surface; water absorption addresses whether water can enter the material interior—these are not the same question.
Interfacial scale (surface wetting)	Does the surface “take water”? In processing, is it “easy to coat/print/bond”?	Water contact angle (CA); advancing/receding angles and hysteresis	ISO 15989 (water contact angle on films and can infer wetting tension); ASTM D5946 (equivalent to ISO 15989, emphasizes multi-point measurement); ASTM D7334 (advancing angle to characterize wettability)	Focusing only on one “static angle” can easily mislead: contamination, roughness, and non-uniform treatment can all cause drift.
Interfacial scale (surface energy / wettability window)	Why can coating/adhesion performance differ greatly even at the same CA?	Surface free energy (SFE, usually back-calculated from contact angles of multiple liquids)	ISO 19403-2: determination of solid surface free energy via contact angles (recommends OWRK or Wu methods; typically requires ≥2 test liquids)	Using only “water” as the sole liquid makes it hard to infer the true wetting window for inks/solvents/adhesives.
Bulk scale (water uptake / swelling)	Will water enter the material? If it does, will it cause swelling/deformation/performance drift?	Water absorption rate/amount; combined with dimensional-change/swelling observation	ASTM D570: water absorption of plastics by immersion; ISO 62: water absorption and procedures for thickness-direction moisture uptake/immersion, and emphasizes swelling and related effects	“Large contact angle” ≠ “no water absorption”: a non-wetting surface does not mean water vapor will not diffuse in over long times.

Notes (standard applicability reminders):

a) ISO 15989 / ASTM D5946 mainly target corona-treated polymer films: they measure water contact angle and can convert it to film wetting tension, for evaluating film surface-treatment effectiveness.

b) If the test object is not a film (bulk parts, coatings, composite substrates, rough/microstructured surfaces, etc.), it is generally preferable to characterize contact angle / surface free energy according to the ISO 19403 series (usually requiring ≥2 test liquids; commonly using OWRK or Wu methods), and to clearly report cleaning procedure, test liquids, timing window (how long after treatment), temperature/humidity, and replicate measurement locations.

II.Three Major Wetting Models

2.1 Three Interfacial States: Young / Wenzel / Cassie–Baxter

For “hydrophobic polymers,” why are some merely “not very wettable,” while others enable “droplets rolling off and self-cleaning”? The answer is often not the “material name,” but the interfacial state: is the droplet contacting a “smooth solid,” a “rough solid fully impregnated by water,” or a “composite solid + air interface”?

State/Model	An intuitive picture	How the apparent contact angle changes	Typical observable behavior	Common risk point(s)
Young: intrinsic wetting (smooth, uniform surface)	A droplet lands on a flat material with relatively uniform surface chemistry (as close as possible to the ideal of “clean and smooth”)	Apparent contact angle is mainly determined by surface chemistry/surface energy: lower surface energy → water is less willing to spread → larger contact angle; higher surface energy → water is more willing to spread → smaller contact angle	Contact angle is sensitive to material type and surface treatment; when the surface is relatively smooth and uniform, measurements are usually more stable and repeatable	Real polymer surfaces can be affected by contamination, aging, or surface-chain rearrangement: even if the bulk material is unchanged, “dirty/aged/surface restructuring” can change contact angle over time, causing inconsistency between measurements
Wenzel: rough surface fully “filled” by water	The surface has micro-asperities and grooves; the droplet nearly “fully conforms,” and water penetrates the texture voids	Roughness amplifies the original wetting tendency: if the material is intrinsically hydrophobic, the apparent contact angle often becomes larger; if intrinsically hydrophilic, the apparent contact angle often becomes smaller (spreads more easily)	A common phenomenon: the static contact angle may be fairly large, but the droplet edge is easily pinned by roughness/defects, making motion difficult; a larger tilt is needed before sliding	Don’t equate “roughness = superhydrophobic.” The Wenzel state often leads to larger hysteresis and stronger adhesion—“the angle looks large, but it doesn’t slide easily and readily holds dirt.”
Cassie–Baxter: composite solid + air interface (air-trapping state)	The droplet mainly contacts the surface protrusions, with a layer of air trapped underneath (like “sitting on an air cushion”)	Because the true solid–liquid contact area is smaller, water is less willing to spread, so the apparent contact angle is usually larger; with few defects/contamination, hysteresis can also be smaller, and droplets move/slide more easily	You may see “large contact angle + low hysteresis/low roll-off angle” (often corresponding to better self-cleaning behavior)	The air-trapping state is fragile: pressure, wear, oil contamination/surfactants, long-term immersion, etc. can collapse the air cushion; water then fills the texture and transitions to the Wenzel state; hysteresis and roll-off angle increase, and droplets become more easily pinned and harder to move/detach

Note: 

These three classic wetting models originate from the following primary literature:

a) Young, T. (1805) An Essay on the Cohesion of Fluids, Philosophical Transactions of the Royal Society of London, 95, 65–87, doi:10.1098/rstl.1805.0005;

b) Wenzel, R. N. (1936) Resistance of Solid Surfaces to Wetting by Water, Industrial & Engineering Chemistry, 28(8), 988–994, doi:10.1021/ie50320a024;

c) Cassie, A. B. D.; Baxter, S. (1944) Wettability of porous surfaces, Transactions of the Faraday Society, 40, 546–551, doi:10.1039/TF9444000546.

