•ZnO NPs-PNIPAM nanocomposites were prepared via surface-initiated atom transfer radical polymerization method.•ZnO NPs-PNIPAM nanocomposites show temperature-controlled switching of photocatalysis.•ZnO NPs-PNIPAM nanocomposites exhibit good reusability.We reported on the fabrication of thermo-responsive polymers of poly(N-isopropylacrylamide) (PNIPAM) graft ZnO by surface-initiated atom transfer radical polymerization (SI-ATRP) to contribute the characteristics of the grafted PNIPAM, meanwhile, without sacrificing the properties of ZnO. The structures of nanoparticles and the grafted polymer were confirmed by XRD and FT-IR and the interactions between the two components were studied by XPS. The morphology of ZnO NPs-PNIPAM nanocomposites was observed by SEM images and a thin layer of polymers (2 nm) formed around NPs was measured by TEM. EDS mapping images revealed the even distribution polymers on the surface of ZnO NPs. Based on the TG results, the grafting density of ATRP initiators at the surface of ZnO NPs was estimated to be 0.7 nm2/initiator. Furthermore, photodegradation of Rhodamine B (Rh-B) in the presence of nanocomposites revealed that ZnO NPs-PNIPAM exhibited photocatalysis, temperature-controlled switching and good recycling performance, indicating the significant potential applications in the practical applications.

One major issue in thermosensitive drug delivery systems is the remote, repeatable control of temperature in vivo through external stimuli such as light, ultrasound, and magnetic field. In this study, an Fe3O4/p(NIPAM-co-MAA) composite microgel (Nms) was fabricated via copolymerizing NIPAM with MAA in water-containing Fe3O4 nanoparticles modified by oleic acid. The photothermal effect and thermal-responsibility of Nms were investigated by adjusting the amount of MAA and Fe3O4 in the reaction, and the result shows an LCST of 37.2 °C, which could be elevated to 45.8 °C under laser treatment at 808 nm. In the drug release experiment, the data show that the drug can be released at an expected rate by controlling the temperature using an 808 nm laser irradiation in vivo. The release rate was fast and the final cumulative drug release rate increased by about 25%. Thus, these properties of the Fe3O4/p(NIPAM-co-MAA) Nms microgel indicate its promising application in multi-responsive microgels, especially in photothermal drug carriers.

Molybdenum oxide nanomaterials have received increasing attention in recent years for their strong localized surface plasmon resonance (LSPR) absorption in the near-infrared (NIR) region and pH-dependent degradability. However, the rapid degradation of MoOx at physiological pH values would decrease the NIR photothermal effect. Here, we designed and prepared PEGMa–MoOx/p(NIPAM-co-MAA) microgels (NCs) exhibiting adjustable degradation. For that purpose, PEGMa (Mn = 400) modified MoOx was synthesized through a simple hydrothermal process. Then, PEGMa–MoOx with existing CC groups was continually polymerized with NIPAM and MAA through emulsion polymerization. MAA was introduced to provide an acidic microenvironment (pH at 3–5) to control the degradation rate of PEGMa–MoOx. The photothermal efficiency of the NCs could be maintained at 54% even after 14 days. Meanwhile, the NCs also displayed a pH-dependent thermal response. Moreover, PEGMa was added again in the emulsion polymerization process to elevate the photothermal efficiency, and the irradiation result indicated that the NCs could increase the temperature by 27 °C. The complex microgel integrates pH/temperature/photothermal triple response characteristics and exhibits huge potential for chemo-photothermal combination cancer therapy.

This work is to fabricate thermo responsive nanofibers of which the thermo response temperatures could be easily tuned, and of which the fibrous shapes could be maintained after heating–cooling cycles in aqueous solution. The nanofibers were further fabricated into a nonwoven mat with size-variable pores for temperature controlled release of a model drug, Erlotinib. The thermo responsive nanofibers were electrospun from the copolymers of PMMA-co-PVCL (synthesized from MMA and PVCL, and had different LCSTs) by changing the solvents and the ratio of initiator/monomer. FT-IR and 1H NMR were used for molecular structural characterization; UV-vis spectra were used for LCST measurement; SEM and metalloscope were used to determine the optimal electrospinning parameters and to observe the shape maintaining abilities of the nanofibers after the heating–cooling recycles. Then, anti-cancer drug, Erlotinib, was incorporated into PMMA/PVCL nanofibers (represent as ‘model I’), or put in a drug reservoir and covered with the PMMA/PVCL electrospinning mat (presented as ‘model II’). UV-vis spectra were used to study the drug release behavior of each model. Results indicate that in model I, drug release was “switch on” below LCST, and “switch off” above LCST; in model II, drug release was faster above LCST than below LCST.

