Dan Sorin Vasilescu

Universitatea Națională de Știință și Tehnologie Politehnica București

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Co-Authors

Dumitru Mircea Vuluga

Romanian Academy

Valentin Victor Jerca

Romanian Academy

Florica Adriana Nicolescu

Romanian Academy

Ana‐Maria Albu

Universitatea Națională de Știință și Tehnologie Politehnica București

Bogdan Mărculescu

Xi’an Jiaotong-Liverpool University

Florica Adriana Jerca

Romanian Academy

Adrian Boborodea

Centre of Technological Resources in Chemistry

Iuliana Stoica

University of Toronto

Camelia Hulubei

Institute of Macromolecular Chemistry

Cristina Stere

University of Manchester

Cooperative Institutions

Romanian Academy

Universitatea Națională de Știință și Tehnologie Politehnica București

University of Bucharest

Institutul de Chimie Macromoleculară Petru Poni

Institute of Macromolecular Chemistry

Grigore T. Popa University of Medicine and Pharmacy

Gheorghe Asachi Technical University of Iași

Centre National de la Recherche Scientifique

Alexandru Ioan Cuza University

Institutul Naţional de Cercetare Dezvoltare pentru Chimie si Petrochimie

Author Statistics

Papers

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New Trends in Architecture of Azo Polymer Materials with Applications in Optical Field. 2. Solvatochromic and Photochromic Investigation

Molecular Crystals and Liquid Crystals (2010)

Ana‐Maria Albu Ionica Ioniţă Maria Maganu Cristian Boscornea Dan Sorin Vasilescu

In the large family of polymers, the azobenzene derivatives represent one fascinating materials class, along with stylbene and azomethinic derivatives. This interest is explained by combination of the properties of anisotropy with the photoinduced behaviors. The photoinduced birefringence, relief grating, the high optical nonlinearity resulted from the sin-anti isomerism, molecular reorientation, the exceptional stability to writing and erasing by laser radiation, are just the most important arguments for their usage of these polymeric architectures in the NLO field as: LCD, chemical sensing, devices for storage and transmission of information. This presentation covers the development and characterization a new series of materials from viewpoint of the modification of the polymer materials by the chemical transformation of the "common" polymer support an underlining: solvatochromic and photorefractivity properties.

Solvatochromism

Azobenzene

10.1080/15421401003724142

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Citations (1)

Characterisation of gel permeation chromatography column by fractal geometry

Polymer Bulletin (2000)

A. G. Boborodea M.L. Clemens Cristina Stere Dan Sorin Vasilescu

Gel permeation chromatography

10.1007/s002890070074

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Citations (2)

Investigations of molecular nonlinear optical polarizabilities of azobenzenes substituted with strong acceptor groups

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE (2014)

Valentin Victor Jerca Florica Adriana Jerca Ileana Rău François Kajzar Dan Sorin Vasilescu

In this paper, a detailed optical characterization of a series of 4-nitro/cyan, 2-nitro/cyan and 2,4-nitro/cyan substituted azobenzenes is carried out. The first-order hyperpolarizabilities of organic chromophores were determined by solvatochromic method. Different nonlinear optical behaviour is evidenced when the ortho position of an azo molecule is occupied by acceptor and donor substituents. An increase of first-order hyperpolarizability was noticed in the case of 2,4-disubstituted azobenzenes as compared to the monosubstituted ones. Solvent effect on the UV-Vis absorption spectra of azo-polymers was investigated using Kamlet-Taft multiparameter equation. Kamlet-Taft equation revealed that hydrogen bond acceptor properties and dipolarity/polarizability of the solvent have a significant contribution upon the solvatochromic behavior of azo-derivatives.

Solvatochromism

Hyperpolarizability

Cyan

Chromophore

Acceptor

10.1117/12.2073075

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Citations (0)

Synthesis and characterization of some polymers with applications in non-linear optics II. Copolymerization of styrene with some monomers containing azo-dyes

European Polymer Journal (1999)

Ana‐Maria Albu Bogdan Mărculescu Dan Sorin Vasilescu

Chromophore

Reactivity

Characterization

10.1016/s0014-3057(99)00019-1

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Citations (14)

New Organic–Inorganic Hybrids with Azo-dye Content

Designed Monomers & Polymers (2010)

Florica Adriana Nicolescu Valentin Victor Jerca Izabela‐Cristina Stancu Dan Sorin Vasilescu Dumitru Mircea Vuluga

Five new organic–inorganic hybrids were generated from their corresponding co-polymer structures using thermal cross-linking process. The hybrid structures contain covalently-linked azobenzene units provided by the previous co-polymerization step between 3-methacryloxypropyl trimethoxy-silane and five novel azo-monomers. All structures have been characterized by FT-IR spectroscopy and TGA-MS analysis. The soluble co-polymers have also been characterized by SEC, elemental analysis and 1H-NMR spectroscopy. It has been found that the thermal stability of the hybrid structures was enhanced, as compared to the soluble co-polymers, due to the newly generated Si–O–Si bonds. The newly prepared structures show a high content in chromophore units, as indicated by 1H-NMR spectra and elemental analyses.

