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Due to its low cost, stiffness, and recyclability, isotactic polypropylene (iPP) is an excellent candidate for packaging applications. However, iPP is notoriously difficult to thermoform due to its low melt strength. The addition of just 10 thin layers of high-molecular-weight, linear low-density polyethylene (LLDPE) into iPP sheets by coextrusion significantly increased extensional viscosity and reduced sag. Both LLDPE and iPP were metallocene-catalyzed with excellent adhesion as measured in our previous work. We performed a series of hot tensile tests and sheet sag measurements to determine the properties of the iPP sheet and the multilayer sheet between 130 and 180 °C. To evaluate the thermoformability of these multilayer sheets, truncated conical cups were positive vacuum formed at different temperatures and heating times, and the crush strength was measured. Cups that released easily from the mold with good shape retention and a crush strength within 80% of the maximum value were used to define a temperature-time thermoformability window. We estimated the maximum stress that occurred during the thermoforming process to be 5 MPa. Layer thicknesses before and after thermoforming were used to estimate an average strain of 0.78. The thin LLDPE layers decreased the yield stress below 5 MPa. This enabled thermoforming at sheet temperatures as low as 150 °C. The immiscible LLDPE interfaces increased extensional viscosity, which decreased sag in the multilayer sheets compared to iPP. This broadened the thermoforming range to temperatures as high as 180 °C and allowed longer heating times. These highly thermoformable, layered sheets may be recycled as iPP since they contain only 8% of LLDPE.

Fire safety in polymers is critically important with products such as textiles and consumer goods, as well as materials used in construction, aerospace, transportation, and furniture. Additives use...

Nanostructured tricontinuous block polymers allow for the preparation of single-component materials that combine multiple properties. We demonstrate the synthesis of a mesoporous material from the selective orthogonal etching of a microphase-separated tricontinuous block polymer precursor. Using the synthetic approach of polymerization-induced microphase separation (PIMS), divinylbenzene (DVB) is polymerized from a mixture of poly(isoprene) (PI) and poly(lactide) (PLA) macro-chain transfer agents. In the PIMS process in situ cross-linking by the DVB arrests structural coarsening, resulting in a disordered block polymer morphology that we posit exhibits three nonintersecting continuous domains. Selective etching of the PI domains by olefin cross metathesis and PLA domains by hydrolytic degradation produces a mesoporous polymer with two independent pore networks arising from the different etch mechanisms.

A renewed focus on the phase behavior of nominally single-component, compositionally asymmetric diblock copolymers has revealed a host of previously unanticipated Frank-Kasper (FK) and quasicrystalline phases. However, these periodic and aperiodic particle packings have thus far only been reported in low molecular weight, highly conformationally asymmetric diblock copolymers, leaving researchers with a relatively small library of polymers in which these phases can be studied. In this work, we report on a simple approach to access these morphologies: blending two diblock copolymers with the same corona block length and varied core block lengths. Compositionally symmetric and asymmetric polystyrene

Graft block copolymers (BCPs) with poly(4-methyl caprolactone)-block-poly(±-lactide) (P4MCL-PLA) side chains containing 80–100% PLA content were synthesized with the aim of producing tough and sust...

The nonlinear rheology of multilayer stacks of alternating isotactic polypropylene (PP) and polyethylene (PE) films with N layers was measured in shear and uniaxial extension. We show that the force to extend N − 1 interfaces can lead to strain hardening. We studied three PE/PP pairs: a Ziegler–Natta catalyzed pair and two metallocene pairs, one with high density PE and one with linear low density PE. Interfacial tension was measured on matrix/droplet blends of each pair using small amplitude oscillatory shear measurements fitted with the Palierne model. Multilayer coextrusion was used to fabricate bilayers and sheets with hundreds of layers for each polyolefin pair. Under shear deformation, disentangling of chains in the N − 1 interfaces led to a decrease in the overall shear viscosity, which is interpreted as an interfacial slip velocity and is in agreement with previous studies on multilayer films. Under extensional flows, the multilayers exhibited an increased transient extensional viscosity (tensile stress growth coefficient, η E , M +) and pronounced strain hardening, even when the constituent homopolymers exhibited no strain hardening behavior. A model based on a force summation was developed to predict this behavior with interfacial tension as a fitting parameter; the extracted interfacial tensions agreed reasonably well with those from the Palierne model. The “slip in shear” and “hardening in extension” behaviors highlight the role of interfacial polymer physics during rheological measurements and polymer processing.

