1D Polymeric Structure Research Articles

Spodium bonds and metal–halogen···halogen–metal interactions in propagation of monomeric units to dimeric or polymeric architectures

In this work we report on crystal structures of a heteroleptic coordination polymer [Hg2(HL)Cl4]n (1) where the nitrogen atom of the peripheral pyridine fragment is linked to another HgCl2 molecule and two discrete mononuclear heteroleptic complexes [Hg(HL)I2] (2) and [Mn(HL)Cl2]·MeOH (3·MeOH), which were obtained through self-assembling of N'-(1-(pyridin-2-yl)ethylidene)isonicotinohydrazide (HL) with HgCl2, HgI2 or MnCl2, respectively. HL coordinates the HgII salts in its keto-form, while MnCl2 is chelated by a zwitterionic form of HL confirmed by the solid state IR spectroscopy. The studied here ligand molecule has a tendency to involve the 4-pyridyl nitrogen atom in coordination bonding which is correlated with the ability to transfer the electric charge and production of a zwitterionic form. The crystal structure and Hirshfeld surface data analysis show a great importance of spodium bonds and metal–halogen⋯halogen–metal interactions. A prominent consequence of lack of σ- or π-hole interactions in case of MnII ion is the isolation of metal center from the external contacts. Apart form this in 3·MeOH the halogen⋯halogen interactions are absent. It seems that the σ- or π-hole regions formed at the HgII cation in 1 and 2 favor the participation of coordinated Cl or I atoms in the M–Hal⋯Hal'–M' halogen⋯halogen interactions, whereas in complex 3·MeOH there are no metal or halogen centered σ-hole interactions. Thus, the 1D coordination polymer in 1 is stabilized by the Hg⋯Cl spodium bonding. Additionally, the observed intermolecular halogen⋯halogen interactions in 1 provide cross-linking of the 1D coordination polymers, yielding a 2D supramolecular double-layered sheet. In 2 an additional contact between halogen and mercury atoms results in a dimeric unit. These dimers are linked into a 1D polymer by halogen⋯halogen interactions between metal bounded iodine atoms. The DFT theoretical studies were applied to analyze the Hg⋯X non-covalent spodium interactions that govern the formation of the 1D polymeric structure in 1 and self-assembled dimers in 2.

Effect of electron-withdrawing fluorine and cyano substituents on photovoltaic properties of two-dimensional quinoxaline-based polymers

In this study, strong electron-withdrawing fluorine (F) and cyano (CN) substituents are selectively incorporated into the quinoxaline unit of two-dimensional (2D) D–A-type polymers to investigate their effects on the photovoltaic properties of the polymers. To construct the 2D polymeric structure, electron-donating benzodithiophene and methoxy-substituted triphenylamine are directly linked to the horizontal and vertical directions of the quinoxaline acceptor, respectively. After analyzing the structural, optical, and electrochemical properties of the resultant F- and CN-substituted polymers, labeled as PBCl-MTQF and PBCl-MTQCN, respectively, inverted-type polymer solar cells with a non-fullerene Y6 acceptor are fabricated to investigate the photovoltaic performances of the polymers. It is discovered that the maximum power conversion efficiency of PBCl-MTQF is 7.48%, whereas that of PBCl-MTQCN is limited to 3.52%. This significantly reduced PCE of the device based on PBCl-MTQCN is ascribed to the formation of irregular, large aggregates in the active layer, which can readily aggravate the charge recombination and charge transport kinetics of the device. Therefore, the photovoltaic performance of 2D quinoxaline-based D–A-type polymers is significantly affected by the type of electron-withdrawing substituent.

