Carmen Racles

Petru Poni Institute of Macromolecular Chemistry · Laboratory of Inorganic Polymers

Although deterioration of silicone maxillofacial prostheses is severely accentuated in smoking patients, the phenomenon has not been systematically studied. To address a gap in the literature concerning the stability of maxillofacial prostheses during service, in this contribution, the effect of cigarette smoke on the aspect and physical properties...

Although it is known (from the observations of medical professionals) that cigarette smoke negatively affects maxillofacial prostheses, especially through staining/discoloration, systematic research in this regard is limited. Herein, the color modifications of M511 maxillofacial silicone, unpigmented and pigmented with red or skin tone pigments, co...

The biomedical applications of silicones are countless due to their outstanding properties. In dentistry, silicone for maxillofacial and plastic surgery has become indispensable, from both physiological and aesthetic points of view. In this mini-review, silicone materials for dentistry and facial prostheses are discussed, focusing on their properti...

Two disiloxanes with pyridyl or isocyanide functional groups, as well as silica materials carrying pyridyl or thiol functionalities were used as ligands for Pt(IV) and Fe(III) ions. The molecular and silica-supported metal complexes were tested in a model hydrosilylation reaction between 1,3-divinyl tetramethyldisiloxane and 1,1,3,3-tetramethyldisi...

Two octakis(carboxyalkyl-thioalkyl)silsesquioxanes (COOH-PSx) were obtained by click photo-induced thiol-ene addition reactions between octavinyl-T8-silsesquioxane and thioalkylcarboxylic acids. Their structures were confirmed by elemental and spectral analyses and in one case by single-crystal X-ray diffraction. The natrium salts of COOH-PSx were...

In spite of its versatility, the emulsion templating method is rather uncommon for the preparation of porous silicones. In this contribution, two siloxane-containing stabilizers, designed to be soluble in polar (water) and non-polar (toluene) solvents, respectively, were used in low concentrations to produce stable emulsions, wherein polysiloxane g...

Amassing remarkable properties, silicones are practically indispensable in our everyday life. In most classic applications, they play a passive role in that they cover, seal, insulate, lubricate, water-proof, weather-proof etc. However, silicone science and engineering are highly innovative, seeking to develop new compounds and materials that meet...

Poly(dimethyl‐co‐methylvinyl)siloxane‐α,ω‐diols with 1.5, 5.5, and 8.5 mol% vinyl group contents, respectively, are obtained via an environmental friendly synthesis and used as platforms for further chemical modification via a green process. This chemical modification consists of UV‐activated thiol‐ene addition of 3‐chloro‐1‐propanethiol to the vin...

Isocyanides (isonitriles) are unique organic compounds that contain a formally divalent carbon. Herein, the synthesis of 1,3-bis(isocyanopropyl)tetramethyldisiloxane was performed by a modified carbylamine method, using a phase transfer agent. Spectral methods (nuclear magnetic resonance [NMR], Fourier transform infrared spectroscopy [FT-IR], and e...

Although three-dimensional metal-organic frameworks (3D MOFs) currently enjoy great attention in the scientific world due to their utility to address challenges concerning energy, environment cleaning and not only, very recently two-dimensional version of these, rather considered two-dimensional coordination polymers (2D CPs), have become of intere...

A spent catalytic converter was treated with concentrated HCl and hydrogen peroxide in very mild conditions to extract approximately half of its platinum group metals (PGMs) content, mainly as chlorides. The noble metals were subsequently charged into functionalized mesoporous silica by complexation with mercapto groups. A combination of methods wa...

Within this study, new materials were synthesized and characterized based on polysiloxane modified with different ratios of N-acetyl-l-cysteine (NAC) and crosslinked via UV-assisted thiol-ene addition, in order to obtain efficient membranes able to resist bacterial adherence and biofilm formation. These membranes were subjected to in vitro testing...

Polydimethylsiloxane (PDMS), in spite of its well-defined helical structure, is an amorphous fluid even at extremely high molecular weights. The cause of this behavior is the high flexibility of the siloxane backbone and the lack of intermolecular interactions attributed to the presence of methyl groups. These make PDMS incompatible with almost any...

