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Novolaks (sometimes: novolacs) are low molecular weight polymers derived from phenols and formaldehyde. They are related to
Novolaks (sometimes: novolacs) are low molecular weight polymers derived from phenols and formaldehyde. They are related to Bakelite
Polyoxybenzylmethylenglycolanhydride, better known as Bakelite ( ), is a thermosetting phenol formaldehyde resin, formed from a condensation reaction of phenol with formaldehyde. The first plastic made from synthetic components, it was developed ...
, which is more highly crosslinked. The term comes from Swedish "lack" for lacquer and Latin "novo" for new, since these materials were envisioned to replace natural lacquers such as copal resin.
Typically novolaks are prepared by the condensation of phenol or a mixture of p- and m- cresol with formaldehyde (as formalin). The reaction is acid catalyzed. Oxalic acid
Oxalic acid is an organic acid with the systematic name ethanedioic acid and formula . It is the simplest dicarboxylic acid. It is a white crystalline solid that forms a colorless solution in water. Its name comes from the fact that early inve ...
is often used because it can be subsequently removed by thermal decomposition. Novolaks have a degree of polymerization of approximately 20-40. The branching density, determined by the processing conditions, m- vs p-cresol ratio, as well as CH2O/cresol ratio is typically around 15%.
Novolaks are especially important in microelectronics where they are used as photoresist materials. They are also used as tackifiers in rubber.
See also
*Epoxy
Epoxy is the family of basic components or cured end products of epoxy resins. Epoxy resins, also known as polyepoxides, are a class of reactive prepolymers and polymers which contain epoxide groups. The epoxide functional group is also coll ...
References
{{reflist Plastics Synthetic resins Semiconductor device fabrication Thermosetting plastics