Polymer Brush Coatings
Modifying the chemical properties of surfaces with various polymer coatings has been widely studied and applied, and it has a huge impact on our everyday life. Such coatings allow the chemist to tailor the surface properties such as hydrophilicity/hydrophobicity, biocompatibility, adhesion, and friction which are important for several applications.
Polymer brushes represent a very interesting subclass of polymer coatings, which are are polymer chains end-tethered to a surface (i.e., 2D polymer brush) or a particle (i.e., 3D polymer brush). The thickness of polymer brush can be well-tuned from the nanometer to micrometer range. Due to the unique feature of long flexible polymers, which combine liquid- and solid-state properties, such brush-layers form surface-bound liquid phases composed of the polymer and solvent, and may contain cosolvents, cosolutes, counter-ions and salt-ions and other molecules. Combing these properties in addition to polymer composition and architecture spawns a plethora of possible applications.
Since firstly reported in 1950’, polymer brushes have attracted wide interest both in the scientific community and in a range of industries. However, despite countless efforts, no scalable, industrially relevant or commercially viable method for synthesizing polymer brushes have been demonstrated to date, polymer brushes are still grown arduously in laboratories under strict environmental control. If the fabrication of polymer brushes can be scaled up, polymer brushes possess an untapped potential for industrial applications.
We have reported an highly efficient and scalable technique to prepare polymer brushes on flat surfaces using metallic Cu(0) plate, namely surface-initiated Cu(0)-mediated controlled radical polymerization (SI-CuCRP). The SI-CuCRP enables the synthesis of plenty of multifunctional structured polymer brushes with high end group fidelity, over large areas, using a small amount of monomer and without deoxygenation process. These features make SI-CuCRP is highly desirable to prepare polymer brushes for industrial applications.
Currently, we are applying the SI-CuCRP and polymer brushes in the following application fields: anti-biofouling, thin-film electronics, adhesive technologies.
Reference:
1. Li, W.; Sheng, W.; Wegener, E.; Du, Y.; Li, B.; Zhang, T.; Jordan, R. Capillary Microfluidic-Assisted Surface Structuring, ACS Macro Lett. 2020, 9 (3), 328-333;
2. Du, Y.; Zhang, T.; Gieseler, D.; Schneider, M.; Hafner, D.; Sheng, W.; Li, W.; Lange, F.; Wegener, E.; Amin, I.; Jordan, R. Facile Fabrication of Bio-and Dual-Functional Poly(2-oxazoline) Bottle-Brush Brush Surfaces, Chem. Eur. J. 2020, 26 (12), 2749-2753;
3. Zhang, T.; Benetti, E. M.; Jordan, R. Surface-Initiated Cu(0)-Mediated CRP for the Rapid and Controlled Synthesis of Quasi-3D Structured Polymer Brushes, ACS Macro Lett. 2019, 8 (2), 145-153;
4. Zhang, T.; Liao, Z.; Sandonas, L. M.; Dianat, A.; Liu, X.; Xiao, P.; Amin, I.; Gutierrez, R.; Chen, T.; Zschech, E.; Cuniberti, G.; Jordan, R. Polymerization Driven Monomer Passage Through Monolayer Chemical Vapour Deposition Graphene, Nat. Commun. 2018, 9, 4051;
5. Che, Y.; Zhang, T.; Du, Y.; Ihsan, A.; Claudia, M.; Rainer, J. "On Water" Surface-Initiated Polymerization of Hydrophobic Monomers, Angew. Chem. Int. Ed. 2018, 57 (50), 16380-16384;
6. Dehghani, E. S.; Du, Y.; Zhang, T.; Ramakrishna, S. N.; Spencer, N. D.; Jordan, R.; Benetti, E. M. Fabrication and Interfacial Properties of Polymer Brush Gradients by Surface-Initiated Cu(0)-Mediated Controlled Radical Polymerization, Macromolecules 2017, 50 (6), 2436-2446.
7. Zhang, T.; Du, Y.; Kalbacova, J.; Schubel, R.; Rodriguez, R. D.; Chen, T.; Zahn, D. R. T.; Jordan, R. Wafer-Scale Synthesis of Defined Polymer Brushes Under Ambient Conditions, Polym. Chem. 2015, 6 (47), 8176-8183;
8. Zhang, T.; Du, Y.; Müller, F.; Amin, I.; Jordan, R., Surface-Initiated Cu(0) Mediated Controlled Radical Polymerization (SI-CuCRP) Using a Copper Plate, Polym. Chem. 2015, 6 (14), 2726-2733.
Two-dimensional Polymers
Two-dimensional polymer (2DP) refers to a sheet-like monomolecular macromolecule consisting of laterally connected repeat units with end groups along all edges. Due to its unique structure, 2DP has the advanced characteristics of polymers, porous materials and two-dimensional materials, and has become a hotspot in the research of synthetic polymers. The spatial confinement of 2DPs triggers unique physical, chemical, electronic, and mechanical properties, as well as special surface morphologies, leading to a number of fascinating applications (e.g., thin-film electronic, nano-membranes, organic catalysis) and thus they have been intensively investigated recently.
In general, 2DPs can be fabricated through covalent (such as C-C, B-N, C=N bonds) or non-covalent (such as metal coordination, hydrogen bonding and host-guest interaction) chemistries. The past decade has witnessed the rapid development of interfacial methodologies such air-water and liquid-liquid interfaces in the synthesis of various 2DPs, since the interface could act as the template to confine the polymerization at lateral directions, and therefore leads to macroscopic 2DPs with excellent ordering. Despite the rapid development of 2DPs, more fabrication strategies or technologies are required to explore novel 2DPs with more reliable functions and applications. We have developed different interfacial methodologies (air-water, liquid-liquid, and liquid-solid) to synthesize 2D polymers of controllable structure, crosslinking and crystallinity by taking the advantages of interfaces and the diversity of chemistry.
