Maria Cazacu

Petru Poni Institute of Macromolecular Chemistry · Laboratory of Inorganic Polymers

The locomotion of various organisms relies on the alternated elongation-contraction of their muscles or bodies. Such biomimicry can offer a promising approach to developing soft robotic devices with improved mobility and efficiency. Most strategies to mimic such motions rely on reversible size modifications of some materials upon exposure to extern...

Ferronematics that are generally based on nematic liquid crystals (LCs) doped with magnetic nanoparticles, synergistically taking advantage of the anisotropic and flow characteristics of the nematic host and the magnetic susceptibility of the dopant, have powerful applications as magnetically actuated soft materials. In this work, a Co(II) complex,...

Background and Objectives: One’s quality of life depends on overall health, and in particular, oral health, which has been and continues to become a public health issue through frequent manifestations in various forms, from simple oral stomatitis (inflammations of the oral cavity) to the complicated oral health pathologies requiring medical interve...

Due to their structural, morphological, and behavioral characteristics (e.g., large volume and adjustable pore size, wide functionalization possibilities, excellent biocompatibility, stability, and controlled biodegradation, the ability to protect cargoes against premature release and unwanted degradation), mesoporous silica particles (MSPs) are em...

A new metal–organic framework {[Mn4(Cx)3(etdipy)5]·2ClO4}n (1) was prepared via the complexation of manganese ion from a Mn(ClO4)2 source with 1,3-bis(carboxypropyl)tetramethyldisiloxane (Cx) and 1,2-di(4-pyridyl)ethylene (etdipy) in the presence of 2,4-lutidine as a deprotonating agent. The single-crystal X-ray diffraction analysis revealed a dens...

Two chemical motifs of interest for medicinal chemistry, silatrane as 1-(3-aminopropyl) silatrane (SIL M), and nitro group attached in position 5 to salicylaldehyde, are coupled in a new structure, 1-(3-{[(2-hydroxy-5-nitrophenyl)methylidene]amino}propyl)silatrane (SIL-BS), through an azomethine moiety, also known as a versatile pharmacophore. The...

The specific features of the siloxane bond unify the compounds based on it into a class with its own chemistry and unique combinations of chemical and physical properties. An illustration of their chemical peculiarity is the behavior of 1,3-bis(2-aminoethylaminomethyl)tetramethyldisiloxane (AEAMDS) in the reaction with carbonyl compounds and metal...

Silicone elastomer composites with piezoelectric properties, conferred by incorporated polyimide copolymers, with pressure sensors similar to human skin and kinetic energy harvester capabilities, were developed as thin film (<100 micron thick) layered architecture. They are based on polymer materials which can be produced in industrial amounts and...

Supramolecular full silicone networks are built on the basis of siloxane polymers with low content of amino (6.4 or 9.8 mol%), and carboxyl (14.9 mo%) groups. Alternatively, the carboxyl groups involved are attached to a polyhedral silsesquioxane cage (i.e., octakis(2-carboxymethylene-thioethyl)silsesquioxane), POSS-COOH, which have also been found...

A Ti50Ni45Cu5 shape memory alloy (SMA) was cast, homogenized and hot rolled into 0.5 mm-thick lamellas. After homogenization, the intercrystalline Ti2(Ni, Cu) based solid solution, gradually decomposed with the increase of hold temperature and time, as pointed out by optical, scanning electron and atomic force microscopy. After hot rolling, by wire...

Hexagonal boron nitride (hBN) has been incorporated, as an active filler, in a customized silicone matrix to obtain high thermal conductivity composites, maintaining high flexibility and low dielectric permittivity, which are of interest for heat dissipation in energy storage systems (e.g., batteries or supercapacitors) and electronics. By the prop...

Silicones are one of the most important classes of synthetic biomaterials. In order to become stand-alone objects, they must be cross-linked. This can be achieved by chemical (radical, addition or condensation reactions) or physical (supramolecular interactions) processes, each requiring the presence of complementary functional groups and specific...

A series of complexes of tetraamine cations of the nickel(II) and zinc(II) and large trigonal aromatic carboxylates have been prepared and their structures have been determined by single crystal X-ray crystallography. All compounds obtained were also characterized by elemental analysis, thermogravimetric investigations, FTIR spectroscopy, diffuse r...

