Author: A. Sezai Sarac
Publisher: CRC Press
ISBN: 9814613525
Category : Science
Languages : en
Pages : 297
Book Description
Conjugated polymer composites with high dielectric constants are being developed by the electronics industry in response to the need for power-grounded decoupling to secure the integrity of high-speed signals and to reduce electromagnetic interference. Electrically conducting polymers are materials that simultaneously possess the physical and chemical properties of organic polymers and the electronic characteristics of metals. Multifunctional micro- and nanostructures of conjugated polymers, such as of pyrrole, have received great attention in recent years because they can polymerize easily and have high conductivity and good thermal stability. They, however, have some disadvantages such as brittleness and hard processability, which can be overcome by developing their nanocomposites. Nanofiber materials with different dielectric properties can be made from conjugated polymer composites and used in the electronics industry, in sensors and batteries, for electrical stimulation to enhance nerve-regeneration process, and for constructing scaffolds for nerve tissue engineering. Electrospinning is a versatile technique that is used to produce ultrathin continuous fibers with high surface-to-volume and aspect ratios from a variety of materials, including polymers, composites, and ceramics. Conductive materials in fibrillar shape may be advantageous compared with films because of their inherent properties such as anisotropy, high surface area, and mechanical strength. They are of particular interest in electroactive composites as they can be efficiently distributed in an insulating polymer matrix to improve both electrical and mechanical properties. Combination of electrical properties with good mechanical performance is of particular interest in electroactive polymer technology. This book covers the general aspects of electrospinning and discusses the fundamental concepts that can be used to produce nanofibers with the help of mathematical models and equations. It also details the methods through which different polymeric structures can be included in conjugated polymers during electrospinning to form composites or blends of conjugated polymer nanofibers.
Nanofibers of Conjugated Polymers
Author: A. Sezai Sarac
Publisher: CRC Press
ISBN: 9814613525
Category : Science
Languages : en
Pages : 297
Book Description
Conjugated polymer composites with high dielectric constants are being developed by the electronics industry in response to the need for power-grounded decoupling to secure the integrity of high-speed signals and to reduce electromagnetic interference. Electrically conducting polymers are materials that simultaneously possess the physical and chemical properties of organic polymers and the electronic characteristics of metals. Multifunctional micro- and nanostructures of conjugated polymers, such as of pyrrole, have received great attention in recent years because they can polymerize easily and have high conductivity and good thermal stability. They, however, have some disadvantages such as brittleness and hard processability, which can be overcome by developing their nanocomposites. Nanofiber materials with different dielectric properties can be made from conjugated polymer composites and used in the electronics industry, in sensors and batteries, for electrical stimulation to enhance nerve-regeneration process, and for constructing scaffolds for nerve tissue engineering. Electrospinning is a versatile technique that is used to produce ultrathin continuous fibers with high surface-to-volume and aspect ratios from a variety of materials, including polymers, composites, and ceramics. Conductive materials in fibrillar shape may be advantageous compared with films because of their inherent properties such as anisotropy, high surface area, and mechanical strength. They are of particular interest in electroactive composites as they can be efficiently distributed in an insulating polymer matrix to improve both electrical and mechanical properties. Combination of electrical properties with good mechanical performance is of particular interest in electroactive polymer technology. This book covers the general aspects of electrospinning and discusses the fundamental concepts that can be used to produce nanofibers with the help of mathematical models and equations. It also details the methods through which different polymeric structures can be included in conjugated polymers during electrospinning to form composites or blends of conjugated polymer nanofibers.