2.2 Can a Droplet “Move/Slide Easily”? Why “Large Angle” Does Not Equal “Usable”

Even when static contact angles are similarly large, on some surfaces a droplet slides off rapidly with a slight tilt, while on others it stays in place. The key difference is often not the static contact angle, but contact angle hysteresis (the difference between advancing and receding angles). Hysteresis reflects how easily the droplet edge is “dragged” or pinned by surface roughness, defects, or contamination.

1. Small hysteresis: the droplet edge is not easily “pinned” → easier to move/slide → closer to a self-cleaning, anti-fouling working state

2. Large hysteresis: the droplet edge is easily “pinned” → even with a large static angle, motion is difficult → a common case of “looks hydrophobic, but is not practically good”

Use two metrics to make “mobility” explicit

Practical question to judge	Most direct metric	How to interpret
Is the droplet easy to move/slide (self-cleaning potential)?	Contact angle hysteresis (advancing angle − receding angle)	Smaller is better: a large difference means the edge is “dragged” by roughness/defects/contamination and mobility is poor; a small difference means less “drag,” enabling easier sliding/detachment
How much tilt is needed before sliding begins (a more intuitive “mobility number”)?	Roll-off/sliding angle	Smaller is better: sliding occurs with a slight tilt, usually corresponding to smaller hysteresis and lower interfacial adhesion

2.3 Why “Easy-Sliding” Surfaces Often Lack Durability: Because the Interfacial State May “Collapse”

Many surfaces that achieve both “large contact angle and easy droplet motion/sliding” rely on a specific interfacial state: the droplet bottom does not fully contact the solid, but instead forms a composite contact of “solid + air” (often called the Cassie–Baxter state). The problem is that this trapped-air state is often fragile and can be destroyed in real operating conditions.

Common failure triggers include:

1. Pressure / water head / scouring: forcing liquid into texture voids;

2. Wear: flattening microstructures or introducing defects, increasing pinning sites;

3. Oil contamination / surfactants: more likely to penetrate texture and displace air;

4. Long-term immersion: gradual loss of trapped air, making the composite interface hard to maintain.

Once air is squeezed out or replaced by liquid, the liquid enters the texture to form a “fully filled” contact state (often called the Wenzel state). At that point, the surface may still show a relatively large static contact angle, but hysteresis increases, roll-off angle increases, and the droplet shifts from “easy to move/slide” to “more easily pinned and hard to detach.”

III.Hydrophobic Surfaces: Implementation Pathways and Verification Methods

3.1 Target–Route–Verification: Align “Hydrophobic / Easy Sliding / Durable / Bondable” with Measurable Metrics

Target/Application	Preferred route	Key “knobs”	Minimum evidence chain	Risk reminder
Only need lower wettability (water repellency / beading appearance)	Mainly surface chemistry (closer to Young; roughness can assist amplification)	① Lower surface energy (material/surface groups); ② contamination control; ③ slight roughness amplification if needed	Static contact angle (multi-point) + surface free energy / wetting tension (optional)	Relying on a single-point static angle; drift due to contamination/aging
Droplets move/slide easily (self-cleaning potential, low adhesion)	Structure + low defects (closer to Cassie for “low hysteresis”)	① Microstructure morphology/scale (air-trapping ability); ② defects/contamination (determine pinning); ③ surface energy as a helper	Contact angle hysteresis (θA − θR) or roll-off angle	“Large angle but large hysteresis”: common for water-filled roughness or defect-rich surfaces
Still “easy sliding” under real service conditions (durable/maintainable)	First achieve “sliding,” then build “anti-collapse” (prevent Cassie → Wenzel)	① Pressure/water-head resistance (air-trapping stability); ② wear resistance; ③ resistance to oils/surfactants	Re-test after pressure/scouring/light abrasion/immersion: do hysteresis or roll-off angle degrade significantly?	Trapped air is squeezed out or displaced by liquid → transitions to filled state: static angle may remain large, but hysteresis/roll-off performance worsens
Reverse need: printing/coating/bonding (make water/adhesive “willing to spread”)	Increase surface wettability (raise wetting tension via surface treatment)	① Treatment intensity (corona/plasma, etc.); ② post-treatment aging (possible hydrophobic recovery); ③ cleanliness	Measure contact angle and convert to wetting tension per standard, to evaluate treatment effectiveness	Performance decay during storage after treatment; relying on “feel/experience” without quantification

