Category: Talk

Feng Zhu^1,2, Vineeth Kumar Bandari, ^1,2, Jinhui Wang^1,2 and Oliver G. Schmidt^1,2

¹Material Systems for Nanoelectronics, Technische Universität Chemnitz, Germany
² Institute for Integrative Nanosciences, IFW Dresden, Germany

Organic nanostructure and nanomembranes are of great importance for developing integrated microelectronic circuits and micro-scale energy storage devices [1, 2]. The fabrication of molecular nanodevices decisively relies on the quality of electronic contacts between the organic nanostructures and electrode layers. However, due to the fragile nature of molecular materials, realizing nondestructive contacts on organic nanostructures becomes technically challenging when the metal electrode layers are fabricated by conventional depositions methods, which restrains the great potential of nanoscale organic materials. In the first part, we present a novel contact method based on strained rolled-up nanomembranes to realize robust, soft and reliable contacts with organic nanostructures [3-5]. The fabrication of fully integrated nanodiode arrays on chip scale which consist of self-assembled monolayers and organic nanocrystals will be demonstrated.
Micro-supercapacitors (MSCs) have been regarded as a promising micro-power source for integrated and miniaturized electronics [2, 6]. One ideal strategy to achieve high areal performance is to transform MSCs from two-dimensional (2D) architectures to three-dimensional (3D) architectures with much reduced area. In the second part, we present PEDOT-based 3D tubular MSCs constructed by rolled-up polymeric nanomembranes [7]. The fabrication of on-chip and free-standing MSCs with small footprint area and their performance will be discussed.

References
[1] M. Ratner, Nat. Nano., 8, 378 (2013).
[2] N. A. Kyeremateng, et al., Nat. Nano., 12, 15 (2016).
[3] O. G. Schmidt and K. Eberl, Nature, 410, 168 (2001).
[4] C. C. Bof Bufon, et al., Nano Lett., 11, 3727 (2011).
[5] A. R. Jalil, et al., Adv. Mater., 28, 2971 (2016).
[6] D. Qi, et al., Adv. Mater., 29, 160802 (2017).
[7] J. Wang, et al., Nat. Comm., In submission.

S. Wu¹, X. Cao¹, Z. Zhang¹, Q. Chen¹, Y. Matsumiya², and H. Watanabe²

¹ State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences; University of Chinese Academy of Sciences, Changchun 130022, China
²Yumi Matsumiya and Hiroshi Watanabe
Institute for Chemical Research, Kyoto University, Uji 611-0011, Japan

Application of ionomers is often disturbed by their brittleness originating from limited stretchability of the network strands physically crosslinked by the ionic sites therein. Thus, an effective method of improving the ductility is to increase the length of network strands (and/or entanglements). Considering this point, this study examined linear viscoelasticity (LVE) and nonlinear elongational rheology of unentangled copolymers of hexyl methacrylate (HMA) and the ionic monomer, Sodium 4-vinylbenzenesulfonate hydrate (SSNa). The ionized SSNa monomer, being randomly distributed along the chain backbone at a concentration ranging from less than one to ~four monomers per chain, served as the physical crosslink (or physical branching point). The LVE data showed a sol-to-gel transition, and the ductility of the sample turns out to be strongly related to the degree of gelation.[1] Analysis of those data gave an average length of the network strands, and the ductility of the ionomer samples detected in the nonlinear elongational test was well correlated with this strand length in most cases. An exception was found for the sample slightly above the gel point: the ductility of this sample was much larger than expected from the strand length, possibly due to the “pseudo-yielding” behavior that reflected exchange of the ionic, physical crosslinks and the resulting motion/displacement of the ionomer chains.

References
[1] Q. Chen, C. Huang, R. Weiss, and R. Colby, Macromolecules 48, 1221 (2015).

