Polysulfone

Key takeaways

Polysulfone belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Polysulfone to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Polysulfone from memory before moving on to harder problems.

Reference excerpt

Polysulfones are a family of high-performance thermoplastics. These polymers are known for their toughness and stability at high temperatures. Technically used polysulfones contain an aryl-SO2-aryl subunit. Due to the high cost of raw materials and processing, polysulfones are used in specialty applications and often are a superior replacement for polycarbonates. Three polysulfones are used industrially: polysulfone (PSU), polyethersulfone (PES/PESU), and polyphenylsulfone (PPSU). They can be used at temperature of −100–200 °C (−148–392 °F) and are used for electrical equipment, vehicle construction, and medical technology. They are composed of para-linked aromatics, sulfonyl groups, and ether groups and partly also alkyl groups. Polysulfones have outstanding resistance to heat, oxidation, hydrolysis, aqueous media, and alkaline media, and they have good electrical properties.

Nomenclature The term "polysulfone" is normally used for polyarylethersulfones (PAES), since only aromatic polysulfones are used commercially. Furthermore, since ether groups are always present in these polysulfones, PAESs are also referred to as polyether sulfones (PES), poly(arylene sulfone)s or simply polysulfone (PSU).

Production

Historical The simplest polysulfone, poly(phenylene sulfone), known as early as 1960, is produced in a Friedel-Crafts reaction from benzenesulfonyl chloride:

n C6H5SO2Cl → (C6H4SO2)n + n HCl With a melting point over 500 °C, the product is difficult to process. It exhibits attractive heat resistance, but its mechanical properties are rather poor. Polyarylether sulphones (PAES) represent a suitable alternative. Appropriate synthetic routes to PAES were developed almost simultaneously, and yet independently, from 3M Corporation, Union Carbide Corporation in the United States, and ICI's Plastics Division in the United Kingdom. The polymers found at that time are still used today, but produced by a different synthesis process. The original synthesis of PAES involved electrophilic aromatic substitution of a diaryl ether with the bis (sulfonyl chloride) of benzene. Reactions typically use a Friedel-Crafts catalyst, such as ferric chloride or antimony pentachloride:

n O(C6H5)2 + n SO2Cl2 → {[O(C6H4)2]SO2}n + 2n HCl

This route is complicated by the formation of isomers arising from both para- and ortho- substitution. Furthermore, cross-linking was observed, which strongly affects the mechanical properties of the polymer. This method has been abandoned.

Contemporary production methods PAES are currently prepared by a polycondensation reaction of diphenoxide and bis(4-chlorophenyl)sulfone (DCDPS). The sulfone group activates the chloride groups toward substitution. The required diphenoxide is produced in situ from a diphenol and sodium hydroxide. The cogenerated water is removed by azeotropic distillation using toluene or chlorobenzene). The polymerization is carried out at 130–160 °C under inert conditions in a polar, aprotic solvent, such as dimethyl sulfoxide, forming a polyether concomitant with elimination of sodium chloride: Bis(4-fluorophenyl)sulfone can be used in place of bis(4-chlorophenyl)sulfone. The difluoride is more reactive than the dichloride but more expensive. Through chain terminators (e.g. methyl chloride), the chain length can be controlled for melt-processing. The diphenol is typically bisphenol-A or 1,4-dihydroxybenzene. Such step polymerizations require highly pure monomer and precise stoichiometry to ensure high-molecular-weight products. DCDPS is the precursor to polymers known as Udel (from bisphenol A), PES, and Radel R. Udel is a high-performance amorphous sulfone polymer that can molded into a variety of different shapes. It is both rigid and temperature-resistant, and has applications in everything from plumbing pipes, to printer cartridges, to automobile fuses. DCDPS also reacts with bisphenol S to form PES. Like Udel, PES is a rigid and thermally-resistant material with numerous applications.

Properties Polysulfones are rigid, high-strength and transparent. They are also characterized by high strength and stiffness, retaining these properties between −100 °C and 150 °C. The glass transition temperature of polysulfones is between 190 and 230 °C. They have a high dimensional stability: the size change when exposed to boiling water or 150 °C air or steam generally falls below 0.1%. Polysulfone is highly resistant to mineral acids, alkali, and electrolytes, in pH ranging from 2 to 13. It is resistant to oxidizing agents (although PES will degrade over time); therefore, it can be cleaned by bleaches. It is also resistant to surfactants and hydrocarbon oils. It is not resistant to low-polar organic solvents (e.g. ketones and chlorinated hydrocarbons) and aromatic hydrocarbons. Mechanically, polysulfone has high compaction resistance, recommending its use under high pressures. It is also stable in aqueous acids and bases and many non-polar solvents; however, it is soluble in dichloromethane and methylpyrrolidone. Polysulfones are counted among the high-performance plastics. They can be processed by injection molding, extrusion, or hot forming.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Polysulfone

Start with the simplest possible case. Write down what Polysulfone claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Polysulfone before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Polysulfone ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Polysulfone

In research: Polysulfone appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Polysulfone in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Polysulfone is common in secondary-school and first-year university syllabi. It links to neighbouring topics Engineering plastic, Plastics, Polymers, so understanding it makes those chapters shorter.
In everyday life: Look for Polysulfone outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study Polysulfone in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Polysulfone means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Polysulfone out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Polysulfone in simple terms?

Polysulfones are a family of high-performance thermoplastics. These polymers are known for their toughness and stability at high temperatures.

Why does Polysulfone matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Polysulfone?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Polysulfone.