Monomers are single atoms or small molecules that bind together to form polymers, macromolecules that are composed of repeating chains of monomers. Essentially, monomers are building blocks for molecules, including proteins, starches and many other polymers. . Large numbers of monomer units combine to form polymers in a process called polymerization.
Monomers are the building blocks of polymers. They can be subdivided into groups based on structure and functionality and include small-molecule and oligomeric compounds, as shown below.
Major monomer categories include acrylics, alcohols, epoxides and amines. In addition to monomers, Sigma-Aldrich offers a large variety of end-functional polymers and crosslinkers that can be used as macro-monomers to create complex or cross-linked polymer architectures.
There are BIOPOLYMERS :
- LIPIDS ( Diglycerides, triglycerides ), the monomers are glycerol and fatty acids.
- PROTEINS ( Polypeptides), the monomers are amino acids.
- NUCLEIC ACIDS ( DNA/ RNA ), the monomers are nucleotides.
- CARBOHYDRATES ( Polysaccharides specifically and disaccharides — depends), the monomers are monosaccharaides
There are INDUSTRIAL POLYMERS :
- ACRYLIC MONOMERS
- EPOXIDE MONOMERS
- ISOCYANATE MONOMERS
- ALLYI MONOMERS
- NORBORENE MONOMERS
- AMINE MONOMERS
- SILICONE MONOMERS
- ANHYDRIDE MONOMERS
- STYRENE AND FUNCTIONALIZED MONOMERS
- BIODEGRADABLE POLYMER MONOMERS
- VINYL ESTERS
- BISPHENOL AND SULFONYLDIPHENOL MONOMERS
- VINYL ETHERS
- CARBOXYLIC ACID MONOMERS
- VINYL HALIDES, AMINES, AMIDES, AND OTHER VINYL MONOMERS
- ETHYLENE GAS ((H2C=CH2) IS THE PRECURSOR MONOMER FOR POLYETHYLENE.
- OTHER MODIFIED ETHYLENE MOLECULES, SUCH AS TETRAFLUORETHYLENE (F2C=CF2) WHICH LEADS TO TEFLON, VINYL CHLORIDE, (H2C=CHCL) WHICH LEADS TO PVC, STYRENE (C6H5CH=CH2) WHICH LEADS TO POLYSTERENE, ETC.
- EPOXIDE MONOMERS MAY BE CROSS LINKED WITH THEMSELVES, OR WITH THE ADDITION OF A CO-REACTANT, TO FORM EPOXY.
- BPA IS THE MONOMER PRECURSOR FOR POLYCARBONATE.
Likewise, there are other developments of new polymers.
We are mainly concerned with ACRYLIC MONOMERS.
ACRYLICS are probably the most versatile family of MONOMERS.
These can be used to make POLYMERS with rigid, flexible, ionic, nonionic, hydrophobic, or hydrophilic properties.
These are classified into 9 groups based on composition and functionality.
They are polymerized primarily by a free radical process, and to a lesser extent by anionic polymerization. Additional acrylic macro monomers can be found in Poly (ethelene glycol) and Poly (ethylene oxide) section, Polyfunctional Acrylics.
Acrylamide and Methacrylamide
- Acrylic Acids and Salts
- Bisphenol Acrylics
- Carbohydrate Monomers
- Fluorinated Acrylics
Acrylic acid and its esters such as Methyl acrylate, Ethyl acrylate, Butyl acrylate and 2-Ethylhexyl acrylate, are known as basic acrylates. Most of the acrylates are flammable, volatile and colourless liquids.
Commercial Acrylic acid is produced by selective gas phase oxidation of propene. The crude acrylic acid is further purified to obtain different acrylic acid qualities of standard or ester grade to high purity grade acrylic acid. The purity of the acrylic acid produced usually exceeds 99.5 wt %.
Acrylic acid and its esters are usually stabilized with inhibitors such as hydroquinone monomethyl ether (MeHQ). Because MeHQ is only effective in the presence of oxygen, the acrylic monomers must be stored under air or an atmosphere containing at least 5 Vol.-% of oxygen.
The stabilized monomers are generally stored below 25 °C. Acrylic acid should not be stored below 15 °C because acrylic acid crystallizes.