Polysulfone-supported silver nanoparticles ([email protected]) were obtained by a combination of polymer nanoprecipitation and redox synthesis of silver, in the presence of two siloxane-based stabilizing agents, and were incorporated into a PDMS matrix. Soft elastic composites ([email protected]) were obtained and were investigated by dielectric re...

The first dielectric elastomer actuators based on electroactive nanocomposites with octakis(phenyl)‐T8‐silsesquioxane (phenyl‐T8), obtained ex‐situ, used as voltage stabilizer filler for silicone elastomers are reported. The incorporation and homogeneous dispersion of crystalline phenyl‐T8 in percentages of 2.5, 3.5, 5, and 10 into the amorphous ma...

With a history of almost 100 years, silicones -polymeric or oligomeric siloxanes- are well known as reliable materials with a wide range of applications, from home to the aerospace sector. The constant interest for these polymers is explained by their unique combination of properties, including chemical and physiological inertness, extreme resistan...

Multi-functional materials were synthesized by on chain modification of dimethyl-methylvinylsiloxane copolymers with mercaptopropionic acid and Disperse Red 1 (DR1). After cross-linking, transparent free-standing films were obtained, showing at the same time light-responsive and electromechanical (electrical actuation and piezoelectric) properties....

Although platinum nanoparticles and complexes ‐especially of Pt(0) and Pt(II)‐ are well known catalysts, siloxane‐based platinum complexes are rarely reported. Herein, a Platinum(IV) complex of 4‐aminopyridinium‐modified disiloxane was prepared and characterized by medium and far infrared spectroscopy, NMR and EDX. The formation of the complex was...

The present paper presents the preparation and characterization of Ni complex of a guanidine functionalized trisiloxane as a model compound for polysiloxanes supported metal complexes. The structures of the ligand and its Ni complex are elucidated by theoretical calculations using semi-empirical PM6 and DFT methods, and experimentally confirmed by...

Cyclotri- and tetrasiloxanes having a methyl group and a carboxylic acid coupled through thioether bridge at each silicon atom were used to coordinate copper(II). The amphiphilic character conferred by the co-existence of the two moieties with opposite behaviour on the silicon atom gives the molecule the ability to form aggregates in solution. When...

Doxorubicin (DOX) is a chemotherapeutic agent from anthracycline class, which acts unselectively on all cells; thus, it may have genotoxic and/or mutagenic effects and cause serious environmental problems. Herein, the decomposition of a diluted solution of DOX hydrochloride for injection has been investigated under photo-oxidative conditions, in am...

Functional siloxane dimmers and polymers carrying two types of hydrophilic groups (tris-(hydroxymethyl)aminomethane and 4-aminopyridyne) were previously prepared and characterized. Their surface properties were investigated by tensiometry, DLS and TEM in water or organic media. The un-modified methylsiloxane units induce hydrophobic character while...

1,3-divinyltetramethyldisiloxane (V2), 1,3,5-trivinyl-1,3,5-trimethylcyclotrisiloxane (V3), and 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane (V4) are used as hydrophobic substrates to attach carboxyl groups by thermal or photochemical activated thiol-ene addition of 3-mercaptopropionic acid (R1), thioglycolic acid (R2) and thioacetic ac...

The iron oxides, widespread in nature, are used in numerous applications in practice due to their well-known properties. These properties can be modified by size lowering at nanoscale. Some applications, such as biomedical, require a rigorous selection of nanoparticles by size, shape, and surface functionality. In other applications, such as cataly...

Carbon black (CB) particles were used as conductive filler for a high molecular weight polydimethylsiloxane-α,ω-diol (PDMS) to obtain conductive stretchable electrodes suitable for dielectric elastomer actuators. To ensure a perfect compliance between electrodes and the dielectric film, both based on the same PDMS, an original procedure consisting...

Polar-nonpolar silicone materials of different morphology and composition were investigated by means of broadband dielectric relaxation spectroscopy in order to elucidate the effect of polar content and nature of the interface on the segmental mobility of polydimethylsiloxane (PDMS) chains. The variation of dielectric parameters with temperature re...

