Fabrication of films with plasmonic nanoparticles (NPs) arrays arranged in chiral configurations of prescribed handedness is highly attractive for the design of new functional materials; however, this remains a formidable challenge in nanotechnology. In this study, we demonstrated the controlled arrangements of gold (Au) NPs into helical structures templated by helical pores created in cross-linked block copolymer (BCP) films. d- and l-tartaric acid (TA) were used to direct the self-assembly of achiral poly(1,4-butadiene)-b-poly(ethylene oxide) BCPs into helical cylindrical morphologies with prescribed handedness, i.e., D or L. Helical pores were generated by BCP cross-linking followed by TA extraction. Helical Au NP arrays, subsequently arranged within the helical pores, exhibited the chiral optical response. The helical structures of NPs arrays and the resulting optical handedness were tunable simply by using either D- or L-porous templates. This simple strategy offers a straightforward pathway for the fabrication of chiral porous BCP films and helical NPs arrays with chiral optical properties.

A self-healing electrically conductive superhydrophobic poly(3,4-ethylenedioxythiophene) (PEDOT) coating has been prepared by chemical vapor deposition of a fluoroalkylsilane (POTS) onto a PEDOT film, which was obtained by electrochemical deposition. The coating not only maintained high conductivity with a low resistivity of 3.2 × 10–4 Ω·m, but also displayed a water contact angle larger than 156° and a sliding angle smaller than 10°. After being etched with O2 plasma, the coating showed an excellent self-healing ability, spontaneously regaining its superhydrophobicity when left under ambient conditions for 20 h. This superhydrophobicity recovery process was found to be humidity-dependent, and could be accelerated and completed within 2 h under a high humidity of 84%. The coating also exhibited good superhydrophobicity recovering ability after being corroded by strong acid solution at pH 1 or strong base solution at pH 14 for 3 h.

Chiral supramolecules prepared by the additive-driven self-assembly of block copolymers provide a facile method to construct helical nanostructures. In this study, we investigated the chiral transfer from chiral tartaric acid to poly(styrene)-b-poly(ethylene oxide) using small-angle X-ray scattering, transmission electron microscopy, circular dichroism, and vibrational circular dichroism. The results showed that the chirality was transferred to both the segments of block copolymer irrespective of the interaction with the chiral additives and formation of helical phase structure. However, the chirality transfer was carried out using different methods: for poly(ethylene oxide) segments, the chirality transfer was carried out via direct hydrogen bond formation; for polystyrene segments, the chirality transfer was carried out via the cooperative motion of block copolymers during the thermal annealing.A facile method to construct helical nanostructures by the additive-driven self-assembly strategy of block copolymers.Download high-res image (138KB)Download full-size image

Azobenzene (azo)-containing polymers have attracted continuous attention due to their excellent photosensitivity. However, practical applications of their photo-induced birefringence have been hampered by low thermal stability. In this work, we report a series of polyimides synthesized by a low-temperature co-polycondensation of azo-containing pyrimidyl diamine, 4,4′-diaminodiphenyl ether, and 4,4′-oxydiphthalic anhydride. The obtained co-polyimides (co-PIs) show good thermal stability, with high glass transition temperatures (Tg) of more than 200 °C and 5% weight loss temperatures (T5%) as high as about 400 °C in nitrogen. Their photo-induced birefringence (Δn) has been determined as 0.013 at room temperature and up to 0.017 at 100 °C. The photo-induced reorientation property of the as-prepared highly thermostable azo-PIs is expected to have wide applications in image recording and electro-optical devices.