A new guaninate hydrate K+·C5H4N5O−·H2O: crystal structure from 100 to 300 K in a comparison with 2Na+·C5H3N5O2−·7H2O

A new guanine salt hydrate, K+·C5H4N5O−·H2O, was obtained and characterized by single-crystal X-ray diffraction in the temperature range 100 K–300 K and compared with that of the previously documented sodium salt hydrate (2Na+·C5H3N5O2−·7H2O) [Gur & Shimon (2015). Acta Cryst. E71, 281–283; Gaydamaka et al. (2019). CrystEngComm, 21, 4484–4492]. Both sodium and potassium salt hydrates have channels. However, the structure of the channels, the cation coordination, the protonation (and, respectively, the charge) of the guanine anions, as well as the role of water molecules in the crystal structure are different for the two salt hydrates. In the crystal structures of the potassium salt, the guanine anions are linked via hydrogen bonds into quartets that form open cylindrical channels in a honeycomb framework. Water molecules `line the walls' of the channels, whereas the potassium cations fill the intra-channel space. This contrasts with the structure of the sodium salt hydrate in which guanine anions form channels with water molecules filling in the channel space together with sodium cations coordinating them. The 1D anionic assembly generated through numerous hydrogen bonds and cation interactions with guanine anions and water molecules is energetically the most distinctive part of the structure of the potassium salt hydrate. In the case of the guanine sodium salt, the structure contains purely inorganic polymeric fragments – sodium cations coordinated to a water molecule forming a 1D polymeric structure and guanine anions interconnecting these polymers via hydrogen bonds with water molecules. The structural differences account for the difference in the anisotropy of strain on temperature variation for the two salt hydrates: whereas in both structures the values of the bulk thermal expansion coefficients are similar in the two structures and the major expansion is observed along the channel axes, the degree of anisotropy for the K salt is more than four times higher than that for the Na salt.

Mn(II), Co(II), Ni(II) and Zn salicylates: Synthesis, structure and biological properties studies

Reaction of acetylsalicylic acid (aspirin) (H2L) with Mn(II), Co(II), Ni(II) and Zn acetates allow to obtain salicylates of related metals. The solid-state structures of prepared complexes were determined by single crystal X-ray crystallography and spectroscopic techniques. Zinc, nickel and cobalt(II) complexes are mononuclear and their crystal structures composed of neutral discrete molecules [Zn(sal)2(H2O)2], [Ni(sal)2(H2O)4] and [Co(sal)2(H2O)4] while manganese derivative has 2D polymeric structure. The cardiorespiratory and skin microcirculation activity of these metal complexes was evaluated. Particularly, the promising therapeutic activities displayed by 1–4 complexes make them potential candidates for the development of a promising drugs.

Printing and characterization of three‐dimensional high‐loaded nanocomposites structures

This study demonstrates the feasibility of fabricating by additive manufacturing composite objects based on acrylic hybrid photocurable formulations, containing 45% by weight of silica nanoparticles, with an average size of about 30 nm. A commercial stereolithography apparatus was used to selectively cure, layer by layer, the high-loaded acrylic resin. The presence of the filler determines an increase in the physical and mechanical properties of the samples that become significantly stiffer and stronger than the pristine matrix. Dynamic mechanical analysis performed on the printed samples gave promising results for the use of developed formulation in the realization of three-dimensional (3D) polymeric structures with improved mechanical properties.

Fused hexacyclic organotin(IV) compounds derived from 3-[((2-hydroxynaphthalen-1-yl)methylene)amino]naphthalen-2-ol

The ligand E-3-[((2-hydroxynaphthalen-1-yl)methylene)amino]naphthalen-2-ol (H2L) and its organotin(IV) complexes (Me)2Sn(H2L) (1a), (n-Bu)2Sn(H2L) (1b), (Ph)2Sn(H2L) (1c), (n-Oct)2Sn(H2L) (1d), (Cy)2Sn(H2L) (1e), and (Me3SiCH2)2Sn(H2L) (1f)] have been synthesized in one pot by multicomponent reactions in moderate yields from 2‑hydroxy-1-naphthaldehyde, 3-amino-2-naphthol and the corresponding diorganotin(IV) oxide. The complexes were characterized by common spectroscopic techniques such as FT-IR, UV–vis, mass spectrometry and NMR (1H, 13C and 119Sn) spectroscopy analysis. 119Sn NMR spectra showed signals between δ = - 143 to -323 ppm for all compounds, indicating the pentacoordination of the tin atoms in solution. Single X-ray structure of complex 1a show a distorted octahedral geometry for tin atoms because of the presence of intermolecular Sn•••O interactions. 1D polymeric structures are formed by CH•••O and CH•••π interactions in solid state.