In our follow-up work on the anisotropy evaluation of Co complexes, we have become aware of an error in a theoretical development included in the ESI, section B, of the aforementioned paper. Namely in the Section titled “Magnetization versus magnetic field and magnetic heat capacity in a random oriented powdered sample of an orthorhombic S = 1/2 sy...

Three new metal–organic frameworks (MOFs) were obtained from a siloxane dicarboxylic acid (CX), 4,4′-bipyridyne (BPy) or 1,2-bis(4-pyridyl)ethylene (EBPy) and copper or cobalt acetates. The compounds were characterized by IR spectroscopy, powder X-ray diffraction, energy-dispersive X-ray fluorescence (XRF), thermogravimetric analysis (TGA), dynamic...

Titanium dioxide-based nanoparticles with nanotube morphology were synthesised and used in low fractions (2 and 5 wt%) as dielectric permittivity enhancers for high molecular weight polydimethylsiloxane matrix (Mn = 350,000 g mol− 1). In order to ensure good dispersability in, and compatibility with the silicone matrix, the filler was treated with...

Iron oxide nanoparticles were prepared by alkaline precipitation method tuning the reaction time, as to afford ferrihydrite with spherical morphology or goethite nanorods. These two nanoparticles types, surface treated with a surfactant (Pluronic L81), were each incorporated in 10 and 20 wt% within a polydimethylsiloxane-α,ω-diol, PDMS (Mn=60000 g/...

A series of elastomers, either natural or synthetic (some of them commercial, while others prepared in the laboratory), suitable for use as active elements in devices for wave energy harvesting, were evaluated concerning their behavior and effects on the marine environment. In this aim, the elastomer films, initially evaluated regarding their aspec...

New all-silicone composite materials were prepared using polar silicone particles dispersed within a high molecular weight polydimethylsiloxane (PDMS) matrix. Polar silicones having either CN or Cl groups attached to the polysiloxane chain in similar proportions were prepared by appropriate post-polymerization reactions and submicron particles were...

Various types, shapes and sizes of iron oxide nanoparticles were obtained depending on the nature of the precursor, preparation method and reaction conditions. The mixed valence trinuclear iron acetate, [Fe2IIIFeIIO(CH3COO)6(H2O)3]·2H2O (FeAc1), μ3-oxo trinuclear iron(III) acetate, [Fe3O(CH3COO)6(H2O)3]NO3∙4H2O (FeAc2), iron furoate, [Fe3O(C4H3OCOO...

Additional experimental data.

Elastic composites were prepared based on a polydimethylsiloxane-α,ω-diol (M w = 139 000 g mol⁻¹), different α,ω-bis(trimethylsiloxy)poly(methylcyanopropyl-methylhexyl-methylhydro)siloxanes as the polar group component and TEOS as a cross-linking agent and silica generator. The resulting materials consisted of polar-nonpolar interconnected networks...

Dielectric silicone elastomers able to respond to an electrical stimulus by a mechanical displacement are prepared through a simple one-pot procedure consisting in cross-linking and simultaneous in situ generation of the filler functionalized with polar groups, as reinforcing and dielectric permittivity enhancer. One and the same reagent, (3-chloro...

A series of polar silicones was synthesized in order to compare their dielectric properties. Different substituents with high dipole moment (epoxy, pyridyl, aldehyde, cyano-, nitroazobenzene) were attached by hydrosilylation to a poly(dimethyl-methylhydro)siloxane. Thiol-ene addition on a dimethyl-methylvinyl siloxane copolymer with similar composi...

Three new poly(siloxane-urethane) crosslinked structures (PSFUs) were prepared from 1,1′-diisocyanatoferrocene (Fc(NCO)2), and two siloxane diols in different proportions, i.e. α,ω-bis(hydroxybutyl)oligodimethylsiloxane (HS-1) and a hybrid diol containing hydrolysable triethoxy (-Si(-O-Et)3) groups (HS-2). The formation of the urethane groups along...

