Editing Liquid crystal (section)

====Smectic phases====
[[File:LiquidCrystal-MesogenOrder-SmecticPhases.jpg|thumb|Schematic of alignment in the smectic phases. The smectic A phase (left) has molecules organized into layers. In the smectic C phase (right), the molecules are tilted inside the layers.]]
The smectic phases, which are found at lower temperatures than the nematic, form well-defined layers that can slide over one another in a manner similar to that of soap. The word "smectic" originates from the Latin word "smecticus", meaning cleaning, or having soap-like properties.<ref>{{cite web| title=smectic| url=http://www.merriam-webster.com/dictionary/smectic| publisher=Merriam-Webster Dictionary| access-date=April 26, 2013| archive-date=July 31, 2013| archive-url=https://web.archive.org/web/20130731023631/http://www.merriam-webster.com/dictionary/smectic| url-status=live}}</ref>
The smectics are thus positionally ordered along one direction. In the Smectic A phase, the molecules are oriented along the layer normal, while in the Smectic C phase they are tilted away from it. These phases are liquid-like within the layers. There are many different smectic phases, all characterized by different types and degrees of positional and orientational order.<ref name=b2/><ref name=b1/> Beyond organic molecules, Smectic ordering has also been reported to occur within colloidal suspensions of 2-D materials or nanosheets.<ref name="Swollen liquid-crystalline lamellar">{{cite journal | vauthors = Gabriel JC, Camerel F, Lemaire BJ, Desvaux H, Davidson P, Batail P | s2cid = 4416985 | title = Swollen liquid-crystalline lamellar phase based on extended solid-like sheets | journal = Nature | volume = 413 | issue = 6855 | pages = 504–8 | date = October 2001 | pmid = 11586355 | doi = 10.1038/35097046 | bibcode = 2001Natur.413..504G | url = https://hal-cea.archives-ouvertes.fr/cea-03194654/file/24-Article.pdf | access-date = September 8, 2021 | archive-date = July 15, 2021 | archive-url = https://web.archive.org/web/20210715065520/https://hal-cea.archives-ouvertes.fr/cea-03194654/file/24-Article.pdf | url-status = live }}</ref><ref>{{cite journal | vauthors = Davidson P, Penisson C, Constantin D, Gabriel JP | title = Isotropic, nematic, and lamellar phases in colloidal suspensions of nanosheets | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 115 | issue = 26 | pages = 6662–6667 | date = June 2018 | pmid = 29891691 | pmc = 6042086 | doi = 10.1073/pnas.1802692115 | bibcode = 2018PNAS..115.6662D | doi-access = free }}</ref> One example of smectic LCs is [[p,p-dinonylazobenzene|''p,p'''-dinonylazobenzene]].<ref>{{Cite book |last1=Vertogen |first1=Ger |page=13 |url=https://books.google.com/books?id=7SHrCAAAQBAJ&dq=examples+of+smectic+liquid+crystals&pg=PA13 |title=Thermotropic Liquid Crystals, Fundamentals |last2=Jeu |first2=Wim H. de |oclc=851375789 |date=2012-12-06 |publisher=Springer Science & Business Media |isbn=9783642831331 |access-date=March 21, 2023 |archive-date=October 17, 2023 |archive-url=https://web.archive.org/web/20231017052201/https://books.google.com/books?id=7SHrCAAAQBAJ&dq=examples+of+smectic+liquid+crystals&pg=PA13 |url-status=live }}</ref>