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Nonlinear Optics || Molecular Origin of the Nonlinear Optical Response
摘要： In Chapter 3, we presented a general quantum-mechanical theory of the nonlinear optical susceptibility. This calculation was based on time-dependent perturbation theory and led to explicit predictions for the complete frequency dependence of the linear and nonlinear optical susceptibilities. Unfortunately, however, these quantum-mechanical expressions are typically far too complicated to be of use for practical calculations. In this chapter we review some of the simpler approaches that have been implemented to develop an understanding of the nonlinear optical characteristics of various materials. Many of these approaches are based on understanding the optical properties at the molecular level. We also present brief descriptions of the nonlinear optical characteristics of conjugated polymers, chiral molecules, and liquid crystals.
关键词： chiral molecules,nonlinear optical susceptibility,liquid crystals,quantum-mechanical theory,conjugated polymers,time-dependent perturbation theory
更新于2025-09-23 15:21:01
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Nanoparticle Gradient Materials by Centrifugation
摘要： Nanoparticle gradient materials are a unique class of functional materials. They combine the specific properties of nanoparticles with macroscopic materials. A continuous spatial gradient of the nanoparticle concentration leads to diverse physical property profiles. Therefore, these materials have a remarkable potential for applications in optics, electronics, and sensors. A novel approach for the defined and controlled synthesis of this material class is the fabrication in ultracentrifugal fields. The formation of a nanoparticle gradient by sedimentation in a gelatin solution is monitored online with optical systems inside an analytical ultracentrifuge. As soon as the desired nanoparticle concentration gradient is generated, the material is solidified by gelation and the desired gradient is fixed in the material. Application of the established theory of analytical ultracentrifugation allows simulations of the sedimentation process of the nanoparticles in advance. Thus, desired nanoparticle gradient materials can also be tailor-made and fabricated on a preparative scale. This is demonstrated for the example of spherical gold nanoparticles of different sizes, gold nanorods, mixtures thereof, and spherical superparamagnetic iron oxide nanoparticles.
关键词： composites,gradient materials,analytical ultracentrifugation,nanoparticles,polymers
更新于2025-09-23 15:21:01
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Alignment of Lyotropic Liquid Crystalline Conjugated Polymers in Floating Films
摘要： Directed alignment of polymer chains plays an indispensable role in charge transport properties. We focus not only on a specific method to induce the alignment but also on the design of a liquid crystalline (LC) conjugated polymer to take advantage of an intrinsic self-assembly characteristic. We synthesized a lyotropic LC conjugated polymer, CP1-P, having o-nitrobenzyl (ONB) esters as photocleavable side chains and adopted a floating film transfer method to induce the polymer chain alignment through a lyotropic LC phase transition. An optimum amount of a high boiling point solvent (1,2-dichlorobenzene) in chloroform turned out to be an important factor to maximize the polymer chain alignment. The hole transport mobility along the polymer chain alignment direction was 13?14 times higher than that in the direction perpendicular to the alignment. In addition, the removal of side chains resulted in the solvent resistivity while maintaining the alignment feature in organic thin-film transistors.
关键词： floating films,liquid crystalline conjugated polymers,photocleavable side chains,polymer chain alignment,charge transport properties
更新于2025-09-23 15:21:01
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One-step electrosynthesized molecularly imprinted polymer on laser scribed graphene bisphenol a sensor
摘要： Bisphenol A (BPA) is a toxic chemical used by industries for production of containers for storage of food and beverages leading to possible health risks. In this work, we present a simple, mask-free, low-cost imprinted sensor based on laser scribed graphene (LSG) technology combined to molecularly imprinted polymers (MIPs) for BPA determination. CO2 laser was used in production of LSG electrodes with high resistivity 58 Ω/square on flexible polyimide sheet leading to the high active surface area of the sensor. LSG device was functionalized with imprinted polypyrrole with a known amount of BPA as template molecule to develop the sensor. The bare LSG, LSG-MIP, LSG-NIP sensors were characterized using Raman spectroscopy, SEM, XRD, AFM. The electrochemical measurements were carried out using cyclic voltammetry and differential pulse voltammetry. Experimental conditions were optimized, including the concentration of pyrrole monomer, the number of polymerization cycles, the concentration of BPA as template and the incubation time. We evaluated the sensitivity of the LSG-MIP sensor in the concentration range between 0.05 μM and 20 μM with a limit of detection of 8 nM. The proposed sensor exhibits high selectivity towards BPA compared to its structural analogs and good reusability. The developed sensor was successfully applied for the detection of BPA in tap, mineral water and in plastic samples. The developed sensor was integrated into a PMMA case connected to the potentiostat to achieve complete isolation and a practical measurement system.