The alignment of liquid crystals (LCs) is the key technology in LC displays, molecular switches and optical systems. Azobenzene (azo) molecules are often incorporated into LC alignment polymer films to make them photoresponsive and thereby anisotropic for light induced alignment; however, in most cases azo-containing materials suffer from the limitation of low thermal stability and poor transparency. We adopted a sequential addition method and synthesized sequence-controlled terpolymers with a terminal azo-containing segment via atom transfer radical polymerization. The control of LC alignment could then be realized by annealing-induced surface migration and polarized-light-induced alignment of azo units in the films of these terpolymers. Terpolymers derived from methyl methacrylate, N-p-anisylmaleimide and 6-[4-(4′-methoxyphenylazo)phenoxy]hexylmethacrylate exhibit excellent transparency, thermal properties, as well as a good LC alignment ability. We demonstrate that sequence-controlled polymerization is useful for precisely controlling the location of functional features along the polymer chain, and thus accurately regulating the properties of the copolymer obtained.

In combination with the breath-figure method, an in situ growth approach of polyphosphazenes was performed on a honeycomb surface resulting in a closely packed nanoparticle coating and a micro/nanoscale hierarchical structure. The hierarchically structured surfaces exhibited high biocompatibility, allowed good cellular adhesion and presented strong potential use as a cell scaffold.

Responsive membranes have been used to construct smart biomaterial interfaces. We report a novel approach to fabricate honeycomb films with a pattern of thermoresponsive polymer, namely poly(N-isopropylacrylamide). The approach was based on a combination of the breath figure method and reversible addition–fragmentation chain transfer. The hybrid film had morphological and chemical patterns resulting in varied wettability and morphology at various stages, as well as high thermo-responsiveness. Enhanced cell adhesion was observed at an incubation temperature of 37 °C, which is above its lower critical solution temperature (LCST). Furthermore, cells could be harvested at temperatures below the LCST without trypsin treatment. The non-invasive characteristics give this membrane potential as a substrate for cell sheet engineering.

Inspired by the typically adhesive behaviors of fish skin and Parthenocissus tricuspidata, two different decorations of polystyrene honeycomb membrane (PSHCM) prepared by the breath figure approach were carried out with poly(N-(3-Sulfopropyl)-N-(methacryloxyethyl)-N,N-dimethylammonium betaine)(polySBMA) to explore controllable bioadhesive surfaces. Casting and dip-coating were employed to graft polySBMA onto the plasma treated PSHCM. The polySBMA casted PSHCM showed a uniform covering layer on the PSHCM similar to the mucus layer of fish skin, presenting excellent antifouling properties. On the contrary, a dip-coated one showed the polySBMA aggregating on the honeycomb pore walls forming a large number of sucking disks such as the adhesive disks of the tendrils of P. tricuspidata, which remarkably boosts cell adhesion on substrates. Thus, bioadhesion could be regulated as desired by tuning the distribution of zwitterionic polymer on the honeycomb surface. The results may provide a new approach for the design of biomaterial surfaces.

•Mesoporporus polymer and carbon films were prepared by using airflow method.•The nanochannels in mesoporous polymers and carbon films were strictly arranged along the airflow direction.•The controlling principal can be attributed to the results of shearing force and the rapid evaporation of the solvent.Ordered mesoporous polymers and carbon films with controllable orientation of two-dimensional (2D) cylinders exhibit interesting properties for many applications. However, the preparation of such films is challenging because of inefficient present methods, which are effective for the preparation of mesoporous metal films. Here, a simple and facile method was developed to control the orientation of nanochannels by the airflow method. The nanochannels in mesoporous polymers and carbon films were strictly arranged along the airflow direction as determined by cross-section transmission electron microscopy and grazing-incidence small-angle X-ray scattering results. The orientation degree of the nanochannels was affected by the airflow speed and precursor concentration. The universality of this method in controlling the nanochannel orientation in various mesostructured films was discussed based on the shearing force generated during the interaction between airflow and precursor solution and the rapid evaporation of the solvent.