Effective surface fluorine enrichment has great potential application value for superhydrophobic electrospun films, which has presented a challenge to researchers. The aim is expected to be achieved by electrospinning functional polymers with controlled structure based on the polarization characteristics of functional groups in polymer chains and their directional ordering induced by an electric field. Herein, an amphiphilic graft copolymer of poly(methyl methacrylate-ran-hydroxypropyl acrylate)-graft-poly(dodecafluoroheptyl methacrylate) (PMMA-r-PHPA-g-PDFMA) was synthesized by the combination of free radical polymerization and atom transfer radical polymerization (ATRP). Superhydrophobic fibrous films with high surface fluorine atomic content of 29.1% and even up to 34.8% were fabricated by eletrospinning the resultant fluoropolymer. It is concluded that the electric field can drive the surface segregation of positively charged fluorinated groups and bulk segregation of negatively charged –OH groups, thus contributing to the effective surface fluorine enrichment, which was confirmed by XPS results. Additionally, we also found that the superhydrophobicity of electrospun films has no apparent dependence on fibre morphologies. The variation in the surface wettability can be attributed to the difference in surface compositions obtained by changing the applied electric field strength and solvents. This research would present potential application prospects in fabricating high surface fluorinated superhydrophobic electrospun fibres or novel surface functionalized electrospun fibres.

Well fabricated ZnO nanorods (ZnO NRs) arrays with preferred-orientation that grown on pre-deposited ZnO seed layers substrate were selected to graft thermo-responsive polymers of poly(N-isopropylacrylamide) (PNIPAM) by surface-initiated atom transfer radical polymerization (SI-ATRP). As a controlled/“living” radical polymerization, SI-ATRP could endow the systems with the characteristics of the grafted PNIPAM, meanwhile, with the maintaining of the properties of the ZnO NRs. The structures of ZnO and the grafted polymer with the relatively high molecular weights (Mn, 24300) and narrow molecular weight distributions (Mw/Mn, 1.19) that determined by GPC detection, were characterized by XRD and FT-IR. The graft amount of PNIPAM on ZnO NRs and the interactions between the two components were determined by TG and XPS, respectively. The relatively thin layers of PNIPAM (∼15 nm) formed around NRs via SI-ATRP method were observed by SEM. And the temperature-sensitivity of the grafted nanorods were proved by contact angles measurements. Furthermore, photodegradation of Rhodamine B (Rh-B) by the grafted nanorods revealed that ZnO NRs–PNIPAM exhibited photocatalysis and temperature responsibility characteristics, indicating the significant potential applications with tunable responsiveness by changing the environmental conditions.

A thermo- and pH-sensitive copolymer of poly(N-isopropylacrylamide)-co-poly(acrylic acid) (P(NIPAAm-co-AAc)) with an adjusted lower critical solution temperature (LCST)(at 37 °C) in an aqueous medium and pH of 7.4 was synthesized by a radical copolymerization, and was characterized by Fourier-transform infrared (FTIR) spectroscopy and 1H nuclear magnetic resonance (1H-NMR) spectroscopy. Then, nanofibers composed of P(NIPAAm-co-AAc) and polyurethane (PU) were fabricated by the single-spinneret electrospinning technique and used as drug carriers by co-spinning with the water insoluble drug nifedipine (NIF). The thermo-responsive behavior of the nanofibers was detected by contact angle (CA) measurements. The release behavior of the NIF from nanofibers was observed by scanning electron microscopy (SEM) and demonstrated by UV-vis spectroscopy. It was found that the wettability of the P(NIPAAm-co-AAc) nanofibers could be switched, due to the incorporation of PU. The release amount of NIF from the nanofibers could be controlled effectively by adjusting the temperature or pH value of the aqueous medium and incorporating the hydrophobic PU.

