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In this paper, a novel fluorescent probe, TPA-PAT, with continuous recognition based on triphenylamine was designed, synthesized, and characterized by NMR, IR, and fluorescence spectrophotometry techniques.

Combining octavinyl-polyhedral oligomeric silsesquioxane (OV-POSS) with amine-containing polyacrylamide (OV-POSS co-poly(acrylamide)) gives a new fluorescent polymeric chemo-sensor with complete water solubility. It shows better selectivity for Fe3+ in water over a wide detection range (pH = 4–10). The incorporation of Fe3+ into OV-POSS co-poly(acrylamide) results in a significant fluorescence enhancement in water over other metal ions. The bound ratio of OV-POSS co-poly(acrylamide)–Fe3+ complex was determined to be 1 : 2 according to the Job's plot. The association constant (Ka) of Fe3+ binding with the chemosensor was 7.416 × 107, and the detection limit was 0.9 × 10−9 M. Moreover, it was found that the system possessed low cytotoxicity, good permeability, high stability, and compatibility. Hence, it can be successfully applied in bio-imaging with bright blue fluorescence. In addition, a visible color change to the naked eye from colorless to bright yellow could be directly observed when Fe3+ was added into the chemosensor OV-POSS co-poly(acrylamide) compared with other metal ions.

A novel multifunctional sensing material, RSPT, incorporating rhodamine B hydrazide, a Schiff base, and a phenolic hydroxyl group into triazine, was identified and prepared. After the molecular structure was characterized by FTIR, 1H NMR, mass spectra and element analysis, it was notably found that there were multichannel turn-on fluorescent responses to Zn2+ and Bi3+, i.e., a strong fluorescence emission at 481 nm in DMF–water (99/1, v/v) for Zn2+ with a color change from colorless to light yellow-green, while an increased fluorescence emission at 580 nm in CH3CN–water (99/1, v/v) for Bi3+ with a color change from colorless to red. Their different action mechanisms for the RSPT–Zn2+ and RSPT–Bi3+ complexes were investigated and confirmed by means of fluorescent titration, binding constant, Job's plot curve, 1H NMR titration, and theoretical simulation. RSPT would be a promising turn-on fluorescent chemo-dosimeter for multichannel detection of Zn2+ and Bi3+ with a detection limit of 3.0 nM for Zn2+ and 8.6 nM for Bi3+.

In this study, novel cellulose/polyvinyl alcohol (PVA) composite hydrogel membranes were prepared by means of immersion-precipitation phase transformation, using the ionic liquid 1-butyl-3-methylimidazolium acetate ([C4mim]+Ac−) as a solvent. The cellulose/PVA composites were characterized by UV-visible light absorption spectroscopy (UV), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), X-ray diffraction measurements (XRD) and scanning electron microscopy (SEM). The results revealed that a novel compact dual-network structure was formed between the cross-linked cellulose network and PVA. With an increase of cellulose in the composites, the tensile strengths of the composite hydrogel membranes were greatly increased as expected. As PVA was added, the swelling and water-absorbing properties of the cellulose/PVA hydrogels were significantly improved. In addition, the possible formation mechanism of the composite hydrogel was also discussed. It is believed that this is an effective method to prepare novel composite hydrogel materials.

A highly flexible, transparent conducting oxide- and Pt-free photo-rechargeable electric energy storage system is demonstrated by integrating a dye-sensitized solar cell and a supercapacitor face-to-face on double-sided uniformly aligned TiO2 nanotube arrays. The energy harvesting part consists of TiO2 nanotubes as the photoanode and CuS networks as the counter electrode, yielding a PCE of 7.73%. Herein, CuS networks exhibited remarkable mechanical flexibility, superior transparency and excellent electronic conductivity, which not only served as conducting films but also as catalysts for dye-sensitized solar cells. The flexible all-solid-state supercapacitors are composed of polyaniline polymerized on TiO2 nanotubes and carbon cloth, which act as the negative and positive electrodes, respectively. The self-powered photo-rechargeable device can be charged to 0.64 V in ∼30 s under standard AM 1.5 (100 mW cm−2) illumination conditions. In particular, the photo-charge and discharge performance remained almost stable under bending tests, which is crucial for applications in wearable and portable electronics.

