Fluorescence methods in polymer science

Various aspects of the application of fluorescence characteristics in the field of polymer research are described. The polarization characteristics of fluorescence, that is, the angular distribution of the intensity of the polarized component, are indicative of the distribution patterns of fluorescent molecules in the medium. This principle can be utilized for the investigation of molecular orientation behavior in polymer solids. Examples are given for the molecular orientation behaviors during the deformation of poly(vinyl alcohol) and polypropylene films. The phenomenon of rotational depolarization of fluorescence is applied to the measurement of micro-Brownian motions of polymer chains and the local viscosity of polymer solutions and melts. The internal structure of concentrated poly(styrene) solutions and the molecular motions in the melts of n-paraffins and polyethylene homologs are discussed. Rotational relaxation time ranging from 10−12 to 10−5 sec can be measured by this method by using the lifetime of excitation of fluorescent groups as the reference time scale. The phenomenon of the excimer fluorescence emitted from the excited dimer provides a new method for studying molecular configuration and conformation of polymer molecules. Examples are given for the case of naphthalenecontaining polymers. The sequence of monomeric units in copolymers of vinylnaphthalene and styrene are studied from the intensity of excimer fluorescence relative to that of ordinary fluorescence from the naphthalene groups. The intramolecular excimer formations of polymer molecules are also discussed in relation to molecular motions.

Various aspects of the application of fluorescence characteristics in the field of polymer research are described. The polarization characteristics of fluorescence, that is, the angular distribution of the intensity of the polarized component, are indicative of the distribution patterns of fluorescent molecules in the medium. This principle can be utilized for the investigation of molecular orientation behavior in polymer solids. Examples are given for the molecular orientation behaviors during the deformation of poly(vinyl alcohol) and polypropylene films. The phenomenon of rotational depolarization of fluorescence is applied to the measurement of micro‐Brownian motions of polymer chains and the local viscosity of polymer solutions and melts. The internal structure of concentrated poly(styrene) solutions and the molecular motions in the melts of n‐paraffins and polyethylene homologs are discussed. Rotational relaxation time ranging from 10−12 to 10−5 sec can be measured by this method by using the lifetime of excitation of fluorescent groups as the reference time scale. The phenomenon of the excimer fluorescence emitted from the excited dimer provides a new method for studying molecular configuration and conformation of polymer molecules. Examples are given for the case of naphthalenecontaining polymers. The sequence of monomeric units in copolymers of vinylnaphthalene and styrene are studied from the intensity of excimer fluorescence relative to that of ordinary fluorescence from the naphthalene groups. The intramolecular excimer formations of polymer molecules are also discussed in relation to molecular motions.

The molecular orientation behavior and molecular motions in polymer solids were investigated utilizing the photoluminescence phenomena. The basic principles of the fluorescence methods were given and the unique features of those methods were discussed with examples of application in the study of the structure of polymer solids. From the angular distribution of the polarized components of fluorescence emitted from the specimen the molecular orientation patterns were ascertained. Examples were given for molecular orientation patterns observed during the deformation of films of polyvinylalcohol and polypropylene. The molecular motions of the relaxation time in the range of 10−12 sec to 10−6 sec were studied using the lifetime of excitation of fluorescent molecules as the reference time scale. The molecular motions in polyethylene melts were investigated by the rotational depolarization of fluorescence. The multiple transitions in polystyrene and polyvinylalcohol were studied by introducing fluorescent molecules capable of internal rotation. The application of excimer emission phenomenon in the study of molecular structure was also discussed.

Permanent hydrophilic modification of polypropylene and poly(vinyl alcohol) films by vacuum ultraviolet radiation

A new method for measuring molecular orientation in polymer solids is developed involving the use of the polarization phenomena of fluorescence emitted from fluorescent groups dispersed in the media. This fluorescence method makes it possible to measure not only the extent of orientation but also the types of orientation. The theoretical background of this method is described and the theoretical patterns of the angular distribution of degree of polarization of fluorescence are given for several types of orientation, including random, perfect uniaxial, partial uniaxial, and perfect biaxial orientations. It is proved that this method is applicable to symmetrical biaxial orientations for which other optical methods fail to provide information. The procedure of this method is to measure the angular distribution of polarized components of fluorescence intensity emitted from the oriented samples. Examples are given for various orientations of poly(vinyl alcohol) films. The process of transformation in orientation pattern is observed in the course of biaxial stretching of the film. An apparatus for continuous measurements is described.

The characteristics of photoluminescence are affected by the molecular motions in the local environment of the excited molecule. Hence, by knowing the lifetime of the excited state, various relaxation times of the molecular motions can be estimated from the emission characteristics. In the present paper the effect of the molecular motions manifested in the fluorescence emission, such as the rotational depolarization of fluorescence, the internal quenching of fluorescence due to internal rotation, and the inter-and intramolecular excimer formation, are reviewed and the possible applications of such phenomena to the study of molecular motions in polymer systems are discussed. The application of fluorescence methods provide unique information about the molecular motions in the nanosecond range in polymer solutions, melts, and solids.