IV.Materials Family Map + Task-Oriented Material Selection

4.1 Hydrophobic Polymer Family Map

Family (Representative materials)	One-line positioning	Typical strengths	Common weaknesses	Best-suited tasks
Polyolefins (PE/PP)	A “baseline hydrophobic platform” with low polarity and low surface energy	Low cost, easy to process, water-resistant and resistant to most acids/bases, low density	Difficult to bond/coat/print (often requires corona/plasma treatment and/or primers); surface contamination can cause wetting-test drift	Packaging films, general water-repellent substrates, water-resistant containers, structural parts
Fluoropolymers (PTFE/FEP/PFA/PVDF, etc.)	A “hardcore water-repellent” class with even lower surface energy and strong chemical resistance	Excellent chemical/weather resistance, low friction, anti-adhesion, wide service-temperature range (varies by grade)	Still difficult to bond/coat; some grades have higher processing barriers/costs; surface modification often requires specialized processes	Anti-stick/anti-fouling coating substrates, corrosion-resistant parts, harsh chemical environments
Siloxanes / Silicone rubbers (PDMS, etc.)	“Soft hydrophobic” materials: low-energy surfaces, compliant and easy to mold	Soft and flexible, good gas permeability/elasticity, easy microstructuring (common in microfluidics/molds)	More “active” surface state: hydrophobic recovery may occur after treatment; sensitive to organic contamination/migration; wear resistance requires design	Elastic sealing, flexible surfaces, microstructured/microfluidic surfaces, demolding
Styrenics and some transparent commodity plastics (PS, etc.)	Common rigid plastics with “moderate hydrophobicity + easy molding”	Good moldability; good transparency (in some systems); mature material ecosystem	Susceptible to solvents/stress cracking (material-dependent); anti-fouling often relies on coating strategies	Transparent parts, disposable device housings, lab consumables (depending on needs)
“Moderately hydrophobic” engineering plastics (PC/PMMA/PET, etc.)	Not the most hydrophobic, but strong in overall performance	Good balance of rigidity/strength/transparency (some)/dimensional stability	Hydrophobicity often not “extreme”; achieving self-cleaning/low adhesion usually needs added structure or coatings	Structural parts, optical components, durable housings, scenarios requiring mechanical/dimensional stability
Hydrophobic elastomers (EPDM, etc.)	“Outdoor rubber” with water and weather resistance	Weather resistance, water-vapor resistance, elastic sealing, strong aging resistance (formulation-dependent)	Fine-tuned wetting control/low adhesion is usually not a strength; oil/solvent resistance depends on the system	Outdoor sealing, waterproof components, weather-resistant protection
Barrier and composite strategies (multilayer co-extrusion / coatings / primers)	“If one material isn’t enough, complete it with structure”	Can deliver water repellency, barrier, mechanical performance, and processing window simultaneously	More complex design and processing; interfacial bonding and long-term reliability are critical	High-barrier packaging, durable water-repellent systems, engineered/industrial deployment

Note:

Some engineering plastics (e.g., nylon) may not look “hydrophilic” at the surface, but can show significant bulk water uptake and dimensional change. Therefore, reliability cannot be judged by contact angle alone; bulk validation should follow ISO 62 / ASTM D570.

4.2 Task-Oriented Selection: Which Hydrophobic Polymer Class to Look at First

Task/Scenario	Priority family/system	Why it matches better	Primary selection signal	Exclusion signal
Water-repellent appearance / short-term waterproofing	Polyolefins (PE/PP), surfaces of some engineering plastics, low–surface-energy coating systems	Intrinsic low surface energy alone can suppress water spreading	Clean surface, stable process, good repeatability	Surface easily contaminated/aged, causing large angle drift
Low adhesion / easy droplet detachment (self-cleaning potential)	Low–surface-energy systems + materials/coatings that can realize low-defect microstructures (including siloxane- and fluorine-containing systems)	The key is not “more hydrophobic,” but “less pinning”	Low hysteresis / low roll-off angle data, defect-control measures	Only a good-looking static angle, but no hysteresis/roll-off information
Durable water repellency (still usable after wear/scouring/immersion)	Wear-resistant systems (hard coatings / composite structures) + low–surface-energy top layer; multilayer/primer strategies when needed	Durability often fails because structures are damaged or interfacial states collapse	Post-condition re-test data (abrasion/pressure/immersion)	Shows only initial superhydrophobicity, without durability re-test
Printing/coating/bonding (need wetting/spreading)	Engineering-plastic surfaces that are easier to treat; polyolefins require corona/plasma and primer support	The core problem is “wettability and time-stability after treatment”	Clear treatment window and aging/time-control plan	Reliance on experience only; not quantified, not reproducible

V.Unavoidable Sustainability and Governance Issues

5.1 Environmental Issues

Hydrophobic polymers matter not only because they are “useful” (waterproofing, anti-fouling, barrier performance, corrosion resistance), but also because they constitute the “main material platform” in the debate on plastic pollution and its governance.

