chemistry

Polyhydroxyethylmethacrylate

Polyhydroxyethylmethacrylate is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Polyhydroxyethylmethacrylate rather than just read about it. In short: Poly(2-hydroxyethyl methacrylate) (pHEMA) is a polymer that forms a hydrogel in water. It was invented by Drahoslav Lim and Otto Wichterle for biological use.

Key takeaways

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

Reference excerpt

Poly(2-hydroxyethyl methacrylate) (pHEMA) is a polymer that forms a hydrogel in water. It was invented by Drahoslav Lim and Otto Wichterle for biological use. Together they succeeded in preparing a cross-linking gel which absorbed up to 40% of water, exhibited suitable mechanical properties and was transparent. They patented this material in 1953.

Synthesis pHEMA hydrogel for intraocular lenses can be synthesized by solution polymerization using 2-hydroxyethyl methacrylate (HEMA) as raw material, ammonium persulfate and sodium pyrosulfite (APS/SMBS) as catalyst, and triethyleneglycol dimethacrylate (TEGDMA) as cross-linking additive.

Applications

Contact lenses In 1959, this material was first used as an optical implant. Wichterle thought pHEMA might be a suitable material for a contact lens and gained his first patent for soft contact lenses. By late 1961, he succeeded in producing the first four pHEMA hydrogel contact lenses on a home-made apparatus. Copolymers of pHEMA are still widely used today. Poly-HEMA functions as a hydrogel by rotating around its central carbon. In air, the non-polar methyl side turns outward, making the material brittle and easy to grind into the correct lens shape. In water, the polar hydroxyethyl side turns outward and the material becomes flexible. Pure pHEMA yields lenses that are too thick for sufficient oxygen to diffuse through, so all contact lenses that are pHEMA based are manufactured with copolymers that make the gel thinner and increase its water of hydration. These copolymer hydrogel lenses are often suffixed "-filcon", such as Methafilcon, which is a copolymer of hydroxyethyl methacrylate and methyl methacrylate. Another copolymer hydrogel lens, called Polymacon, is a copolymer of hydroxyethyl methacrylate and ethylene glycol dimethacrylate.

Cell culture pHEMA is commonly used to coat cell culture flasks in order to prevent cell adhesion and induce spheroid formation, particularly in cancer research. Older alternatives to pHEMA include agar and agarose gels.

References

Illustrations

Worked examples

Example 1 — a first encounter with Polyhydroxyethylmethacrylate

Start with the simplest possible case. Write down what Polyhydroxyethylmethacrylate 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 Polyhydroxyethylmethacrylate 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 Polyhydroxyethylmethacrylate 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 Polyhydroxyethylmethacrylate

In research: Polyhydroxyethylmethacrylate 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 Polyhydroxyethylmethacrylate 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: Polyhydroxyethylmethacrylate is common in secondary-school and first-year university syllabi. It links to neighbouring topics Acrylate polymers, Czech inventions, Plastics, so understanding it makes those chapters shorter.
In everyday life: Look for Polyhydroxyethylmethacrylate 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.

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How to study Polyhydroxyethylmethacrylate in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Polyhydroxyethylmethacrylate 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 Polyhydroxyethylmethacrylate out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Polyhydroxyethylmethacrylate in simple terms?

Poly(2-hydroxyethyl methacrylate) (pHEMA) is a polymer that forms a hydrogel in water. It was invented by Drahoslav Lim and Otto Wichterle for biological use.

Why does Polyhydroxyethylmethacrylate 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 Polyhydroxyethylmethacrylate?

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 Polyhydroxyethylmethacrylate.