Langmuir and Langmuir-Blodgett Films of Polyfluorenes and Their Use in Polymer Light-Emitting Diodes

Ferreira, Marystela; Olivati, Clarissa de Almeida; Machado, A.M.; Assaka, Andressa M.; Giacometti, J.A.; Akcelrud, Leni; Oliveira, Osvaldo N.

doi:10.1007/s10965-006-9078-2

Cited by 16 publications

(9 citation statements)

References 24 publications

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“… 24 The band gap of the film appears to change from nanosheet suspension to film in 1(f) . This has been observed previously for Langmuir–Blodgett 49 and other deposited films. It has also been observed that apparent decreases in band gap may occur due to the presence of scattering artefacts within films of nanoscale objects.…”

supporting

confidence: 87%

Preparation of solution processed photodetectors comprised of two-dimensional tin(ii) sulfide nanosheet thin films assembled via the Langmuir–Blodgett method

et al. 2021

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supporting

confidence: 87%

Preparation of solution processed photodetectors comprised of two-dimensional tin(ii) sulfide nanosheet thin films assembled via the Langmuir–Blodgett method

et al. 2021

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“…For a 9-layer film of pure PDOF- co -3HTh, the TR values ranged from 1.47 to 0.73, and for the mixed film with phytase, the values varied between 1.06 and 0.51. Values distancing from 1.0 are expected considering the complexity of polymers, which can adopt other conformations when transferred from the liquid interface to the solid supports. ,,,− There was noted a general decrease in the TR values for the LB film composed of mixed components compared to the pure film, indicating that with the higher complexity of the system (with enzyme insertion), possible molecular rearrangements and formation of aggregates can occur during deposition on the solid support, hindering a more homogeneous deposition. Through the QCM technique, it was possible to observe that the mass increases linearly with the number of deposited layers for both kinds of LB films, which indicates a relatively uniform transfer in terms of mass.…”

Section: Resultsmentioning

confidence: 97%

Langmuir and Langmuir–Blodgett Films of Poly[(9,9-dioctylfluorene)-co-(3-hexylthiophene)] for Immobilization of Phytase: Possible Application as a Phytic Acid Sensor

2020

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In this work, the copolymer poly[(9,9-dioctylfluorene)-co-(3-hexylthiophene)] was employed as a matrix for immobilizing phytase, aiming at the detection of phytic acid. The copolymer was spread on the air–water interface forming Langmuir monolayers and phytase adsorbed from the aqueous subphase. The interactions between the copolymer and the enzyme components were investigated with surface pressure and surface potential–area isotherms, Brewster angle microscopy, and polarization modulation infrared reflection–absorption spectroscopy (PM-IRRAS). The enzyme could be incorporated in the monolayers from the aqueous subphase, expanding the copolymer films and maintaining its secondary structure. The polymeric films presented a morphological heterogeneous pattern at the air–water interface because of the ability of their chains to fold and entangle, causing inherent defects in the organization as well as unbalanced lateral distribution at the air–water interface because of the formation of aggregates. The interfacial films were transferred to solid supports as Langmuir–Blodgett films and characterized by PM-IRRAS and scanning electronic microscopy, which showed not only the co-transfer of the enzyme but also the maintenance of their heterogeneous morphological pattern. The enzymatic activity of the blended film was analyzed by UV–vis spectroscopy and allowed the estimation of the value of the Michaelis constant (13.08 mM), demonstrating the feasibility of the system to selectively detect phytic acid for biosensing purposes.

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“…Polymeric structures are molecularly more complex than classical amphiphiles employed as Langmuir monolayers (such as fatty acids and phospholipids) and usually do not form isotherms with well-defined stages/phases (gaseous, liquid, and solid). Thus, the compression of the monolayer may lead to the formation of aggregates and domains. , However, as this copolymer present acyl chains linked to its backbone structure, the deposition of organic solutions on the water surface may lead to the assembly of structures that can be regularly arranged at the air–water interface after spreading along the surface because of amphiphilic properties of the copolymer. In fact, this was observed for PTPF in previous reports, although slightly different profiles of the π– A isotherm are observed, which may be related to the polydispersity of the samples.…”

Section: Resultsmentioning

confidence: 99%

Conjugated Polymers Blended with Lipids and Galactosidase as Langmuir–Blodgett Films To Control the Biosensing Properties of Nanostructured Surfaces

2019

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The structure of enzymes must be conserved when incorporated in nanoelectronic devices because their activity determines the function of the device as sensors. Among the systems that can retain their conformational structures, Langmuir–Blodgett (LB) films can be useful to exploit the construction of bioelectronic devices organized at the molecular level because biological and polymeric materials can be coupled as ultrathin films for biosensors and actuators. In this paper, we immobilized a β-galactosidase enzyme in the LB films of stearic acid and the conjugated polymer poly[(9,9-dioctylfluorene)-co-thiophene]. After the characterization of the floating films using tensiometry, vibrational spectroscopy, and Brewster angle microscopy, they were transferred to solid supports as LB films, and the catalytic activity of the enzyme could be preserved as analyzed using UV–vis spectroscopy. We noted that the presence of a supramolecular structure formed in the LB films not only conserved the enzyme activity but also exhibited regular and distinctive output signals in all molecular architectures employed in this work. These results are related to the synergism between the compounds on the active layer associated with a surface morphology that facilitated the analyte diffusion because of an adequate molecular accommodation of all components. This work then demonstrates the viability of employing LB films composed of lipids, enzymes, and synthetic polymers as devices for biosensing applications.

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Langmuir and Langmuir-Blodgett Films of Polyfluorenes and Their Use in Polymer Light-Emitting Diodes

Cited by 16 publications

References 24 publications

Preparation of solution processed photodetectors comprised of two-dimensional tin(ii) sulfide nanosheet thin films assembled via the Langmuir–Blodgett method

Preparation of solution processed photodetectors comprised of two-dimensional tin(ii) sulfide nanosheet thin films assembled via the Langmuir–Blodgett method

Langmuir and Langmuir–Blodgett Films of Poly[(9,9-dioctylfluorene)-co-(3-hexylthiophene)] for Immobilization of Phytase: Possible Application as a Phytic Acid Sensor

Conjugated Polymers Blended with Lipids and Galactosidase as Langmuir–Blodgett Films To Control the Biosensing Properties of Nanostructured Surfaces

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