1. UNEP notes that approximately 19–23 million tonnes (19–23 Mt) of plastic waste leak into aquatic ecosystems such as lakes, rivers, and oceans each year.

2. OECD’s Global Plastics Outlook reports that in 2019 alone, about 22 million tonnes (22 Mt) of plastic materials leaked into the environment; macroplastics account for about 88%, and microplastics about 12%.

This leads to a key conclusion: “More hydrophobic / more durable” is not, by itself, a complete solution. It can extend service life and reduce maintenance frequency, but if the product ultimately remains “hard to recycle and easy to escape into the environment,” then performance gains may simply delay or shift the problem from the “use phase” to the “environment phase.”

Therefore, when advancing global plastic-pollution governance, UNEP emphasizes covering the full life cycle of plastics (production, design, use, disposal/recycling) and reducing pollution through coordinated action by governments and industry.

5.2 A “Sustainability Checklist” for Research and Engineering Readers

The hydrophobic-material work you are doing	Add one sustainability question	Minimum evidence
Water-repellent / anti-fouling surfaces or coatings	Does improved durability come with a risk of particle/debris shedding?	After one light abrasion/scouring test: re-test surface performance + observe whether visible debris/turbidity appears (qualitative evidence can still be valuable)
“Superhydrophobic / low-adhesion” structured surfaces	What does it become after the trapped-air state collapses? Does it increase maintenance cost?	Post-condition re-test: focus on whether hysteresis/roll-off angle worsens significantly (more sensitive than static angle)
Multilayer barrier / composite structures	Can it be separated at end-of-life? Does it turn recyclable materials into “hard-to-recycle composites”?	Simplification assessment: can layers be reduced / adhesive dependence lowered; preset a recycling route (which sorting method, which recycling pathway)
Upgrading material systems (additives/modification)	Does performance improvement introduce higher governance costs (harder sorting / more complex processing)?	Include “identifiability/sortability/recycling compatibility” in selection metrics—not only contact angle

VI.Hydrophobic Polymer Product Navigation Table (Locate Tables 1–3 by “Research Task / Experimental Need”)

