Preparation and characterization of silicone rubber through the reaction between γ‐chloropropyl and amino groups with siloxane polyamidoamine dendrimers as cross‐linkers

A novel heat‐curable silicone rubber (MCSR/Si‐PAMAM) was prepared by using siloxane polyamidoamine (Si‐PAMAM) dendrimers as cross‐linkers and polysiloxane containing γ‐chloropropyl groups as gums. The chemical cross‐linking occurs through the reaction between Si‐PAMAM dendrimers and polysiloxane containing γ‐chloropropyl groups. The effect of various amounts of cross‐linkers on mechanical properties of MCSR/Si‐PAMAM was discussed in this paper. MCSR/Si‐PAMAM exhibits favorable mechanical properties with a tensile strength of 10.06 MPa and a tear strength of 47.9 kN/m when the molar ratio r of [N‐H]/[CH₂CH₂CH₂Cl] is 1:1. These excellent mechanical properties can be attributed to the formation of concentrative cross‐linking from Si‐PAMAM dendrimers in the cross‐linking networks, along with the introduction of Si–O–Si units in the internal structure of dendrimers. The introduction of Si–O–Si units reduces the steric hindrance of molecular structure, which facilitates the N–H bonds in the interior layers of dendrimers to react with γ‐chloropropyl groups. In addition, thermogravimetric analysis results indicate that MCSR/Si‐PAMAM is thermally stable even at high temperatures in a nitrogen atmosphere. Differential scanning calorimetry analysis reveals that the glass transition peak of MCSR/Si‐PAMAM is not identified in the temperature range −150 to −30°C, only a melting endothermic peak at −40°C.     

A facile preparation method for synthesis of silica sulfuric acid/poly(o‐methoxyaniline) core–shell nanocomposite

A new nanocomposite of poly(o‐methoxyaniline) (POMA) is introduced by overlayer formation of POMA on silica. The key appealing feature of the synthesis is the role of silica sulfuric acid (SSA) both as solid acid dopant and template in overlayer self‐assembly of POMA on silica surface. Hereon siloxide group (Si―O^?) of silica surface is replaced with dopant anion of SSA (≡Si―O―SO₃^?), which leads to formation of a overlayer of POMA on the silica surface. The composite particles are spherical in the nanoscale range of 50 nm without application of any external template (no‐template synthesis). Nanocomposite was fully characterized by various instrumentation methods: Fourier transform infrared (FT‐IR), ultraviolet–visible (UV–vis), thermogravimetric analysis (TGA), diffrential thermal analysis (DTA), elemental analysis (CHNS), energy dispersive X‐ray (EDX), X‐ray photoelectron spectroscopy (XPS) and X‐ray difraction (XRD). Based on XPS and CHNS results, it is demonstrated that the doping level of POMA is as high as 50% and for the first time the ratio of 4:2:2 is obtained for ―NH― (amine): ―HN^.+― (polarons): ?HN⁺― (bipolarons), respectively. In fact, bipolarons may also coexist with polarons with a 1:1 ratio of them. Moreover, the synthesis benefits from the perspective of green chemistry which is preparation under solid‐state (solvent‐free) condition. Copyright © 2015 John Wiley & Sons, Ltd.     

Application of a bio‐based polyester plasticizer modified by hydrosilicon‐hydrogenation reaction in soft PVC films

A kind of bio‐based plasticizer, poly (hexanediol maleic) (MH), was synthesized using 1,6‐hexalene and maleic acid as raw materials, and it was modified by hydrosilicon‐hydrogenation reaction to improve its plasticizing efficiency. The chemical structure and plasticizing performance of MH and its modification product (MHA) were characterized by Fourier‐transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (¹H‐NMR), X‐ray photoelectron spectroscopy (XPS), and Dynamic mechanical analysis (DMA). It was found that the hydrosilicon‐hydrogenation modification effectively improved the plasticizing efficiency of MH, reflecting on the decreased T_g and the increased elongation at break of PVC blends. The migration resistance of PVC blends was tested and analyzed by solubility parameters, which revealed that the migration stabilities of PVC blends were promoted after modification. It was verified that the hydrogen bonding interaction between the C?O group of plasticizers and α‐hydrogen of PVC exhibited in FTIR analysis was the main reason for the improvement of plasticizer performance of MH. Moreover, a new hydrogen bonding formed between Si? O? Si of MHA and the α‐hydrogen of PVC derived from XPS also caused the further improvement of plasticity for MHA.     