Micromechanical deformation of polyethylene terephthalate (PET)/ethylene-stat-methyl acrylate copolymer [p(E-s-MA)] blends was investigated for various MA contents and molar masses of p(E-s-MA). Th...

The segregation kinetics of deuterated polystyrene (d-PS) within the grain boundary regions of a lamellar poly(styrene-b-isoprene) copolymer is analyzed using a combination of electron imaging and ...

A series of isotactic polypropylene (iPP) and polyethylene (PE) diblock, tetrablock, and hexablock copolymers (BCPs) were synthesized with tunable molecular weights using a hafnium pyridylamine catalyst. The BCPs were melt blended with 70 wt % high-density PE (HDPE) and 30 wt % iPP commercial homopolymers at concentrations between 0.2 and 5 wt %. The resulting blend morphologies were investigated using TEM, revealing uniformly dispersed iPP droplets ranging progressively in size with increasing BCP content from three-quarters to one-quarter of the diameter of the uncompatibilized mixture. Tensile tests revealed a dramatic enhancement in toughness based on the strain at break which increased from 10% for the unmodified blend to more than 300% with just 0.2 wt % BCP and over 500% with the addition of 0.5 wt % BCP or greater. Incorporation of BCPs in blends also improved the impact toughness, doubling the Izod impact strength to a level comparable to the neat HDPE with just 1 wt % additive. These improved bl...

Polymerization-induced self-assembly (PISA) has attracted growing interest as facile fabrication process of polymer-based nanomaterials. However, PISA of acrylonitrile (AN) by atom transfer radical polymerization (ATRP) has remained an outstanding challenge due to the high activity of AN and poor solubility of polyacrylonitrile (PAN) in AN monomer. Here the application of PISA by using an initiators for continuous activator regeneration (ICAR) ATRP for the synthesis of PAN-based nano-objects is demonstrated. A highly active ATRP macroinitiator, methoxy-poly(ethylene oxide) 2-bromo-2-phenylacetate ( m PEO-BPA) was synthesized by esterification and used also as a stabilizer. The molecular weight of the macroinitiator was found to determine the structure of self-assembled nano-objects. The high molecular macroinitiator ( m PEO 113 -BPA) formed nano-objects with spherical or worm-like morphology, while the lower molecular weight analogue ( m PEO 45 -BPA) resulted in precipitation in most cases due to insufficient stabilization of the nano-objects.

The modification of nanoparticles with polymer ligands has emerged as a versatile approach to control the interactions and organization of nanoparticles in polymer nanocomposite materials. Besides their technological significance, polymer-grafted nanoparticle (PGNP) dispersions have attracted interest as model systems to understand the role of entropy as a driving force for microstructure formation. For instance, densely and sparsely grafted nanoparticles show distinct dispersion and assembly behaviors within polymer matrices due to the entropy variation associated with conformational changes in brush and matrix chains. Here we demonstrate how this entropy change can be harnessed to drive PGNPs into spatially organized domain structures on submicrometer scale within topographically patterned thin films. This selective segregation of PGNPs is induced by the conformational entropy penalty arising from local perturbations of grafted and matrix chains under confinement. The efficiency of this particle segregation process within patterned mesa−trench films can be tuned by changing the relative entropic confinement effects on grafted and matrix chains. The versatility of topographic patterning, combined with the compatibility with a wide range of nanoparticle and polymeric materials, renders SCPINS (soft-confinement pattern-induced nanoparticle segregation) an attractive method for fabricating nanostructured hybrid films with potential applications in nanomaterial-based technologies.

Polymerization-induced self-assembly (PISA) was achieved by conducting an initiators for continuous activator regeneration atom transfer radical polymerization (ICAR ATRP) at low ppm of copper catalyst concentration. A poly(oligo(ethylene oxide) methyl ether methacrylate)50 (POEOMA50) macroinitiator and stabilizer was synthesized by an aqueous ICAR ATRP using CuIICl2/tris(pyridin-2-ylmethyl)amine (TPMA) complex. Subsequently, the dispersion polymerization of benzyl methacrylate (BnMA) in ethanol was realized with a CuIIBr2/TPMA complex either at room temperature or at 65 °C using V-70 or AIBN as radical initiators, respectively. The effect of catalyst concentration, radical initiators, targeted degree of polymerization (DP) of PBnMA, solids content, and temperature on the molecular characteristics and self-assembly behavior of block copolymers POEOMA–PBnMA was evaluated by gel permeation chromatography (GPC), transmission electron microscopy (TEM), and dynamic light scattering (DLS). Block copolymers asse...