Publisher: CRC Press
ISBN: 9814613525
Category : Science
Languages : en
Pages : 297
Book Description
Conjugated polymer composites with high dielectric constants are being developed by the electronics industry in response to the need for power-grounded decoupling to secure the integrity of high-speed signals and to reduce electromagnetic interference. Electrically conducting polymers are materials that simultaneously possess the physical and chemical properties of organic polymers and the electronic characteristics of metals. Multifunctional micro- and nanostructures of conjugated polymers, such as of pyrrole, have received great attention in recent years because they can polymerize easily and have high conductivity and good thermal stability. They, however, have some disadvantages such as brittleness and hard processability, which can be overcome by developing their nanocomposites. Nanofiber materials with different dielectric properties can be made from conjugated polymer composites and used in the electronics industry, in sensors and batteries, for electrical stimulation to enhance nerve-regeneration process, and for constructing scaffolds for nerve tissue engineering. Electrospinning is a versatile technique that is used to produce ultrathin continuous fibers with high surface-to-volume and aspect ratios from a variety of materials, including polymers, composites, and ceramics. Conductive materials in fibrillar shape may be advantageous compared with films because of their inherent properties such as anisotropy, high surface area, and mechanical strength. They are of particular interest in electroactive composites as they can be efficiently distributed in an insulating polymer matrix to improve both electrical and mechanical properties. Combination of electrical properties with good mechanical performance is of particular interest in electroactive polymer technology. This book covers the general aspects of electrospinning and discusses the fundamental concepts that can be used to produce nanofibers with the help of mathematical models and equations. It also details the methods through which different polymeric structures can be included in conjugated polymers during electrospinning to form composites or blends of conjugated polymer nanofibers.
Nanofibers of Conjugated Polymers
Author: A. Sezai Sarac
Publisher: CRC Press
ISBN: 131534128X
Category : Science
Languages : en
Pages : 219
Book Description
Conjugated polymer composites with high dielectric constants are being developed by the electronics industry in response to the need for power-grounded decoupling to secure the integrity of high-speed signals and to reduce electromagnetic interference. Electrically conducting polymers are materials that simultaneously possess the physical and chemical properties of organic polymers and the electronic characteristics of metals. Multifunctional micro- and nanostructures of conjugated polymers, such as of pyrrole, have received great attention in recent years because they can polymerize easily and have high conductivity and good thermal stability. They, however, have some disadvantages such as brittleness and hard processability, which can be overcome by developing their nanocomposites. Nanofiber materials with different dielectric properties can be made from conjugated polymer composites and used in the electronics industry, in sensors and batteries, for electrical stimulation to enhance nerve-regeneration process, and for constructing scaffolds for nerve tissue engineering. Electrospinning is a versatile technique that is used to produce ultrathin continuous fibers with high surface-to-volume and aspect ratios from a variety of materials, including polymers, composites, and ceramics. Conductive materials in fibrillar shape may be advantageous compared with films because of their inherent properties such as anisotropy, high surface area, and mechanical strength. They are of particular interest in electroactive composites as they can be efficiently distributed in an insulating polymer matrix to improve both electrical and mechanical properties. Combination of electrical properties with good mechanical performance is of particular interest in electroactive polymer technology. This book covers the general aspects of electrospinning and discusses the fundamental concepts that can be used to produce nanofibers with the help of mathematical models and equations. It also details the methods through which different polymeric structures can be included in conjugated polymers during electrospinning to form composites or blends of conjugated polymer nanofibers.
Publisher: CRC Press
ISBN: 131534128X
Category : Science
Languages : en
Pages : 219
Book Description
Conjugated polymer composites with high dielectric constants are being developed by the electronics industry in response to the need for power-grounded decoupling to secure the integrity of high-speed signals and to reduce electromagnetic interference. Electrically conducting polymers are materials that simultaneously possess the physical and chemical properties of organic polymers and the electronic characteristics of metals. Multifunctional micro- and nanostructures of conjugated polymers, such as of pyrrole, have received great attention in recent years because they can polymerize easily and have high conductivity and good thermal stability. They, however, have some disadvantages such as brittleness and hard processability, which can be overcome by developing their nanocomposites. Nanofiber materials with different dielectric properties can be made from conjugated polymer composites and used in the electronics industry, in sensors and batteries, for electrical stimulation to enhance nerve-regeneration process, and for constructing scaffolds for nerve tissue engineering. Electrospinning is a versatile technique that is used to produce ultrathin continuous fibers with high surface-to-volume and aspect ratios from a variety of materials, including polymers, composites, and ceramics. Conductive materials in fibrillar shape may be advantageous compared with films because of their inherent properties such as anisotropy, high surface area, and mechanical strength. They are of particular interest in electroactive composites as they can be efficiently distributed in an insulating polymer matrix to improve both electrical and mechanical properties. Combination of electrical properties with good mechanical performance is of particular interest in electroactive polymer technology. This book covers the general aspects of electrospinning and discusses the fundamental concepts that can be used to produce nanofibers with the help of mathematical models and equations. It also details the methods through which different polymeric structures can be included in conjugated polymers during electrospinning to form composites or blends of conjugated polymer nanofibers.