Supramolecular Silicone Elastomers with Healable and Hydrophobic Properties Crosslinked by “Salt‐Forming Vulcanization”

In this article, supramolecular silicone elastomers with self‐healing function were first prepared by simple and controllable “salt‐forming vulcanization” of polyaminopropylmethylsiloxane with acids. Their structures and micrographs were verified by Fourier transform infrared spectra, Small‐angle X‐ray scattering experiments and atomic force microscope. The experimental results showed that the ion‐association complexes were formed during vulcanization, and the obtained elastomers displayed self‐healing and good mechanical properties even if the cross‐linking agent was excessed. The thermogravimetric analysis showed that the elastomers crosslinked by inorganic acid were stable under high temperature. Unexpectedly, bionic structures were observed in the elastomers, which further changed the hydrophobicity of the surfaces of the elastomers physically. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 903–911     

Novel organotin‐containing shell‐cross‐linked knedel and core‐cross‐linked knedel: Synthesis and application in catalysis

A series of novel organotin‐containing core‐cross‐linked knedels and shell‐cross‐linked knedels were first synthesized facilely from poly(styrene)‐b‐poly(acrylate acid) nanoparticles in different selective solvents [Tetrahydrofuran (THF)/H₂O or THF/n‐octane] by using organotin compound 1,3‐dichloro‐tetra‐n‐butyl‐distannoxane as a new cross‐linker. The formation of the 1‐chloro‐3‐carboxylato‐tetra‐n‐butyl‐distannoxane layer in our cross‐linking reaction was supported by Fourier transform infrared (FT‐IR) and inductive coupled plasma emission spectrometer (ICP) analysis of the resulting shell‐cross‐linked knedels and core‐cross‐linked knedels. Transmission electron microscopy (TEM) study showed the spherical morphology and the size of the core‐cross‐linked knedels and shell‐cross‐linked knedel. Especially, the layer structure of the core‐cross‐linked knedels was clearly displayed in TEM image. The increase of extent of cross‐linking lead to the increasing of diameter for the shell‐cross‐linked knedels, whereas there was no significant effect on the core‐cross‐linked knedels. Dynamic light scattering (DLS) measurements gave hydrodynamic diameters of the core‐cross‐linked knedels that were in agreement with the TEM diameters. Moreover, the wall thickness of the shell layer of the core‐cross‐linked knedels could be easily modified by varying the block copolymer composition. Notably, the organotin‐containing core‐cross‐linked knedel exhibited highly efficient catalytic activity for the aqueous esterification reaction under nearly neutral conditions. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Cross‐linking induced thermoresponsive hydrogel with light emitting and self‐healing property

Development of self‐healing hydrogels with thermoresponse is very important for artificial smart materials. In this article, the self‐healing hydrogels with reversible thermoresponses were designed through across‐linking‐induced thermoresponse (CIT) mechanism. The hydrogels were prepared from ketone group containing copolymer bearing tetraphenyl ethylene (TPE) and cross‐linked by naphthalene containing acylhydrazide cross‐linker. The mechanical property, light emission, self‐healing, and thermo‐response of the hydrogels were investigated intensively. With regulation of the copolymer composition, the hydrogels showed thermoresponse with the LCST varied from above to below body temperature. At the same time, the hydrogels showed self‐healing property based on the reversible characteristic of the acylhydrazone bond. The hydrogel also showed temperature‐regulated light emission behavior based on AIE property of the TPE unit. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 869–877     