Research/Experimental situation	Which table to check first	Why check it first	Representative products in the table
Need a general hydrophobic matrix for film/injection/extrusion benchmarking (get the process running first)	Table 1 | Commodity thermoplastics + engineering plastics	Table 1 spans commodity resins (PE/PS/PMMA/PVC) through engineering plastics (PC/PPS/PSU/PPE/nylons, etc.), best for first defining “what the matrix is” and the basic processing window	PE, PS, PMMA, PVC, PC, PPS, PSU, PPE, PA6/66/12, PET (glass-fiber reinforced), PEEK
Building structural/high-strength parts; care about rigidity, impact resistance, creep resistance, dimensional stability (incl. glass-fiber reinforcement)	Table 1	Engineering plastics and reinforced resins are in Table 1; suitable for selecting a matrix via a “mechanics–temperature–dimensional stability” trade-off	PC, PPS, PSU, PPE, PET (30% glass), PEEK, PA series
Need high-temperature and high chemical stability (strong solvents, corrosive media, thermal aging)—material must survive	Table 2 first; if load-bearing structure is needed, return to Table 1	Table 2 is the core set for corrosion resistance and low surface energy in fluorinated systems; if load-bearing/rigidity is also required, use engineering plastics in Table 1 as structural options for comparison	Table 2: PVDF, ETFE, FEP, PCTFE, PTFE micropowder; Table 1: PEEK, PPS, PSU
Developing low–surface-energy hydrophobic anti-stick/anti-fouling coatings or surface modification (core requirement: “surface energy must be low”)	Table 2 + Table 3 (formulation components)	Table 2 provides low–surface-energy fluoropolymer matrices/powders; Table 3 provides typical “slippery/anti-stick” formulation routes such as silicone oils, reactive siloxanes, and PTFE micropowder (commonly used in formulations)	Table 2: PVDF, FEP, ETFE, PCTFE; Table 3: silicone oil, polymethylhydrosiloxane, PTFE micropowder
Barrier/moisture-proof/low WVTR needs (packaging, sealing, dry isolation, vacuum/cryogenic scenarios)	Table 2	Low surface energy is not the same as low water-vapor transmission; for barrier performance, prioritize fluoropolymer families with strong barrier performance (especially for low WVTR/low-temperature/sealing scenarios)	PCTFE, FEP, ETFE, PVDF
Hydrophobic membrane materials / corrosion-resistant membranes or coating film formation (powders/particles for coating, sintering, phase inversion, etc.)	Table 2	Table 2 concentrates fluoropolymers and powder-form materials usable in membrane/coating systems—closer to experimental routes focused on “film formation/corrosion resistance/low surface energy”	PVDF (powder), PTFE micropowder, PCTFE (powder), FEP, ETFE
Sealing/waterproof/weather-resistant elastic layers (outdoor, ozone, heat–humidity; focus on resilience and aging)	Table 3 | Elastomers/TPE + siloxanes	Table 3 gathers EPDM, SBS/SEBS, neoprene, and siloxane additives—good for selecting routes by “weather/water resistance, elasticity, and processing method”	EPDM, SEBS, SBS, polychloroprene, silicone oil
Oil-/solvent-resistant rubbers/seals (oil immersion, fuels, solvent environments)	Table 3	NBR/PIB better match oil-phase swelling behavior and sealing tack needs; failure modes differ from “water resistance/hydrophobicity,” so oil-resistant elastomer systems should be prioritized	NBR (51% acrylonitrile), PIB (and neoprene as needed for comparison)
Toughening/hot-melt adhesive/bonding layers (need hydrophobic-phase viscoelasticity + thermal processability)	Table 3	SBS/SEBS and PEVA are classic formulation platforms: one provides a microphase-separated elastic framework; the other provides adhesion/compatibility “bridging phases,” making selection more formulation-driven	SBS, SEBS, PEVA, PIB
Lubrication/demolding/defoaming/slip feel (additive strategy rather than changing the base resin)	Table 3	These needs are often best solved by “additives/fluids” with lower cost than swapping the main resin; Table 3 is the concentration zone for formulation-type hydrophobic components	Silicone oil, polymethylhydrosiloxane, PTFE micropowder
Need comparable processing and rheology (across batches/equipment; align MFR data)	Table 3	Reference materials calibrate melt-flow and processing-rheology tests to be comparable—useful for methodology and aligning process windows	Polypropylene melt flow rate reference material
Comparing “engineering plastics vs fluorinated systems”: need both chemical resistance and load-bearing/rigidity	Set chemical-resistance threshold with Table 2 first, then set structural load-bearing with Table 1	Fluorinated systems prioritize chemical resistance and low surface energy; structural parts still require mechanics and processability, so return to Table 1 for engineering-plastic choices and benchmarking	Table 2: PVDF/ETFE/FEP; Table 1: PEEK/PPS/PSU/PC/glass-reinforced PET

Table 1 | Commodity Thermoplastics + Engineering Plastics (primarily for structural matrices and processing/forming)