A One‐Dimensional Cadmium Coordination Polymer: Synthesis, Structure, and Application as Luminescent Sensor for Cu2+ and CrO42−/Cr2O72− Ions

AbstractA novel coordination polymer {[Cd4(CPIP)3Cl8]}n (CP1) was constructed from the reaction of CPIP (CPIP=1‐chloro‐3‐(pyridine‐2‐yl)imidazo[1,5‐a]pyridine) and CdCl2⋅2.5H2O under solvothermal conditions. The employment of CPIP as the ligand was based on the consideration that two types of Lewis basic sites (the fused nitrogen atom and the chlorine substituent) are present on the backbone of the ligand. These sites can be utilized for interacting with cations and anions, thus for the sensing functionality. Single‐crystal X‐ray diffraction studies revealed that CP1 exhibits interesting one‐dimensional (1D) polymeric chain structure. The adjacent four CdII ions are connected by one μ3‐Cl and five μ2‐Cl atoms to form a Chinese‐lantern‐like topology. CP1 is an excellent luminescent sensor for detecting Cu2+, CrO42− and Cr2O72− ions with high selectivity, sensitivity, and recyclability. Moreover, CP1 is the first reported chloride‐bridged coordination polymer that is capable of sensing Cu2+ ion. The mechanisms for sensing Cu2+, CrO42− and Cr2O72− ions were investigated and discussed.

A simple method to align cells on 3D hydrogels using 3D printed molds

Vascular smooth muscle cells align circumferentially around the vessel lumen, which allows these cells to control vascular tone by contracting and relaxing. It is essential that this circumferential alignment is recapitulated in tissue engineered blood vessels. While many methods have been reported to align cells on 2D polymeric substrates, few techniques enable cell alignment on a 3D physiologically relevant hydrogel substrate. We hypothesized that the ridges inherent to the sides of fused deposition modeling 3D printed molds could be used to topographically pattern both stiff and soft substrates and thereby align cells on flat and curved surfaces. Flat and curved molds with 150, 250, and 350 µm ridges were 3D printed and used to topographically pattern polydimethylsiloxane and gelatin-methacryloyl. The ridges transferred to both substrates with less than 10% change in ridge size. Vascular smooth muscle cells were then seeded on each substrate, and nuclear and actin alignment were quantified. Cells were highly aligned with the molded ridges to a similar extent on both the stiffer polydimethylsiloxane and the softer gelatin-methacryloyl substrates. These data confirm that fused deposition modeling 3D printed molds are a rapid, cost-effective way to topographically pattern stiff and soft substrates in varied 3D shapes. This method will enable investigators to align cells on 3D polymeric and hydrogel structures for tissue engineering and other applications.

New Solids in As-O-Mo, As(P)-O-Mo(W) and As(P)-O-Nb(W) Systems That Exhibit Nonlinear Optical Properties.

Interactions between well-mixed fine powders of As2O3, P2O5, MoO3, WO3 and Nb2O5 at different stoichiometry in quartz ampoules under vacuum at ~1000 °C in the presence of metallic molybdenum (or niobium), over several weeks, led to shiny dichroic crystalline materials being formed in cooler parts of the reaction vessel. An addition of small quantities of metals-Mo or Nb-was made with the aim of partially reducing their highly oxidized Mo(VI), W(VI) or Nb(V) species to corresponding Mo(V), W(V) and Nb(IV) centers, in order to form mixed valence solids. Sublimed crystals of four new compounds were investigated using a variety of techniques, with prime emphasis on the X-ray analysis, followed by spectroscopy (diffusion reflectance, IR, Raman and EPR), second harmonic generation (SHG), thermal analysis under N2 and air atmosphere, and single crystals electrical conductivity studies. The results evidenced the formation of new complex solids of previously unknown compositions and structures. Three out of four compounds crystallized in non-centrosymmetric space groups and represent layered 2D polymeric puckered structures that being stacked on each other form 3D lattices. All new solids exhibit strong second-harmonic-generation (SHG effect; based on YAG 1064 nm tests with detection of 532 nm photons), and a rare photosalient effect when crystals physically move in the laser beam. Single crystals’ electrical conductivity of the four new synthesized compounds was measured, and the results showed their semiconductor behavior. Values of band gaps of these new solids were determined using diffusion reflectance spectroscopy in the visible region. Aspects of new solids’ practical usefulness are discussed.