Thermal Stability

Hybrid material

Thermogravimetric analysis

Azobenzene

Chromophore

Proton NMR

10.1163/138577210x521332

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Citations (16)

Three-Dimensional Nanostructures with Biocidal Activity Created on a Siloxane-Containing Copolyimide Film

Key engineering materials (2015)

Iuliana Stoica Andreea Irina Barzic Magdalena Aflori Camelia Hulubei Valeria Harabagiu

Surface morphological characteristics of a copolyimide film prepared from a fluorine-based dianhydride combined with an aliphatic siloxane-based diamine and an aromatic containing ether linkages one, were studied before and after oxigen plasma treatment using atomic force microscopy (AFM). The three-dimensional texture parameters calculated from the AFM data have highlighted a more pronounced surface morphology (higher average roughness and developed interfacial area ratio), improved bearing properties and no predominant orientation, as the plasma exposure time was increased from 6 to 10 minutes, using the same power (40 W). The reactive groups generated on the binding surface have facilitated the interaction with a biocidal agent, such as silver nitrate. This creates silver-containing nanoparticles, of about 120-150 nm, uniformly distributed on the copolymer surface, with a density of 10±2 particles/μm 2 . The functionalization with the biocidal agent of the flourinated copolyimide surface was conducted for testing its antimicrobial properties, namely the inhibition/destruction of Escherichia coli bacterium.

Siloxane

Surface Modification

Morphology

10.4028/www.scientific.net/kem.638.98

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Citations (2)

The polymerization of N-vinylcarbazole with metal salts in basic solvents

Journal of Polymer Science Part B Polymer Letters (1968)

O. F. Solomon N. Cobianu Dan Sorin Vasilescu C. Boghinǎ

10.1002/pol.1968.110060804

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Citations (17)

New side-chain azo-polymers for optical applications: synthesis and characterization

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE (2012)

Mitica Cezar Spiridon Florica Adriana Jerca Valentin Victor Jerca Dumitru Mircea Vuluga Dan Sorin Vasilescu

In this paper we report a series of side-chain polymers bearing a push-pull azo-moiety, from pseudo-stylbene type molecules. The azobenzene monomer is chemically incorporated through radical copolymerization in: poly(methacrylate), poly(styrene); and poly(oxazoline) matrices. The different classes of azo-polymers are discussed comparatively to one another from the point of view of: solubility, molecular weights, glass transition temperatures and thermal stability, chromophore contents, and as well as from the point of view of their spectral features.

Moiety

Azobenzene

Side chain

Thermal Stability

Chromophore

10.1117/12.965884

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Citations (3)

Synthesis and characterization of organic-inorganic polymers from new methacrylate monomers and silane derivatives

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE (2009)

Florica Adriana Nicolescu Valentin Victor Jerca Ana Maria Albu Dan Sorin Vasilescu Dumitru Mircea Vuluga

We report the synthesis of five new hybrid polymeric structures obtained by free radical copolymerization of some organic azo-based methacrylate monomers and 3-methacryloxypropyl trimethoxysilane (MEMO). The copolymers are soluble in common solvents like methylene chloride, chloroform, dichlorbenzene, dimethylsulfoxide, dimethylformamide. The copolymeric structures might be interesting from the point of view of nonlinear optical response due to a rich content in chromophoric units determined by H-NMR spectroscopy. The structures were also characterized by FT-IR spectroscopy, TGA and SEC analysis.

Methylene

Dimethyl formamide

10.1117/12.832282

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Citations (1)

Oxazoline-functional polymer particles graft with azo-dye

Reactive and Functional Polymers (2010)

Valentin Victor Jerca Florica Adriana Nicolescu Roxana Truşcă Eugeniu Vasile Adriana Bãran

Dispersity

Oxazoline

Particle (ecology)

Thermal Stability

10.1016/j.reactfunctpolym.2010.12.004

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Citations (31)