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{{Short description|Lightweight aldehyde- and phenol-derived polymer}} |
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[[File:NovolakCresol.png|thumb|300 px|Segment of novolak, illustrating the predominance of cresol subunits and presence of [[Cross-link|crosslinking]].]] |
[[File:NovolakCresol.png|thumb|300 px|Segment of novolak, illustrating the predominance of cresol subunits and presence of [[Cross-link|crosslinking]].]] |
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'''Novolaks''' (sometimes: novolacs) are low molecular weight [[polymer]]s derived from [[phenol]]s and [[formaldehyde]]. They are related to [[Bakelite]], 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|copal resin]]. |
'''Novolaks''' (sometimes: novolacs) are low molecular weight [[polymer]]s derived from [[phenol]]s and [[formaldehyde]]. They are related to [[Bakelite]], 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|copal resin]]. |
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Typically novolaks are prepared by the condensation of a mixture of p- and m-[[cresol]] with formaldehyde (as formalin). The reaction is catalyzed |
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]] 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 CH<sub>2</sub>O/cresol ratio is typically around 15%.<ref>{{Cite book |last=Ralph Dammel |title=Diazonaphthoquinone-based Resists |publisher=Int. Soc. Optical Engineering |year=1993 |isbn=9780819410191 |chapter=Basic Chemistry of Novolaks |doi=10.1117/3.2265072.ch3}}</ref> |
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Novolaks are especially important in microelectronics where they are used as photoresist materials.<ref>{{Kirk-Othmer|title=Lithographic Resists |
Novolaks are especially important in [[microelectronics]] where they are used as [[photoresist]] materials.<ref>{{Kirk-Othmer|title=Lithographic Resists |
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|first1=W. D. |last1=Hinsberg |first2=G. M. |last2=Wallraff |year=2005 |doi=10.1002/0471238961.1209200808091419.a01.pub2}}</ref><ref>{{cite report |url=https://ntp.niehs.nih.gov/ntp/htdocs/Chem_Background/ExSumPdf/Photoresists_DNQcmpds2_508.pdf |title=Chemical Information Review Document for Diazonaphthoquinone Derivatives Used in Photoresists |author=Integrated Laboratory Systems |publisher=National Toxicology Program |date=January 2006}}</ref> |
|first1=W. D. |last1=Hinsberg |first2=G. M. |last2=Wallraff |year=2005 |doi=10.1002/0471238961.1209200808091419.a01.pub2 |mode=cs1}}</ref><ref>{{cite report |url=https://ntp.niehs.nih.gov/ntp/htdocs/Chem_Background/ExSumPdf/Photoresists_DNQcmpds2_508.pdf |title=Chemical Information Review Document for Diazonaphthoquinone Derivatives Used in Photoresists |author=Integrated Laboratory Systems |publisher=National Toxicology Program |date=January 2006}}</ref> They are also used as [[tackifier]]s in rubber. |
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==See also== |
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* [[Epoxy]] |
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==References== |
==References== |
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Latest revision as of 11:55, 24 May 2024
Novolaks (sometimes: novolacs) are low molecular weight polymers derived from phenols and formaldehyde. They are related to Bakelite, 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 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%.[1]
Novolaks are especially important in microelectronics where they are used as photoresist materials.[2][3] They are also used as tackifiers in rubber.
See also
[edit]References
[edit]- ^ Ralph Dammel (1993). "Basic Chemistry of Novolaks". Diazonaphthoquinone-based Resists. Int. Soc. Optical Engineering. doi:10.1117/3.2265072.ch3. ISBN 9780819410191.
- ^ Hinsberg, W. D.; Wallraff, G. M. (2005). "Lithographic Resists". Kirk-Othmer Encyclopedia of Chemical Technology. New York: John Wiley. doi:10.1002/0471238961.1209200808091419.a01.pub2. ISBN 9780471238966.
- ^ Integrated Laboratory Systems (January 2006). Chemical Information Review Document for Diazonaphthoquinone Derivatives Used in Photoresists (PDF) (Report). National Toxicology Program.