Hydrogen‐bonding‐aided synthesis of novel ladderlike organobridged polysiloxane containing side‐chain naphthyl groups

With a hydrogen‐bonding template, a novel soluble aryl amide‐bridged ladderlike polysiloxane, containing naphthyl as the side‐chain group, has been successfully synthesized via a stepwise coupling polymerization. It is proposed that the monomer, N,N′‐di(3‐naphthyldiethoxylsilyl‐propyl)‐[4,4′‐oxybis(benzyl amide)], prepared by Grignard and hydrosilylation reactions, undergoes self‐assembly first via amido hydrogen bonding and then via hydrolysis, followed by condensation under controlled reaction conditions to yield a high molecular weight, soluble, dark yellow polymer. The analytical results (Fourier transform infrared, ¹H NMR, ²⁹Si NMR, X‐ray diffraction, differential scanning calorimetry, and vapor pressure osmometry) show that the polymer possesses an ordered ladderlike architecture. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 636–644, 2003     

A low‐temperature modification of hexa‐tert‐butyldisilane and a new polymorph of 1,1,2,2‐tetra‐tert‐butyl‐1,2‐diphenyldisilane

Crystals of hexa‐tert‐butyldisilane, C₂₄H₅₄Si₂, undergo a reversible phase transition at 179 (2) K. The space group changes from Ibca (high temperature) to Pbca (low temperature), but the lattice constants a, b and c do not change significantly during the phase transition. The crystallographic twofold axis of the molecule in the high‐temperature phase is replaced by a noncrystallographic twofold axis in the low‐temperature phase. The angle between the two axes is 2.36 (4)°. The centre of the molecule undergoes a translation of 0.123 (1) Å during the phase transition, but the conformation angles of the molecule remain unchanged. Between the two tri‐tert‐butylsilyl subunits there are six short repulsive intramolecular C—H...H—C contacts, with H...H distances between 2.02 and 2.04 Å, resulting in a significant lengthening of the Si—Si and Si—C bonds. The Si—Si bond length is 2.6863 (5) Å and the Si—C bond lengths are between 1.9860 (14) and 1.9933 (14) Å. Torsion angles about the Si—Si and Si—C bonds deviate by approximately 15° from the values expected for staggered conformations due to intramolecular steric H...H repulsions. A new polymorph is reported for the crystal structure of 1,1,2,2‐tetra‐tert‐butyl‐1,2‐diphenyldisilane, C₂₈H₄₆Si₂. It has two independent molecules with rather similar conformations. The Si—Si bond lengths are 2.4869 (8) and 2.4944 (8) Å. The C—Si—Si—C torsion angles deviate by between −3.4 (1) and −18.5 (1)° from the values expected for a staggered conformation. These deviations result from steric interactions. Four Si—C(t‐Bu) bonds are almost staggered, while the other four Si—C(t‐Bu) bonds are intermediate between a staggered and an eclipsed conformation. The latter Si—C(t‐Bu) bonds are about 0.019 (2) Å longer than the staggered Si—C(t‐Bu) bonds.     

Self‐assembled polyurea macromer nanodispersion and resulting hybrid polyurea‐acrylic emulsions and films

A polyurea macromer (PUM) was synthesized and dispersed in basic conditions to form self‐assembled nanoparticles (<20 nm dispersions, up to 30 wt % aq. soln.). These nanoparticles enabled surfactant‐free emulsion polymerization to form hybrid polyurea‐acrylic particles despite the absence of a measureable water‐soluble fraction. The T_g of the starting PUM material was a strong function of the PUM's extent of neutralization and hydration (varying between 100 °C and >175 °C) due to changes in hydrogen and ionic bonding. Two separate hybrid polyurea‐acrylic emulsion systems were prepared: one by direct polymerization of (meth)acrylic monomers in the presence of the nanodispersion and a second by a physical blend of PUM nanodispersion with an acrylic latex control. The direct polymerization method resulted in a hybrid emulsion particle size that developed by a mechanism resembling conventional emulsion polymerization and was unlike that described for seeded polyurethane dispersion systems. Film hardness was shown to increase with increasing coating thickness for the hybrid film prepared by direct polymerization. The resulting mechanical properties could be explained by applying mechanical models for a composite foam structure. These results were unprecedented for normal elastomer films. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1373–1388     

