| 1. |
- Abdel Aziz, Ilaria, et al.
(författare)
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Drug delivery via a 3D electro-swellable conjugated polymer hydrogel
- 2024
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Ingår i: Journal of materials chemistry. B. - : ROYAL SOC CHEMISTRY. - 2050-750X .- 2050-7518.
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Tidskriftsartikel (refereegranskat)abstract
- Spatiotemporal controlled drug delivery minimizes side-effects and enables therapies that require specific dosing patterns. Conjugated polymers (CP) can be used for electrically controlled drug delivery; however so far, most demonstrations were limited to molecules up to 500 Da. Larger molecules could be incorporated only during the CP polymerization and thus limited to a single delivery. This work harnesses the record volume changes of a glycolated polythiophene p(g3T2) for controlled drug delivery. p(g3T2) undergoes reversible volumetric changes of up to 300% during electrochemical doping, forming pores in the nm-size range, resulting in a conducting hydrogel. p(g3T2)-coated 3D carbon sponges enable controlled loading and release of molecules spanning molecular weights of 800-6000 Da, from simple dyes up to the hormone insulin. Molecules are loaded as a combination of electrostatic interactions with the charged polymer backbone and physical entrapment in the porous matrix. Smaller molecules leak out of the polymer while larger ones could not be loaded effectively. Finally, this work shows the temporally patterned release of molecules with molecular weight of 1300 Da and multiple reloading and release cycles without affecting the on/off ratio.
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| 2. |
- Abdel Aziz, Ilaria, et al.
(författare)
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Electrochemical modulation of mechanical properties of glycolated polythiophenes
- 2024
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Ingår i: Materials Horizons. - : ROYAL SOC CHEMISTRY. - 2051-6347 .- 2051-6355.
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Tidskriftsartikel (refereegranskat)abstract
- Electrochemical doping of organic mixed ionic-electronic conductors is key for modulating their conductivity, charge storage and volume enabling high performing bioelectronic devices such as recording and stimulating electrodes, transistors-based sensors and actuators. However, electrochemical doping has not been explored to the same extent for modulating the mechanical properties of OMIECs on demand. Here, we report a qualitative and quantitative study on how the mechanical properties of a glycolated polythiophene, p(g3T2), change in situ during electrochemical doping and de-doping. The Young's modulus of p(g3T2) changes from 69 MPa in the dry state to less than 10 MPa in the hydrated state and then further decreases down to 0.4 MPa when electrochemically doped. With electrochemical doping-dedoping the Young's modulus of p(g3T2) changes by more than one order of magnitude reversibly, representing the largest modulation reported for an OMIEC. Furthermore, we show that the electrolyte concentration affects the magnitude of the change, demonstrating that in less concentrated electrolytes more water is driven into the film due to osmosis and therefore the film becomes softer. Finally, we find that the oligo ethylene glycol side chain functionality, specifically the length and asymmetry, affects the extent of modulation. Our findings show that glycolated polythiophenes are promising materials for mechanical actuators with a tunable modulus similar to the range of biological tissues, thus opening a pathway for new mechanostimulation devices. This work investigates the changes in the mechanical properties of glycolated polythiophenes induced by electrochemical addressing and by electrolyte concentration, due to its ability to stabilize water.
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| 3. |
- Alsufyani, Maryam, et al.
(författare)
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Lactone Backbone Density in Rigid Electron-Deficient Semiconducting Polymers Enabling High n-type Organic Thermoelectric Performance
- 2022
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Ingår i: Angewandte Chemie International Edition. - : WILEY-V C H VERLAG GMBH. - 1433-7851 .- 1521-3773. ; 61:7
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Tidskriftsartikel (refereegranskat)abstract
- Three lactone-based rigid semiconducting polymers were designed to overcome major limitations in the development of n-type organic thermoelectrics, namely electrical conductivity and air stability. Experimental and theoretical investigations demonstrated that increasing the lactone group density by increasing the benzene content from 0 % benzene (P-0), to 50 % (P-50), and 75 % (P-75) resulted in progressively larger electron affinities (up to 4.37 eV), suggesting a more favorable doping process, when employing (N-DMBI) as the dopant. Larger polaron delocalization was also evident, due to the more planarized conformation, which is proposed to lead to a lower hopping energy barrier. As a consequence, the electrical conductivity increased by three orders of magnitude, to achieve values of up to 12 S cm and Power factors of 13.2 mu Wm(-1) K-2 were thereby enabled. These findings present new insights into material design guidelines for the future development of air stable n-type organic thermoelectrics.
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| 4. |
- Alsufyani, Maryam, et al.
