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Hydroxyethylmethacrylate (also known as glycol methacrylate) is the
organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...
with the chemical formula . It is a colorless viscous liquid that readily
polymerize In polymer chemistry, polymerization (American English), or polymerisation (British English), is a process of reacting monomer molecules together in a chemical reaction to form polymer chains or three-dimensional networks. There are many form ...
s, i.e. it is a
monomer A monomer ( ; ''mono-'', "one" + '' -mer'', "part") is a molecule that can react together with other monomer molecules to form a larger polymer chain or two- or three-dimensional network in a process called polymerization. Classification Chemis ...
that is used to make various
polymer A polymer () is a chemical substance, substance or material that consists of very large molecules, or macromolecules, that are constituted by many repeat unit, repeating subunits derived from one or more species of monomers. Due to their br ...
s.


Synthesis

Hydroxyethylmethacrylate was first synthesized around 1925. Common methods of synthesis are: * reaction of
methacrylic acid Methacrylic acid, abbreviated MAA, is an organic compound with the formula CH2=C(CH3)CO2H. This colorless, viscous liquid is a carboxylic acid with an acrid unpleasant odor. It is soluble in warm water and miscible with most organic solvents. Me ...
with
ethylene oxide Ethylene oxide is an organic compound with the chemical formula, formula . It is a cyclic ether and the simplest epoxide: a three-membered ring (chemistry), ring consisting of one oxygen atom and two carbon atoms. Ethylene oxide is a colorless ...
: : *
esterification In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distin ...
of methacrylic acid with a large excess of
ethylene glycol Ethylene glycol ( IUPAC name: ethane-1,2-diol) is an organic compound (a vicinal diol) with the formula . It is mainly used for two purposes: as a raw material in the manufacture of polyester fibers and for antifreeze formulations. It is an odo ...
. : Both these methods give also some amount of
ethylene glycol dimethacrylate Ethylene glycol dimethylacrylate (EGDMA) is a ester, diester formed by condensation of two equivalents of methacrylic acid and one equivalent of ethylene glycol. EGDMA can be used in free radical copolymer Cross-link, crosslinking reactions. W ...
. During polymerization of hydroxyethylmethacrylate, it works as crosslinking agent.


Properties

Hydroxyethylmethacrylate is completely miscible with water and ethanol, but its polymer is practically insoluble in common solvents. Its
viscosity Viscosity is a measure of a fluid's rate-dependent drag (physics), resistance to a change in shape or to movement of its neighboring portions relative to one another. For liquids, it corresponds to the informal concept of ''thickness''; for e ...
is 0.0701 Pa⋅s at 20°C and 0.005 Pa⋅s at 30°C. During polymerization, it shrinks by approximately 6%.


Applications


Contact lenses

In 1960, O. Wichterle and D. Lím described its use in synthesis of hydrophilic crosslinked networks, and these results had great importance for manufacture of soft
contact lenses Contact lenses, or simply contacts, are thin lens (optics), lenses placed directly on the surface of the Human eye, eyes. Contact lenses are ocular prosthetic devices used by over 150 million people worldwide, and they can be worn to correct ...
.
Polyhydroxyethylmethacrylate Poly(2-hydroxyethyl methacrylate) (pHEMA) is a polymer that forms a hydrogel in water. Poly (hydroxyethyl methacrylate) (PHEMA) hydrogel for intraocular lens (IOL) materials was synthesized by solution polymerization using 2- hydroxyethyl methac ...
is hydrophilic: it is capable of absorbing from 10 to 600%
water Water is an inorganic compound with the chemical formula . It is a transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance. It is the main constituent of Earth's hydrosphere and the fluids of all known liv ...
relative to the dry weight. Because of this property, it was one of the first materials to be used in the manufacture of soft contact lenses.


Use in 3D printing

Hydroxyethylmethacrylate lends itself well to applications in 3D printing as it cures quickly at room temperature when exposed to UV light in the presence of photoinitiators. It may be used as a monomeric matrix in which 40nm silica particles are suspended for 3D glass printing. When combined with a suitable
blowing agent A blowing agent is a substance which is capable of producing a cellular structure via a foaming process in a variety of materials that undergo hardening or phase transition, such as polymers, plastics, and metals. They are typically applied whe ...
such as
BOC anhydride Di-''tert''-butyl dicarbonate is a reagent widely used in organic synthesis. Since this compound can be regarded formally as the acid anhydride derived from a ''tert''-butoxycarbonyl (Boc) group, it is commonly referred to as Boc anhydride. This ...
it forms a foaming resin which expands when heated.


Other

In
electron microscopy An electron microscope is a microscope that uses a beam of electrons as a source of illumination. It uses electron optics that are analogous to the glass lenses of an optical light microscope to control the electron beam, for instance focusing i ...
, later in
light microscopy Microscopy is the technical field of using microscopes to view subjects too small to be seen with the naked eye (objects that are not within the resolution range of the normal eye). There are three well-known branches of microscopy: optical, el ...
, hydroxyethylmethacrylate serves as an embedding medium. When treated with
polyisocyanate In organic chemistry, isocyanate is the functional group with the formula . Organic compounds that contain an isocyanate group are referred to as isocyanates. An organic compound with two isocyanate groups is known as a diisocyanate. Diisocyan ...
s, polyhydroxyethylmethacrylate makes a crosslinked polymer, an
acrylic resin 186 px, Polyhydroxyethylmethacrylate is a typical acrylate resin. An acrylic resin is a thermoplastic or thermosetting plastic substance typically derived from acrylic acid, methacrylic acid and acrylate monomers such as butyl acrylate and me ...
, that is a useful component in some paints.


Hazards

Hydroxyethylmethacrylate is a mild skin irritant and can cause allergic skin reactions.


References

{{DEFAULTSORT:Hydroxyethylmethacrylate Methacrylate esters Monomers Hydroxyethyl compounds