Our current research works are to extend the interfacial methodologies/concepts to conjugated bond-forming chemistries (e.g., C-C coupling), which will result in fully-conjugated 2D polymers (C-2DP). Our attentions will be paid specially in the interfacial synthesis methodologies, mechanisms of crystallization and film formation, structure-property relationships, as well as their performance in functional membranes, organic devices.
Reference:
1. Zhang, T.; Qi, H.; Liao, Z.; Horev, Y. D.; Panes-Ruiz, L. A.; Petkov, P. S.; Zhang, Z.; Shivhare, R.; Zhang, P.; Liu, K.; Bezugly, V.; Liu, S.; Zheng, Z.; Mannsfeld, S.; Heine, T.; Cuniberti, G.; Haick, H.; Zschech, E.; Kaiser, U.; Dong, R.; Feng, X. Engineering Crystalline Quasi-Two-Dimensional Polyaniline Thin Film with Enhanced Electrical and Chemiresistive Sensing Performances, Nat. Commun. 2019, 10, 4225.
2. Liu, K.; Qi, H.; Dong, R.; Shivhare, R.; Addicoat, M.; Zhang, T.; Sahabudeen, H.; Heine, T.; Mannsfeld, S.; Kaiser, U.; Zheng, Z.; Feng, X. On-Water Surface Synthesis of Crystalline, Few-Layer Two-Dimensional Polymers Assisted by Surfactant Monolayer, Nat. Chem. 2019, 11 (11), 994-1000.
3. Zhang, T.; Hou, Y.; Dzhagan, V.; Liao, Z.; Chai, G.; Löffler, M.; Olianas, D.; Milani, A.; Xu, S.; Tommasini, M.; Zahn, D. R. T.; Zheng, Z.; Zschech, E.; Jordan, R.; Feng, X. Copper-Surface-Mediated Synthesis of Acetylenic Carbon-Rich Nanofibers for Active Metal-Free Photocathodes, Nat. Commun. 2018, 9, 1140.
4. Dong, R.; Zhang, T.; Feng, X. Interface-Assisted Synthesis of 2D Materials: Trend and Challenges, Chem. Rev. 2018, 118 (13), 6189-6235.
5. Sahabudeen, H.; Qi, H.; Ballabio, M.; Polozij. M.; Olthof, S.; Shivhare, R.; Jing, Y.; Park, S.; Liu, K.; Zhang, T.; Ma, J.; Rellinghaus, B.; Mannsfeld, S.; Heine, T.; Bonn, M.; Canovas, E.; Zheng, Z.; Kaiser, U.; Dong, R.; Feng, X. Highly Crystalline and Semiconducting Imine-Based Two-Dimensional Polymers Enabled by Interfacial Synthesis, Angew. Chem. Int. Ed. 2020, 59 (15), 6028-6036.
6. Park, S.; Liao, Z.; Ibarlucea, B.; Qi, H.; Lin, H.; Becker, D.; Melidonie, J.; Zhang, T,; Sahabudeen, H.; Baraban, L.; Baek, C. K.; Zheng, Z.; Zschech, E.; Fery, A.; Heine, T.; Kaiser, U.; Cuniberti, G.; Dong, R.; Feng, X. Two-Dimensional Boronate Ester Covalent Organic Framework Thin Films with Large Single Crystalline Domains for Neuromorphic Memory Device, Angew. Chem. Int. Edit. 2020, 59 (21), 8218-8224.
2D Membranes towards Confined Mass Transfer
Mass transfer at the nanometric scale is a universal phenomenon in biology as well as in a variety of emerging technologies related to energy storage and conversion, separation, signal transmission.
When fluid molecules transfer in a nanoporous membrane where the dimensions of channels for mass transfer lower to the free motion distance of molecules, the intermolecular forces between the fluids and channel wall become the most prominent ones in nanoconfined systems and determine the mass transfer efficiency. In this case, both the mass transfer flux and selectivity of the membranes could be remarkable, which is expected to break the trade-off effect between flux and selectivity.
Two-dimensional polymer (2DP), as an emerging crystalline material, possess highly ordered structure and adjustable nanopore in the range of 0.5-5 nm which is difficult to be realized by other materials. Through appropriate synthesis strategy, build block and linkage chemistry, atomically thin 2DP film with precise pore size and surface properties can be fabricated. With these designed 2DP membranes, we aim to fundamentally understand the transport behaviors and mechanisms of ions and molecules under the subnanometer confinement, facilitating potential applications in water desalination, iontronics and new energies.
Reference:
1. Zhang, T.; Liao, Z.; Sandonas, L. M.; Dianat, A.; Liu, X.; Xiao, P.; Amin, I.; Gutierrez, R.; Chen, T.; Zschech, E.; Cuniberti, G.; Jordan, R. Polymerization Driven Monomer Passage through Monolayer Chemical Vapour Deposition Graphene. Nature communications, 2018, 9 (1), 4051.
2. Zhang, Z.; Zhang, P.; Yang, S.; Zhang, T.; Löffler, M.; Shi, H.; Lohe, M. R.; Feng, X. Oxidation Promoted Osmotic Energy Conversion in Black Phosphorus Membranes. Proceedings of the National Academy of Sciences of the United States of America, 2020, 117 (25), 13959–13966.
3. Dong, R.; Zhang, T.; Feng, X. Interface-Assisted Synthesis of 2D Materials: Trend and Challenges. Chemical reviews 2018, 118 (13), 6189–6235.