•Preferred-oriented ZnO nanorods were grown on pre-deposited ZnO seed layers using solution method.•Seed layers of ZnO were fabricated by Langmuir–Blodgett method.•The seed layers and growing parameters had the influences on morphology and orientation of ZnO nanorods.•ZnO nanorods in good orientation show higher transmittance and optical properties.In this paper, vertical aligned ZnO nanorod arrays were successfully grown by solution method onto seed layers of ZnO that fabricated by Langmuir–Blodgett (LB) method. The influences of seed layers (numbers of layers, fabricating routes, and with/without seed layers) and growing parameters (temperature, time and solution concentration) on morphology and orientation of ZnO nanorods were observed by SEM analysis results and discussed in details. XRD analysis results revealed that ZnO nanorods were preferred-oriented in (0 0 2) planes with wurtzite structure and highly crystallinity. UV–Vis transmission spectra showed the importance of the microstructures and the array degrees of ZnO nanorods to its optical properties. ZnO nanorods in good orientation led to higher transmittance and improved optical properties.Graphical abstract

Electrospun micro- and nanofibers are being increasingly investigated for drug delivery. The components and stimuli-responsive properties of the fibers are important factors influencing the drug release behavior. The aim of this study was to fabricate thermo-responsive poly(N-isopropylacrylamide) (PNIPAAm)/polyurethane (PU) nanofibers using a single-spinneret electrospinning technique. The electrospun nanofibers were used as drug carriers by co-spinning with nifedipine (NIF) and the release behavior of NIF can be controlled by the response of the nanofibers to temperature. The morphologies of the nanofibers and the composites with NIF were investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The interactions between PNIPAAm and PU and the existence of the water-insoluble drug NIF were introduced and confirmed by Fourier-transform infrared spectroscopy (FTIR). The thermo-responsive behavior of the nanofibers was detected by contact angle (CA) measurements. Mechanical properties were analyzed by tensile test and the release behavior of NIF from the PNIPAAm/PU nanofibers was observed by SEM and demonstrated by UV-vis spectroscopy. It was found that uniform fibers of NIF and PNIPAAm/PU could be fabricated without the appearance of particles on the surface. The release of NIF from the nanofibers could be controlled effectively by adjusting the temperature of the environment surrounding the thermo-responsive nanofibers.

We describe a controllable method to fabricate hexagonally close-packed Langmuir–Blodgett (LB) monolayers with stearic acid (SA) as co-surfactant and methanol as co-solvent. The optimal SA concentrations and volume ratios of chloroform to methanol are 0.8 mg/mL and 3:1 for particles of 140 nm, 0.50 mg/mL and 4:1 for particles of 300 nm, and 0.05 mg/mL and 5:1 for particles of 550 nm, respectively. Additionally, SEM detections of the monolayers transferred at different surface pressures indicate that the monolayers deposited from the binary systems are more compressible. The experimental results indicate that the interparticle repulsions and particle–water interactions can be enhanced without decreasing the particle hydrophobicity by adding SA and methanol; thus, particulate monolayers with large hexagonally close-packed domains composed of small silica particles can be successfully fabricated using LB technique. We propose that the enhanced interparticle repulsion is attributed to the Columbic repulsion resulting from the attachment of SA molecules to the CTAB modified particles around the three phase contact line.

This article reports on the fabrication of hybrid titanium dioxide (TiO2) nanoparticles grafted with thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) and their self-flocculation effect caused by the thermal phase transition and entanglement behavior of PNIPAM. Surface-initiated atom transfer radical polymerization (ATRP) of N-isopropylacrylamide (NIPAM) was conducted rapidly (within a few minutes) in aqueous solution at ambient temperature by using CuBr/N,N,N′,N′′,N′′-pentamethyldiethylenetriamine (PMDETA) as the catalysts and started from the surface of TiO2 nanoparticles derivatized with ATRP initiators. Without purifying the inhibitor, the grafted PNIPAM gives low molecular weights (Mn < 3000) and a narrow molecular weight distribution (PDI < 1.1) determined by GPC detection, which gives the hybrid TiO2–PNIPAM both a self-flocculation effect with rapid response to temperature, and a temperature-controlled switching effect of the degradation of Rhodamine B in solution. Moreover, the hybrid TiO2–PNIPAM exhibits a particular dispersion effect at ambient temperature in aqueous solution caused by the hydrophilicity and the entanglement interaction of the grafted PNIPAM. These effects for hybrid TiO2–PNIPAM provide a new way to re-use TiO2 nanoparticles for pollutant degradation systems and to avoid secondary pollution effectively due to the thermal phase transition and entanglement behavior.