Surface characterization of a cross‐linked cytochrome c film on cysteamine‐modified gold electrodes

The aim of the present paper is to characterize a cross‐linked horse heart cytochrome c (HHC) film on cysteamine‐modified gold electrodes. The HHC film was deposited using 1‐ethyl‐3‐(3‐dimethylaminopropyl)‐carbodiimide (EDC) as a coupling agent. Attenuated total reflection infrared (ATR‐IR) spectroscopic analyses were performed to characterize the newly formed surface on a qualitative and conformational level. The film thickness was measured using a noncontact optical surface profiler, while quantitative data and information on the heterogeneity of the film were obtained by means of synchrotron radiation X‐ray micro fluorescence (SR micro‐XRF). Results indicate that, in addition to electrochemical studies, spectroscopic analysis methods are essential to gain insight in the effect of immobilization strategies on protein conformations. The latter is of relevance in the development and optimization of biosensors. Copyright © 2009 John Wiley & Sons, Ltd.     

Surface oxidation process of a diamond‐like carbon film analyzed by difference X‐ray photoelectron spectroscopy

Difference X‐ray photoelectron spectroscopy (D‐XPS) revealed the surface oxidation process of a diamond‐like carbon (DLC) film. Evaluation of surface functional groups on DLC solely by the C 1s spectrum is difficult because the spectrum is broad and has a secondary asymmetric lineshape. D‐XPS clarified the subtle but critical changes at the DLC surface caused by wet oxidation. The hydroxyl (C―OH) group was dominant at the oxidized surface. Further oxidized carbonyl (C?O) and carboxyl (including carboxylate) (COO) groups were also obtained; however, the oxidation of C?O to COO was suppressed to some extent because the reaction required C―C bond cleavage. Wet oxidation cleaved the aliphatic hydrogenated and non‐hydrogenated sp² carbon bonds (C―H sp² and C―C sp²) to create a pair of C―OH and hydrogenated sp³ carbon (C―H sp³) bonds. The reaction yield for C―H sp² was superior at the surface, suggesting that the DLC film was hydrogen rich at the surface. Oxidation of aromatic sp² rings or polycyclic aromatic hydrocarbons such as nanographite to phenols did not occur because of their resonance stabilization with electron delocalization. Non‐hydrogenated sp³ carbon (C―C sp³) bonds were not affected by oxidation, suggesting that these bonds are chemically inert. Copyright © 2014 John Wiley & Sons, Ltd.     

N,N′‐Dicyclohexyl‐N‐[4‐(1H‐indol‐3‐yl)butanoyl]urea

The title compound, C₂₅H₃₅N₃O₂, is a novel urea derivative. Pairs of intermolecular N—H...O hydrogen bonds join the molecules into centrosymmetric R₂²(12) and R₂²(18) dimeric rings, which are alternately linked into one‐dimensional polymeric chains along the [010] direction. The parallel chains are connected via C—H...O hydrogen bonds to generate a two‐dimensional framework structure parallel to the (001) plane. The title compound was also modelled by solid‐state density functional theory (DFT) calculations. A comparison of the molecular conformation and hydrogen‐bond geometry obtained from the X‐ray structure analysis and the theoretical study clearly indicates that the DFT calculation agrees closely with the X‐ray structure.     

