•Vapour jet deposition of DNTT at speed of up to 200 nm/s onto a moving substrate to manufacture transistors at high yield.•A vacuum roll-to-roll-applicable process to functionalise an acrylic dielectric surface to improve transistor performance.•The first all-vacuum processed five stage ring oscillator fabricated use the techniques above.Roll-to-roll (R2R) production of organic transistors and circuits require patterned deposition of organic layers at high deposition rate. Here we demonstrate a vapour-jet process for the rapid deposition of the organic semiconductor dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene (DNTT). The deposition rate achieved, equivalent to ∼200 nm/s onto a stationary substrate, was several orders of magnitude faster than ordinary thermal evaporation. Nevertheless, transistor yield was 100% with an average mobility of 0.4 cm2/V in a single pass deposition onto a substrate moving at 0.15 m/min. We also demonstrate a vacuum, high rate R2R-compatible process for surface-functionalising a gate dielectric layer with lauryl acrylate which enabled an all-vacuum route to the fabrication of a five-stage ring oscillator.

In this paper we demonstrate the potential of high molecular weight hyperbranched methacrylate polymers for inkjet printing. Using the Strathclyde method, a series of hyperbranched poly (methylmethacrylate) polymers of increasing branch density were prepared. All hyperbranched polymers show both a significantly greater maximum printable concentration compared to equivalent linear polymers with implications for faster print speed. Increasing chain branching above a critical value across the molecular weight distribution was found to result in suppression of molecular weight degradation. This resistance to molecular degradation is because the longest chain segment being much smaller, such that upon jetting the polymer rapidly retains its thermodynamically stable Gaussian coil conformation and the full force of the constrictional flow in the print head is not passed on to the polymer and degradation is supressed. We further go on to show using Electron Paramagnetic Resonance that degradation occurs via a free radical chain scission mechanism.

Correction for ‘Inkjet printed paper based frequency selective surfaces and skin mounted RFID tags: the interrelation between silver nanoparticle ink, paper substrate and low temperature sintering technique' by Veronica Sanchez-Romaguera et al., J. Mater. Chem. C, 2015, DOI: 10.1039/c4tc02693d.

Inkjet printing of functional frequency selective surfaces (FSS) and radio frequency identification (RFID) tags on commercial paper substrates using silver nanoparticle inks sintered using low temperature thermal, plasma and photonic techniques is reported. Printed and sintered FSS devices demonstrate performances which achieve wireless communication requirements having a forward transmission scattering parameter, S21, depth greater than −20 dB at 13 GHz. Printed and plasma sintered RFID tags on transfer paper, which are capable of being mounted on skin, improved read distances compared to previously reported single layer transfer RFID tags fabricated by conventional thermal sintering.

Results are reported for the first time on the possibility and cause of polymer degradation in a full commercial inkjet printer. The behaviour of three linear poly(methyl methacrylate) (PMMA) samples, having Mw 90, 310 and 468 kDa respectively, in a continuous inkjet (CIJ) Domino A-Series+ printer is investigated and compared with earlier reported results for two experimental drop on demand (DOD) printers, a Dimatix DMP-2800 and a Microfab single nozzle glass capillary. Despite all three printheads having equivalent strain rate at the nozzle tip (ε) no degradation is observed within the CIJ head alone whereas single pass degradation is observed in both DOD printheads. This can be attributed to a consequence of a number of factors including the slightly greater nozzle diameter, and different nozzle geometry, which includes cone angle and nozzle cylinder length, for CIJ, the different mode of drop generation or the higher polymer concentration investigated. It should also be noted that the flow through the CIJ nozzle is continuous, where it is pulsed in the case of DOD. The calculated maximum strain rates are similar, but in DOD it is being periodically ramped up and switched off.The main source of polymer degradation in CIJ printing through a CIJ Domino A-Series+ printer is found to be the continuous recycling of ink through the pump resulting in mechano-chemical polymer degradation. Molecular weight degradation proceeds by random scission, and is obtained at the lower shear rates experience as a consequence of the longer residence time due to mechano-chemical damage in the pump. These results have significance in the total design of inkjet systems for the delivery of high molecular weight polymers and materials sensitive to mechano-chemical degradation and highlight the need for careful consideration when moving from laboratory based print tools to full scale application.