The controlled organization of nanoparticle (NP) constituents into superstructures of well-defined shape, composition, and connectivity represents a continuing challenge in the development of novel hybrid materials for many technological applications. We show that the phase separation of polymer-tethered nanoparticles immersed in a matrix of a chemically different polymer provides an effective and scalable method for fabricating well-defined submicron-sized amorphous NP domains in melt polymer thin films. We investigate this phenomenon with a view toward a better understanding and control of the phase separation process in these novel “blends”. In particular, we consider isothermally annealed thin films of polystyrene-grafted gold nanoparticles (AuPS) dispersed in a poly(methyl methacrylate) (PMMA) matrix. A morphology transition from discrete AuPS domains to bicontinuous to inverse domain structure is observed with increasing nanoparticle loading, consistent with composition dependence of classic binary ...

Application of shear stress has been shown to unidirectionally orient the microstructures of block copolymers and polymer blends. In the present work, we study the phase separation of a novel nanoparticle (NP)-polymer blend thin film system under shear using a soft-shear dynamic zone annealing (DZA-SS) method. The nanoparticles are densely grafted with polymer chains of chemically dissimilar composition from the matrix polymer, which induces phase separation upon thermal annealing into concentrated nanoparticle domains. We systematically examine the influence of DZA-SS translation speed and thus the effective shear rate on nanoparticle domain elongation and compare this with the counterpart binary polymer blend behavior. Unidirectionally aligned nanoparticle string-domains are fabricated in the presence of soft-shear in confined thin film geometry. We expect this DZA-SS method to be applicable to various NP-polymer blends towards unidirectionally aligned nanoparticle structures, which are important to functional nanoparticle structure fabrication. The Royal Society of Chemistry 2016. We acknowledge the National Science Foundation via Grant NSF DMR-1411046 for support of this Cold Zone Annealing Soft-Shear study. MRB further acknowledges funding by the National Science Foundation via DMR-1410845. The authors extend their sincere appreciation to the Deanship of Scientific Research at King Saud University for its funding of the Prolific Research group (PRG-1436-14). We are grateful to Dr C. C. Han and Dr K. B. Migler for valuable discussions. Scopus

The phase behavior of poly(styrene)-$b$-poly(1,4-butadiene) diblock copolymers with a polymer block invariant degree of polymerization ${\overline{N}}_{b}\ensuremath{\approx}800$ shows no evidence of Frank-Kasper phases, in contrast to low molar mass diblock copolymers (${\overline{N}}_{b}l100$) with the same conformational asymmetry. A universal self-concentration crossover parameter ${\overline{N}}_{x}\ensuremath{\approx}400$ is identified, directly related to the crossover to entanglement dynamics in polymer melts. Mean-field behavior is recovered when ${\overline{N}}_{b}g{\overline{N}}_{x}$, while complex low symmetry phase formation is attributed to fluctuations and space-filling constraints, which dominate when ${\overline{N}}_{b}l{\overline{N}}_{x}$.

The synthesis, characterization, and self-assembly of a series of linear poly(ethylene-b-styrene-b-isoprene) (PEO−PS−PI) triblock copolymers containing nearly equal volume fractions of PEO and PI (fPEO ≈ fPI) and various fractions of the middle PS block (70.8 vol % ≤ fPS ≤ 75.6 vol %) is reported. A range of azide-functionalized poly(ethylene oxide-b-styrene) diblock copolymers were prepared by atom transfer radical polymerization (ATRP) of styrene using the same batch of PEO-macroinitiator, followed by azide-functionalization. Monohydroxyl-terminated poly(cis-1,4-isoprene) was first alkyne-functionalized and then sequentially attached to azide-functionalized PEO−PS via copper(I)-catalyzed azide−alkyne cycloaddition reaction, producing PEO−PS−PI triblock copolymers with low dispersity. Bulk samples of each linear triblock copolymer reveal the formation of a binary microdomain structure in which a PS and PI domains mix to form a uniform matrix for spherical PEO microdomains, and the PEO microdomains are ar...