7‐Cyclopropyl‐2′‐deoxytubercidin: a carbocyclic side‐chain derivative of 7‐deaza‐2′‐deoxyadenosine

The title compound {systematic name: 4‐amino‐5‐cyclopropyl‐7‐(2‐deoxy‐β‐D‐erythro‐pentofuranosyl)‐7H‐pyrrolo[2,3‐d]pyrimidine}, C₁₄H₁₈N₄O₃, exhibits an anti glycosylic bond conformation, with the torsion angle χ = −108.7 (2)°. The furanose group shows a twisted C1′‐exo sugar pucker (S‐type), with P = 120.0 (2)° and τ_m = 40.4 (1)°. The orientation of the exocyclic C4′—C5′ bond is ‐ap (trans), with the torsion angle γ = −167.1 (2)°. The cyclopropyl substituent points away from the nucleobase (anti orientation). Within the three‐dimensional extended crystal structure, the individual molecules are stacked and arranged into layers, which are highly ordered and stabilized by hydrogen bonding. The O atom of the exocyclic 5′‐hydroxy group of the sugar residue acts as an acceptor, forming a bifurcated hydrogen bond to the amino groups of two different neighbouring molecules. By this means, four neighbouring molecules form a rhomboidal arrangement of two bifurcated hydrogen bonds involving two amino groups and two O5′ atoms of the sugar residues.     

Self‐assembling directed synthesis of a novel terephthalamide‐bridged ladderlike polysiloxane

A novel, soluble terephthalamide‐bridged ladderlike polysiloxane ( L ) was synthesized successfully for the first time by stepwise coupling polymerization. The process involved the hydrogen‐bonding self‐assembly of amido groups, which resulted in the formation of a more highly ordered polymeric structure. A novel monomer, bis(3‐methyldimethoxysilylpropyl) terephthalamide ( M ), was prepared by a hydrosilylation reaction in the presence of dicyclopentadienyl platinum dichloride as a catalyst. The structures of the monomer ( M ) and the polymer ( L ) were characterized by Fourier transform infrared, ¹H NMR, ¹³C NMR, ²⁹Si NMR, mass spectrometry, X‐ray diffraction, differential scanning calorimetry, and vapor pressure osmometry. All the characterization data indicated that the synthesized polymer ( L ) possessed an ordered ladderlike structure. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3161–3170, 2002     

Synthesis of spiro[indoline‐3,3′‐pyrrolizines] by 1,3‐dipolar reactions between isatins,l‐proline and electron‐deficient alkenes

Two spiro[indoline‐3,3′‐pyrrolizine] derivatives have been synthesized in good yield with high regio‐ and stereospecificity using one‐pot reactions between readily available starting materials, namely l ‐proline, substituted 1H‐indole‐2,3‐diones and electron‐deficient alkenes. The products have been fully characterized by elemental analysis, IR and NMR spectroscopy, mass spectrometry and crystal structure analysis. In (1′RS ,2′RS ,3SR ,7a′SR )‐2′‐benzoyl‐1‐hexyl‐2‐oxo‐1′,2′,5′,6′,7′,7a′‐hexahydrospiro[indoline‐3,3′‐pyrrolizine]‐1′‐carboxylic acid, C₂₈H₃₂N₂O₄, (I), the unsubstituted pyrrole ring and the reduced spiro‐fused pyrrole ring adopt half‐chair and envelope conformations, respectively, while in (1′RS ,2′RS ,3SR ,7a′SR )‐1′,2′‐bis(4‐chlorobenzoyl)‐5,7‐dichloro‐2‐oxo‐1′,2′,5′,6′,7′,7a′‐hexahydrospiro[indoline‐3,3′‐pyrrolizine], which crystallizes as a partial dichloromethane solvate, C₂₈H₂₀Cl₄N₂O₃·0.981CH₂Cl₂, (II), where the solvent component is disordered over three sets of atomic sites, these two rings adopt envelope and half‐chair conformations, respectively. Molecules of (I) are linked by an O—H…·O hydrogen bond to form cyclic R ₆⁶(48) hexamers of (S ₆) symmetry, which are further linked by two C—H…O hydrogen bonds to form a three‐dimensional framework structure. In compound (II), inversion‐related pairs of N—H…O hydrogen bonds link the spiro[indoline‐3,3′‐pyrrolizine] molecules into simple R ₂²(8) dimers.     

