Ladder polymer
In chemistry, a ladder polymer is a type of double stranded polymer with the connectivity of a ladder. In a typical one-dimensional polymer, e.g. polyethylene and polysiloxanes, the monomers form two bonds, giving a chain. In a ladder polymer the monomers are interconnected by four bonds. Inorganic ladder polymers are found in synthetic and natural settings. Ladder polymers are a special case of cross-linked polymers because the crosslinks exist only with pairs of chains.
According to one definition, a ladder polymer, adjacent rings have two or more atoms in common.[1]
Organic ladder polymers[edit]
Organic ladder polymers are interesting because they can exhibit exceptional thermal stabilities and the conformation of the subunits is constrained. Because they are less flexible, their processing can be challenging. An early example was derived from condensation of the 1,2,4,5-tetraaminobenzene with naphthalenetetracarboxylic dianhydride.[2][3]
Inorganic and organometallic ladder polymers[edit]
Some polysilicates are ladder polymers. One example is provided by the mineral tremolite.
In the area of coordination chemistry, the ladder structure is seen in some coordination polymers. Illustrative is the polymer [CuI(2-picoline]n. When the 2-picoline is replaced by a tertiary phosphine, it forms a tetrameric cubane-type cluster, [CuI([[PR3]]4. In both cases, the Cu(I) centers adopt tetrahedral molecular geometry.[4]
BBL ladder polymer[edit]
Poly(benzimidazobenzophenanthroline) (BBL) is a conjugated ladder polymer with conductive features. It has many interesting properties ranging from mechanical stability to usage in electronic devices such as microelectrodes or transistors.[5]Its backbone is composed of aromatic rings and the ladder structures enable the uninterrupted polymer chains with periodic linkages. However, conjugated ladder polymers additionally contain pi conjugation via strong pi-pi stacking interactions and charge transport.[6] Traditionally, p-typed doped poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is used as conductive polymers, but BBL doped with poly(ethyleneimine) (PEI) can provide a n-type doped conductive properties for fabricating high-performance organic electronic devices.[7] The images for trans and cis conjugated BBL monomer structures with pi conjugated bonds on aromatic rings can be found in Lee et al.'s paper.[8]
Mechanical properties[edit]
It is assumed that BBL displays no achievable glass transition temperature (Tg) due to its rigid chain structure. It is estimated to have a Tg around 500 C after differential scanning calorimetry (DSC) measurements.[9] [10]This mechanical property of Tg enables BBL to be mechanically stable at higher temperatures with less thermal degradation. In addition to this, the stress-strain curves of BBL fibers were observed to be very high compared to other semiconductor fibers with a value around 105.8 MPa with the highest BBL polymer concentration according to Wang et al. and decreasing the BBL content would lead in a lower overall tensile strength.[11]
References[edit]
- ^ Metanomski, W. V.; Bareiss, R. E.; Kahovec, J.; Loening, K. L.; Shi, L.; Shibaev, V. P. (1993). "Nomenclature of Regular Double-Strand (Ladder and Spiro) Organic Polymers" Pure Appl. Chem. 65 (7): 1561–1580.
- ^ Scherf, Ullrich "Ladder-type materials" Journal of Materials Chemistry 1999, volume 9, 1853-1864. {{DOI: 10.1039/A900447E}}
- ^ Grimsdale, Andrew C.; Muellen, Klaus "Phenylene-based ladder polymers" in Design and Synthesis of Conjugated Polymers, Edited by Leclerc, Mario; Morin, Jean-Francois 2010. Pp. 227-245.
- ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
- ^ Mamand, Dyari Mustafa; Qadr, Hiwa Mohammed (2021). "Comprehensive Spectroscopic and Optoelectronic Properties of BBL Organic Semiconductor". Protection of Metals and Physical Chemistry of Surfaces. 57 (5): 943–953. doi:10.1134/S207020512105018X. ISSN 2070-206X.
- ^ Lee, Jongbok; Kalin, Alexander J.; Yuan, Tianyu; Al-Hashimi, Mohammed; Fang, Lei (28 March 2017). "Fully conjugated ladder polymers". Chemical Science. 8 (4): 2503–2521. doi:10.1039/C7SC00154A.
- ^ Yang, Chi-Yuan; Stoeckel, Marc-Antoine; Ruoko, Tero-Petri; Wu, Han-Yan; Liu, Xianjie; Kolhe, Nagesh B.; Wu, Ziang; Puttisong, Yuttapoom; Musumeci, Chiara; Massetti, Matteo; Sun, Hengda; Xu, Kai; Tu, Deyu; Chen, Weimin M.; Woo, Han Young; Fahlman, Mats; Jenekhe, Samson A.; Berggren, Magnus; Fabiano, Simone (21 April 2021). "A high-conductivity n-type polymeric ink for printed electronics". Nature Communications. 12 (1): 2354. doi:10.1038/s41467-021-22528-y.
- ^ Lee, Jongbok; Kalin, Alexander J.; Yuan, Tianyu; Al-Hashimi, Mohammed; Fang, Lei (28 March 2017). "Fully conjugated ladder polymers". Chemical Science. 8 (4): 2503–2521. doi:10.1039/C7SC00154A.
- ^ Jenekhe, Samson A.; Roberts, Michael F. (August 1993). "Effects of intermolecular forces on the glass transition of polymers". Macromolecules. 26 (18): 4981–4983. doi:10.1021/ma00070a041. ISSN 0024-9297.
- ^ Zimmerman, Catherine M.; Koros, William J. (September 1999). "Comparison of gas transport and sorption in the ladder polymer BBL and some semi-ladder polymers". Polymer. 40 (20): 5655–5664. doi:10.1016/S0032-3861(98)00777-0.
- ^ Wang, Xiu; Zhang, Zhi; Li, Peiyun; Xu, Jingcao; Zheng, Yuting; Sun, Wenxi; Xie, Mingyue; Wang, Juanrong; Pan, Xiran; Lei, Xun; Wang, Jingyi; Chen, Jupeng; Chen, Yiheng; Wang, Shu‐Jen; Lei, Ting (8 March 2024). "Ultrastable N‐Type Semiconducting Fiber Organic Electrochemical Transistors for Highly Sensitive Biosensors". Advanced Materials. doi:10.1002/adma.202400287.