|Bio-inspired Polymers and Functional Materials
|Group Leader |
wanxb (AT) qibebt.ac.cn
03/2010-present: Research Faculty at Qingdao Bioenergy &Bioprocess Technology, leader of Bio-inspired polymers and Functional Materials group;05/2008-03/2010: Postdoctoral Fellow at Arkema Inc.;
09/2001-04/2008: Ph.D. in Organic Chemistry, University of Pennsylvania,
09/1995-12/2000: Ph.D. in Polymer Chemistry and Physics,
09/1991-06/1995: B.S. at Nankai University
|Research Focus |
1. Organic electronics, especially the design and synthesis of novel organic and polymeric material for organic thin-film transistors.
Large p-conjugated systems, including small organic molecules and conjugated polymers, are well-known for their potential applications in organic electronics, such as organic thin-film transistors(OFET), organic photovoltaic cells (OPV), organic light-emitting diodes (OLED). The development of p-conjugated systems with novel structures is one of the key factors to improve the efficiency and stability of organic electronics. Especially, my research in this area is focused on the design of novel organic semiconductors, both n-type and p-type, for OFETs.
2. Synthesis of bio-mimetic organic and polymeric materials for better nano-structure control and novel functions.
“Learn from nature.” In the long history of evolution, living creatures have developed accurate, multi-functional, multi-responsive bio-systems that could execute complicated missions. On the basis of these bio-systems, are biomolecules and biomacromolecules that could self-assembly into various nanostructures, which in turn interact with each other to achieve certain functionalities. On the other hand, artificial organic molecules and polymers, still have a long way to reach the same level (in terms of both structure and function) as bio-systems. My research is this area is focused on synthesis of novel bio-conjugated systems using the segments from biomolecules and synthetic functional molecules, to achieve certain nano-structures and functionalities.
|Research Activities |
The design and synthesis of novel p-conjugated systems
1. Magic between aromaticity and anti-aromaticity: switching from p-type to n-type organic semiconductors
Figure 1. Stability evolution of antiaromatic heteroacenes bearing 1,4-diazapentalene core.
Although p-type heteroacenes have been widely studied for OFETs, the design and synthesis of n-type heteroacenes are equally important but much more challenging. Especially, the reports on anti-aromatic n-type heteroacenes are rare. We were delighted to find that the oxidation of 6,13-dihydrobenzo[f]benzo[5,6]indolo[3,2-b]indole (DHBBII, a p-type heteroacene) afforded a stable anti-aromatic n-type heteroacenes benzo[f]benzo[5,6]indolo [3,2-b]indole (DBII) in high yield. We further investigated the structure-stability relationship of such heteroacenes containing antiaromatic cores. It turns out that the fusing patterns of peripheral phenyl rings to the centre core play a very important role on the stability of the antiaromatic heteroacene. See Chem. Comm. 2014, 50, 3324.We are currently investigating the possible application of DBII in n-type OFETs.
2. Novel OFET material based heteroacenes bearing pyrrole[3,2-b]pyrrole core
Figure 2. Synthesis of heteroacenes bearing pyrrole[3,2-b]pyrrole core and their OFET performance.
Heteroacenes bearing pyrrolo[3,2-b]pyrrole core are potential OFET materials and hold a few advantages such as (1) it is a strong electron-donor for good p-type organic semiconductors; (2) it could be easily N-alkylated for low cost, solution-processible OFET materials. An expedient novel synthetic methodology has been developed in our group for such material. See: Chem. Comm. 2012, 48, 12225. We are currently working on the systematical study of this heteroacenes family and the polymeric material based on it.
3. Stable n-type organic semiconductors based on isoindigo with extended fused ring system
Figure 3. An unexpected rapid way to construct thiophene-fused isoindigo.