A series of functional polyacetylenes bearing the fluorene moiety with different conjugated lengths and terminal substituents, poly[2-ethynyl-7-(4-nitrostyryl)-9,9-dioctyl-9H-fluorene] (P1), poly[2-ethynyl-7-(4-(4-nitrostyryl)styryl)-9,9-dioctyl-9H-fluorene] (P2), poly[2-ethynyl-7-(4-(4-methoxystyryl)styryl)-9,9-dioctyl-9H-fluorene] (P3), poly[2-ethynyl-7-(4-(4-methylstyryl)styryl)-9,9-dioctyl-9H-fluorene] (P4), and poly[2-ethynyl-7-(4-(4-methylstyryl)styryl)-9,9-didodecyl-9H-fluorene] (P5), were designed and prepared using [Rh(nbd)Cl]2 as the catalyst. Their structures and properties were characterized and evaluated by FTIR, NMR, UV, FL, GPC and TGA analyses. The optical limiting properties were investigated using 450 fs laser pulses at 780 nm. These results show that the incorporation of styryl/stilbene functionalized polyfluorenylacetylenes has endowed resultant polyacetylenes with novel near-infrared laser protection properties and enhanced thermal stability. The optical limiting mechanism for laser protection was studied. It was found that the optical limiting properties mainly originated from two-photon absorption (TPA) of molecules in the resulting polyacetylenes. Additionally, it was also found that the functionalized polyacetylene with a longer fluorene-based conjugated chromophore and a stronger terminal electron acceptor group exhibits better optical limiting properties because of the larger π-electron delocalization and dipolar effect.

The effect of surface functionalization of carbon materials on the morphology and performance of carbon/polymer composite materials for supercapacitor electrodes was investigated here. Three kinds of functionalized carbon fibers were prepared by the simple chemical modification of carbon fiber, named oxidated carbon fiber (OCF), amino-functionalized carbon fiber (AFCF) and aminated triazine functionalized carbon fiber (ATFCF). Then functionalized carbon fibers were used to fabricate nanostructural polyaniline/CFs composites (PANI/OCF, PANI/AFCF, PANI/ATFCF) by electrochemical in situ polymerization under pulse current. The chemical compositions and morphologies of these PANI/CFs composites were studied by FTIR, Raman spectra and SEM. It was found that PANI on OCF composites displayed a disordered nanofiber structure owing to the non-covalent connection between PANI with OCF. Conversely, PANI grew on the surface of AFCF and ATFCF in an ordered fashion due to chemically covalent connection, exhibiting nanowire arrays and petal-like nanosheets, respectively. It hints that the morphology of PANI/CFs composites can be effectively adjusted by molecular structural design of functional groups on the functionalized CF. The electrochemical properties of these PANI/CF composites were evaluated by an electrochemical workstation. In comparison with noncovalent PANI/OCF composites, the strong covalent interactions together with the ordered nanostructures of PANI/AFCF and PANI/ATFCF facilitated faster charge transfer, smaller internal resistance and better mechanical properties, resulting in improved electrochemical performance.