The first cyclic ferrocenylsiloxane-urea, {1,1'-ferrocene-diurea-[1,3-bis(propylene)tetramethyldisiloxane]} (FSU), has been formed by reacting 1,1'-ferrocenediisocyanate with 1,3-bis(aminopropyl)-tetramethyldisiloxane in a chloroform-toluene mixture. The ferrocenylsiloxane urea was structurally characterized by FTIR and 1H NMR spectroscopy, element...

Mixed silicone interpenetrating networks have been prepared using two groups of siloxane polymers and copolymers as precursors in different combinations. Each combination chosen, after a good mixing in solution with cross-linking agents was processed into film, which has been stabilized through sequential crosslinking using separate chemical pathwa...

Five R-trialkoxysilanes, with R: CH3, C6H5, NH2(CH2)3, Cl(CH2)3, or NC(CH2)3 are used as crosslinkers for two polydimethylsiloxane-α,ω-diols with different molecular masses (35,000 and 125,000 g · mol−1) The crosslinking occurs by condensation at room temperature under the influence of the environmental moisture and in presence of dibutyltindilaura...

Abstract A ceramic material consisting in a zirconium dioxide-lead zirconate mixture has been obtained by precipitation method, its composition being proved by wide angle X-ray powder diffraction and energy-dispersive X-ray spectroscopy. The average diameter of the ceramic particles ranged between 50 and 100 nm, as revealed by transmission electron...

Elastic materials with increased permittivity (ε’) were obtained in a three-step process starting from a hydroxyl endfunctionalized polydimethylsiloxane (PDMS) of a high molecular weight (Mw = 139 kDa), trimethylsilyl end-blocked silicones that carry hydrosilane, cyanopropyl and hexyl groups Px (where x represents the mol% of cyanopropyl groups), a...

A series of novel polysiloxanes is presented the glass transition temperatures and dielectric properties of which are systematically fine-tuned by utilizing thiol-ene post-polymerization reactions. The pendant vinyl groups of a high molecular weight polymethylvinylsiloxane P1 were exhaustively reacted with the thiol compounds 1-butanethiol (2) and...

A series of novel polysiloxanes is presented, the glass transition temperatures and dielectric properties of which are systematically fine-tuned by utilizing thiol-ene post-polymerization reactions. The pendant vinyl groups of a high molecular weight polymethylvinylsiloxane P1 were exhaustively reacted with the thiol compounds 1-butanethiol (2) and...

Three complexes of copper with organosiloxane ligands of bis-azomethine type derived from 1,3-bis(3-aminopropyl)tetramethyldisiloxane and 2-hydroxybenzaldehyde (1), 5-nitro-2-hydroxybenzaldehyde (2) and 3,5-di-tert-butyl-2-hydroxybenzaldehyde (3) having well-established structures were investigated for their ability to form aggregates in organic so...

It has been the dream of many scientists to create polymeric materials which exhibit simultaneously high dielectric permittivity, low glass transition temperature, and excellent elastic properties. Such materials would be a highly attractive dielectric in electromechanical transducers. Within this topic we are focusing on silicones because of their...

A tris(hydroxymethyl)aminomethane-modified polysiloxane has previously been investigated for surface properties and valuable practical applications have been proposed, including nanoparticle stabilization, complexing of 3d metals, micellar solubilization of drugs and water dispersion of metal oxide nanoparticles. In this article we show the ability...

New polymers with tuneable dielectric properties were prepared by modifying trimethylsilyl end-terminated poly(methylhydro)siloxane with polar γ-cyanopropyl groups. The amount of polar groups was tuned by adjusting the allyl cyanide/n-hexene ratio in poly(methylhydro)siloxane co-hydrosilylation. The copolymers were characterized by FTIR and NMR spe...

Two siloxane copolymers containing pendant mesogenic units were synthesized by reacting the chloromethyl groups of a siloxane precursor copolymer with potassium phenolates of aromatic azomethine mesogens. Their structure was confirmed by spectral methods (FT-IR and NMR) and their thermotropic behavior was studied by polarized optical microscopy (PO...

Although silicones possess low dielectric constant, they are between the most used polymers in actuation due to their appropriate mechanical properties (low modulus and high elongation). These can be easily tuned by the preparation strategy: proper choice of the molecular mass and microstructure of the polymer matrix; adding or not of more or less...