Aiming at the synthesis of platinum complexes, a ligand containing a dimethylsilane moiety was designed by a two-step reaction, respectively Williamson ether synthesis and carbonyl-amine condensation, starting from bis(chloromethyl)dimethylsilane, 3,5-dichlorosalycylaldehyde and 2-aminophenol. By reacting the new bis-imine with Pt(acac)2, an uncomm...

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...

Active elements made of Ti50Ni45Cu5 shape memory alloy (SMA) were martensitic at room temperature (RT) after hot rolling with instant water quenching. These pristine specimens were subjected to two thermomechanical training procedures consisting of (i) free recovery shape memory effect (FR-SME) and (ii) work generating shape memory effect (WG-SME)...

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...

Mesoporous silica nanoparticles (MSNs) bearing methyl, thiol or glucose groups were synthesized, and their encapsulation and release behaviors for the anticancer drug Doxorubicin (Dox) were investigated in comparison with nonporous homologous materials. The chemical modification of thiol-functional silica with a double bond glucoside was completed...

Raw sodium bentonite (Bent) without preliminary treatments is incorporated as a filler in a silicone matrix, from 5 to 100 parts per hundred (pph), by weight, by simple mixing in solution. The mixtures are processed as films and stabilized by condensation crosslinking at room temperature. Besides being environmentally safe and non-toxic, bentonite...

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...

An original approach for the design of hydrophobized heterogeneous platinum-based catalytic systems is reported here. Heterogenization was performed by depositing the platinum precursor (H2PtCl6) on macroporous styrene-divinylbenzene (SDVB) beads with a high surface area, ∼330 m² g⁻¹, as determined by N2 sorption data, followed by treating with 1,1...

3-Formylsalicylic acid (3-FSA) was treated in a weak acidic medium with 1,3-bis(2-aminoethylaminomethyl)tetramethyldisiloxane to form a salen-type ligand, followed by the addition of copper(II) chloride to build the corresponding coordination compound in a one-pot procedure. Along with the CH=N bond formation, Si-O-Si bond was also broken down to f...

We present the magnetic properties of the metal-organic framework {[CoCxAPy]·2.15 H2O}n (Cx = bis(carboxypropyl)tetramethyldisiloxane; APy = 4,4`-azopyridine) (1) that builds up from the stacking of 2D coordination polymers. The 2D-coordination polymer in the bc plane is formed by the adjacent bonding of [CoCxAPy] 1D two-leg ladders with Co dimer r...

A series of metal salen complexes, original in view of the presence in their structure of a highly flexible and hydrophobic spacer, were prepared on the basis of the reaction of 1,3-bis(3-aminopropyl)tetramethyldisiloxane with 3,5-dichloro-, 3,5-dibromo- and 3-hydroxy-salicylaldehyde and various metal ions (Co2+, Ni2+, Cu2+ and Zn2+). The isolated...

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...

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...

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...

A di‐manganese(III) complex structure was built by an original approach consisting of a two‐step procedure. First, the mononuclear complex of the manganese(III) with the Schiff base of the salen‐type ligand (H2L) derived from 1,3‐bis(3‐aminopropyl)tetramethyldisiloxane and 3,5‐di‐tert‐butyl‐2‐hydroxybenzaldehyde was prepared. The main feature of no...

Even through nowadays technology and robotics seem to have taken a front seat on the medical field, there are still conventional methods being used in dental medicine, especially related to impression techniques. Elastomers such as silicone rubbers are widely used as impression materials for their suitable properties and behavior in dentistry. As t...

An unusual highly flexible, organic-inorganic diamine, 1,3-bis(3-aminopropyl)tetramethyldisiloxane (APDS), is reacted with 3,5-dichloro-, 3,5-dibromo- and 3-hydroxysalicylaldehyde resulting the salen-type Schiff bases H2L¹, H2L² and H2L³. For comparison, organic homologues derived from 3-hydroxysalicylaldehyde with hexamethylenediamine (H2L⁴) and d...