The mechanical and catalytic behavior of nanoporous copper film on octet-truss lattice via magnetron sputtering

A hierarchical structure featuring both nano- and macro- structure has emerged as prospective candidates for the application requiring high flow rates and specific surface area. A unique physical and mechanical behavior could be discovered by designing a special structure. A random orientated nanoporous copper thin film coated on a three-dimensional (3D) microporous periodical octet-truss lattice was utilized as a hierarchical structure to evaluate the mechanical and catalytic behaviors. Nanoporous copper films with ligament size ranging from 16 to 28 nm were synthesized using magnetron co-sputtering CuAl alloy films and subsequent dealloying process, while the octet-truss with a pore size of 120 μm was fabricated by digital light processing. The yield strengths of the octet-truss lattice with nanoporous Cu (L-NPC) films are 3 times higher than those of low-density bulk Cu or Cu films predicted by the Gibson-Ashby equation. The current densities and electrochemical surface area of the l-NPC films are also 10 times higher than those of octet-truss lattice with solid Cu films or NPC films coating on a two-dimensional substrate. In addition to the nano-scale pore size effect, the 3D polymer structure produced a high curly surface for NPC films to attach on the truss which could be the reason for the different mechanical and electrochemical behaviors.

Effect of Synthesis Conditions on the Composition and Structure of Chromium(III) Complexes with Cyclobutane-1,1-Dicarboxylic Acid Anions

The reaction of Cr(NO3)3·9H2O with potassium cyclobutane-1,1-dicarboxylate (K2(Cbdc)) in 1 : 3 ratio was studied. It was shown that, depending on the reaction conditions and the solvents used for synthesis and crystallization, compounds of various compositions and structures can be isolated from the reaction system. Conducting the reaction in water followed by recrystallization from ethanol and methanol results in isolation of 2D polymeric complexes [KCr(Cbdc)2(H2O)2]n (I) and {[K4Cr2(OMe)2(Cbdc)4(MeOH)6]· MeOH}n (II), respectively. The addition of excess KOH to the same reaction mixture and recrystallization from alcohols gives rise to the crystals of 3D polymeric compound [K3Cr(Cbdc)3(H2O)2]n (III). Conducting the reaction in methanol followed by slow diffusion of diethyl ether affords complex [K3Cr(Cbdc)3(MeOH)2(H2O)2]n (IV) with a 2D polymeric structure. The crystal structures of compounds I–IV were determined by X-ray diffraction (CIF files CCDC nos. 2006090 (I), 2006109 (II), 2006116 (III), and 2 006 117 (IV)).

3D printing of inherently nanoporous polymers via polymerization-induced phase separation

3D printing offers enormous flexibility in fabrication of polymer objects with complex geometries. However, it is not suitable for fabricating large polymer structures with geometrical features at the sub-micrometer scale. Porous structure at the sub-micrometer scale can render macroscopic objects with unique properties, including similarities with biological interfaces, permeability and extremely large surface area, imperative inter alia for adsorption, separation, sensing or biomedical applications. Here, we introduce a method combining advantages of 3D printing via digital light processing and polymerization-induced phase separation, which enables formation of 3D polymer structures of digitally defined macroscopic geometry with controllable inherent porosity at the sub-micrometer scale. We demonstrate the possibility to create 3D polymer structures of highly complex geometries and spatially controlled pore sizes from 10 nm to 1000 µm. Produced hierarchical polymers combining nanoporosity with micrometer-sized pores demonstrate improved adsorption performance due to better pore accessibility and favored cell adhesion and growth for 3D cell culture due to surface porosity. This method extends the scope of applications of 3D printing to hierarchical inherently porous 3D objects combining structural features ranging from 10 nm up to cm, making them available for a wide variety of applications.