Siloxane surfactants containing tromethamol or carboxylate groups, with very good surface properties, are tested for the first time for biocompatibility using MTT cytotoxicity test. They are used for encapsulation of superparamagnetic iron oxide nanoparticles (SPION), and of a combination of these with nystatin as model un-soluble drug, in order to...

The new dicarboxylic acid, 1,3-bis(p-carboxyphenyIene-ester-methylene)tetramethyldisiloxane (H2L, 1) was obtained by treating 1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisiloxane with a mixture of terephthalic acid and terephthalic acid sodium salt in a 1:1 ratio. In this approach, besides the desired compound 1 (33 wt % yield), the condensation cyc...

Organic-coated iron–chromium oxide (chromite) nanoparticles have been prepared by using the thermal decomposition procedure. For this purpose, the substrate – bimetallic acetate – was treated with oleic acid and dodecylamine as co-ligands in trichloroacetic acid solvent at high temperature (320 °C). The main characteristics and behaviors of the obt...

All-polymer composites were prepared in a simple manner from a pair of incompatible polymers: polysulfone (PSF) as the matrix polymer and cross-linked polydimethylsiloxane (PDMS) submicron particles as the disperse phase. The obtained composites, containing approximately 50 wt.% of PDMS particles, were compared with neat PSF and with blends of the...

Two H-bond polymers from carboxypropyl disubstituted disiloxane and bipyridyl compounds, as well as the starting components in different ratios were reacted with zinc acetate. Two new siloxane-containing coordination polymers were thus obtained and characterized. They exhibited highly ordered structures, which were investigated by single crystal XR...

Three different small molecule or polymeric well-determined complex structures containing siloxane moieties and 3d metals were incorporated into a polymeric matrix based on a polydimethylsiloxane of low molecular weight. After the incorporation of the complex, matrix crosslinking was performed with tetraethylorthosilicate, resulting in free-standin...

Polydimethylsiloxanes (PDMS) have recently been used as dielectric elastomer materials in electromechanical actuators. When they are soft enough, electric fields can change their shape. However, due to their low dielectric permittivity, large electric fields are required to induce a change. The approach presented here is to chemically modify silico...

Siloxane-containing polyazomethines with linear (PAZ) and cross-linked (CPAZ) architectures and their iron complexes (FePAZ and CFePAZ) have been prepared. The structures of the resulted compounds were investigated by spectral meth-ods (FT-IR, 1 H NMR, UV–vis) and electrospray ionization mass spectrometry (ESI-MS). X-ray fluorescence spectrome-try...

A new siloxane diamine, 1,3-bis(amino-phenylene-ester-methylene)tetramethyldisiloxane (1), was obtained by a two-step procedure and used to prepare a series of Schiff bases (2–5), by reaction with different carbonylic compounds: salicylaldehyde, 3,5-dibromosalicylaldehyde, 5-chlorosalicylaldehyde and 3,5-di-tert-butyl-2-hydroxybenzaldehyde. All com...

Silver nanoparticles (AgNPs) were obtained by a redox reaction, using a glucose-containing cyclosiloxane as a reduction agent and stabilizer. Then the AgNPs aqueous solution was used as the reaction medium for the sol-gel process, starting from tetraethylorthosilicate (TEOS) as silica precursor. The nanocomposite material resulted (SilAg) after sol...

A series of blends of polydimethylsiloxane (PDMS) and indomethacin (IMC), containing 20-80 wt.% IMC were obtained and characterized by differential scanning calorimetry, Fourier transform-infrared spectroscopy, and powder X-ray diffraction in order to observe the mutual influence of the two components. The main thermal transitions of PDMS remained...

Three poly(arylene ether sulfone)s (two polymers and one copolymer) containing diphenylfluorene, phenolphthalein and 2,4-bis[(4-chlorophenyl)sulfonyl]-1-(phenyltio) benzene)] units were synthesized by the classical Williamson polyetherification reaction. The association phenomenon in N,N-dimethylformamide (DMF) was investigated by different methods...