The controlled organization of nanoparticle (NP) constituents into superstructures of well-defined shape, composition and connectivity represents a continuing challenge in the development of novel hybrid materials for many technological applications. We show that the phase separation of polymer-tethered nanoparticles immersed in a chemically different polymer matrix provides an effective and scalable method for fabricating defined submicron-sized amorphous NP domains in melt polymer thin films. We investigate this phenomenon with a view towards understanding and controlling the phase separation process through directed nanoparticle assembly. In particular, we consider isothermally annealed thin films of polystyrene-grafted gold nanoparticles (AuPS) dispersed in a poly(methyl methacrylate) (PMMA) matrix. Classic binary polymer blend phase separation related morphology transitions, from discrete AuPS domains to bicontinuous to inverse domain structure with increasing nanoparticle composition is observed, yet the kinetics of the AuPS/PMMA polymer blends system exhibit unique features compared to the parent PS/PMMA homopolymer blend. We further illustrate how to pattern-align the phase-separated AuPS nanoparticle domain shape, size and location through the imposition of a simple and novel external symmetry-breaking perturbation via soft-lithography. Specifically, submicron-sized topographically patterned elastomer confinement is introduced to direct the nanoparticles into kinetically controlled long-range ordered domains, having a dense yet well-dispersed distribution of non-crystallizing nanoparticles. The simplicity, versatility and roll-to-roll adaptability of this novel method for controlled nanoparticle assembly should make it useful in creating desirable patterned nanoparticle domains for a variety of functional materials and applications.

Block copolymers have attracted interests for potential application ranging from dynamic photonic sensors to solid-state ion conductors. However, due to nucleation and growth mechanism, block copolymer inherently forms granular microstructure with defects such as grain boundaries. Understanding the microstructure of block copolymer is thus crucial in many applications because the microstructure determines the transport property of functional fillers such as ions in block copolymer template. Previous research has shown that athermal filler segregated to grain boundary of lamellae block copolymer and retards the grain coarsening. However, the kinetics of this grain boundary segregation during thermal annealing has not been revealed. Polystyrene-b-polyisoprene blended with deuterated polystyrene is used for neutron scattering study on studying the kinetics of grain boundary segregation. Deuterated polystyrene will segregate to grain boundaries, therefore, decorate grain boundary. The filler segregation behavior will be studied by comparing neutron scattering of polystyrene-b-polyisoprene/deuterated polystyrene with different annealing times (at T=130 deg C, duration of 0hr, 3hr, 1day, 3day and 7day, respectively). Invariant (Q) analysis along with grain mapping is conducted to quantitatively analyze the kinetics of grain boundary segregation. This kinetic was in good agreement with the McLean’s kinetic model for grain boundary segregation in metals. By applying Langmuir-Mclean’s segregation isotherm equation, we have predicted the equilibrium concentration of filler in grain boundary by calculating the strain energy stored in grain boundary.

We demonstrate an efficient middle electrode of indium zinc oxides (IZOs) for flexible organic tandem solar cells. A bulk hetero-junction polymer solar cell and a bi-layer hetero-junction organic solar cell are used as the bottom and top cell, respectively. Insertion of a thin interfacial layer of Rb2CO3 or Cs2CO3 between the polymer and IZO and UV–ozone treatment of the IZO surface results in Ohmic contact with the top and bottom cells, respectively. The tandem devices showed that the open circuit voltage (Voc) was almost the same as the sum of the Voc of the individual cells with a fill factor of 0.57. The tandem devices fabricated on flexible PES substrate showed comparable results.

This paper describes design methodologies for the optimal inductive peaking structures used for the 40-Gb/s serializing transmitter circuits presented in. The implemented transmitter had more than 400 on-chip inductors and transformers in order to achieve the bandwidth required for the 38.4-Gb/s operation demonstrated in a 0.13-μm CMOS process. A bridged T-coil network with inverted mutual coupling was found more effective than the conventional T-coil with sizeable driver-side capacitance. An iterative refinement procedure that directly optimizes the circuit's large-signal transient response at the presence of the inductor parasitics and device nonlinearities via HSPICE-ASITIC joint-simulation is described. The procedure resulted in more than 3 × improvement in bandwidth for the CML buffer, multiplexer, and latch circuits. It is shown that the area and the achievable bandwidth of the optimal inductive peaking structures will scale favorably with the CMOS technology trends.