Conjugated Polymer Nanostructures for Energy Conversion and Storage Applications
Author: Srabanti Ghosh
Publisher: John Wiley & Sons
ISBN: 3527345574
Category : Technology & Engineering
Languages : en
Pages : 38
Book Description
A timely overview of fundamental and advanced topics of conjugated polymer nanostructures Conjugated Polymer Nanostructures for Energy Conversion and Storage Applications is a comprehensive reference on conjugated polymers for energy applications. Distinguished academic and editor Srabanti Ghosh offers readers a broad overview of the synthesis, characterization, and energy-related applications of nanostructures based on conjugated polymers. The book includes novel approaches and presents an interdisciplinary perspective rooted in the interfacing of polymer and synthetic chemistry, materials science, organic chemistry, and analytical chemistry. This book provides complete descriptions of conjugated polymer nanostructures and polymer-based hybrid materials for energy conversion, water splitting, and the degradation of organic pollutants. Photovoltaics, solar cells, and energy storage devices such as supercapacitors, lithium ion battery electrodes, and their associated technologies are discussed, as well. Conjugated Polymer Nanostructures for Energy Conversion and Storage Applications covers both the fundamental topics and the most recent advances in this rapidly developing area, including: The design and characterization of conjugated polymer nanostructures, including the template-free and chemical synthesis of polymer nanostructures Conjugated polymer nanostructures for solar energy conversion and environmental protection, including the use of conjugated polymer-based nanocomposites as photocatalysts Conjugated polymer nanostructures for energy storage, including the use of nanocomposites as electrode materials The presentation of different and novel methods of utilizing conjugated polymer nanostructures for energy applications Perfect for materials scientists, polymer chemists, and physical chemists, Conjugated Polymer Nanostructures for Energy Conversion and Storage Applications also belongs on the bookshelves of organic chemists and any other practicing researchers, academics, or professionals whose work touches on these highly versatile and useful structures.
Publisher: John Wiley & Sons
ISBN: 3527345574
Category : Technology & Engineering
Languages : en
Pages : 38
Book Description
A timely overview of fundamental and advanced topics of conjugated polymer nanostructures Conjugated Polymer Nanostructures for Energy Conversion and Storage Applications is a comprehensive reference on conjugated polymers for energy applications. Distinguished academic and editor Srabanti Ghosh offers readers a broad overview of the synthesis, characterization, and energy-related applications of nanostructures based on conjugated polymers. The book includes novel approaches and presents an interdisciplinary perspective rooted in the interfacing of polymer and synthetic chemistry, materials science, organic chemistry, and analytical chemistry. This book provides complete descriptions of conjugated polymer nanostructures and polymer-based hybrid materials for energy conversion, water splitting, and the degradation of organic pollutants. Photovoltaics, solar cells, and energy storage devices such as supercapacitors, lithium ion battery electrodes, and their associated technologies are discussed, as well. Conjugated Polymer Nanostructures for Energy Conversion and Storage Applications covers both the fundamental topics and the most recent advances in this rapidly developing area, including: The design and characterization of conjugated polymer nanostructures, including the template-free and chemical synthesis of polymer nanostructures Conjugated polymer nanostructures for solar energy conversion and environmental protection, including the use of conjugated polymer-based nanocomposites as photocatalysts Conjugated polymer nanostructures for energy storage, including the use of nanocomposites as electrode materials The presentation of different and novel methods of utilizing conjugated polymer nanostructures for energy applications Perfect for materials scientists, polymer chemists, and physical chemists, Conjugated Polymer Nanostructures for Energy Conversion and Storage Applications also belongs on the bookshelves of organic chemists and any other practicing researchers, academics, or professionals whose work touches on these highly versatile and useful structures.