A series of novel multifunctional polyacetylenes bearing oxadiazole and azo groups as molecular pendants were designed and synthesized via highly effective click chemistry. The resultant polymers showed good solubility in common organic solvents. The structure and properties of the resulting polymer were characterized and evaluated by FT-IR, 1H-NMR, UV-vis, TGA and FL analyses. The results show that the thermal stability of the synthesized functional polyacetylene was significantly increased when compared to single polyacetylene due to the jacket effect between the functional groups and backbone. The influence mechanism of the oxadiazole and azo groups was also discussed in detail. Simultaneously, the optical properties of the functional polyacetylene were investigated. It was found that the optical properties of the resulting polyacetylene were affected by the oxadiazole and azo groups. For P5–P7, the intensity of the absorption peak at ca. 452 nm, belonging to the azo group, decreased gradually as the content of M1 was reduced. In contrast, the intensity of the absorption peak at ca. 312 nm, belonging to the oxadiazole group, increased as the content of M2 increased. Due to azo group isomerization under the photo-thermal conditions, quenching of the fluorescence occurred in the range of molecules for M1, P2 and P3.

A convenient and efficient strategy for preparing active functional hybrid materials was proposed based on an investigation of the controllable preparation of a series of anthracene-containing organic–inorganic functional hybrid materials with active ethylene groups. These functional hybrid materials with different active vinyls were controllably prepared through a Heck reaction with octavinyl-polyhedral oligomeric silsesquioxane (OV-POSS) as the raw material by adjusting the feed ratio. Their structures and properties were characterized and evaluated by various measurements. The influence of molecular structure on the optical properties of the resulting hybrids was investigated in detail. It was found that the incorporation of nano-sized inorganic polyhedral oligomeric silsesquioxane (POSS) can efficiently prevent aggregation of hybrid molecules owing to the prohibition of π–π stacking between chromophore groups, which was also confirmed by theoretical simulation. Simultaneously, thermogravimetric analysis (TGA) results also show that the inorganic POSS causes the good thermal stabilities of the hybrids.

A group of novel polyacetylenes containing BODIPY pendants have been synthesized in satisfactory yield using a [Rh(nbd)Cl]2–Et3N catalyst. The pendant BODIPY unit has been directly conjugated to the polyacetylene backbone either through the 8 position of the BODIPY cores in P1, or through the 3 position in P2 and P3. Their optoelectronic properties have been investigated by UV-vis, FL, CV and Z-scan techniques. Interestingly, the spectroscopy results show that little electronic interaction exists between the BODIPY chromophoric units and the polyacetylene main chain for P1. However, the electronic interaction between the side pendant and the main chain becomes notable for P2 and P3, resulting in a significant broadening and red-shift of their UV-vis absorption and fluorescence emission wavelengths in comparison with those of their respective monomers. The polymers display thermal stabilities and nonlinear optical properties that are dependent on the connectivities of the BODIPY pendants and the polyacetylene backbones. P1 exhibits relatively better thermal stability and poorer nonlinear optical properties than P1 and P2. The third-order nonlinear optical coefficient (χ(3)) of P1 is 8.5 × 10−12 esu, which is shown to be ∼15 times smaller than those of P2 and P3.

The rheological properties of supramolecular soft functional materials are determined by the networks within the materials. This research reveals for the first time that the volume confinement during the formation of supramolecular soft functional materials will exert a significant impact on the rheological properties of the materials. A class of small molecular organogels formed by the gelation of N-lauroyl-L-glutamic acid din-butylamide (GP-1) in ethylene glycol (EG) and propylene glycol (PG) solutions were adopted as model systems for this study. It follows that within a confined space, the elasticity of the gel can be enhanced more than 15 times compared with those under un-restricted conditions. According to our optical microscopy observations and rheological measurements, this drastic enhancement is caused by the structural transition from a multi-domain network system to a single network system once the average size of the fiber network of a given material reaches the lowest dimension of the system. The understanding acquired from this work will provide a novel strategy to manipulate the network structure of soft materials, and exert a direct impact on the micro-engineering of such supramolecular materials in micro and nano scales.

Silk scaffolds having biomimetic hierarchical porous structures were achieved by carefully tuning liquid-liquid separation in regenerated silk fibroin solutions. Such scaffolds show greatly enhanced cellular responses.