3D nonlinear photolithography of Tin oxide ceramics via femtosecond laser

As a wide band gap semiconductor material, tin oxide (SnO2) has been widely used in gas sensing, optoelectronics and catalysis. The complex micro and nanoscale three-dimensional (3D) geometric structures endow the conventional SnO2 ceramics with novel properties and functionalities. Nevertheless, ceramics cannot be cast or machined easily due to their high mechanical toughness and resistance. The additive manufacturing opens a great opportunity for flexibly geometrical shaping, while the arbitrary shaping of SnO2 ceramics at micro and nanoscale is always a challenge. Herein, preceramic monomers which can be polymerized under ultrafast laser irradiation, were utilized to form complex and arbitrary 3D preceramic polymer structures. After calcination treatment, these green-body structures could be converted into pure high-dense SnO2 ceramics with uniform shrinkage, and the feature size was down to submicron. Transmission electron microscopy (TEM) analysis displays that the printed SnO2 ceramic nanostructures can be nanocrystallized with grain sizes of 2.5 ± 0.4 nm. This work provides the possibility of manufacturing 3D SnO2 ceramic nanostructures arbitrarily with sub-100 nm resolution, thus making it promising for the applications of SnO2 in different fields.

Azido derivatives of dinuclear copper(II) and 1D polynuclear nickel(II) complexes containing an unsymmetrical bidentate amine: synthesis, crystalline architecture, and magnetic behavior

Dinuclear copper(II) complex [Cu2(L)2(μ2-1,1-N3)2(N3)2] (1) with double μ1,1-azido bridges and polynuclear nickel(II) complex [Ni(L)(μ2-1,1-N3)(μ2-1,3-N3)]n (2) with alternate double μ1,1-azido and μ1,3-azido bridges [L = 1-amino-2-(dimethylamino)ethane, N 3 − = azide ion] have been synthesized and were characterized by physicochemical and spectroscopic methods. X-ray structural analysis revealed that each Cu(II) center of 1 adopts a distorted square-pyramidal geometry with a CuN5 chromophore ligated through two N atoms of L, two N atoms of double bridging (μ1,1-N3), and one N atom of terminal azide ion. On the other hand, each Ni(II) center around the asymmetric unit of 2 adopts a distorted octahedral geometry with a NiN6 chromophore ligated through two N atoms of L, two N atoms of double μ1,1-N3, and two N atoms of double μ1,3-N3 bridges. The adjacent nickel centers are connected to alternate double μ1,1-N3 and double μ1,3-N3 bridges, affording a one-dimensional (1D) polymeric chain structure. Temperature-dependent magnetic susceptibility measurements evidenced a dominant antiferromagnetic interaction between the metal centers of both complexes 1 and 2.

Structural Diversity in Oxadiazole-Containing Silver Complexes Dependent on the Anions

Two coordination polymers, namely [Ag2(L)(SO3CF3)(H2O)](SO3CF3)•CH2Cl2 (1) and [Ag5(L)4(H2O)2](SbF6)5•5THF (2), were obtained by reacting oxadiazole-containing tri-armed ligand 1,3,5-tri(2-methylthio-1,3,4-oxadiazole-5yl) ben-zene (L) and silver salts in CH2Cl2/THF medium. The two complexes crystallized in the tetragonal space group I41/a and orthorhombic space group Fdd2, respectively. The Single-crystal X-ray diffraction revealed that the two complexes ex-hibit strikingly different 3D polymeric structures, which can be ascribed to the different counter anions. L in compound 1 acted as a hexa-dentate ligand, binding to two types of Ag+ atoms to form a 3D polymeric structure. L in compound 2acted as a hexa- and penta-dentate ligand, binding to three types of Ag+ atoms to form the 3D polymeric structure. The antibacterial activity of the complexes was also investigated.