Herein we report a novel synthetic strategy for the synthesis of micrometre sized core–shell particles comprising a polyelectrolyte core and a porous hydrophobic shell. A water-in-oil-in-water (W1/O/W2) double-emulsion was used as the template for the simultaneous polymerisation of both the internal aqueous and the intermediate oil phase leading to the formation of a cross-linked poly(acrylic acid) (PAAc) core contained in a poly(4-tert-butylstyrene-co-divinylbenzene) (poly(4-tBSty-co-DVB)) shell. The mass transport process from the internal aqueous phase to the external phase was reduced by means of an “oil phase locking” mechanism in which a rapid gel point transition of the oil phase ensured stability against internal aqueous–external aqueous phase (W1–W2) coalescence. The formation of core–shell particles was favoured by the effect of acrylic acid monomer which was responsible for the selective destabilization of the internal aqueous/oil interface (W1/O) allowing rapid internal aqueous phase coarsening. The particles thus obtained were investigated as potential sorbent materials for the simultaneous removal and encapsulation of organic and inorganic cationic species from aqueous solutions.

In this study, we consider segregative phase separation in aqueous mixtures of quaternary ammonium surfactants didecyldimethylammonium chloride (DDQ) and alkyl (C12, 70%; C14 30%) dimethyl benzyl ammonium chloride (BAC) upon the addition of poly(diallyldimethylammonium) chloride (pDADMAC) as a function of both concentration and molecular weight. The nature of the surfactant type is dominant in determining the concentration at which separation into an upper essentially surfactant-rich phase and lower polyelectrolyte-rich phase is observed. However, for high-molecular-weight pDADMAC there is a clear indication of an additional depletion flocculation effect. When the BAC/DDQ ratio is tuned, the segregative phase separation point can be precisely controlled. We propose a phase separation mechanism for like-charged quaternary ammonium polyelectrolyte/surfactant/water mixtures induced by a reduction in the ionic atmosphere around the surfactant headgroup and possible ion pair formation. An additional polyelectrolyte-induced depletion flocculation effect was also observed.

Here we report the synthesis of polymer stabilised anthraquinone dye-based aqueous nanoparticles using evaporative precipitation from dichloromethane into water and their use as novel aqueous inkjet colorants. Polymer stabilised dye nanoparticles in the 100 nm size range are demonstrated and the mechanism of formation of stable nanoparticles and the role of polymer stabiliser design is discussed. Formation of stable small particle size nanoparticles requires a fast dye crystal nucleation rate followed by a subsequent slow growth rate so as to avoid Ostwald ripening. Rapid nucleation can be achieved by metering small amounts of water-miscible organic solution of the dye to the non-solvent water under rapid mixing, referred to as quasi-emulsion solvent diffusion (QESD). These conditions result in high-supersaturation which causes spontaneous nucleation, followed by a rapid decrease in local supersaturation and hence slow crystal growth rate.Highlights► Synthesis of stable 100 nm aqueous dye–polymer composite particles. ► New process methodology. ► Role of polymer–dye interaction in controlling particle morphology. ► Preliminary data on suitability as water-fast inkjet inks.