The asymmetric unit of the title compound, catena-poly[[[(1,4,8,11-tetra­aza­cyclo­tetra­decane-κ⁴N¹,N⁴,N⁸,N¹¹)nickel(II)]-μ-4,4′-(di­phenyl­silanedi­yl)dibenz­o­ato-κ²O:O′] sesquihydrate], {[Ni(C26H18O4Si)(C10H24N4)]·1.5H2O}n, consists of the halves of the centrosymmetric macrocyclic cation and the C2-symmetric di­carboxyl­ate dianion and of the w...

An original co‐ligand association, consisting of 4,4'‐azopyridine and 1,3‐bis(carboxypropyl)tetramethyldisiloxane, is used for complexing MnII, to obtain a 2D dinuclear coordination array having infinite horizontal dimensions and nanometric thickness. Due to the shielding effect of the tetramethyldisiloxane units facing outwards on both sides, the...

The well-known particularities of the siloxane bond (dual character and flexibility) induce certain behaviors of the compounds in the structures in which it is found. Thus, carboxylic or azomethine ligands containing tetramethyldisiloxane spacers or trimethylsilane tails were prepared and used to build 0D, 1D, 2D or 3D metal complexes. Despite thei...

Metalloporphyrins are highly recognized for their capacity to act as sensitive substances used in formulation of optical, fluorescent, and electrochemical sensors. A novel compound, namely Pt(II)-5,10,15,20-tetra-(4-allyloxy-phenyl) porphyrin, was synthesized by metalation with PtCl 2 (PhCN) 2 of the corresponding porphyrin base and was fully chara...

The preformed nickel(II) com­plex of the 14-membered macrocyclic ligand 1,4,8,11-tetra­aza­cyclo­tetra­decane (cyclam, L), when treated with 4,4′-(di­methyl­silanedi­yl)diphthalic acid (H4A) in a DMF/H2O mixture (4:1 v/v) under heating, leads to [Ni(L)]3(HA)2·3DMF (I·DMF). Redissolution of this com­pound in a DMF/H2O/MeOH mixture (4:1:30 v/v/v) wit...

Silicone elastomers are one of the most promising materials for dielectric elastomer transducers (DETs). In the context of the intense research that is being done to improve the electromechanical performances,...

1,3-Bis(3-aminopropyl)tetramethyldisiloxane is a valuable tool for the introduction of siloxane segments into different organic-inorganic structures. This paper demonstrates how 1,3-bis(3-aminopropyl)tetramethyldisiloxane can easily form crystalline salts with different counterparts with which it comes into contact. Thus, in the reaction chamber 1,...

Silicones which possess, amongst others, remarkable mechanical properties, thermal stability over a wide range of temperatures and processability, and rare earth oxides (REO), known for their unique optic, magnetic and catalytic properties can be coupled into multifunctional composite materials (S-REOs). In addition, the intrinsic hydrophobicity of...

The asymmetric units of the title compounds, namely, catena-poly[[(1,4,8,11-tetra­aza­cyclo­tetra­decane-κ⁴N¹,N⁴,N⁸,N¹¹)nickel(II)]-μ-1,3-bis­(3-carboxyl­ato­prop­yl)tetra­methyl­disiloxane-κ²O:O′], [Ni(C10H24O5Si2)(C12H24N4)]n (I), and catena-poly[[[(1,4,8,11-tetra­aza­cyclo­tetra­decane-κ⁴N¹,N⁴,N⁸,N¹¹)nickel(II)]-μ-4-({[(3-carb­oxy­prop­yl)di­met...

Pairs of different substituted 3-mercapto-1,2,4-triazole units are coupled, through thioether bridges, to organic-inorganic substrates consisting in short hydrophobic silicone segment. A library of six compounds are isolated as crystalline solids and structurally characterized by X-ray single crystal diffraction, elemental, spectral and thermal ana...

A polydimethylsiloxane-α,ω-diol (UHMW-PDMS) with unusually high molecular weight (Mw = 1,395,000 g/mol) and narrow polydispersity (PDI = 1.49), free of monomer or catalyst traces, was obtained in high yield by a scalable process, easy to achieve (bulk anionic ring-opening polymerization of octamethylcyclotetrasiloxane catalyzed by tetramethylammoni...

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...

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...