ABSTRACTIn this article, we present a process for preparing organovermiculites, which consist of expanded vermiculite (EVMT)–poly(vinyl alcohol) (PVOH) created by the mechanical ball‐milling of EVMT in a PVOH–water solution. We then discusses the influence of EVMT–PVOH on the barrier performance, crystallization behavior, thermal stability, and mechanical properties of modified blown polypropylene (PP) films. EVMT was intercalated and exfoliated by PVOH macromolecules to obtain a kind of hybrid EVMT–PVOH. PVOH served as both an intercalating agent into EVMT and a compatibilizer between EVMT and PP. Compared with the original (unmodified) PP, when the EVMT loading ranged from 0.1 to 2.0%, although the crystallinity decreased for most PP films, the thermal stability and mechanical properties all improved. Moreover, EVMT platelike particles with a high aspect ratio (ca. 550) dispersed in the PP matrix also improved the barrier properties of the modified PP films, which was in accordance with the Nielsen model. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 132, 42846.

Photochemistry in polymer solids: 12. Effects of main-chain structures and formation of hydrogen bonds on photoisomerization of azobenzene in various polymer films

Deformation of poly(vinyl alcohol)–poly(sodium acrylate) composite hydrogel (PVA–PAA gel) under sinusoidally varying electric fields was studied in electrolyte solutions. The PVA–PAA gel was prepared by repeatedly freezing and thawing a mixed solution of PVA and polyacrylic acid. A cyclic bending–straightening motion of the PVA–PAA gel rods of about 1 mm in diameter have been observed in Na2CO3 aqueous solutions under the fields. The PVA–PAA gel had a response time of less than several hundreds milliseconds. The bending has also been observed in organic solvents containing an electrolyte when the organic solvent is electrolyzed. It was found that the motion of the gel under electric fields of less than 1 Hz occurred mainly through swelling due to the change of the osmotic pressure based upon the difference of the ion concentration. However, it has not been determined whether the motion at higher frequencies is caused by the osmotic effect. © 1993 John Wiley & Sons, Inc.

ABSTRACTThe deformation of poly(acrylic acid)—co—(acrylamide) gels and poly(vinyl alcohol)—poly(acrylic acid) gels under an electric field was investigated. Bending of these ionic gels was induced by an electic field. Using this deformation, we constructed a prototype of a robot hand having soft fingers, and an artificial fish able to swim.

Biaxially stretched poly (ethylene terephthalate) (PET), isotactic polypropylene (PE) and isotactic high density poly-propylene (HCPP) films have been characterized by crystallinity, dielectric constant, refractive index and birefringence. Anisotropy of refractive index by microwave for PET, PP and HCPP biaxially stretched films indicated higher value than refractive index by Abbe refractometer. We recognized good correlation between refractive indices by microwave and Abbe refractometer for biaxially stretched PET, PP and HCPP films, respectively.

Shear induced crystallization, a relaxation phenomenon in polymer melts.- Contour-length fluctuation of polymers: NMR experiments and statistical physics.- Photoelectric response in the pTS diacetylene monomer-polymer single crystals.- Characterization of network structure by branching theory and correlation with viscoelastic properties.- Dispersive and non-dispersive transport processes in polymers.- Hypersonic properties of a smectic side chain polymer liquid crystal with a PA main chain.- Neutron spin-echo investigations on the dynamics of polymer systems.- Optical measurements of the deformation behavior of thin metallized viscoelastic layers for light valves.- Two-dimensional NMR studies of structure and dynamics of solid polymers.- The influence of the molecular weight distribution on the viscosity and elastic properties of polymer melts.- Molecular motion and orientational distribution in polymer electrets as detected by nuclear magnetic resonance and relaxation.- Nonlinear dynamics of polymer crystals. Soliton models of structural defects in the polyethylene crystals.- Applications of "Forced Rayleigh Scattering" and "Photon Correlation Spectroscopy" for the examination of transport properties in polymer melts.- TSD-?-peak and non-equilibrium processes.- Deterministic chaos in the motion of chain molecules.- Interrelation of phase and relaxation behavior in polymer blends and block copolymers with crystallizable components.- Field-induced structure conversions in PVDF.- Broadband dielectric spectroscopy on the molecular dynamics in polymer model-systems: polyphenylmethylsiloxane and linear and star-branched poly(cis-1,4-isoprene).- Plastic deformation and mobility in glassy polymers.- Dynamic light scattering from polymer solutions.- Study of the glass transition of polybutadiene by neutron scattering.- Viscoelastic relaxation in amorphous bulk polymers.- Small-angle neutron scattering investigation of phase separation kinetics of a diblock copolymer.- The role of diffusion of free volume at volume relaxation of amorphous polymers.- Dynamics of density fluctuations in glass forming liquids and polymers as measured by light scattering.- Relaxation in permanent networks.- Relaxation processes in flexible mesomorphic polymers.- Relaxation currents in insulating polymers and their dependence on the polymer structure.- Theoretical problems and dynamic models of the relaxation behavior of macromolecules in anisotropic ordered polymer systems.- Electron spin resonance and relaxation studies on conducting poly(tetrathiafulvalenes).- Paraelasticity of organic colloid systems.

ESR studies on molecular motion and chemical reactions in solid polymers in relation to structure

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhotochemistry in polymer solids. 8. Mechanism of photoreaction of benzophenone in poly(vinyl alcohol)Kazuyuki Horie, Harumi Ando, and Itaru MitaCite this: Macromolecules 1987, 20, 1, 54–58Publication Date (Print):January 1, 1987Publication History Published online1 May 2002Published inissue 1 January 1987https://doi.org/10.1021/ma00167a011RIGHTS & PERMISSIONSArticle Views413Altmetric-Citations46LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (566 KB) Get e-Alerts Get e-Alerts

Hygroscopicity of a sugarless coating layer formed by the interaction between mannitol and poly(vinyl alcohol) (PVA)