The positive effects on the inkjet drop ejection process, thin film morphology and subsequent thin film transistor performance caused by the blending a low molar mass semi-crystalline organic semiconductor, 6,13-triisopropylsilylethynylpentacene (TIPS-pentacene), with a low ε dielectric polymer, polystyrene (350 kDa) are reported. The presence of the high molecular weight polymer at a reduced concentration c/c* = 0.44 gives greater control of the drop generation process (when compared to low molar mass semi-crystalline organic semiconductor alone) due to stabilisation of the ligament break-up process with pinch off occuring at the nozzle plate and satellites coalescing within the main droplet. The addition of a small fraction of a high boiling point solvent results in the removal of droplet drying artefacts by generating a Marangoni flow in which double convection counteracts coffee stain formation. This results in more uniform solute coverage over the substrate, simplifying the print process. Whilst TIPS-pentacene and amorphous polystyrene do not undergo gross phase separation irrespective of deposition process the degree of crystallinity and extent of TIPS-pentacene stratification to the active interface was found to be strongly process dependant. Whilst a lower degree of crystallinity is observed when a dual solvent mixture is used there is strong evidence of greater stratification of the TIPS-pentacene at the active interface resulting in higher saturated hole mobility.

Two-component blends of amorphous poly(triarylamines) with selected amorphous and semi-crystalline polymeric binders are investigated as the semiconducting layer in organic field effect transistors (OFET). The blends can be deposited at room temperature from a good solvent and allow the fabrication of devices based on environmentally stable, low-cost organic semiconductors whose solution and solid state properties can be fine-tuned by careful binder selection making them suitable as the active layer in OFET based electronic nose arrays. A preliminary comparison of devices fabricated using drop casting and inkjet printing shows that the thin film morphology and the electronic properties of these blends are strongly dependent on the deposition method.

1,4,8,11-Methyl-substituted 6,13-triethylsilylethynylpentacene shows extended π–π overlap when deposited from solution, yielding organic thin film transistors with high and reproducible hole mobility with negligible hysteresis.

The morphology and organic field effect transistor (OFET) properties of two component blends of semi-crystalline 6,13-bis(triisopropylsilylethinyl)pentacene (TIPS-pentacene) with selected amorphous and semi-crystalline side chain aromatic low permittivity insulating binders deposited at room temperature under vacuum from a good solvent are reported. When blended with an amorphous binder there is evidence from X-ray photoelectron spectroscopy (XPS) of a strong interaction between TIPS-pentacene and the binder in the solidified film giving rise to twisted TIPS-pentacene crystals containing dislocations. Due to this strong interaction we see no evidence of segregation of TIPS-pentacene towards the active interface and hence we observe a rapid fall off in saturated hole mobility at an active concentration less than 50 wt%. When blended with a crystalline binder there is no evidence from XPS of any interaction between TIPS-pentacene and the binder in the solidified film. We propose that when a semi-crystalline binder is used, which crystallizes more slowly from solution than TIPS-pentacene, we observe stratification of the active material to both interfaces and as a result retention of saturated hole mobility even down to 10 wt%. The potential applications of the approach are in the formulation of low-cost organic semiconductors whose solution and solid state properties can be fine-tuned by careful binder selection.

An approach for the high-throughput preparation and characterisation of aqueous polymer pigment dispersions is described and evaluated. Co- and ter-polymers of methacrylic acid and methacrylate esters were synthesised, neutralised with 2-amino-2-methyl-propan-1-ol and formulated with carbon black to give an aqueous pigment dispersion and screened with respect to colloid stability. All stages were undertaken using parallel methodology with the formulation and screening performed in a 96-well micro-titre plate format. The condition of the dispersion arrays could be assessed through optical density analysis using a flatbed scanner and digital image.