Category	CAS No.	Aladdin Cat. No.	Product name	Specification / Purity	Key features & applications (hydrophobic polymers–related)
Polyolefins | Commodity thermoplastics (hydrophobic matrix / films)	9002-88-4	P434354	Polyethylene (PE)	Medium density	A typical hydrophobic commodity plastic matrix (low water uptake, resistant to most acids/bases, electrically insulating). Widely used in hydrophobic barrier films/packaging, containers and pipes, and as a matrix for hydrophobic encapsulation and composites with powders/fillers. Also serves as a “hydrophobic reference material” for evaluating wetting/contact angle and water-vapor barrier performance.
Glassy hydrophobic thermoplastics | Transparent rigid plastics (optics / coating matrix)	9011-14-7	P141444	Poly(methyl methacrylate) (PMMA)	General-purpose injection grade	A transparent, rigid, low-water-uptake, glassy hydrophobic polymer. Used in optical parts/transparent covers, hard coatings, and composite matrices. In research, often used for surface modification studies (enhancing hydrophobicity/anti-fouling or improving adhesion) and for optical performance benchmarking.
Glassy hydrophobic thermoplastics | General rigid plastics (model matrix)	9003-53-6	P107087	Polystyrene (PS)	General grade III; high strength; extrusion grade; food grade	A classic low-polarity hydrophobic polymer: easy to process and low cost. Common in general injection molding/extrusion and as an experimental “hydrophobic matrix reference.” Also frequently used as the hard block in block copolymers (microphase separation with elastomeric blocks).
Glassy hydrophobic thermoplastics | SAN (chemical resistance / dimensional stability)	9003-54-7	P304886	Styrene–acrylonitrile copolymer (SAN)	General grade	Compared with PS, offers better chemical resistance, rigidity, and dimensional stability. Used for housings, transparent/semi-transparent parts, and as a base resin for modified plastics. Can serve as a hydrophobic hard-matrix resin while tuning interfacial compatibility and adhesion via polarity (AN content).
Engineering plastics | PC (impact resistance / weatherable grade)	25037-45-0	P301659	Polycarbonate (PC)	UV-resistant grade; melt index: 5 g/10 min (300°C/1.2 kg)	A high-toughness transparent engineering plastic; UV-resistant grade suits outdoor weathering. Used for transparent protective parts, structural housings, and impact-resistant components. Hydrophobic-relevant applications often involve weatherable housings/transparent covers paired with anti-fouling and scratch-resistant coating systems.
Vinyl chloride resin | PVC (barrier / electrical insulation)	9002-86-2	P434341	Poly(vinyl chloride) (PVC)	Low molecular weight	Low water uptake with good barrier and electrical insulation properties. Lower molecular weight can be favorable for formulation processing (plasticization/blending) and film formation. Used in pipes/films/coatings and as a barrier-material benchmark (note that plasticizers and thermal-stabilizer systems can significantly affect performance).
Engineering plastics | PPE/PPO (low water uptake / dimensional stability)	25134-01-4	P476429	Poly(2,6-dimethyl-1,4-phenylene ether)	Mw 40,000–50,000	Low water uptake, good dimensional stability, and strong electrical performance. Commonly used in engineering plastic alloys (e.g., blends with PS) and electrical components. Suitable as a “low-water-uptake hydrophobic engineering matrix” for evaluating interfacial compatibility and thermo-electrical performance.
Engineering plastics | PSU (heat resistance / relatively better hydrolysis resistance)	25135-51-7	P707031	Polysulfone (PSU)	Mw ~75,000	A high-temperature engineering plastic with high strength, heat resistance, and dimensional stability. Used in high-temperature structural parts, porous supports for filtration/separation, and heat-resistant components. Hydrophobic-relevant scenarios often include heat-resistant matrices, composite membrane support layers, and anti-fouling surface modification research.
Engineering plastics | Reinforced PET (structural parts / creep resistance)	25038-59-9	P303204	Poly(ethylene terephthalate) (PET)	Granular; 30% glass particles as reinforcer	Glass-fiber-reinforced PET: improved rigidity, dimensional stability, and creep resistance. Used in structural parts, heat-resistant components, and engineering housings. Hydrophobic-relevant applications often target engineering composite matrices balancing “load-bearing structure + some barrier/hot-humid resistance.”
Engineering plastics | PPS (heat/chemical resistance / low water uptake)	25212-74-2	P477919	Poly(1,4-phenylene sulfide) (PPS)	Average Mₙ ~10,000; powder	High rigidity, excellent heat and chemical resistance, and low water uptake. Powder form is suitable for composite modification, coating/sintering, or as a chemically resistant structural matrix. Common in corrosion-resistant parts, electrical/electronic structural components, and high-temperature hydrophobic engineering applications.
Engineering plastics | High-temp high-strength (chemical/wear resistance)	29658-26-2	P580719	PEEK neat resin pellets	Medium flow; for injection molding	A high-temperature, high-strength hydrophobic engineering matrix with excellent chemical and wear resistance. Suitable for injection-molded structural parts, solvent-resistant components, and friction/sliding parts. In research, often used as a “high-performance hydrophobic matrix” to evaluate glass/carbon fiber or filler reinforcement and interfacial modification.
Engineering plastics | Nylon (crystalline engineering plastic sensitive to water uptake: requires bulk water-uptake/dimensional-stability validation)	25038-54-4	N477565	Nylon 6 (PA6)	Pellets	An engineering plastic matrix with good strength and wear resistance; usable in composites, structural parts, and films. In research, often used to study water-uptake–mechanical-property coupling, hydrophobic surface modification, and the impact of filler reinforcement on performance.
Engineering plastics | Nylon (moderate polarity / modifiable for lower water uptake)	32131-17-2	N432620	Nylon 6/6 (PA66)	Pellets	A crystalline engineering plastic with strong mechanical and wear performance. More water-absorbing than polyolefins, yet widely used for structural and wear parts; hydrophobicity and dimensional stability can be improved via formulation, fillers, and surface treatment. Suitable as a matrix for composite reinforcement and tribology studies.
Engineering plastics | Nylon (lower water uptake / better dimensional stability)	24937-16-4	N477569	Nylon 12 (PA12)	Pellets	Lower water uptake, better dimensional stability, and good toughness compared with PA6/PA66. Common in tubing, flexible structural parts, and impact-resistant components. Well suited for “low water uptake + engineering strength” hydrophobic/quasi-hydrophobic applications and benchmarking.