A 20-GHz phase-locked loop with 4.9 ps/sub pp//0.65 ps/sub rms/ jitter and -113.5 dBc/Hz phase noise at 10-MHz offset is presented. A half-duty sampled-feedforward loop filter that simply replaces the resistor with a switch and an inverter suppresses the reference spur down to -44.0 dBc. A design iteration procedure is outlined that minimizes the phase noise of a negative-g/sub m/ oscillator with a coupled microstrip resonator. Static frequency dividers made of pulsed latches operate faster than those made of flip-flops and achieve near 2:1 frequency range. The phase-locked loop fabricated in a 0.13-/spl mu/m CMOS operates from 17.6 to 19.4GHz and dissipates 480mW.

This paper describes the design and the implementation of a fully integrated 10 Gb Ethernet transceiver in a 0.13-/spl mu/m CMOS process using only a 1.2 V supply. A coarse control algorithm that combines a voltage range monitoring circuit with a frequency lock detector provides a robust operation against process, voltage, and temperature (PVT) variations for a VCO with a ring oscillator. With the use of a blind oversampling DPLL architecture, four channels of XAUI transceivers can share a single PLL, eliminating the clock synchronization problem between channels. Also, the total number of clock domains for the entire chip is reduced to three, making the integration of the XAUI with the 10G transceiver much simpler. The test chip consumes 898 mW from a 1.2 V supply.

This paper describes a technique for stabilizing the binary phase detector (PD) gain under various jitter conditions. A dead zone in the phase detector estimates the magnitude of high-frequency data jitter, and the resulting jitter information is used to control the charge-pump current. An alternating edge-sampling (AES) PD reduces hardware overhead by removing possible redundancies in previous dead-zone implementations. A series sense amplifier driven by a single-phase clock helps high-speed data sampling with increased data evaluation time. A dual path voltage-controlled oscillator incorporating dual-loop architecture enables wide-range operation of clock/data recovery circuits with low jitter. Fabricated in a 0.18-/spl mu/m CMOS process, a test transceiver operates from 2.5 to 11.5 Gb/s with a bit-error rate of less than 10/sup -12/ while consuming 540 mW from a 1.8-V supply.

This paper describes a clock/data recovery circuit (CDR) incorporating a variable-interval 3/spl times/-oversampling method for enhanced high-frequency jitter tolerance. The CDR traces the eye-opening region to place the data-sampling clock exactly at the center of the data eye, responding to the shape and magnitude of jitter. A sampler with a pair of input-holding switches enables high-speed data sampling with reduced dynamic offset voltage. From the linearized model of the phase detector, the loop dynamics of the CDR are analyzed. Integrated in a single-chip transceiver with 0.25-/spl mu/m CMOS technology, the CDR operates at a data rate of 5 Gb/s. The CDR shows a bit error rate of less than 10/sup -13/ when the magnitude of data jitter reaches 60.5% of bit time.

In this work, we demonstrate fully uniform blue fluorescence graphene anode OLEDs, which have an emission area of 10u7 mm 2 . Catalytically grown multilayered graphene films have been used as the anode material. In order to compensate the current drop, which is due to the graphene’s electrical resistance, we have furnished metal bus lines on the support. Processing and optical issues involved in graphene anode OLED fabrications are presented. The fabricated OLEDs with graphene anode showed comparable performances to that of ITO anode OLEDs. Our works shows that metal bus furnished graphene anode can be extended into large area OLED lighting applications in which flexibility and transparency is required.

We describe photopatterning technique that employs the photodegradation of cell-adhesive-modified poly(ethyleneimine) (m-PEI) to fabricate precise micropatterns on the indium tin oxide (ITO) substrate for guided neuronal growth. The photodegradation of m-PEI coated on hydroxyl group-terminated ITO substrate created micropatterns over a large area through deep UV irradiation. The photopatterned m-PEI layer can effectively guide neurite outgrowth and control neurite extensions from individual neurons.

A bandpass ΔΣ interface IC for sacrificial bulk micromachined inertial sensors is presented. To achieve high resolution without precision analog circuits, the proposed architecture replaces the analog mixer of a chopper-stabilized readout amplifier with a 1-bit, 4th-order bandpass ΔΣ modulator and a digital decimator/demodulator. Leveraging the high over-sampling ratio of 8192 and the supporting circuit techniques, the interface IC provides a 128-Hz, 20-bit digital output with 113 dB peak SNR and 115 dB dynamic range (DR). Fabricated in 0.18 μm CMOS, the IC dissipates 56.1 mW.