关键词： Molecularly imprinted polymers,Water samples,Electropolymerization,Electrochemical devices,Bisphenol A,Laser scribed graphene
更新于2025-09-23 15:21:01
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Red-Emitting Thermally Activated Delayed Fluorescence Polymers with Poly(fluorene- <i>co</i> -3,3′-dimethyl diphenyl ether) as the Backbone
摘要： A series of red-emitting thermally activated delayed ?uorescence (TADF) polymers have been designed and synthesized based on poly(?uorene-co-3,3′-dimethyl diphenyl ether) (PFDMPE) as the backbone. Compared with poly?uorene (PF, 2.16 eV), the introduction of 3,3′-dimethyl diphenyl ether into the main chain of PFDMPE leads to the increased triplet energy of 2.58 eV, which is higher enough than the tethered red TADF guest (2.13 eV) to prevent the unwanted triplet energy back-transfer. Meanwhile, there is a good overlap between the absorption spectrum of the red guest and the photoluminescence (PL) spectrum of the polymeric host, ensuring the e?cient energy transfer from host to guest. Consequently, the resultant polymers PFDMPE-R01 to PFDMPE-R10 in solid states show obvious red TADF properties with delayed ?uorescence lifetimes of 126?191 μs and PL quantum yields of 0.18?0.55. Among them, PFDMPE-R05 obtains the best device performance, revealing a bright red electroluminescence peaked at 606 nm and a promising current e?ciency of 10.3 cd/A (EQE = 5.6%). The results compete well with those of red phosphorescent polymers and indicate that PFDMPE other than PF is a suitable polymeric host for the construction of e?cient red TADF polymers.
关键词： PFDMPE,electroluminescence,polymers,poly?uorene,triplet energy,PF,energy transfer,red-emitting,thermally activated delayed ?uorescence,poly(?uorene-co-3,3′-dimethyl diphenyl ether)
更新于2025-09-23 15:21:01
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Synthesis and Electropolymerization of Furan End?capped Dibenzothiophene/Dibenzofuran and Electrochromic Properties of Their Polymers
摘要： Two furan end?capped dibenzothiophene/dibenzofuran five?membered ring monomers, 2,8?bis?(furan?2?yl)?dibenzothiophene (DBT?Fu) and 2,8?bis?(furan?2?yl)?dibenzofuran (DBF?Fu) were successfully synthesized via Stille couple reaction. Corresponding polymers, P(DBT?Fu) and P(DBF?Fu), were obtained by employed the electropolymerization. The surface morphology, electrochemical and optical properties of monomers and polymers were researched by cyclic voltammetry (CV), scanning electron microscopy (SEM), and UV?via spectra method. Both polymers exhibited obvious color changes from neutral state to oxidation state (from green?yellow to dark grey for P(DBT?Fu) and from beige to celadon for P(DBF?Fu)).
