Small-angle x-ray scattering experiments conducted with compositionally asymmetric low molar mass poly(isoprene)-b-poly(lactide) diblock copolymers reveal an extraordinary thermal history dependence. The development of distinct periodic crystalline or aperiodic quasicrystalline states depends on how specimens are cooled from the disordered state to temperatures below order-disorder transition temperature. Whereas direct cooling leads formation documented morphologies, rapidly quenched...

Self-consistent field theory (SCFT) is a powerful tool for the design and interpretation of experiments on block polymer materials. In this Perspective, we lower barrier to entry use SCFT by experimental groups two means. First, present pedagogical introduction an improved version open-source Polymer Self-Consistent Field (PSCF) software package underlying theory. Second, discuss methods generating robust initial guesses fields that are computed in SCFT. To demonstrate our approach, case...

We present a system for the electrocoalescence of microfluidic droplets immersed in an immiscible solvent, where undeformed droplet diameters are comparable to channel diameter. The electrodes not direct contact with carrier liquid or droplets, thereby minimizing risk cross-contamination between different coalescence events. Results presented buffered aqueous both quiescent and flowing fluorocarbon streams, on-flight is demonstrated. capillary-based here readily amenable further...

We have used a realistic model for double stranded DNA and Monte Carlo simulations to compute the extension (mean span) of molecule confined in nanochannel over full range confinement high ionic strength buffer. The simulation data square nanochannels resolve apparent contradiction between prior studies predictions from Flory theory, demonstrating existence two transition regimes weak (the de Gennes regime) strong Odijk regime). rectangular support use geometric mean mapping obtained...

Picking up at the conclusion of Viovy's review physics gel electrophoresis [J.-L. Viovy, Rev. Mod. Phys. 72, 813 (2000)], this synthesizes experimental data, theoretical models, and simulation results for DNA in microfabricated nanofabricated devices appearing since seminal paper by Volkmuth Austin [Nature (London) 358, 600 (1992)]. Prototype versions these separate molecular weight a rate far superior to electrophoresis. After providing an overview requisite background material polymer...

Single molecular species can self-assemble into Frank-Kasper (FK) phases, finite approximants of dodecagonal quasicrystals, defying intuitive notions that thermodynamic ground states are maximally symmetric. FK phases speculated to emerge as the minimal-distortional packings space-filling spherical domains, but a precise measure this distortion and how it affects assembly thermodynamics remains ambiguous. We use two complementary approaches demonstrate principles driving lattice formation in...

We designed a microfluidic chemostat consisting of 600 sub-micron trapping/growth channels connected to two feeding channels. The microchemostat traps E. coli cells and forces them grow in lines for over 50 generations. Excess cells, including the mother captured at start process, are removed from both ends growth by media flow. With aid time-lapse microscopy, we have monitored dynamic properties such as rate GFP expression single-cell level many generations while maintaining population...

The details surrounding the crossover from wormlike-specific to universal polymeric behavior has been subject of debate and confusion even for simple case a dilute, unconfined wormlike chain. We have directly computed polymer size, form factor, free energy, Kirkwood diffusivity chains as function molecular weight, focusing on persistence lengths effective widths that represent single-stranded double-stranded DNA in high ionic strength buffer. To do so, we use chain-growth Monte Carlo...

Cooling disordered compositionally asymmetric diblock copolymers leads to the formation of nearly spherical particles, each containing hundreds molecules, which crystallize upon cooling below order-disorder transition temperature (

Significance The main stabilizer of the DNA double helix is not base-pair hydrogen bonds but coin-pile stacking base pairs, whose hydrophobic cohesion, requiring abundant water, indirectly makes interior dry so that can exert full recognition power. We report certain semihydrophobic agents depress energy (measurable in single-molecule experiments), leading to transiently occurring holes stack (monitorable via binding threading intercalators). Similar structures observed complexes with RecA...

We report the phase behavior of a series poly(styrene)-b-poly(isoprene)-b-poly(styrene)′-b-poly(ethylene oxide) (SIS′O) tetrablock terpolymers. This study was motivated by self-consistent field theory (SCFT) calculations that anticipate rich array sphere-forming morphologies with variations in molecular symmetry parameter τ = NS/(NS + NS′), where N is block degree polymerization and volume fraction O less than about 0.22. Eight SIS′O samples, ranging from 0.21 to 0.73, were synthesized...

The discovery of the Frank–Kasper σ phase in diblock copolymer and tetrablock terpolymer melts catalyzed a renewed interest over past decade understanding particle-forming phases block polymer systems. This Perspective provides concise overview seen to date polymers (A15, σ, C14 C15 Laves phases) mechanisms known produce them: conformational asymmetry neat melts, interfacial segregation effects blends, particle swelling copolymer/homopolymer matrix melts. While qualitative emergence systems...

We present a fully automated system performing continuous sampling, reagent mixing, and polymerase chain reaction (PCR) in microdroplets transported immiscible oil. Sample preparation analysis are totally automated, using an original injection method from modified 96-well plate layered with three superimposed liquid layers in-capillary laser-induced fluorescence endpoint detection. The process is continuous, allowing sample droplets to be carried uninterruptedly into the zone while new drops...

DNA confinement in nanochannels is emerging as an important tool for genomics and excellent platform testing the theories of confined wormlike polymers. Using cutting-edge, large scale Monte Carlo simulations asymptotically long chains, we show that, analogy to rod-to-coil transition free polymers, there exists a universal, Gauss--de Gennes regime that connects classic Odijk de regimes channel-confined chains. For nanochannel, this spans practically entire experimentally relevant range...

We report a method to measure DNA hybridization potentiometrically in manner conducive portable or hand-held biosensors. An electrolyte-gated transistor (EGT) based on poly(3-hexylthiophene) (P3HT) and an ion-gel serves as transducer for surface of DNA. The key aspect the design is use floating-gate electrode functionalized with ssDNA whose potential determined by both capacitive coupling primary, addressable gate presence adsorbed molecules. When hybridized at floating gate, it offsets...

Using pruned-enriched Rosenbluth method (PERM) simulations of a discrete wormlike chain model, we provide compelling evidence in support Odijk's prediction two distinct Odijk regimes for long confined nanochannel. In both cases, the persistence length lp is renormalized into series deflection segments characteristic D2/3lp1/3, where D channel size. first (classic) regime, these are linearly ordered. second thin, chains can backfold at scale quantified by global length. We have measured this...

Significance Frank–Kasper phases are low-symmetry packings of particles, originally discovered in metals and alloys now observed a wide range soft matter. Understanding how such arise materials is an outstanding challenge, as they tend to form high-symmetry, close-packed structures. This work uncovers mechanism for generating diblock copolymers with matrices that prefer body-centered cubic structure the neat-melt state. As homopolymer loaded into core system selects series increasing...

We present a method for performing polymerase chain reaction (PCR) using isolated droplets flowing in an immiscible fluorinated solvent system. Thanks to optimized control of interfacial properties, we could achieve this capillary-based system reproducible amplification factors, without any detectable contamination between neighboring droplets. The is readily amenable further miniaturization and automation serves as the first step toward clinically viable, high-throughput, quantitative...