Table 2 | Fluoropolymers (low surface energy / chemical resistance / barrier-related)

Category	CAS No.	Aladdin Cat. No.	Product name	Specification / Purity	Key features & applications (hydrophobic polymers–related)
Fluoropolymers | PVDF (chemical/weather resistance / film-forming)	24937-79-9	P1492342	Poly(vinylidene fluoride) (PVDF)	Melt viscosity (K Poise): 23.5–29.5; powder	Low surface energy with strong chemical and weather resistance; many solvent-processable/film-forming systems. Widely used in corrosion-resistant coatings, hydrophobic membrane materials (microporous/phase-inversion membranes), and lithium-battery binder/separator-coating related applications. Powder form is convenient for coatings/membranes and composite modification.
Fluoropolymers | ETFE (melt-processable / chemical resistance)	25038-71-5	P478435	Poly(ethylene-co-tetrafluoroethylene) (ETFE)	Melt index 11 g/10 min (279°C/49 N); pellets	Low surface energy, chemical resistance, and melt processability. Used in corrosion-resistant linings, tubing, cables, and films. Suitable where a “processable hydrophobic fluoropolymer matrix” is needed (easier to process than PTFE).
Fluoropolymers | PFA-type / fluorinated ether copolymer (corrosion resistance / processable)	26655-00-5	H670400	Polymer of 1,1,1,2,2,3,3-heptafluoro-3-[(trifluorovinyl)oxy]propane and tetrafluoroethylene	Melt index 10–18 (g/10 min)	A representative “fluorinated ether/TFE” copolymer system: combines low surface energy and excellent corrosion resistance while retaining melt processability. Common in high-purity chemical transfer/linings, corrosion-resistant coatings, and sealing components. Suitable for strong acids/strong solvents and low-contamination hydrophobic material systems.
Fluoropolymers | FEP (chemical resistance / extrudable)	25067-11-2	P670398	Fluorinated ethylene propylene resin (FEP)	Melt index: 35.5–42.0 (g/10 min)	A fully fluorinated system with low surface energy, strong chemical resistance, and excellent electrical insulation. Melt-processable (extrusion/overcoating). Used for cable insulation, tubing, corrosion-resistant films, and coatings. Suitable when a “high-flow, processable fluoropolymer matrix” is required.
Fluoropolymers | PTFE micropowder (lubrication / anti-stick / wear-resistant additive)	9002-84-0	P670338	Polytetrafluoroethylene (PTFE) micropowder resin	Average particle size: ~610 μm; bulk density: ~490 g/L	Low-friction, anti-stick, chemically resistant micropowder. Often used as a lubricant/wear-resistant additive in hydrophobic coatings, inks, and plastics to improve slip, scratch resistance, and blocking resistance. Also used for low-surface-energy surface modification and anti-fouling systems (pay attention to dispersion and interfacial bonding).
Fluoropolymers | PCTFE (low moisture permeability / low-temperature performance)	9002-83-9	P476437	Poly(chlorotrifluoroethylene) (PCTFE)	Powder	Low surface energy with outstanding water-vapor barrier performance. Used in high-barrier packaging, low-temperature/vacuum sealing, and chemically resistant films/linings. Powder form is convenient for coatings/membranes and barrier-material research (focus on film formation/sintering process windows).

Table 3 | Elastomers/TPE + Siloxanes/Additives + Reference Materials (flexibility, tackification, lubrication, and testing)