The influence of polymer concentration, going from the dilute through the overlap into the concentrated regime, during drop on demand inkjet printing is investigated for a range of cellulose ester (CE) polymers from visual examination of ligament stretching as a function of applied wave form. The physical behaviour of the polymer fluids in drop formation is indicative of the dominance of viscoelastic effects within the timescale of the process, in preventing ligament break-up at the pinch point compared with a water–glycerol–isopropanol blend Newtonian fluid of similar viscosity. This has previously been described in terms of the polymer chain undergoing a coil–stretch transition at the strain rates experienced in the inkjet process. When formulated at the coil overlap concentration all polymers showed qualitatively similar behaviour with respect to time and length of ligament at rupture irrespective of polymer molecular weight. Beyond the overlap concentration the ligament rupture time continues to increase with increasing elasticity of the solution but the ligament rupture length decreases rapidly. In this regime chain entanglement becomes important, dramatically increasing the elastic nature of the ligament. Additionally it is proposed that in the case of weakly associating polymers such as cellulose esters, the effective relaxation time is further increased due to the possibility that on chain extension intramolecular H-bonds are broken and may reform as intermolecular associations whilst the polymer chains are extended. These intermolecular associations act as physical crosslinks, thereby creating a transient network structure. This network structure is capable of having a finite large viscosity. Once the strain is removed the network will decay as the chains return to the more thermodynamically stable coil state.

Inkjet printing of functional frequency selective surfaces (FSS) and radio frequency identification (RFID) tags on commercial paper substrates using silver nanoparticle inks sintered using low temperature thermal, plasma and photonic techniques is reported. Printed and sintered FSS devices demonstrate performances which achieve wireless communication requirements having a forward transmission scattering parameter, S21, depth greater than −20 dB at 13 GHz. Printed and plasma sintered RFID tags on transfer paper, which are capable of being mounted on skin, improved read distances compared to previously reported single layer transfer RFID tags fabricated by conventional thermal sintering.

An approach for the high-throughput preparation and characterisation of aqueous polymer pigment dispersions is described and evaluated. Co- and ter-polymers of methacrylic acid and methacrylate esters were synthesised, neutralised with 2-amino-2-methyl-propan-1-ol and formulated with carbon black to give an aqueous pigment dispersion and screened with respect to colloid stability. All stages were undertaken using parallel methodology with the formulation and screening performed in a 96-well micro-titre plate format. The condition of the dispersion arrays could be assessed through optical density analysis using a flatbed scanner and digital image.

1,4,8,11-Methyl-substituted 6,13-triethylsilylethynylpentacene shows extended π–π overlap when deposited from solution, yielding organic thin film transistors with high and reproducible hole mobility with negligible hysteresis.

The morphology and organic field effect transistor (OFET) properties of two component blends of semi-crystalline 6,13-bis(triisopropylsilylethinyl)pentacene (TIPS-pentacene) with selected amorphous and semi-crystalline side chain aromatic low permittivity insulating binders deposited at room temperature under vacuum from a good solvent are reported. When blended with an amorphous binder there is evidence from X-ray photoelectron spectroscopy (XPS) of a strong interaction between TIPS-pentacene and the binder in the solidified film giving rise to twisted TIPS-pentacene crystals containing dislocations. Due to this strong interaction we see no evidence of segregation of TIPS-pentacene towards the active interface and hence we observe a rapid fall off in saturated hole mobility at an active concentration less than 50 wt%. When blended with a crystalline binder there is no evidence from XPS of any interaction between TIPS-pentacene and the binder in the solidified film. We propose that when a semi-crystalline binder is used, which crystallizes more slowly from solution than TIPS-pentacene, we observe stratification of the active material to both interfaces and as a result retention of saturated hole mobility even down to 10 wt%. The potential applications of the approach are in the formulation of low-cost organic semiconductors whose solution and solid state properties can be fine-tuned by careful binder selection.