A generic and efficient strategy to realize a high effective “intrinsic” single molecular luminescence in the condensed state was proposed by theoretical simulation at the macrostructure level at first, and then was confirmed by molecular design and preparation of a dumbbell-type (H2) and tadpole-type (H1) polyhedral oligomeric silsesquioxane (POSS) based hybrid. The enhancement mechanism of the optical properties was investigated in theory and with experiments. It was found that the incorporation of a “huge” inorganic POSS core on the nanoscale into the organic light-emitting molecules to form three-dimensional (3D) organic–inorganic hybrids effectively improved the optical properties in the condensed matter by decreasing the intermolecular dipole–dipole and π–π stacking interactions owing to the hindrance of the intermolecular charge-transfer between adjacent organic molecules. The dumbbell-type hybrid (H2) showed a better enhancement effect of the optical properties than the resultant tadpole-type hybrid (H1) owing to the crisscross-type arrangement of its dimer induced by the incorporation of POSS. Simultaneously, the two hybrids exhibited high thermal stability and good film forming ability.

Due to the specially rigid, planar and zwitterionic structures, squaraine dyes have strong absorption (e ≥ 105 L mol−1 cm−1) in the visible to near-infrared region. Therefore, squaraine dyes have been extensively investigated from both fundamental and technological viewpoints. To present the readers a better understanding of the important dyes, in this article, we will highlight the recent synthetic developments of squaraine derivatives as a class of functional near infrared absorbing optic materials and their application in the areas of anti-aggregation, sensor, solar cell, nonlinear optics and self-assembly functional materials based on our own work during the recent years.

To further investigate the influence of H-bond combining with π–π stack interaction on the optical performances, a few rigid zwitterionic squaraine molecules, with different terminal H-bond recognition abilities, are identified and designed. They can controllably construct a series of supramolecular self-assemblies with different morphologies and dimensions via a simple solution-based self-assembly method under mild conditions. The morphologies, synergetic reinforcing effect, and optical-thermal properties are investigated and confirmed by both theoretical and experimental methods. The results indicate that the morphologies of the resultant self-assemblies can be effectively controlled by rational molecular design, whose absorption and emission spectra and thermal stabilities accordingly change with the alteration of zwitterionic squaraine molecular structures.

The substituent group and hydrogen bonds play important roles in supramolecular self-assembly. To exploit the influential mechanism of hydrogen bonds during the dipole-dipole induced supramolecular self-assembly, some rigid azobenzene molecules with different electronegativity and hydrogen bonding capabilities were identified and designed. Different regular-shaped architectures were constructed via a simple solution process under mild conditions. Both experimental results and density functional theory calculations show that weak π-π stacking interactions lead to thick and short nanocylinders, strong dipole-dipole interactions and dipole induced π-π stacking lead to long and thin nanorods, appropriate hydrogen bonds consolidate the dipole-dipole interactions and dipole induced π-π stacking, forming thin nanosheets, while excessive hydrogen bonds in azobenzene would ruin the regular-shaped structures, giving irregular and stochastic aggregates. Namely there exists a certain hydrogen bond saturation effect in generating azobenzene nanostructures driven by dipole-dipole interactions. The results indicate that the morphologies of organic materials with azobenzene structures can be effectively controlled through rational molecular design by way of introducing appropriate dipole and hydrogen bonds.

The formation of fiber networks and the resulting rheological properties of supramolecular soft materials are dramatically influenced when the volume of the system is reduced to a threshold. Unlike un-confined systems, the formation of fiber networks under volume confinement is independent of temperature and solute concentration.