A new three‐dimensional zinc(II) coordination polymer involving 2‐[(1H‐1,2,4‐triazol‐1‐yl)methyl]‐1H‐benzimidazole and benzene‐1,4‐dicarboxylate ligands

Metal–organic frameworks (MOFs) based on multidentate N‐heterocyclic ligands involving imidazole, triazole, tetrazole, benzimidazole, benzotriazole or pyridine present intriguing molecular topologies and have potential applications in ion exchange, magnetism, gas sorption and storage, catalysis, optics and biomedicine. The 2‐[(1H‐1,2,4‐triazol‐1‐yl)methyl]‐1H‐benzimidazole (tmb) ligand has four potential N‐atom donors and can act in monodentate, chelating, bridging and tridentate coordination modes in the construction of complexes, and can also act as both a hydrogen‐bond donor and acceptor. In addition, the tmb ligand can adopt different coordination conformations, resulting in complexes with helical structures due to the presence of the flexible methylene spacer. A new three‐dimensional coordination polymer, poly[[bis(μ₂‐benzene‐1,4‐dicarboxylato)‐κ⁴O¹,O^1′:O⁴,O^4′;κ²O¹:O⁴‐bis{μ₂‐2‐[(1H‐1,2,4‐triazol‐1‐yl)methyl‐κN⁴]‐1H‐benzimidazole‐κN³}dizinc(II)] trihydrate], {[Zn(C₈H₄O₄)(C₁₀H₉N₅)]·1.5H₂O}_n, has been synthesized by the reaction of ZnCl₂ with tmb and benzene‐1,4‐dicarboxylic acid (H₂bdic) under solvothermal conditions. There are two crystallographically distinct bdic²⁻ ligands [bdic²⁻(A) and bdic²⁻(B)] in the structure which adopt different coordination modes. The Zn^II ions are bridged by tmb ligands, leading to one‐dimensional helical chains with different handedness, and adjacent helices are linked by bdic²⁻(A) ligands, forming a two‐dimensional network structure. The two‐dimensional layers are further connected by bdic²⁻(B) ligands, resulting in a three‐dimensional framework with the topological notation 6⁶. The IR spectra and thermogravimetric curves are consistent with the results of the X‐ray crystal structure analysis and the title polymer exhibits good fluorescence in the solid state at room temperature.     

A two‐dimensional copper(II) coordination polymer based on 2‐propyl‐1H‐imidazole‐4,5‐dicarboxylic acid

Single‐crystal X‐ray diffraction analysis of poly[bis(μ₂‐5‐carboxy‐2‐propyl‐1H‐imidazole‐4‐carboxylato‐κ³N³,O⁴:O⁵)copper(II)], [Cu(C₈H₉N₂O₄)₂)]_n, indicates that one carboxylic acid group of the 2‐propyl‐1H‐imidazole‐4,5‐dicarboxylic acid (H₃PDI) ligand is deprotonated. The resulting H₂PDI⁻ anion, acting as a bridge, connects the Cu^II cations to form a two‐dimensional (4,4)‐connected layer. Adjacent layers are further linked through interlayer hydrogen‐bond interactions, resulting in a three‐dimensional supramolecular structure.     

Versatile Supramolecular Cross‐Linker: A Rotaxane Cross‐Linker That Directly Endows Vinyl Polymers with Movable Cross‐Links