Among the building blocks of n-type conducting polymer for OFETs, Isoindigo stands out for its high stability and high charge carrier mobility. On the other hand, building blocks with larger co-planar structure are preferred for better performance of OFETs. Thus, an isoindigo derivative with extended fused ring system became an idea choice. We found out that indolin-2-one fused with a thiophene ring (4-chloro-5H-thieno[2,3-f]indol-6(7H)-one, CTIO) could be easily dimmerized when treated with a suitable base and alkylbromide under ambient conditions, and afforded an isoindigo with fused thiophene rings on its terminals(BT-indigo). See: Tetrahedron Lett., 2014, 55, 1040. This building block could be easily incorporated into conducting polymers for polymeric OFETs. Such work is currently going on in my group.
4. Synthetic methodology: Novel way to construct dibenzodiazocines
Figure 4. Mechanism study of dibenzodiazocine synthesis.
Dibenzo[b,f][1,5]diazocine, a potential building block for electric actuator, was synthesized in a catalytic, mild way. See: Org. Lett., 2011, 13,711; Teterahedron, 2012, 68, 9665.
Bio-mimetic soft materials and polymers
5. Learn from Spider
Spider silk is known to be one of the strongest yet most resilient fibers in the world. Its superior mechanical properties are derived from its unique structure. Although its detailed structure remains elusive, the alternative formation of amorphous elastic domain and crystalline domain may account for it. A typical crystalline domain in spider silk protein is composed of the repeating GAGA sequence, it forms antiparallel β-sheet structures by self-assembly. Inspired by the unique structure of spider silk proteins, one of my research areas is focused on using oligopeptides which have strong tendency to self-assmebly to regulate the nano-structure of organogels and polymers.
5.1. GVGV regulated multi-responsive organogels
Figure 5. A multiple responsive organogel
GVGV segment could be attached to dithienylcyclopentene, a photoresponsive unit, to form organogels. The formation of antiparallel β-sheet was confirmed. The organogel is multi-responsive to various external stimuli including temperature, light, chemical, mechanical force, and the addition of chemicals. See: Soft Matter, 2013, 9, 7538.
5.2. GVGV regulated polythiophene nanostructure
Figure 6. Oligopeptide modified polythiophene which showed well-defined nano-structure
Although oligopeptides were used to modify oligothiophenes to achieve nanostructure control (mainly as nanofibers in organogel or hydrogels), little attention was paid to whether the nano-structure of polythiophenes (PThs)could be controlled by oligopeptide side chains. We found that GVGV sequence could be used to regulate the nanostructure of PThs when it was attached to the side chain. The polymer forms nano rods after cultivation. The size of the nano rods could be controlled by adjusting the reaction conditions. See: Supramol. Chem. 2013, 25, 842.
6. Learn from Mussels
Blue mussel can cling to nearly all kinds of surfaces in turbulent environments. The secret lies in the special proteins it secretes, riching in 3, 4-dihydroxy-L-phenylalanine (DOPA) moieties. The extracted mussel foot protein (Mfp) can be used as adhesives which combine many advantages in one, such as underwater bonding, biocompatibility, biodegradability, etc. Till to date, the synthesis of a mussel-inspired polymer with similar or even superior properties to Mfp is a intriguing goal of scientist. My research in this area is focused on the synthesis of mussel-inspired polymers for biocompatible adhesives, anti-fouling applications and so on.
A Mussel-Inspired Adhesive Based on Polyoxetane
Figure 7. A mussel-inspired biomimetic glue
A novel mussel-inspired adhesive polymer was synthesized, in which the catechol moiety is attached to a biocompatible polyoxetane backbone using “Click Chemistry.” Using environmental-friendly FeCl3 as the cross-linker, strong bonding strength was achieved when this adhesive polymer was applied to various substrate. Polyoxetanes have similar polyether backbone as PEGs, but could be more easily tuned, by attaching various side chains onto the backbone. See Polymer, 2014, 55, 1160. Further modification on this polymer would make it an excellent platform for biomedical applications as adhesives.
|Selected Publications |
Qiu, L.; Zhuang, X.; Zhao, N.;Wang, X.; An, Z.; Lan, Z.; * Wan, X.*a “Benzo[f]benzo [5,6]indolo[3,2-b]indole: a stable unsubstituted 4np-electron acene with an antiaromatic 1,4-diazapentalene core.” Chem. Commun., 2014, 50, 3324.