A series of oxadiazole-containing molecular hybrid materials with different structures (H1–H5) are controllably prepared by a hydrosilylation method based on the octahydridosilsesquioxane (POSS, T88HH). All these resultant hybrid materials are soluble in common organic solvents, such as chloroform, toluene, tetrahydrofuran, and 1,2-dichloroethane, and possess good film-forming properties. Their structure and properties are characterized and evaluated by FTIR, 1H NMR, 29Si NMR, GPC, TGA, DSC, UV-vis, PL, CV, and elemental analysis, respectively. It is found that the hydrosilylation reaction almost proceeds quantitatively when the feed ratio (molar number of organic monomer to molar number of POSS) is less than 4, at which the resultant hybrids can be controllably prepared by varying the feed ratio. These hybrids possess high thermal stability and good electron injecting properties and an intense blue emission was observed in these hybrids. Simultaneously, it is found that the hybrids (H3–H5) with a strong π electron conjugation effect between POSS and the oxadiazole moiety show higher thermal stability, better electron injecting properties and more intense blue emission than those (H1 and H2) without a π electron conjugation effect between POSS and the oxadiazole moiety.

Four organic–inorganic hybrids were respectively synthesized via hydrosilylative addition reaction between octahydridosilsesquioxane (POSS) and linear dienes with different numbers of methylene groups, and well characterized by FTIR, 13C NMR and 29Si NMR technologies. It is confirmed that the hybrids have well-defined three-dimensional network structures with POSS cages uniformly dispersed in the networks. The four hybrids were then used as templates to produce silica films through an optimized spin-coating and calcination process. N2 sorption–desorption determination reveals that the silica films are nanoporous with a narrow pore distribution. Cross-section HRTEM images of the four films further confirm that the nanosize pores are evenly dispersed. SEM observation shows that the surfaces of the films are smooth and free of cracks or flaws. By altering the number of methylene groups of the dienes linking the POSS cages, pore size and porosity of the porous silica films are easily adjusted. After dehydroxylation treatment with trimethylchlorosilane (TMCS), the porous films show very low dielectric constants, which is closely related to the porosity of the film. This result reveals that the controllable preparation of low dielectric silica films has been achieved in this study.

Molecular design and architecture of four novel organic–inorganic network hybrids were implemented via hydrosilylative addition reaction of octahydridosilsesquioxanes (H8-POSS) with dienes. The structural characterization by the FTIR, 13C MAS NMR and 29Si MAS NMR technologies, respectively, indicates that two monomers are chemically bound to each other to form three-dimensional network hybrids that possess well film-formability. Atomic force microscopy (AFM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) show that no phase separation occurred in the hybrid films, implying that the POSS molecules are uniformly dispersed into the polymeric system at the nanoscale. All POSS-containing well-dispersed hybrid films exhibit a good thermal stability with a decomposition temperature higher than 350 °C, and enhanced mechanical properties of a hardness of 0.21–0.26 GPa and the elastic modulus of 7.67–8.85 GPa, and low dielectric properties with a dielectric constant of 2.43–2.78. Interestingly, these properties can be further tuned by adjusting the length and the structure of the linking chain between POSS cages.

Two novel high molecular weight functional polyacetylenes bearing oxadiazole groups as pendants, poly(2-(4-decyloxyphenyl)-5-(4-ethynylphenyl)-1, 3, 4-oxadiazole) (P1) and poly(2-(4-butyloxyphenyl)-5-(4-ethynylphenyl)-1, 3, 4-oxadiazole) (P2) were designed and synthesized by a multistep reaction route. The structures and properties were characterized and evaluated with FTIR, NMR, UV, TGA, GPC, optical-limiting (OL) and nonlinear optical (NLO) analyses. The incorporation of oxadiazole into polyacetylene significantly endows polyacetylenes with higher thermal stability and optical limiting property. The solubility, stereoregularity and optical properties of resultant polyacetylenes are obviously affected by flexible terminal alkoxy chain length. The cis olefinic structure content in polyacetylene backbone increases with increasing terminal alkoxy group length. The functional polyacetylene with the higher cis olefinic structure content shows higher thermal stability, better optical limiting property and larger third-order nonlinear optical performance. The optical limiting mechanism of resulting polymers was investigated, which is mainly originated from larger excitation state absorption cross-section of molecules to result in reverse saturable absorption.