Two kinds of liquid crystalline (LC) supramolecules with anisotropic fluorescence emission were prepared by ionic self-assembly from a copolymer, derived from acrylic acid and 6-(4′-cyanobiphenyl-4-yloxy)hexyl acrylate, and oppositely charged fluorescent molecules: stilbene-based rod-like dye (Stil) or tetraphenylethene-based propeller-like dye (TPE). The supramolecules exhibited a nematic LC nature and the different structure of the fluorescent units showed different effect on the LC behaviour of the supramolecules. After being spin-coated onto an oriented PVA film, the liquid crystalline supramolecule film was thermally annealed and the anisotropic fluorescence emission was investigated. A different thermal amplification effect was found depending on the different structure of the fluorescent unit. This conclusion provides a new perspective on the design of a high-performance fluorescence polarization film.

A novel photoresponding ionic complex (PANDAZO) was prepared by the ionic self-assembly (ISA) of sodium polyacrylate (PANa) and azobenzene chromophores (NDAZO). The ionic complex forms an interdigitated lamellar structure with full overlap of the side chains. The optical anisotropy was investigated by using a polarization pulse laser (355 nm). Furthermore, a high photoinduced birefringence (Δn = 0.365) was measured by using a continuous 488 nm laser as the pump light.A novel photoresponding ionic complex bearing azobenzene chromophores is prepared. The photoinduced anisotropic properties of the ionic complex are explored. A high birefringence value (0.365) is obtained in the complex film.

A self-healing electrically conductive superhydrophobic poly(3,4-ethylenedioxythiophene) (PEDOT) coating has been prepared by chemical vapor deposition of a fluoroalkylsilane (POTS) onto a PEDOT film, which was obtained by electrochemical deposition. The coating not only maintained high conductivity with a low resistivity of 3.2 × 10–4 Ω·m, but also displayed a water contact angle larger than 156° and a sliding angle smaller than 10°. After being etched with O2 plasma, the coating showed an excellent self-healing ability, spontaneously regaining its superhydrophobicity when left under ambient conditions for 20 h. This superhydrophobicity recovery process was found to be humidity-dependent, and could be accelerated and completed within 2 h under a high humidity of 84%. The coating also exhibited good superhydrophobicity recovering ability after being corroded by strong acid solution at pH 1 or strong base solution at pH 14 for 3 h.

A colourimetric sensor based on supramolecular fibres composed of polydiacetylene acid and polystyrene-co-poly(4-vinylpyridine) was fabricated through electrospinning. The obtained fibres show high sensitivity and selectivity to organic amine vapour at ppb concentrations.

A series of azobenzene-containing fluorescent complexes with stilbene fluorescent unit were prepared based on the ionic self-assembly approach. The incorporation of the stilbene unit did not change the lamellar structure of the azobenzene-containing complex. Under pulsed laser irradiation, the azobenzene group oriented in the direction perpendicular to the laser polarization, and as a result, the fluorescent stilbene unit was cooperatively oriented following the direction of azobenzene group orientation. This oriented complex films presented anisotropic emission of fluorescence, and the anisotropic ratio of fluorescence increases with the increase of the content of azobenzene unit in the complex.

Controlling of the orientation of mesochannels in mesostructured thin films is important for the development of novel molecular devices and, in particular, generating vertically aligned mesochannels with respect to the substrate plane is extremely challenging for nonsiliceous materials. We describe a facile and highly effective air flow method, which is able to control the unidirectional alignment of titania mesochannels in a desired direction (e.g., parallel, perpendicular, or oblique) on a large scale, via manipulation of the air flow rate and incident angle. The titania mesochannels were characterized by TEM, SEM, SAXRD, and GISAXS. The unidirectional, vertically aligned mesostructured titania films were found to exhibit excellent ion conductivity.