(författare)
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The effect of aromatic ring size in electron deficient semiconducting polymers for n-type organic thermoelectrics
- 2020
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Ingår i: Journal of Materials Chemistry C. - : ROYAL SOC CHEMISTRY. - 2050-7526 .- 2050-7534. ; 8:43, s. 15150-15157
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Tidskriftsartikel (refereegranskat)abstract
- N-type semiconducting polymers have been recently utilized in thermoelectric devices, however they have typically exhibited low electrical conductivities and poor device stability, in contrast to p-type semiconductors, which have been much higher performing. This is due in particular to the n-type semiconductors low doping efficiency, and poor charge carrier mobility. Strategies to enhance the thermoelectric performance of n-type materials include optimizing the electron affinity (EA) with respect to the dopant to improve the doping process and increasing the charge carrier mobility through enhanced molecular packing. Here, we report the design, synthesis and characterization of fused electron-deficient n-type copolymers incorporating the electron withdrawing lactone unit along the backbone. The polymers were synthesized using metal-free aldol condensation conditions to explore the effect of enlarging the central phenyl ring to a naphthalene ring, on the electrical conductivity. When n-doped with N-DMBI, electrical conductivities of up to 0.28 S cm(-1), Seebeck coefficients of -75 mu V K-1 and maximum Power factors of 0.16 mu W m(-1) K-2 were observed from the polymer with the largest electron affinity of -4.68 eV. Extending the aromatic ring reduced the electron affinity, due to reducing the density of electron withdrawing groups and subsequently the electrical conductivity reduced by almost two orders of magnitude.
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| 5. |
- Chen, Hu, et al.
(författare)
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Acene Ring Size Optimization in Fused Lactam Polymers Enabling High n-Type Organic Thermoelectric Performance
- 2021
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Ingår i: Journal of the American Chemical Society. - : AMER CHEMICAL SOC. - 0002-7863 .- 1520-5126. ; 143:1, s. 260-268
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Tidskriftsartikel (refereegranskat)abstract
- Three n-type fused lactam semiconducting polymers were synthesized for thermoelectric and transistor applications via a cheap, highly atom-efficient, and nontoxic transition-metal free aldol polycondensation. Energy level analysis of the three polymers demonstrated that reducing the central acene core size from two anthracenes (A-A), to mixed naphthalene-anthracene (A-N), and two naphthalene cores (N-N) resulted in progressively larger electron affinities, thereby suggesting an increasingly more favorable and efficient solution doping process when employing 4-(2,3-dihydro-1,3-dimethyl-1H-benzimidazol-2-yl)-N,N-dimethylbenzenamine (N-DMBI) as the dopant. Meanwhile, organic field effect transistor (OFET) mobility data showed the N-N and A-N polymers to feature the highest charge carrier mobilities, further highlighting the benefits of aryl core contraction to the electronic performance of the materials. Ultimately, the combination of these two factors resulted in N-N, A-N, and A-A to display power factors (PFs) of 3.2 mu W m(-1) K-2, 1.6 mu W m(-1 )K(-2), and 0.3 mu W m(-1) K-2, respectively, when doped with N-DMBI, whereby the PFs recorded for N-N and A-N are among the highest reported in the literature for n-type polymers. Importantly, the results reported in this study highlight that modulating the size of the central acene ring is a highly effective molecular design strategy to optimize the thermoelectric performance of conjugated polymers, thus also providing new insights into the molecular design guidelines for the next generation of high-performance n-type materials for thermoelectric applications.
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| 6. |
- Clarke, Andrew J., et al.
(författare)
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Non-fullerene acceptor photostability and its impact on organic solar cell lifetime
- 2021
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Ingår i: Cell Reports Physical Science. - : Elsevier. - 2666-3864. ; 2:7
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Tidskriftsartikel (refereegranskat)abstract
- The development of non-fullerene acceptors (NFAs) has facilitated the realization of efficient organic solar cells (OSCs) with minimal burn-in losses and excellent long-term stability. However, the role of NFA molecular structures on device stability remains unclear, limiting commercialization of NFA-based OSCs. Herein, the photostability of 10 OSC devices, fabricated with various NFAs (O-IDTBR, EH-IDTBR, ITIC, and ITIC-M) blended with donor polymers (PTB7-Th, PffBT4T-2OD, and PBDB-T), is investigated. O-IDTBR and EH-IDTBR form highly stable devices with all three polymers, whereas ITIC and ITIC-M devices suffer from burn-in losses and long-term degradation. Conformational instability is found to be responsible for the poor photostability of ITIC and ITIC-M, resulting in poor device stability. Twisting and potential breakage of the chemical bond that links the end group to the main backbone of ITIC and ITIC-M molecules causes undesirable conformational changes. Potential strategies to overcome such detrimental photo-induced conformational changes in NFAs are proposed.