A supramolecular cross‐linked cross‐linker, capable of introducing rotaxane cross‐links to vinyl polymers, has been developed for the rational synthesis of polyrotaxane networks. The experimental results reveal that the combination of an oligocyclodextrin (OCD) and a terminal bulky group‐tethering macromonomer (TBM) forms a polymer‐network structure having polymerizable moieties through supramolecular cross‐linking. Radical polymerization of a variety of typical vinyl monomers in the presence of the vinylic supramolecular cross‐linker (VSC) afforded the corresponding vinyl polymers cross‐linked through the rotaxane cross‐links (RCP) as transparent stable films in high yields under both photoinitiated and thermal polymerization conditions. A poly(N,N‐dimethylacrylamide)‐based hydrogel synthesized by using VSC, RCP_DMAAm, displayed a unique mechanical property. The small‐angle X‐ray scattering (SAXS) results, indicating patterns characteristic of a polyrotaxane network, clearly suggested the presence and role of the rotaxane cross‐links. The confirmation of the introduction of rotaxane‐cross‐links into vinyl polymers strongly reveals the significant usefulness of VSC.     

Preparation and properties of novel fluorosilicone thermoplastic vulcanizate with cross‐linking–controlled core‐shell structure

A new fluorosilicone thermoplastic vulcanizate (TPV) composed of poly(vinylidene fluoride) (PVDF), silicone rubber (SR), and fluororubber (FKM) was successfully prepared through dynamic vulcanization. The morphological structure of the TPVs had core‐shell elastomer particles dispersed in a continuous PVDF matrix. Furthermore, the cross‐linking of core‐shell structure was controlled by adopting different curing agent. The effect of cross‐linking–controlled core‐shell structure on the morphology, crystallization behavior, stress relaxation test, solvent‐resistant properties of the obtained TPVs were investigated. It was found that the shell cross‐link had a significant influence on the crystallinity of the PVDF phase. The core‐shell bicross‐linked TPV was found to provide the lowest rate of relaxation. An obvious stress softening phenomenon was observed in the uniaxial loading‐unloading cycles in tension. The bicross‐linked TPV had good solvent resistant properties. The tensile strength of the bicross‐linked TPV was still 12 MPa even after immersed in butyl acetate for 48 hours.     

Construction and photoluminescence properties of a three‐dimensional ZnII coordination network based on naphthalene‐1,4‐dicarboxylic acid and 1,6‐bis(pyridin‐3‐yl)‐1,3,5‐hexatriene

In recent years, coordination polymers constructed from multidentate carboxylate and pyridyl ligands have attracted much attention because these ligands can adopt a rich variety of coordination modes and thus lead to the formation of crystalline products with intriguing structures and interesting properties. A new coordination polymer, namely poly[[μ₂‐1,6‐bis(pyridin‐3‐yl)‐1,3,5‐hexatriene‐κ²N:N′](μ₃‐naphthalene‐1,4‐dicarboxylato‐κ⁴O¹,O^1′:O⁴:O^4′)zinc(II)], [Zn(C₁₂H₆O₄)(C₁₆H₁₄N₂)]_n, has been prepared by the self‐assembly of Zn(NO₃)₂·6H₂O, naphthalene‐1,4‐dicarboxylic acid (1,4‐H₂ndc) and 1,6‐bis(pyridin‐3‐yl)‐1,3,5‐hexatriene (3,3′‐bphte) under hydrothermal conditions. The title compound has been structurally characterized by IR spectroscopy, elemental analysis, powder X‐ray diffraction and single‐crystal X‐ray diffraction analysis. Each Zn^II ion is six‐coordinated by four O atoms from three 1,4‐ndc²⁻ ligands and by two N atoms from two 3,3′‐bphte ligands, forming a distorted octahedral ZnO₄N₂ coordination geometry. Pairs of Zn^II ions are linked by 1,4‐ndc²⁻ ligands, leading to the formation of a two‐dimensional square lattice ( sql ) layer extending in the ab plane. In the crystal, adjacent layers are further connected by 3,3′‐bphte bridges, generating a three‐dimensional architecture. From a topological viewpoint, if each dinuclear zinc unit is considered as a 6‐connected node and the 1,4‐ndc²⁻ and 3,3′‐bphte ligands are regarded as linkers, the structure can be simplified as a unique three‐dimensional 6‐connected framework with the point symbol 4⁴6¹⁰8. The thermal stability and solid‐state photoluminescence properties have also been investigated.