Dielectric elastomer transducers (DETs) consisting of thin elastomeric membranes trapped between two electrodes are emerging technology for electromechanical soft actuators, sensors and energy harvesters. Among the current challenges in DE actuators are the reduction of driving voltage by acting on the mechanical and dielectric properties of the 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...

Three dimanganese(III) complexes have been synthesised and fully characterised by standard spectroscopic methods and spectroelectrochemistry. Each Mn(III) ion is chelated by a salen type ligand (H2L), but there is variation in the bridging group: LMn(OOCCH=CHCOO)MnL, LMn(OOCC6H4COO)MnL, and LMn(OOCC6H4C6H4COO)MnL. X-ray diffraction revealed an axia...

New Schiff base-type products starting from 1-(3-aminopropyl)silatrane and three derivatives of salicylaldehyde having as substituents 3,5-dichloro- (1), 3-methoxy- (2) and 3,5-di-tert-butyl- (3), respectively were obtained and isolated with high yields (78-87%) in pure, crystalline forms and their structures were established by different methods....

Due to their high stability over a wide range of temperature or moisture, silicone-based dielectric elastomer transducers (DETs) are of great scientific interest. In this regard, highly stretchable silicone elastomer films were prepared on the basis of a high molecular weight (Mn = 380,000 gmol⁻¹) polydimethylsiloxane‑α,ω‑diol (PDMS) and stabilized...

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...

Two metallo-supramolecular polymers {[Zn2(L)4(DMF)2]·0.8DMF}n (1) and {[Mn2L2(DMSO)4]·2DMSO}n (2) (H2L = bis(p-carboxyphenyl)diphenylsilane) have been synthetized by the reaction of Zn(NO3)2·6H2O and Mn(NO3)2·4H2O respectively, with the above mentioned acid as ligand under solvothermal conditions. Both coordination polymers were structurally charac...

In this paper we describe the synthesis and characterization of three metal complexes, namely CuL(Id3c), NiL(Id4c) and MnL(Id6c), obtained from a Schiff base ligand containing a flexible tetramethyldisiloxane group. The molecular structures of the metal complexes are determined by X-ray single-crystal diffraction analysis, FT-IR and UV–vis spectros...

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...

A new bis(µ-chlorido) bridged cobalt(II) complex [Co2(µ-Cl)2(HL2)4][CoCl4] (1), where HL2 is a silyl-containing Schiff base, was synthesised. The structure of this compound was established by X-ray crystallography revealing a zwitterionic form adopted by the organic ligand. The temperature dependence of magnetic susceptibility and field dependence...

Dielectric elastomer transducers (DET's) essentially consisting in highly deformable insulating films sandwiched between electrodes are able to convert mechanical work in electrical energy and vice-versa. Although still immature, these represent a simple and low-cost alternative to already known technologies for harvesting energy from renewable sou...

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 new high-spin d4 trigonal-bipyramidal (TBP) manganese(III) complex with a salen type ligand (H2L), namely MnL(NCS)·0.4H2O, has been synthesised and characterised by elemental analysis, ESI mass spectrometry, IR und UV‒vis spectroscopies and spectroelectrochemistry. X-ray diffraction revealed an axial compression of the TBP. Temperature dependent...

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...

As ribonucleotide reductase (RNR) plays a crucial role in nucleic acid metabolism, it is an important target for anticancer therapy. The thiosemicarbazone Triapine is an efficient R2 inhibitor, which has entered ∼20 clinical trials. Thiosemicarbazones are supposed to exert their biological effects through effectively binding transition-metal ions....

A hydrophobic filler with the siloxane skeleton, fluorinated polyhedral oligomeric silsesquioxane (F-POSS), was incorporated in varying percentages (2.5, 5, and 10 wt%) in a polydimethylsiloxane-α,ω-diol (PDMS) of molecular weight 230,000 g/mol, in solution. Some structural characteristics and properties derived from F-POSS (low polarizability, wea...

A new class of elastomers that shows simultaneously sensing, actuation and energy conversion functionalities is created to meet the current requirements for electroactive materials. These new materials consist of a silicone network (polydimethylsiloxane-α,ω-diol crosslinked through chain ends) semi-interpenetrated with different percentages (2, 5,...