The primary use of acrylic acid and esters is as an intermediate in the production of polyacrylates. Polyacrylates can be produced by various processes, with emulsion polymerization being the most important industrial polymerization process. Polyacrylates are produced by exothermic radical polymerization. The variety of the properties of polyacrylates and copolymers gives a large range of products, with their applications and uses. As a result, polyacrylates are used for the manufacture of polymer dispersions (coatings, paints and printing inks), adhesives, binding agents, super absorbent polymers, flocculants, detergents, varnishes, fibres and plastics, as well as chemical intermediates.
Acrylic resins are a group of related thermoplastic or thermosetting plastic substances derived from Acrylic Acid, Methacrylic Acid or other related compounds. Polymethyl Acrylate is an acrylic resin used in an emulsified form for lacquer, textile finishes, adhesives, and, when mixed with clay, to gloss paper. Another acrylic resin is polymethyl methacrylate, which is used to make hard plastics with various light transmitting properties. It is used for the materials which need some light transmitting properties, because it is transparent as glass, some amount of titanium dioxide can be added for a translucent effect.
Poly(methyl acrylate) ( PMA ) is a hydrophobic synthetic acrylate polymer.
PMA, though softer than Poly(methyl methacrylate) ( PMMA ) is tough, leathery and flexible. It has a low glass-tension temperature about 10°C (12.5°C in case of PMA.
High energy radiation leads to cross linking in PMA. However in PMMA, a compound similar to PMA, degradation occurs instead.
It is soluble in dimethyl sulfoxide ( DMSO).
PMA is water sensitive and unlike PMMA, is not stable against alkalies.
It is used as macro initiator to initiate the copolymerization of HEMA and DMAEMA. Also used in leather finishing and textiles.
Methacrylate (MMA) monomers can be found as a raw material in various adhesive and sealant formulations. Most popular are reactive adhesives based on methacrylates, though pressure-sensitive adhesives and sealants, e.g. for construction applications.
Anaerobic acrylic adhesives are well known for their superior properties in fixing and sealing metal joints, for example.
With anaerobic adhesives, adhesion is provided by hydroxyl functionalized monomers. On the other hand, multifunctional methacrylates, provide cohesive strength.
Structural acrylic adhesives are used in the transportation industry for OEM assembly and in marine applications.
Methacrylate(MMA) monomers or PAINTS AND COATINGS
Waterborne coatings, solvent-based coatings and reactive systems.
Waterborne coatings have gained more and more significance in coatings applications due to their advantageous properties. As a consequence of increasingly stringent environmental standards, waterborne coatings, which have an inherently low solvent content, continue to hold the pole position in the race towards ever lower VOC levels.
Traditional solvent-based coatings have, to some degree, also evolved into environmentally friendly products. With coatings made from high solids resins, excellent performance results are possible with an extremely low solvent content.
Reactive systems enable the manufacture of make resins, e.g. for wood coatings, using environmentally friendly and fast-curing UV or EB technologies, MMA is used as a reactive diluent.
Methacrylate monomers and their typical paints & coatings applications can be made possible with special necessary treatment as per relevant applications.
Typical application fields:
Automotive Coatings, Architectural & Decorative Coatings, Industrial Coatings, Marine & Protective Coatings, Paper & Packaging Coatings, Printing Inks.
Methacrylate ( MMA ) monomers for plastics :
Methacrylate ( MMA ) monomers are used in the production and modification of a wide variety of polymers – mainly in cast sheet, methacrylate molding compounds and graft copolymers as impact modifiers for thermoplastics.
Further application fields include artificial marble, PVC modifiers and PVC plastisols. Molding compounds based on unsaturated polyester resins may also contain multifunctional methacrylates as crosslinking agents.
In addition, methacrylates are used as comonomers to improve the performance of polymers in extrusion coating applications. Typical end-use applications, here, include liquid carton packaging, photographic paper, flexible and commercial packaging (e.g. coffee pouches).
Methacrylate ( MMA) monomers for textile applications :
Typical application fields: Textile Coatings, Silk Grafting, Water & Oil Repellent Agents