Implemented in 0.13/spl mu/m CMOS, the 40Gb/s transmitter uses shunt-and-double-series inductive peaking and negative feedback for bandwidth enhancement and pulsed latch-based dividers and retimers for timing closure. The 38.4Gb/s 2/sup 31/-1 PRBS transmitted eye has differential voltage swing of 549mV/sub pp/, rise time of 14ps, and clock jitter of 0.65/sub rms/ and 4.9/sub pp/.

This paper describes a quad 3.125 Gbps transceiver focusing on digital data recovery circuits. Effect of each design parameters on jitter tolerance (JTOL) is analyzed and for better JTOL, a new phase-averaging method with internal forward path is proposed. On-chip JTOL measurement circuits are implemented to characterize the transceiver performance, and it shows that the proposed method improves the JTOL about 0.1 UI. Implemented in 0.13 CMOS, the transceiver tolerates up to 0.67 UI of total jitter at 3.125Gbps.

A 20GHz phase-locked loop with 4.9ps/sub pp//0.65ps/sub rms/ jitter and -101.2dBc/Hz phase noise at 1MHz offset is presented. A half-duty sampled-feedforward loop filter that simply replaces the resistor with a switch and an inverter suppresses the reference spur down to -44.0dBc. A design iteration procedure is outlined that minimizes the phase noise of a negative-g/sub m/ oscillator with a coupled-microstrip resonator. Static frequency dividers made of pulsed latches operate faster than a flip-flop based divider and achieve near 2:1 frequency range. The PLL fabricated in 0.13/spl mu/m CMOS operates from 17.6GHz to 19.4GHz and dissipates 480mW.

A 10 Gb Ethernet transceiver chip integrated with 10 Gb/s serial and quad 3.125 Gb/s XAUI interfaces is implemented in 0.13 /spl mu/m CMOS and dissipates 898 mW from 1.2 V. A digital coarse control algorithm for VCOs reduced the VCO gains for noise immunity. A blind oversampling technique enabled synthesis of the XAUI interface.

We present here the design of a novel variable q-range x-ray scattering instrument recently installed at Sector 12 of the Advanced Photon Source. This device provides automated, computer-controlled q-range changes for x-ray scattering experiments by varying the sample-to-detector distance within a large vacuum chamber. Eliminating the need to vent the system when changing camera lengths allows for quick and efficient change-overs between experimental setups. The detector cannot operate in a vacuum environment; therefore it is housed within an air chamber open to atmospheric pressure. A large carbon window isolates the detector from vacuum while allowing high x-ray transmission. An array of motorized beam stops mounted directly upstream of the window protects the detector from the direct x-ray beam for various types of scattering experiments. A smaller detector protrudes into the lower front section for simultaneous wide-angle x-ray scattering data collection. A fully automated support structure aligns the vacuum chamber to the x-ray trajectory.

In this paper, we demonstrated a facile photopatterning method that uses photocrosslinkable polyfluorene to fabricate micro-sized photopatterns on transparent indium tin oxide substrate for neuronal patterning. The modified poly(ethyleneimine) (m-PEI) with trimethoxysilane moiety was chemically attached to the hydroxyl group-terminated ITO surface and then the photopatternable polyfluorene derivative was spin coated as a cell-repellent layer onto the m-PEI-coated surface. The well-defined micropatterns were easily created over an entire surface by photocrosslinking of bromoalkyl-substituted polyfluorene (Br-PF) via the radical coupling reaction of a C–Br bond under UV irradiation without an initiator. UV-Vis absorbance, photoluminescence, ATR-FTIR and X-ray photoelectron spectroscopy were used to confirm the photocrosslinking process and the surface composition before and after the photocrosslinking of polyfluorene. The pairing of adhesive m-PEI and repulsive Br-PF effectively guided the neurite outgrowth and controlled neurite extension from individual neurons to the pre-patterned direction with excellent pattern fidelity. Guided neuronal cells were maintained for at least 25 days in vitro without any detachment of neuronal cells during cell culture. A photopatternable polyfluorene derivative in combination with cell-adhesive m-PEI is proved to be an effective way to modify the electrode surface to achieve single cell level neuronal networks.