Category	CAS No.	Aladdin Cat. No.	Product name	Specification / Purity	Key features & applications (hydrophobic polymers–related)
Siloxanes | Inert hydrophobic fluid (lubrication / defoaming / demolding)	63148-62-9	S433164	Silicone oil	Viscosity 5 cSt (25°C)	A low–surface-energy hydrophobic fluid with strong lubrication/demolding/anti-stick effects. Commonly used for hydrophobic wetting modification, defoaming, lubrication, and as an electrical insulating medium. Also useful for surface-energy-gradient experiments, and as a slip/migratory component in hydrophobic coating formulations (consider migration and potential impacts on adhesion).
Reactive siloxanes | Crosslinker / hydrophobic modifier (Si–H)	63148-57-2	P477954	Poly(methylhydrosiloxane) (trimethylsiloxy-terminated)	Viscosity ~3 cSt	A reactive hydrophobic siloxane containing Si–H groups: used in addition-cure silicone rubber/silicone resin crosslinking systems and for hydrophobization surface modification (paired with vinyl/alkenyl-containing systems). Suitable as a reactive component for “hydrophobic coatings/surface modification” and for tuning crosslink density.
Elastomers | Diene rubber (low Tg / toughening)	9003-17-2	P485919	Polybutadiene, predominantly 1,2-addition	~90% 1,2-vinyl	A hydrophobic diene-rubber elastomer. High 1,2-vinyl content provides distinct segmental dynamics and a window for subsequent modification reactions. Used for resin/plastic toughening, elastic tackifying phases, and hydrophobic composites; also serves as a “structure–property reference” rubber phase.
Elastomers | Diene rubber (cis-polyisoprene)	104389-31-3	P485890	Polyisoprene, cis	Made from natural rubber; GPC average Mw ~38,000	A typical hydrophobic rubber matrix with good elasticity and rebound. Used in elastomer/viscoelastic systems, toughening modification, and hydrophobic buffer layers. In research, often used as a “natural-rubber-like model” to study crystallization/mechanics and interfacial adhesion.
Elastomers | EPDM (weather/water/steam resistance)	25038-36-2	P301651	Ethylene–propylene–diene terpolymer (EPDM)	Ethylene content: 72%; ENB: 4%	A low-polarity hydrophobic rubber with outstanding weather, water/steam, and ozone resistance. Used for seals, weather-resistant coatings/modification, and hydrophobic waterproofing systems. Also suitable as a hydrophobic elastomer matrix for outdoor aging and water-contact scenarios.
Elastomers | NBR (oil/solvent resistance)	9003-18-3	A1375681	Poly(acrylonitrile-co-butadiene) (NBR)	Acrylonitrile 51%	High acrylonitrile content → stronger oil/fuel/solvent resistance and more controllable swelling behavior in hydrophobic phases. Used in seals, oil-resistant hoses, and chemically resistant elastomer systems. Suitable as a benchmark for elastomers under “oil/solvent environments” and for failure-mode evaluation.
Elastomers | Neoprene (weather resistance / flame retardancy / moderate oil resistance)	9010-98-4	P466846	Polychloroprene	85% trans, 10% cis	A chlorinated elastomer with relatively improved weather resistance, oil resistance, and flame retardancy. Used for adhesives, sealing, weather-resistant rubber products, and protective coatings. Hydrophobic-relevant scenarios often include waterproof/weatherable bonding and environmental-aging evaluation of rubber layers.
Thermoplastic elastomer (TPE) | SBS (toughening / hot-melt adhesive matrix)	9003-55-8	P434455	Polystyrene-block-polybutadiene-block-polystyrene (SBS)	Styrene 30 wt.%; average Mw ~140,000 by GPC	A classic SBS TPE: PS hard blocks + PB soft blocks form microphase-separated morphology, combining elasticity and thermal processability. Used in hot-melt adhesives, asphalt modification, plastic toughening, and hydrophobic elastomer matrices. Suitable as a model material for “hydrophobic elastic/viscoelastic systems.”
Thermoplastic elastomer (TPE) | SEBS (weather resistance / low-polarity elastomer)	66070-58-4	P478290	Polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SEBS)	Crumbs; Mw ~90,000	A low-polarity SEBS TPE with relatively better weather resistance; suitable for flexible modification and elastomer matrices. Used in soft-touch materials, toughening, sealing, and bonding layers. Also common in hydrophobic surface “hand-feel/slip” design and weatherable elastomer formulations.
Copolyolefins | EVA/PEVA (bonding / flexibility)	24937-78-8	P432376	Poly(ethylene-co-vinyl acetate) (PEVA)	Vinyl acetate 12 wt.%; melt index 8 g/10 min (190°C/2.16 kg)	Combines polyolefin hydrophobicity with some polar adhesion capability. Used in hot-melt adhesives, toughening modification, films, and flexible bonding layers. Can serve as a compatibility/adhesion “bridging phase” to optimize interfaces in hydrophobic-matrix composites.
Low-polarity tackifier | PIB (viscoelastic / sealing)	9003-27-4	P304883	Polyisobutylene (PIB)	Molecular weight 2400	A low-polarity hydrophobic viscoelastic polymer with strong tackification and sealing performance. Used for sealants/adhesive tackification, barrier and lubrication systems, hydrophobic-phase thickening, and rheology control. Also used as a “hydrophobic tackifying matrix” to study swelling and permeation.
Testing / Reference material | Processing rheology calibration	9003-07-0	P308012	Polypropylene melt flow rate reference material	Melt flow rate: 1.65 g/10 min	Used for calibration/benchmarking in melt flow rate (MFR) and related processing-rheology tests. Suitable for establishing comparable data when defining “processing windows for hydrophobic polymers” (consistency across batches/equipment).

Note: The above are representative Aladdin products. For more specifications, please refer to the product list at the end of the article or search the Aladdin website by product name/CAS number.

Aladdin: https://www.aladdinsci.com/