Conducting Polymer-Based Nanocomposites
Author: Ayesha Kausar
Publisher: Elsevier
ISBN: 0128224630
Category : Science
Languages : en
Pages : 306
Book Description
Conducting Polymer-Based Nanocomposites: Fundamentals and Applications delivers an up-to-date overview on cutting-edge advancements in the field of nanocomposites derived from conjugated polymeric matrices. Design of conducting polymers and resultant nanocomposites has instigated significant addition in the field of modern nanoscience and technology. Recently, conducting polymer-based nanocomposites have attracted considerable academic and industrial research interest. The conductivity and physical properties of conjugated polymers have shown dramatic improvement with nanofiller addition. Appropriate fabrication strategies and the choice of a nanoreinforcement, along with a conducting matrix, may lead to enhanced physicochemical features and material performance. Substantial electrical conductivity, optical features, thermal stability, thermal conductivity, mechanical strength, and other physical properties of the conducting polymer-based nanocomposites have led to high-performance materials and high-tech devices and applications. This book begins with a widespread impression of state-of-the-art knowledge in indispensable features and processing of conducting polymer-based nanocomposites. It then discusses essential categories of conducting polymer-based nanocomposites such as polyaniline, polypyrrole, polythiophene, and derived nanomaterials. Subsequent sections of this book are related to the potential impact of conducting polymer-based nanocomposites in various technical fields. Significant application areas have been identified for anti-corrosion, EMI shielding, sensing, and energy device relevance. Finally, the book covers predictable challenges and future opportunities in the field of conjugated nanocomposites. Integrates the fundamentals of conducting polymers and a range of multifunctional applications Describes categories of essential conducting polymer-based nanocomposites for polyaniline, polypyrrole, polythiophene, and derivative materials Assimilates the significance of multifunctional nanostructured materials of nanocomposite nanofibers Portrays current and future demanding technological applications of conjugated polymer-based nanocomposites, including anti-corrosion coatings, EMI shielding, sensors, and energy production and storage devices
Publisher: Elsevier
ISBN: 0128224630
Category : Science
Languages : en
Pages : 306
Book Description
Conducting Polymer-Based Nanocomposites: Fundamentals and Applications delivers an up-to-date overview on cutting-edge advancements in the field of nanocomposites derived from conjugated polymeric matrices. Design of conducting polymers and resultant nanocomposites has instigated significant addition in the field of modern nanoscience and technology. Recently, conducting polymer-based nanocomposites have attracted considerable academic and industrial research interest. The conductivity and physical properties of conjugated polymers have shown dramatic improvement with nanofiller addition. Appropriate fabrication strategies and the choice of a nanoreinforcement, along with a conducting matrix, may lead to enhanced physicochemical features and material performance. Substantial electrical conductivity, optical features, thermal stability, thermal conductivity, mechanical strength, and other physical properties of the conducting polymer-based nanocomposites have led to high-performance materials and high-tech devices and applications. This book begins with a widespread impression of state-of-the-art knowledge in indispensable features and processing of conducting polymer-based nanocomposites. It then discusses essential categories of conducting polymer-based nanocomposites such as polyaniline, polypyrrole, polythiophene, and derived nanomaterials. Subsequent sections of this book are related to the potential impact of conducting polymer-based nanocomposites in various technical fields. Significant application areas have been identified for anti-corrosion, EMI shielding, sensing, and energy device relevance. Finally, the book covers predictable challenges and future opportunities in the field of conjugated nanocomposites. Integrates the fundamentals of conducting polymers and a range of multifunctional applications Describes categories of essential conducting polymer-based nanocomposites for polyaniline, polypyrrole, polythiophene, and derivative materials Assimilates the significance of multifunctional nanostructured materials of nanocomposite nanofibers Portrays current and future demanding technological applications of conjugated polymer-based nanocomposites, including anti-corrosion coatings, EMI shielding, sensors, and energy production and storage devices
Polymer Nanofibers
Author: Dario Pisignano
Publisher: Royal Society of Chemistry
ISBN: 1849737746
Category : Science
Languages : en
Pages : 445
Book Description
Research into polymer nanofibers has increased significantly over the last decade, prompting the need for a comprehensive monograph examining the subject as knowledge of their properties and potential applications has increased. Postgraduate students and researchers new to the field will benefit from the "from materials to applications" approach to the book, which examines the physio-chemical properties in detail, demonstrating how they can be exploited for a diverse range of applications, including the production of light and wound dressings. Techniques for the fabrication, notably electrospinning, are discussed at length. This book provides a unique and accessible source of information, summarising the last decade of the field and presenting an entry point for those entering the field and an inspiration to established workers. The author is currently the national coordinator for several research projects examining the applications of polymer nanofibers, alongside active international collaborations.