New 3-D Mn(II) coordination polymer with redox active oxalate linker; an efficient and robust electrocatalyst for oxygen evolution reaction

A novel three dimensional coordination polymer {[Mn(ox)3/2][bap].(H2O)}n, (1) (ox = oxalate, bap = N-benzyl-4-aminopyridinium) is reported in this work as an efficient electrocatalyst for oxygen evolution reaction (OER). 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) based dispersion condition as well as interactions between the adjacent layers of anionic coordination polymer and N-benzyl-4-aminopyridinium were found necessary for the growth and stability of this architecture. Single crystal XRD, IR and elemental analysis confirmed the formation of compound (1). Morphology and thermal stability were evaluated by SEM and TG respectively. Electrochemical studies were carried out in a three-electrode system using 1 coated FTO as a working electrode using 0.1 M KOH solution. The electrochemical investigation showed that 1 produced a current density of 10 mAcm−2 at a relatively low overpotential (η = 404 mV) while a maximum current density of 62 mAcm−2 was achieved. A catalytic onset potential for OER was observed at 1.5 V (vs RHE) and needed overpotential of 258 mV. The catalyst offered a turnover frequency (TOF) of 0.06 s−1 for OER at 404 mV. Long-term stability measurements of 1 were recorded by using chronoamperometry, IR analysis and LS voltammograms for the pristine and post-catalytic 1 coated FTO electrodes that confirmed the durability of the catalyst. The fascinating electrochemical behaviour of 1 toward oxygen evolution reaction can be attributed to its 3D polymeric structure and represents 1 as a robust and efficient catalyst towards OER.

Solvothermal synthesis, crystal structure of a new Ca(II) coordination polymer [CaII(4–ABA)(CH3COO)(H2O)(DMF)]n and its catalytic epoxidation of cyclohexene

A novel 1D-Linear coordination polymer [CaII(4–ABA)(CH3COO)(H2O)(DMF)]n (4-ABA = 4-aminobenzoic acid, DMF= Dimethyl formamide) has been synthesized successfully using DMF as one of the solvent by solvothermal synthesis. A single crystal X-ray studies of [CaII(4–ABA)(CH3COO)(H2O)(DMF)]n complex confirms the octa-coordinated calcium center with 4-ABA, DMF and water. It crystallizes in orthorhombic space group Pnma and has a 1D polymeric ribbon structure containing Ca(II) structure with distorted bicapped trigonal prismatic geometry. The complex was successfully employed as a homogenous catalyst in bicarbonate mediated epoxidation of cyclohexene and the complex was found to be selective in oxidation as only one product was formed i.e. cyclohexene oxide.

Effect of Substituents on the Crystal Structures, Optical Properties, and Catalytic Activity of Homoleptic Zn(II) and Cd(II) β-oxodithioester Complexes.