We present the fabrication of superhydrophobic surfaces by electrospraying structure controlled poly(methyl methacrylate-bromine) (PMMA-Br) homopolymer and degree of fluorination controlled poly(methyl methacrylate)-b-poly(dodecafluoroheptyl methacrylate) (PMMA-b-PDFMA) copolymers synthesized via atom transfer radical polymerization (ATRP). The flow rate has great effects on the surface hydrophobicity of PMMA50.6, and superhydrophobic surface was obtained at a higher flow rate of 5 μL/min. For fluorinated diblock copolymers, superhydrophobic surfaces can be obtained by electrospraying PMMA50.6-b-PDFMA0.8 and PMMA147.9-b-PDFMA17.5 at the selected flow rates. X-ray photoelectron spectroscopy (XPS) detections reveal that, during the film formation, more hydrophobic surfaces would be fabricated due to the surface segregations of C–C and C–H groups with THF as solvent instead of C–O–C═O group with DMF as solvent. This investigation may be of great value in fabricating superhydrophobic polymer materials.

This article reports on the fabrication of hybrid titanium dioxide (TiO2) nanoparticles grafted with thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) and their self-flocculation effect caused by the thermal phase transition and entanglement behavior of PNIPAM. Surface-initiated atom transfer radical polymerization (ATRP) of N-isopropylacrylamide (NIPAM) was conducted rapidly (within a few minutes) in aqueous solution at ambient temperature by using CuBr/N,N,N′,N′′,N′′-pentamethyldiethylenetriamine (PMDETA) as the catalysts and started from the surface of TiO2 nanoparticles derivatized with ATRP initiators. Without purifying the inhibitor, the grafted PNIPAM gives low molecular weights (Mn < 3000) and a narrow molecular weight distribution (PDI < 1.1) determined by GPC detection, which gives the hybrid TiO2–PNIPAM both a self-flocculation effect with rapid response to temperature, and a temperature-controlled switching effect of the degradation of Rhodamine B in solution. Moreover, the hybrid TiO2–PNIPAM exhibits a particular dispersion effect at ambient temperature in aqueous solution caused by the hydrophilicity and the entanglement interaction of the grafted PNIPAM. These effects for hybrid TiO2–PNIPAM provide a new way to re-use TiO2 nanoparticles for pollutant degradation systems and to avoid secondary pollution effectively due to the thermal phase transition and entanglement behavior.

A thermo- and pH-sensitive copolymer of poly(N-isopropylacrylamide)-co-poly(acrylic acid) (P(NIPAAm-co-AAc)) with an adjusted lower critical solution temperature (LCST)(at 37 °C) in an aqueous medium and pH of 7.4 was synthesized by a radical copolymerization, and was characterized by Fourier-transform infrared (FTIR) spectroscopy and 1H nuclear magnetic resonance (1H-NMR) spectroscopy. Then, nanofibers composed of P(NIPAAm-co-AAc) and polyurethane (PU) were fabricated by the single-spinneret electrospinning technique and used as drug carriers by co-spinning with the water insoluble drug nifedipine (NIF). The thermo-responsive behavior of the nanofibers was detected by contact angle (CA) measurements. The release behavior of the NIF from nanofibers was observed by scanning electron microscopy (SEM) and demonstrated by UV-vis spectroscopy. It was found that the wettability of the P(NIPAAm-co-AAc) nanofibers could be switched, due to the incorporation of PU. The release amount of NIF from the nanofibers could be controlled effectively by adjusting the temperature or pH value of the aqueous medium and incorporating the hydrophobic PU.