Publisher: Royal Society of Chemistry
ISBN: 1849737746
Category : Science
Languages : en
Pages : 445
Book Description
Research into polymer nanofibers has increased significantly over the last decade, prompting the need for a comprehensive monograph examining the subject as knowledge of their properties and potential applications has increased. Postgraduate students and researchers new to the field will benefit from the "from materials to applications" approach to the book, which examines the physio-chemical properties in detail, demonstrating how they can be exploited for a diverse range of applications, including the production of light and wound dressings. Techniques for the fabrication, notably electrospinning, are discussed at length. This book provides a unique and accessible source of information, summarising the last decade of the field and presenting an entry point for those entering the field and an inspiration to established workers. The author is currently the national coordinator for several research projects examining the applications of polymer nanofibers, alongside active international collaborations.
Conjugated Polymers
Author: Terje A. Skotheim
Publisher: CRC Press
ISBN: 1420043595
Category : Technology & Engineering
Languages : en
Pages : 1030
Book Description
Many significant fundamental concepts and practical applications have developed since the publication of the best-selling second edition of the Handbook of Conducting Polymers. Now divided into two books, the third edition continues to retain the excellent expertise of the editors and world-renowned contributors while providing superior coverage of
Publisher: CRC Press
ISBN: 1420043595
Category : Technology & Engineering
Languages : en
Pages : 1030
Book Description
Many significant fundamental concepts and practical applications have developed since the publication of the best-selling second edition of the Handbook of Conducting Polymers. Now divided into two books, the third edition continues to retain the excellent expertise of the editors and world-renowned contributors while providing superior coverage of
Polymers for Light-emitting Devices and Displays
Author: Inamuddin
Publisher: John Wiley & Sons
ISBN: 1119654602
Category : Technology & Engineering
Languages : en
Pages : 288
Book Description
Polymers for Light-Emitting Devices and Displays provides an in-depth overview of fabrication methods and unique properties of polymeric semiconductors, and their potential applications for LEDs including organic electronics, displays, and optoelectronics. Some of the chapter subjects include: • The newest polymeric materials and processes beyond the classical structure of PLED • Conjugated polymers and their application in the light-emitting diodes (OLEDs & PLEDs) as optoelectronic devices. • The novel work carried out on electrospun nanofibers used for LEDs. • The roles of diversified architectures, layers, components, and their structural modifications in determining efficiencies and parameters of PLEDs as high-performance devices. • Polymer liquid crystal devices (PLCs), their synthesis, and applications in various liquid crystal devices (LCs) and displays. • Reviews the state-of-art of materials and technologies to manufacture hybrid white light-emitting diodes based on inorganic light sources and organic wavelength converters.
Publisher: John Wiley & Sons
ISBN: 1119654602
Category : Technology & Engineering
Languages : en
Pages : 288
Book Description
Polymers for Light-Emitting Devices and Displays provides an in-depth overview of fabrication methods and unique properties of polymeric semiconductors, and their potential applications for LEDs including organic electronics, displays, and optoelectronics. Some of the chapter subjects include: • The newest polymeric materials and processes beyond the classical structure of PLED • Conjugated polymers and their application in the light-emitting diodes (OLEDs & PLEDs) as optoelectronic devices. • The novel work carried out on electrospun nanofibers used for LEDs. • The roles of diversified architectures, layers, components, and their structural modifications in determining efficiencies and parameters of PLEDs as high-performance devices. • Polymer liquid crystal devices (PLCs), their synthesis, and applications in various liquid crystal devices (LCs) and displays. • Reviews the state-of-art of materials and technologies to manufacture hybrid white light-emitting diodes based on inorganic light sources and organic wavelength converters.