Five novel zinc(II) and cadmium(II) β-oxodithioester complexes, [Zn(L1)2] (1), [Zn(L2)2]n (2), [Zn(L3)2]n (3) [Cd(L1)2]n (4), [Cd(L2)2]n (5), with β-oxodithioester ligands, where L1 = 3-(methylthio)-1-(thiophen-2-yl)-3-thioxoprop-1-en-1-olate, L2 = 3-(methylthio)-1-(pyridin-3-yl)-3-thioxoprop-1-en-1-olate, and L3 = 3-(methylthio)-1-(pyridin-4-yl)-3-thioxoprop-1-en-1-olate, were synthesized and characterized by elemental analysis, IR, UV-vis, and NMR spectroscopy (1H and 13C{1H}). The solid-state structures of all complexes were ascertained by single-crystal X-ray crystallography. The β-oxodithioester ligands are bonded to Zn(II)/Cd(II) metal ions in an O∧S and N chelating/chelating-bridging fashion leading to the formation of 1D (in 2-4) and 2D (in 5) coordination polymeric structures, but complex 1 was obtained as a discrete tetrahedral molecule. Complex 4 crystallizes in the C2 chiral space group and has been studied using circular dichroism (CD) spectroscopy. The multidimensional assemblies in these complexes are stabilized by many important noncovalent C-H···π (ZnOSC3, chelate), π···π, C-H···π, and H···H interactions. The catalytic activities of 1-5 in reactions involving C-C and C-O bond formation have been studied, and the results indicated that complex 3 can be efficiently utilized as a heterogeneous bifunctional catalyst for the Knoevenagel condensation and multicomponent reactions to develop biologically important organic molecules. The luminescent properties of complexes were also studied. Interestingly, zinc complexes 1-3 showed strong lumniscent emission in the solid state, whereas cadmium complexes 4 and 5 exhibited bright luminescent emission in the solution phase. The semiconducting behavior of the complexes was studied by solid-state diffuse reflectance spectra (DRS), which showed optical band gaps in the range of 2.49-2.62 eV.

In-situ synthesis of 3D printable mono- and Bi-metallic (Cu/Ag) nanoparticles embedded polymeric structures with enhanced electromechanical properties

The interest of additive manufacturing with 3D printing increases day by day, which provides improved mechanical, electrical, magnetic and thermal properties of 3D parts. The production of 3D parts with the stereolithography (SLA) method, which allows it to be produced with high precision, resolution and complex geometries, distinguishes itself from other alternative additive manufacturing methods (FDM. SLS. LOM. LMD etc.). However, studies on the preparation of functional 3D polymer nanocomposites with the SLA method are quite limited. This study aims to produce silver (Ag) and/or copper (Cu) based 3D polymer nanocomposites for enhancing its mechanical strength, thermal stability and electrical conductivity. Mono and bimetallic (Cu/Ag) nanoparticles have been in-situ synthesized by selective irradiation of laser beam method using a commercial SLA device. In this method, metal (Cu/Ag) acrylate containing photocurable resin is not only cured but also leads to thermal decomposition of metal ions into nanoparticles to form functional 3D structures. The mechanical, electrical and thermal properties of polymer nanocomposites are characterized in detail. As a result of the analysis, the nanoparticles, with an average diameter of 25–55 nm, are well dispersed in the polymer matrix without agglomeration. The temperature at which 5% weight loss of Ag and Cu based polymer structures is measured as 179.3 °C while the glass transition temperature is found to be 223.81 °C. Most importantly, the resistance values are significantly decreased from 456.62 GΩ (Gigaohm) to 1.50 GΩ by increasing the amount of Ag addition at 3D polymeric structures. Therefore, this study allows the production of polymer nanocomposites not only in complex structures but also in desired properties especially for electrically conductive materials, capacitors and electronic applications.

High‐Resolution 3D Printed Photonic Waveguide Devices

AbstractPhotonic building blocks fabricated using two‐photon polymerization laser lithography are reported. 3D polymer structures are fabricated using a direct laser writing process with nonlinear two‐photon absorption in photosensitive material. The 3D photonic structures include 3D photonic waveguides, Bragg gratings, and resonators. In particular, high‐quality spiral and air‐bridge waveguides providing 3D light guiding beyond a single plane are demonstrated. Sub‐micrometer features as well as unique coupling interfaces with 1.6 dB coupling losses and large 3 dB bandwidth are also demonstrated. Experimental characterization reveals the good transmission performance of the fabricated photonic devices. In addition, the waveguides are demonstrated to support 30 Gb s−1 NRZ (nonreturn to zero) and 56 Gb s−1 PAM4 (pulse amplitude modulation 4) high‐speed data. Small power penalties of 0.7 dB for NRZ (BER = 10−12) and 1.5 dB for PAM4 (BER = 10−6) are obtained.