Dapeng Wang¹, Daniel K. Schwartz²

¹State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China
²Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309, United States 80309

We recently developed a high-throughput single-molecule fluorescence tracking method that allows us to image dynamics of millions of individual molecules at solid/liquid and liquid/liquid interfaces[1-3]. These single-molecule experiments go beyond understanding the average behavior of adsorbates and enable us to probe variability in surface chemistry, molecular conformations, and adsorbate dynamics. Making such measurements, we often find that the behavior is much richer and more interesting than conventional wisdom suggests. In this abstract, we demonstrated that polymer diffusion at solid/liquid interfaces can be described by an analytical theory involving intermittent hopping where diffusion is switched between apparent immobile periods and occasional long flights[1,3]. This type of diffusion could be adequately modeled by continuous time random walk (CTRW) statistics. Moreover, we provided clear evidence that the occasional long flights are a process involving desorption, bulk diffusion, and readsorption at a new surface location. Very recently, we developed a 3D tracking method to in-situ visualize the full process desorption-mediated diffusion of tracer polymers at solid/liquid interfaces with varying surface-polymer electrostatic interactions[4,5]. We realized that the lateral length between consecutive surface encounters is associated with the surface-polymer interaction. The desorption-mediated diffusion at the direction vertical to the interface was well-described by kinetic Monte Carlo simulations of one-dimensional biased Brownian motion where the biased probability (the main undetermined parameter) was conceptually related to the surface-polymer interaction.

References
[1] D Wang, et al. ACS nano, 9, 1656-1664 (2015).
[2] D Wang, et al. Journal of the American Chemical Society, 137, 12312-12320 (2015).
[3] D Wang, et al. ACS Macro Letters, 5, 509-514 (2016).
[4] D Wang, et al. Applied Physics Letters, 110, 211107 (2017).
[5] D Wang, et al. Physical Review Letters,119, 268001 (2017)

Zhigang Xie

State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun, Jilin 130022, P. R. China

Polymeric nanoparticles (NPs) play a key role in nanoscale formulations for bioimaging, cancer treatment and theranostics. We designed and synthesized a series of hydrophobic polymers (P1-6) with different pendent groups via one-step multicomponent Passerini reaction. These polymers possessed similar molecular structures and various biomedical functions. Interestingly, they could self-assemble into stable NPs in aqueous media. All formed NPs were redox-sensitive because of the existence of disulfide bonds in the backbone. The stability of NPs in aqueous media with or without glutathione was systematically evaluated and compared. The optical performance, including fluorescence resonance energy transfer (FRET), was characterized in different conditions for those polymers with fluorescent components. Importantly, all formed NPs showed good cytocompatibility towards HeLa cells, and different biological functions, including drug loading and delivery, bioimaging with variable fluorescence, and photodynamic activity, as evidenced by experiments in vitro and in vivo [1]. These results demonstrate that the great potential of multicomponent reaction to customize versatile polymeric nanoparticles for biomedical applications.

References
[1] W. Lin, W. Zhang, T. Sun, S. Liu, Y. Zhu and Z. Xie, ACS Applied Materials & Interfaces 9, 29612 (2017

Zhao-Yan Sun, Yan-Wei Li, and Wen-Sheng Xu

State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, China

Crystallization is an important process in both condensed-matter physics and technology. The liquid-crystal transition of a system is normally accompanied with the change of both “order” and “density”. Although this process is well known on the qualitative level, the understanding of it in microscopic detail is still far and seems to be quite complex. In this presentation, I will give a numerical study of the relation between the order and density for colloidal particles. By investigating locally dense-packed particles and particles with relatively high bond-orientational order in the compressing process, we find sharp increases of the spatial correlations for both densely packed particles and highly bond-orientational ordered particles at the phase transition point, which provide new characterization methods of the liquid-crystal transition. Moreover, we find that the nucleation process is triggered by the bond-orientational order but not the local density. This may help understand the crystallization process of colloidal particles.

References
(1) P. R. ten Wolde and D. Frenkel, Science, 277, 1975 (1997).
(2) T. Kawasaki and H. Tanaka, Proc. Natl. Acad. Sci. U.S.A., 107, 14036 (2010).
(3) P. Tan, N. Xu and L. Xu, Nat. Phys., 10, 73 (2014).

P. Liu^1,2 and Y. Men^1,2

¹ State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Renmin Street 5625, 130022 Changchun, P.R. China
² University of Science and Technology of China, Hefei 230026, P.R.China

Using the method of differential scanning calorimetry (DSC), it was found that isotactic polybutene-1 (iPB-1) with a specific weight average molecular weight (M_w ~ 188 kg/mol) showed an unique melt memory effect, which was dependent on the initial lamellar thickness. Even though iPB-1 was molten at the temperature (T_ms) higher than the equilibrium melting point of iPB-1 (133 ^oC), the memory effect was still observed, which affected the subsequent crystallization behavior. Briefly speaking, the total crystallization rate increased greatly with the decrease of T_ms. Moreover, the thinner the initial lamellae of the iPB-1 sample, the faster it can crystallize. The results reveal that the increase of crystallization rate is directly related to the increased density of iPB-1 nuclei originated from some “specific structures” remaining in the melt. These specific structures, considered as high temperature clusters, are rather stable since aging two hours at T_ms is not able to evidently reduce nucleation density. Only if T_ms is higher than 170 ^oC, much higher than 133 ^oC, the crystallization rate of iPB-1 reaches a constant value.