Jia, M.; Li, A.; Mu, Y.; Jiang, W.; Wan, X.* “Synthesis and adhesive property study of polyoxetanes grafted with catechols via Cu(I)-catalyzed click chemistry.” Polymer, 2014, 55, 1160.
Zhao, N.; Qiu, L.; Wang, X.; An, Z.; Wan, X.* “Synthesis of a thiophene-fused isoindigo derivative: a potential building block for organic semiconductors.” Tetrahedron Lett., 2014, 55, 1040.
Jiang, Y.; Zeng, F.; Gong, R.; Guo, Z.; Chen,C.-F.; Wan, X.* “Multi-stimuli responsive organogel based on tetrapeptide-dithienylcyclopentene conjugate.” Soft Matter, 2013, 9, 7538.
Mu, Y.; Jia, M. C.; Jiang, W.; Wan, X.* “A novel branched polyoxymethylene synthesized by cationic copolymerization of 1,3,5-trioxane with 3-(alkoxymethyl) -3-ethyloxetane.” Macromol. Chem. Phys. 2013, 214, 2752.
Wang, X.; Gong, R.; Mu, Y.; Guo, Z.; Wan, X.;* Jiang, W.* “Polythiophenes with oligopeptide side chains: preparation and nano-structure.” Supramol. Chem., 2013, 25, 842.
Gong, R.; Song, Y.; Guo, Z.; Li, M.; Jiang, Y. Wan, X.* “A clickable, highly soluble oligopeptide that easily forms organogels.” Supramol. Chem., 2013, 25, 269.
Sun, X.; Zhang, J.; Wang, X.; Zhang, C.; Hu, P.; Mu, Y.; Wan, X.; Guo, Z.;* Lei, S.* “Oligothiophenes on CVD graphene grown on multi-crystalline copper foil: supramolecular assembly and impact of morphology.” Chemical Commun., 2013, 49, 10317.
Li, J. Z.;* Wan, X.. “Synthesis of Novel Polydiazocine for Electroactive Materials Based on Diazocine.”J. Polym. Sci. Part A: Polym. Chem. 2013, 51, 4694.
Qiu, L.; Yu, C..; Zhao, N.; Chen, W..; Guo, Y..; Wan, X.*; Yang, R. Q.; Liu, Y. * “An exedient synthesis of fused heteroacences bearing a pyrrolo[3,2-b]pyrrole core.” Chem. Commun., 2012, 48, 12225.
Zhao, N.; Qiu, L.; Wang, X.; Li, J.; Jiang, Y., Wan, X.* “Trifluoroacetic acid catalyzed dibenzodiazocine synthesis: optimization and mechanism study.” Tetrahedron, 2012, 68, 9665.
Mu, Y.; Wan, X.*, Han, Z.; Peng, Y.; Zhong, S. “Rigid Polyurethane Foams Based on Activated Soybean Meal.” J. Appl. Ploym. Sci., 2012, 124, 4331.
Gong, R.; Ning, K.; Mu, Y.; Li, J.; Wan, X. “Synthesis of superporous hydrogels by a postpolymerization foaming protocol and their water absorbent behavior.” J. Appl. Ploym. Sci., 2012, 125, 3100.
Wang, X.; Li, J.; Zhao, N.; Wan,X.* "A rapid and efficient access to diaryldibenzo[b,f][1,5]diazocines." Org. Lett.. 2011, 13, 709-711.
Wan, X.; Jia, M.; Mu, Y. “Production of bionic mussel glue based on trimethylene oxide derivatives,” Faming Zhuanli Shenqing 2013, CN 103289074 A 20130911.
Wan, X.; Qiu, L.; Zhao, N. “Preparation of indolo[3,2-b]indole derivatives as organic field effect transistor materials.” Faming Zhuanli Shenqing, 2013, CN 103214490 A 20130724.
Wan, X.; Mu, Y. “Preparation of a lignin-based adhesive.” Faming Zhuanli Shenqing , 2013, CN 103031108 A 20130410.