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| 7. |
- Craighero, Mariavittoria, 1995, et al.
(författare)
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Impact of Oligoether Side-Chain Length on the Thermoelectric Properties of a Polar Polythiophene
- 2024
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Ingår i: ACS Applied Electronic Materials. - : AMER CHEMICAL SOC. - 2637-6113. ; 6:5, s. 2909-2916
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Forskningsöversikt (refereegranskat)abstract
- Conjugated polymers with oligoether side chains make up a promising class of thermoelectric materials. In this work, the impact of the side-chain length on the thermoelectric and mechanical properties of polythiophenes is investigated. Polymers with tri-, tetra-, or hexaethylene glycol side chains are compared, and the shortest length is found to result in thin films with the highest degree of order upon doping with the p-dopant 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F(4)TCNQ). As a result, a stiff material with an electrical conductivity of up to 830 +/- 15 S cm(-1) is obtained, resulting in a thermoelectric power factor of about 21 mu W m(-1) K-2 in the case of as-cast films. Aging at ambient conditions results in an initial decrease in thermoelectric properties but then yields a highly stable performance for at least 3 months, with values of about 200 S cm(-1) and 5 mu W m(-1) K-2. Evidently, identification of the optimal side-chain length is an important criterion for the design of conjugated polymers for organic thermoelectrics.
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| 8. |
- Gladisch, Johannes, et al.
(författare)
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An Electroactive Filter with Tunable Porosity Based on Glycolated Polythiophene
- 2022
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Ingår i: Small Science. - : Wiley. - 2688-4046. ; 2:4
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Tidskriftsartikel (refereegranskat)abstract
- The porosity of filters is typically fixed; thus, complex purification processes require application of multiple specialized filters. In contrast, smart filters with controllable and tunable properties enable dynamic separation in a single setup. Herein, an electroactive filter with controllable pore size is demonstrated. The electroactive filter is based on a metal mesh coated with a polythiophene polymer with ethylene glycol sidechains (p(g3T2)) that exhibit unprecedented voltage-driven volume changes. By optimizing the polymer coating on the mesh, controllable porosity during electrochemical addressing is achieved. The pores reversibly open and close, with a dynamic range of more than 95%, corresponding to over 30 mu m change of pores widths. Furthermore, the pores widths could be defined by applied potential with a 10 mu m resolution. From among hundreds of pores from different samples, about 90% of the pores could be closed completely, while only less than 1% are inactive. Finally, the electroactive filter is used to control the flow of a dye, highlighting the potential for flow control and smart filtration applications.
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| 9. |
- Gladisch, Johannes, et al.
(författare)
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Reversible Electronic Solid-Gel Switching of a Conjugated Polymer
- 2020
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Ingår i: ADVANCED SCIENCE. - : WILEY. - 2198-3844. ; 7:2
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Tidskriftsartikel (refereegranskat)abstract
- Conjugated polymers exhibit electrically driven volume changes when included in electrochemical devices via the exchange of ions and solvent. So far, this volumetric change is limited to 40% and 100% for reversible and irreversible systems, respectively, thus restricting potential applications of this technology. A conjugated polymer that reversibly expands by about 300% upon addressing, relative to its previous contracted state, while the first irreversible actuation can achieve values ranging from 1000-10 000%, depending on the voltage applied is reported. From experimental and theoretical studies, it is found that this large and reversible volumetric switching is due to reorganization of the polymer during swelling as it transforms between a solid-state phase and a gel, while maintaining percolation for conductivity. The polymer is utilized as an electroactive cladding to reduce the void sizes of a porous carbon filter electrode by 85%.
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| 10. |
- Hallam, Toby, et al.
(författare)
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Local Charge Trapping in Conjugated Polymers Resolved by Scanning Kelvin Probe Microscopy
- 2009
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 103:25
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Tidskriftsartikel (refereegranskat)abstract
- The microstructure of conjugated polymers is heterogeneous on the length scale of individual polymer chains, but little is known about how this affects their electronic properties. Here we use scanning Kelvin probe microscopy with resolution-enhancing carbon nanotube tips to study charge transport on a 100 nm scale in a chain-extended, semicrystalline conjugated polymer. We show that the disordered grain boundaries between crystalline domains constitute preferential charge trapping sites and lead to variations on a 100 nm scale of the carrier concentration under accumulation conditions.
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