Acknowledgement: This work is supported by NSFC (51525305, 21134006).

Xiaoniu Yang¹*, Xiaoli Zhao¹, Tong Zhang¹, Zelin Li^1,2, Dalei Yang^1,2 and Zidong Li^1,2

¹State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Renmin Str. 5625, Changchun 130022, P. R. China
²University of Chinese Academy of Sciences, Beijing 100049, P.R. China

Polymer solar cells (PSCs) have attracted more and more attentions, due to the features of light-weight, flexibility, low cost and the power conversion efficiency (PCE) has been boosted up to be over 13%.[1] Nevertheless, the long-term stability of PSCs still remains to be a great challenge for fullerene and non-fullerene PSCs. We systemically investigated the relationship between the molecular structure and thermal stability in fullerene system. The results showed that with the increase of conjugated side chain length, the polymer bearing thieno[3,2-b]thiophene as side chains (P3) showed outstanding thermal stability and could preserve 90% of their initial efficiencies after thermal annealing at 100 ℃ for one month.[2] After finely modifying the molecular structure of P3,[3] the resulted polymer PBTIBDTT afforded an enhanced efficiency of over 9.4% with an active layer thickness over 200 nm and high thermal stability, which fulfills the prerequisite of solution printing technology and practical application. More interesting, when this polymer was paired with the typical non-fullerene small acceptor (ITIC-F), the device without any additive or post-treatment delivered an efficiency over 11% with active layer thickness over 200 nm, which indicates the potential application of non-fullerene PSCs in future mass production technology. By optimizing the ink formulations and spray-coating parameters, large area PSC modules with active layer over >38.5 cm² were achieved and the efficiency could retain ca. 80% of the corresponding small area device made by spin-coating method. Furthermore, “Layer-Filter Threshold” technique for near-infrared laser was developed to realize over 90% of geometric fill factor for the first time, which was beneficial for further improving the efficiency of PSC module.[4]

References:
[1] Y. Cui, H. Yao, B. Gao, Y. Qin, S. Zhang, B. Yang, H. Chang, B. Xu, J. Hou,  J. Am. Chem. Soc. 139, 7302 (2017)
[2] Z. D. Li, W. Fan, H. Y. Lv, D. L. Yang, Z. B. Chen, X. L. Zhao,  X. N. Yang,  Adv. Mater. 27, 6999 (2015)
[3] Z. L. Li, D. L. Yang, X. L. Zhao, T. Zhang, J. D. Zhang, X. N. Yang,  Adv. Funct. Mater. 28, 1705257 (2018)
[4] F. Ye, Z. B. Chen, X. L. Zhao, J. Y. Chen, X. N. Yang,  Adv. Funct. Mater. 25, 4453 (2015)

S. Hamidreza Arabi, Behdad Aghelnejad, Christian Schwieger, Annette Meister, Andreas Kerth and Dariush Hinderberger

Institut für Chemie, Martin-Luther-Universität Halle-Wittenberg, Von-Danckelmann-Platz 4, 06120 Halle, Saale, Germany

We report extended pH- and temperature-induced preparation procedures and explore the materials and molecular properties of different types of hydrogels made from human and bovine serum albumin, the major transport protein in the blood of mammals. We describe the diverse range of properties of these hydrogels at three levels: (1) their viscoelastic (macroscopic) behavior, (2) protein secondary structure changes during the gelation process (via ATR-FTIR spectroscopy), and (3) the hydrogel fatty acid (FA) binding capacity and derive from this the generalized tertiary structure through CW EPR spectroscopy. We describe the possibility of preparing hydrogels from serum albumin under mild conditions such as low temperatures (notably below albumin’s denaturation temperature) and neutral pH value. As such, the proteins retain most of their native secondary structure. We find that all the combined data indicate a two stage gelation process that is studied in detail. We summarize these findings and the explored dependences of the gels on pH, temperature, concentration, and incubation time by proposing phase diagrams for both HSA and BSA gel-states. As such, it has become possible to prepare gels that have the desired nanoscopic and macroscopic properties, which can, in future, be tested for, e.g., drug delivery applications. [1].