The magnetic properties of the porous metal-organic complex Co(bpy)(1.5)(NO(3))(2) (bpy = 4,4'-bipyridine), investigated by SQUID magnetometry, EPR and heat capacity measurements, are reported. The tongue-and-groove structure of this complex is formed by the assembly of T-shaped building blocks, where each Co is bound to three bpy ligands. Co(II) i...

New complexes of the composition: {Fe3O(OOCR1COO)3}+ and {Fe3O(R2COO)6}+, where R1 = –(CH2)3–Si(CH3)2–O–Si(CH3)2–(CH2)3– or –(CH2)8–COO–CH2–Si(CH3)2–O–Si(CH3)2–CH2–COO–(CH2)8–; R2 = Si(CH3)3–O–Si(CH3)2–CH2–COO–(CH2)8–, were synthesized by direct synthesis using siloxane carboxylic salts and iron nitrate or by ligand exchange in μ3-oxo trinuclear ir...

Silver nanoparticles are of high importance due to their electrical, magnetic, and optical properties, as well as catalytic and biocidal activity that are superior to the bulk silver and other metals. To prepare certain devices, generally, silver is incorporated into a matrix either as preformed or in situ-generated particles. Silver nanoparticles...

Polysulfone−silver composite nanoparticles have been prepared by combining polymer nanoprecipitation and redox synthesis of silver, in the presence of a glucose-modified cyclosiloxane as stabilizing agent. Based on previous kinetic investigations and on model reactions, we concluded that the reducing agent in this case is the tetrahydrofuran (THF)...

Polydimethylsiloxane nanoparticles were obtained by nanoprecipitation, using a siloxane surfactant as stabilizer. Two neural networks and a genetic algorithm were used to optimize this process, by minimizing the particle diameter and the polydispersity, finding in this way the optimum values for surfactant and polymer concentrations, and storage te...

Polydimethylsiloxane-α,ω-diols with different contents of pendant chloromethyl groups were reacted with an aromatic diamine (3,3′-dimethoxybenzidine) when cross-linking occurred. The reactions were performed in silica — generating sol— gel system; so two interconnected networks (silica and cross-linked polydimethylsiloxane) were formed. The resulti...

New crosslinked siloxane-cellulose polyester materials were synthesized by direct solution polycondensation, at room temperature, starting from cellulose acetate and two siloxane diacids. Dicyclohexylcarbodiimide (DCC) was used as activator and 4-(N,N-dimethylamino)pyridinium-p-toluenesulfonate (DPTS) as catalyst. IR spectroscopy was used for the c...

Polydimethylsiloxanes, side functionalized in different degrees with chloromethyl groups, were reacted with 4,4′-bipyridyl and crosslinking occurred by the formation of ionic (bipyridinium) groups. The reactions were carried out in a silica sol–gel system, and thus, two networks were generated simultaneously: amphiphile siloxane-organic and silica...

A simplified alternative for the synthesis of carbohydrate-modified siloxanes is described. The starting siloxane precursors contain glycidyl functional groups, which are reacted with glucose in dimethylformamide (DMF), in the presence of a gel type cation exchanger. The method eliminates protection-deprotection reactions, as well as moisture-sensi...

New siloxane-based amphiphilic compounds (a dimer and two copolymers with pendant functional groups) have been synthesized starting from tris(hydroxymethyl)aminomethane (tromethamol) and glycidyl-functionalized siloxane precursors. They have been characterized by spectroscopic methods (Fourier transform infrared (FTIR) spectroscopy and H-nuclear ma...

Silver nanoparticles were obtained in aqueous medium, at room temperature, by redox reactions, with or without glucose, in the presence of a glucose-containing cyclosiloxane. The siloxane surfactant can act as stabilizer when glucose is present in the system, but also as reducing agent and stabilizer when no glucose is added. The kinetics was follo...

Cellulose acetate was reacted in different ratios with poly[dimethyl(methyl-H)siloxane] containing 25mol% Si–H side groups along the chain. A dehydrocoupling reaction between Si–H and C–OH groups occurred in presence of Karstedt’s catalyst, leading to the formation of Si–O–C bond, as proved by FTIR spectra, thus crosslinking the cellulose derivativ...