A simple copolymer, copoly(ionic liquid), consisting of N-isopropylacrylamide (NIPAM) and 1-benzyl-4-vinylpyridine bromide (4-VPBn+Br–) units as thermo-responsive and ionic liquid parts, respectively, has been synthesized. Fluorescent nanoparticles (FNPs) were then formed under the driving forces of electrostatic interaction between 2-(4-amino-2-hydroxyphenyl) benzothiazole derivative (AHBTA) and copoly(ionic liquid) due to hydrophilic/hydrophobic balance. The fluorescent intensity of the FNPs enhanced by a factor of about 50 times when the pH was increased from 7 to 10, and was effectively doubled within 1 °C around LCST in pH 9 buffer solution, thus showing a dramatic pH and thermal dual-dependent property. The FNPs exhibited reversible fluorescence enhancement/quenching over more than five cycles, regardless of the heating/cooling process. Furthermore, the FNPS proved to be much more stable to UV light irradiation than pure fluorescence molecule AHBTA.

In this paper, hybrid film of mesoporous silica film with oriented mesochannels and semiconductor quantum dot has been prepared. Encapsulation of CdS and PbS within the oriented mesochannels leads to a regular arrangement at the macro scale. The hybrid film thus obtained showed remarkable anisotropic photoelectronic properties due to the confinement effect of the oriented mesochannels. Furthermore, due to the independence of the orientations of the mesochannels on the substrate, bilayer films containing both CdS and PbS could be prepared. This design has allowed an extension of the range of light absorption by the thin film as well as an amplification of the response to external photoelectronic effects. Such a hybrid film may prove useful in the design of anisotropic electrodes and electronic nanodevices.

Fluorescent nanoparticles were formed from a poly(ionic liquid) through ion interactions. The fluorescent nanoparticles show highly fluorescent intensity and stability to UV light irradiation and were utilized for highly sensitive and selectivity fluorescent sensor of copper ion.

A new family of dual-photoresponsive complexes has been fabricated based on the method of Precipitation Ionic Self-assembly (PISA). Poly (acrylic acid sodium salt) was coupled with two types of ionic mesogenic units containing azobenzene and cinnamate group, respectively, yielding a series of thermotropic liquid crystalline supramolecules. By changing the ratio of the two mesogenic units, different phase behaviors and nanostructures were obtained. Comparable photoinduced orientation of azo groups was observed in all the complex films after being irradiated by linearly polarized laser, while cinnamate groups can be crosslinked under UV light exposure. Furthermore, the influence of crosslinked cinnamate groups on the photoinduced orientation and its thermal stability was investigated in detail. This novel material may be utilized in many fields, such as surface relief gratings, liquid crystal display and nonlinear optics. This green and facial method can provide guidelines for the convenient design of multi-functional supramolecular materials.

Fluorescent nanoparticles were formed from a poly(ionic liquid) through ion interactions. The fluorescent nanoparticles show highly fluorescent intensity and stability to UV light irradiation and were utilized for highly sensitive and selectivity fluorescent sensor of copper ion.

In combination with the breath-figure method, an in situ growth approach of polyphosphazenes was performed on a honeycomb surface resulting in a closely packed nanoparticle coating and a micro/nanoscale hierarchical structure. The hierarchically structured surfaces exhibited high biocompatibility, allowed good cellular adhesion and presented strong potential use as a cell scaffold.

Inspired by the typically adhesive behaviors of fish skin and Parthenocissus tricuspidata, two different decorations of polystyrene honeycomb membrane (PSHCM) prepared by the breath figure approach were carried out with poly(N-(3-Sulfopropyl)-N-(methacryloxyethyl)-N,N-dimethylammonium betaine)(polySBMA) to explore controllable bioadhesive surfaces. Casting and dip-coating were employed to graft polySBMA onto the plasma treated PSHCM. The polySBMA casted PSHCM showed a uniform covering layer on the PSHCM similar to the mucus layer of fish skin, presenting excellent antifouling properties. On the contrary, a dip-coated one showed the polySBMA aggregating on the honeycomb pore walls forming a large number of sucking disks such as the adhesive disks of the tendrils of P. tricuspidata, which remarkably boosts cell adhesion on substrates. Thus, bioadhesion could be regulated as desired by tuning the distribution of zwitterionic polymer on the honeycomb surface. The results may provide a new approach for the design of biomaterial surfaces.