The influence of polymer concentration, going from the dilute through the overlap into the concentrated regime, during drop on demand inkjet printing is investigated for a range of cellulose ester (CE) polymers from visual examination of ligament stretching as a function of applied wave form. The physical behaviour of the polymer fluids in drop formation is indicative of the dominance of viscoelastic effects within the timescale of the process, in preventing ligament break-up at the pinch point compared with a water–glycerol–isopropanol blend Newtonian fluid of similar viscosity. This has previously been described in terms of the polymer chain undergoing a coil–stretch transition at the strain rates experienced in the inkjet process. When formulated at the coil overlap concentration all polymers showed qualitatively similar behaviour with respect to time and length of ligament at rupture irrespective of polymer molecular weight. Beyond the overlap concentration the ligament rupture time continues to increase with increasing elasticity of the solution but the ligament rupture length decreases rapidly. In this regime chain entanglement becomes important, dramatically increasing the elastic nature of the ligament. Additionally it is proposed that in the case of weakly associating polymers such as cellulose esters, the effective relaxation time is further increased due to the possibility that on chain extension intramolecular H-bonds are broken and may reform as intermolecular associations whilst the polymer chains are extended. These intermolecular associations act as physical crosslinks, thereby creating a transient network structure. This network structure is capable of having a finite large viscosity. Once the strain is removed the network will decay as the chains return to the more thermodynamically stable coil state.

Two-component blends of amorphous poly(triarylamines) with selected amorphous and semi-crystalline polymeric binders are investigated as the semiconducting layer in organic field effect transistors (OFET). The blends can be deposited at room temperature from a good solvent and allow the fabrication of devices based on environmentally stable, low-cost organic semiconductors whose solution and solid state properties can be fine-tuned by careful binder selection making them suitable as the active layer in OFET based electronic nose arrays. A preliminary comparison of devices fabricated using drop casting and inkjet printing shows that the thin film morphology and the electronic properties of these blends are strongly dependent on the deposition method.

Correction for ‘Inkjet printed paper based frequency selective surfaces and skin mounted RFID tags: the interrelation between silver nanoparticle ink, paper substrate and low temperature sintering technique' by Veronica Sanchez-Romaguera et al., J. Mater. Chem. C, 2015, DOI: 10.1039/c4tc02693d.

Herein we report a novel synthetic strategy for the synthesis of micrometre sized core–shell particles comprising a polyelectrolyte core and a porous hydrophobic shell. A water-in-oil-in-water (W1/O/W2) double-emulsion was used as the template for the simultaneous polymerisation of both the internal aqueous and the intermediate oil phase leading to the formation of a cross-linked poly(acrylic acid) (PAAc) core contained in a poly(4-tert-butylstyrene-co-divinylbenzene) (poly(4-tBSty-co-DVB)) shell. The mass transport process from the internal aqueous phase to the external phase was reduced by means of an “oil phase locking” mechanism in which a rapid gel point transition of the oil phase ensured stability against internal aqueous–external aqueous phase (W1–W2) coalescence. The formation of core–shell particles was favoured by the effect of acrylic acid monomer which was responsible for the selective destabilization of the internal aqueous/oil interface (W1/O) allowing rapid internal aqueous phase coarsening. The particles thus obtained were investigated as potential sorbent materials for the simultaneous removal and encapsulation of organic and inorganic cationic species from aqueous solutions.

The positive effects on the inkjet drop ejection process, thin film morphology and subsequent thin film transistor performance caused by the blending a low molar mass semi-crystalline organic semiconductor, 6,13-triisopropylsilylethynylpentacene (TIPS-pentacene), with a low ε dielectric polymer, polystyrene (350 kDa) are reported. The presence of the high molecular weight polymer at a reduced concentration c/c* = 0.44 gives greater control of the drop generation process (when compared to low molar mass semi-crystalline organic semiconductor alone) due to stabilisation of the ligament break-up process with pinch off occuring at the nozzle plate and satellites coalescing within the main droplet. The addition of a small fraction of a high boiling point solvent results in the removal of droplet drying artefacts by generating a Marangoni flow in which double convection counteracts coffee stain formation. This results in more uniform solute coverage over the substrate, simplifying the print process. Whilst TIPS-pentacene and amorphous polystyrene do not undergo gross phase separation irrespective of deposition process the degree of crystallinity and extent of TIPS-pentacene stratification to the active interface was found to be strongly process dependant. Whilst a lower degree of crystallinity is observed when a dual solvent mixture is used there is strong evidence of greater stratification of the TIPS-pentacene at the active interface resulting in higher saturated hole mobility.