Electrospun Nanofibers
Author: Mehdi Afshari
Publisher: Woodhead Publishing
ISBN: 0081009119
Category : Technology & Engineering
Languages : en
Pages : 650
Book Description
Electrospun Nanofibers covers advances in the electrospinning process including characterization, testing and modeling of electrospun nanofibers, and electrospinning for particular fiber types and applications. Electrospun Nanofibers offers systematic and comprehensive coverage for academic researchers, industry professionals, and postgraduate students working in the field of fiber science. Electrospinning is the most commercially successful process for the production of nanofibers and rising demand is driving research and development in this field. Rapid progress is being made both in terms of the electrospinning process and in the production of nanofibers with superior chemical and physical properties. Electrospinning is becoming more efficient and more specialized in order to produce particular fiber types such as bicomponent and composite fibers, patterned and 3D nanofibers, carbon nanofibers and nanotubes, and nanofibers derived from chitosan. - Provides systematic and comprehensive coverage of the manufacture, properties, and applications of nanofibers - Covers recent developments in nanofibers materials including electrospinning of bicomponent, chitosan, carbon, and conductive fibers - Brings together expertise from academia and industry to provide comprehensive, up-to-date information on nanofiber research and development - Offers systematic and comprehensive coverage for academic researchers, industry professionals, and postgraduate students working in the field of fiber science
Publisher: Woodhead Publishing
ISBN: 0081009119
Category : Technology & Engineering
Languages : en
Pages : 650
Book Description
Electrospun Nanofibers covers advances in the electrospinning process including characterization, testing and modeling of electrospun nanofibers, and electrospinning for particular fiber types and applications. Electrospun Nanofibers offers systematic and comprehensive coverage for academic researchers, industry professionals, and postgraduate students working in the field of fiber science. Electrospinning is the most commercially successful process for the production of nanofibers and rising demand is driving research and development in this field. Rapid progress is being made both in terms of the electrospinning process and in the production of nanofibers with superior chemical and physical properties. Electrospinning is becoming more efficient and more specialized in order to produce particular fiber types such as bicomponent and composite fibers, patterned and 3D nanofibers, carbon nanofibers and nanotubes, and nanofibers derived from chitosan. - Provides systematic and comprehensive coverage of the manufacture, properties, and applications of nanofibers - Covers recent developments in nanofibers materials including electrospinning of bicomponent, chitosan, carbon, and conductive fibers - Brings together expertise from academia and industry to provide comprehensive, up-to-date information on nanofiber research and development - Offers systematic and comprehensive coverage for academic researchers, industry professionals, and postgraduate students working in the field of fiber science
Semiconducting Polymers
Author: Georges Hadziioannou
Publisher: John Wiley & Sons
ISBN: 3527312714
Category : Technology & Engineering
Languages : en
Pages : 786
Book Description
Halbleitende Polymere sind ein faszinierendes interdisziplinäres Forschungsgebiet, das kurz vor dem anwendungstechnischen Durchbruch steht. Insbesondere für neue Komponenten in der Photonik und Optoelektronik bieten diese Materialien ein enormes Potential. Dieses zweibändige Handbuch mit Beiträgen herausragender Experten aus den Feldern Organische und Physikalische Chemie, Festkörperphysik bis hin zur Verfahrenstechnik, beschreibt detailliert die Grundlagen, die zum Verständnis und zur Kontrolle dieser faszinierenden Materialien notwendig sind.
Publisher: John Wiley & Sons
ISBN: 3527312714
Category : Technology & Engineering
Languages : en
Pages : 786
Book Description
Halbleitende Polymere sind ein faszinierendes interdisziplinäres Forschungsgebiet, das kurz vor dem anwendungstechnischen Durchbruch steht. Insbesondere für neue Komponenten in der Photonik und Optoelektronik bieten diese Materialien ein enormes Potential. Dieses zweibändige Handbuch mit Beiträgen herausragender Experten aus den Feldern Organische und Physikalische Chemie, Festkörperphysik bis hin zur Verfahrenstechnik, beschreibt detailliert die Grundlagen, die zum Verständnis und zur Kontrolle dieser faszinierenden Materialien notwendig sind.
Conjugated Polymers
Author: John R. Reynolds
Publisher: CRC Press
ISBN: 0429524420
Category : Technology & Engineering
Languages : en
Pages : 853
Book Description
This book covers properties, processing, and applications of conducting polymers. It discusses properties and characterization, including photophysics and transport. It then moves to processing and morphology of conducting polymers, covering such topics as printing, thermal processing, morphology evolution, conducting polymer composites, thin films
Publisher: CRC Press
ISBN: 0429524420
Category : Technology & Engineering
Languages : en
Pages : 853
Book Description
This book covers properties, processing, and applications of conducting polymers. It discusses properties and characterization, including photophysics and transport. It then moves to processing and morphology of conducting polymers, covering such topics as printing, thermal processing, morphology evolution, conducting polymer composites, thin films