References
[1] S. H. Arabi, B. Aghelnejad, C. Schwieger, A. Meister, A. Kerth, D. Hinderberger, Biomater. Sci. 6, 478-492 (2018).

Nazmul Hasan, Christian Schwieger, Karsten Busse, and Jörg Kressler

Department of Chemistry, Martin Luther University Halle-Wittenberg, D-06099 Halle (Saale), Germany

We are interested in studying the crystallization of synthetic polymers on the water surface [1]. Also water soluble polymers can be studied on the water surface when they have some amphiphilic character as e.g. poly(ethylene oxide) (PEO) with the hydrophilic ether oxygen and the two hydrophobic CH2 groups in its repeat unit. Thus, PEO remains on the water surface of a Langmuir trough when spread from solution and evaporation of the solvent. Even crystallization of PEO can be studied when the water subphase is replaced by certain aqueous salt solutions [2]. But usually hydrophobic polymers are spread from solution onto the water subphase having some polar anchor groups as the most prominent example of poly(-caprolactone) (PCL). Here we report about the crystallization on the water surface of a polyethylene-like material synthesized by acyclic diene metathesis (ADMET) polymerization [3]. The precision polymer contains a phenylphosphate group separated by exactly 20 CH₂ groups in its repeat unit (PPE). It was dissolved in chloroform and spread on the water surface of a Langmuir trough. The surface pressure vs area per monomer unit Langmuir isotherm together with epifluorescence and Brewster angle microscopy indicated polymer crystallization upon film compression. The extended plateau region of the Langmuir isotherm corresponds to the 2D crystallization of most polymer chains. Brewster angle and epifluorescence microscopy show that during the crystallization of PPE in the Langmuir film single crystal like hexagonal entities are formed with lateral dimensions of up to 20 µm. These entities break upon compression beyond the limiting area per monomer unit which leads to a decrease of the elasticity modulus of the Langmuir film. The morphology of the single crystals and their failure upon compression are also observed in Langmuir-Blodgett films by atomic force microscopy. The polymer crystallization on the water surface is also confirmed by infrared reflection absorption spectroscopy (IRRAS).

References
[1] C. Fuchs, K. Busse, A.-K. Flieger, J. Kressler, Polymer crystallization on the surface of water or aqueous salt solutions, Chem. Eng. Technol. 39 (2016) 1333–1340.
[2] C. Fuchs, H. Hussain, E. Amado, K. Busse, J. Kressler, Self-organization of poly(ethylene oxide) on the surface of aqueous salt solutions, Macromol. Rapid Comm., 36 (2015) 211-218.
[3] F. Marsico, M. Wagner, K. Landfester, F.R. Wurm, Unsaturated polyphosphoesters via acyclic diene metathesis polymerization, Macromolecules 45 (2012) 8511–8518.
[4] N. Hasan, C. Schwieger, H.T. Tee, F.R. Wurm, K. Busse, J. Kressler, Crystallization of a polyphosphoester at the air-water interface, Eur. Polym. J., in press. https://doi.org/10.1016/j.eurpolymj.2018.03.001.

Wolfhard Janke

Institut für Theoretische Physik, Universität Leipzig,
Postfach 100 920, 04009 Leipzig, Germany

A new simulation method to study temperature-driven droplet formation is discussed that allows a shape-free determination of free-energy barriers [1]. Combined with theoretical considerations for nucleation in particle systems,this leads to finite-size scaling predictions for the barrier at fixed density. Using parallelized multicanonical Monte Carlo computer simulations [2], this approach is first validated for a Lennard-Jones particle gas and thengeneralized to flexible bead-spring polymers. Our results suggest an analogy of polymer aggregation with particle condensation, when the macromolecules are interpreted as extended particles. The talk concludes with a brief comment on the role of kinetic energy [3], which is commonly neglected in Monte Carlo simulations.

References
[1] J. Zierenberg, P. Schierz, and W. Janke, Canonical free-energy barrier of particle and polymer cluster formation, Nat. Commun. 8 (2017) 14546.
[2] J. Zierenberg, M. Marenz, and W. Janke, Scaling properties of a parallel implementation of the multicanonical algorithm, Comput. Phys. Commun. 184 (2013) 1155.
[3] P. Schierz, J. Zierenberg, and W. Janke, First-order phase transitions in the real microcanonical ensemble, Phys. Rev. E 94 (2016) 021301(R) (Editors’ Suggestion).