关键词： electrochromism,conducting polymers,furan,electropolymerization,dibenzothiophene/furan
更新于2025-09-23 15:21:01
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[IEEE 2018 2nd International Conference on Biomedical Engineering (IBIOMED) - Bali, Indonesia (2018.7.24-2018.7.26)] 2018 2nd International Conference on Biomedical Engineering (IBIOMED) - Design of Mass-Sensitive Sensor Array for Biomedical Application: Sensing Lipoproteins
摘要： Herein we report the design of a novel sensor array based on molecularly imprinted polymer (MIP) for low-density lipoprotein (LDL) and high-density lipoprotein (HDL) determination. MIP of each lipoprotein class comprising co-monomer of methacrylic acid (MAA) and vinyl pyrrolidone (NVP) in the ratio of 3:2 and 2:3, were screened onto three-electrode quartz crystal microbalance (QCM) as selective elements toward LDL and HDL, respectively. Sensor array device reveals concentration-dependent sensor responses toward varying amount of each standard LDL and HDL solution with a linear correlation coefficient of R2 = 0.89 and 0.99, respectively. HDL-MIP presents cross-reactivity to LDL at 9-19% compared to the LDL-MIP signal. LDL-MIP also has cross-reactivity to HDL at 0-3% of LDL-MIP responses. All sensor signals are fully reversible and the sensor array can be reused.
关键词： molecularly imprinted polymers,low-density lipoprotein,high-density lipoprotein,QCM sensor array
更新于2025-09-23 15:21:01
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Dipole Switchable Poly(para-phenyleneethynylene)s: Ferroelectric Conjugated Polymers
摘要： Dipolar 2,3-difluorobenzene-units are introduced into the backbone of a poly(para-phenyleneethynylene) (PPE) to generate a ferroelectric conjugated polymer. The structural features of the partially fluorinated PPE allow for the generation of a remanent polarization in the solid state: The difluorinated benzene rings behave as molecular rotors at high temperature, while at room temperature, stacking of such rings clamps down the ring orientation. The molecular dipoles can still be oriented by moderate external electrical fields at room temperature, and this PPE is then a ferroelectric. The concept should be transferable to other poly(aryleneethynylene)s and novel conjugated ferroelectric conjugated polymers will be accessible using this concept.
关键词： Molecular Rotors,Molecular devices,Organic Ferroelectrics,Polymers
更新于2025-09-23 15:21:01
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Dipole Switchable Poly(para-phenyleneethynylene)s: Ferroelectric Conjugated Polymers
摘要： Dipolar 2,3-difluorobenzene-units are introduced into the backbone of a poly(para-phenyleneethynylene) (PPE) to generate a ferroelectric conjugated polymer. The structural features of the partially fluorinated PPE allow for the generation of a remanent polarization in the solid state: The difluorinated benzene rings behave as molecular rotors at high temperature, while at room temperature, stacking of such rings clamps down the ring orientation. The molecular dipoles can still be oriented by moderate external electrical fields at room temperature, and this PPE is then a ferroelectric. The concept should be transferable to other poly(aryleneethynylene)s and novel conjugated ferroelectric conjugated polymers will be accessible using this concept.
关键词： Molecular Rotors,Molecular devices,Organic Ferroelectrics,Polymers
更新于2025-09-23 15:21:01
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Recent Advances in Isoindigo-Inspired Organic Semiconductors
摘要： Over the past decade, isoindigo has become a widely used electron-deficient subunit in donor-acceptor organic semiconductors, and these isoindigo-based materials have been widely used in both organic photovoltaic (OPV) devices and organic field effect transistors (OFETs). Shortly after the development of isoindigo-based semiconductors, researchers began to modify the isoindigo structure in order to change the optoelectronic properties of the resulting materials. This led to the development of many new isoindigo-inspired compounds; since 2012, the Kelly Research Group has synthesized a number of these isoindigo analogues and produced a variety of new donor-acceptor semiconductors. In this Personal Account, recent progress in the field is reviewed. We describe how the field has evolved from relatively simple donor-acceptor small molecules to structurally complex, highly planarized polymer systems. The relevance of these materials in OPV and OFET applications is highlighted, with particular emphasis on structure-property relationships.
关键词： isoindigo,organic field effect transistors,organic materials,organic photovoltaics,conjugated polymers
更新于2025-09-23 15:21:01