Miktoarm Star Copolymer Capsules Bearing pH-Responsive Nanochannels

Despite the diversity of nanostructures that have been created from block copolymers over the past two decades, the challenging fabrication of polymer nanocapsules bearing regularly sized nanochannels has not been possible until now. In this study, a pseudo miktoarm copolymer μ-(PtBA)­(PCEMA)­(PEO)_1.14 was prepared. The copolymer consisted of 1 poly­(<i>tert</i>-butyl acrylate) (PtBA) chain, 1 poly­(2-cinnamoyloxyethyl methacrylate) (PCEMA) chain, and an average 1.14 poly­(ethylene oxide) (PEO) chains. This polymer formed vesicles in a tetrahydrofuran/water solvent mixture with the soluble PEO block as the corona. At 100 units long, the PtBA chains formed cylinders that permeated the wall made of PCEMA chains at 130 units long. Photo-cross-linking the PCEMA wall and hydrolyzing the PtBA chains in the cylindrical domains yielded unprecedented capsules bearing regularly packed uniform poly­(acrylic acid)-gated nanochannels. These capsules exhibited pH-responsive reagent release in aqueous media

UV-Curable Antismudge Coatings

Current antismudge coatings that bear nano-pools of a grafted liquid ingredient for dewetting enablement (NP-GLIDE) are cured at high temperatures, which are undesirable for application on heat-sensitive substrates. Reported herein is the development of a NP-GLIDE coating that can be photocured at room temperature. Of the various formulations that have been tested, robust coatings were obtained from one recipe consisting of a photoinitiator, a trifunctional monomer that bears three double bonds, and a graft copolymer. The last bears pendent double bonds and a poly­(dimethylsiloxane) (PDMS) side chain as the antismudge agent. Coatings were prepared by casting films from a solution containing these three components and then photolyzing the resultant films. A systematic study revealed that the liquid sliding property developed on the coating at a lower cross-linking density than that required for ink to contract. Further, retaining the ability to contract ink traces after many writing and erasing cycles was the most demanding of the three antismudge tests. For our optimized formulation, only 5 min of irradiation was required to yield a transparent coating with superior antismudge properties. Moreover, irradiating selected regions and then removing, with a solvent, reagents in the nonirradiated regions can yield a surface with patterned wettability. These advantageous properties of the new photocurable coating facilitate its applications

DataSheet1_Detection of copy number variations based on a local distance using next-generation sequencing data.docx

As one of the main types of structural variation in the human genome, copy number variation (CNV) plays an important role in the occurrence and development of human cancers. Next-generation sequencing (NGS) technology can provide base-level resolution, which provides favorable conditions for the accurate detection of CNVs. However, it is still a very challenging task to accurately detect CNVs from cancer samples with different purity and low sequencing coverage. Local distance-based CNV detection (LDCNV), an innovative computational approach to predict CNVs using NGS data, is proposed in this work. LDCNV calculates the average distance between each read depth (RD) and its k nearest neighbors (KNNs) to define the distance of KNNs of each RD, and the average distance between the KNNs for each RD to define their internal distance. Based on the above definitions, a local distance score is constructed using the ratio between the distance of KNNs and the internal distance of KNNs for each RD. The local distance scores are used to fit a normal distribution to evaluate the significance level of each RDS, and then use the hypothesis test method to predict the CNVs. The performance of the proposed method is verified with simulated and real data and compared with several popular methods. The experimental results show that the proposed method is superior to various other techniques. Therefore, the proposed method can be helpful for cancer diagnosis and targeted drug development.</p

Support-Free Porous Polyamine Particles for CO₂ Capture

CO₂ emission from fossil fuel combustion is a major anthropogenic factor for global warming. Solid amine sorbents may be used to remove CO₂ from waste flue gases before their emission into the atmosphere. These particles are currently obtained by loading amine-containing compounds or polymers onto premade or commercially available porous supports. These supports play no active role in CO₂ uptake and increase the amount of heat or cost required to regenerate CO₂-sorbed particles by heating. Reported in this communication are the preparation, by precipitation polymerization, of support-free polyamine porous particles and the performance of these particles in CO₂ capture at room temperature and release at 100 °C

Simultaneous Coating of Silica Particles by Two Diblock Copolymers

Silica particles have been coated by two diblock copolymers, P1 and P2, through a one-pot reaction, and the resultant particles were characterized. The P1 and P2 used were synthesized by anionic polymerization and denote PIPSMA-<i>b</i>-PFOEMA and PIPSMA-<i>b</i>-PtBA, respectively. Here PIPSMA, PFOEMA, and PtBA correspond individually to poly­[3-(triisopropyloxysilyl)­propyl methacrylate], poly­(perfluorooctylethyl methacrylate), and poly­(<i>tert</i>-butyl acrylate). Catalyzed by HCl, the PIPSMA blocks of P1 and P2 co-condensed onto the surface of the same silica particles, exposing the PtBA and PFOEMA blocks. The relative amounts of grafted P1 and P2 could be tuned by changing the P1 to P2 weight ratio and were quantified by thermogravimetric analysis. The vertical segregation of the PFOEMA and PtBA chains could also be adjusted. Casting a dispersion of the coated particles in a solvent selective for either PFOEMA or PtBA onto glass plates or silicon wafers yielded films consisting of bumpy silica particles whose surfaces were enriched by the polymer that was soluble in the casting solvent. Particulate coatings with tunable surface wetting properties were obtained by changing either the proportion of grafted P1 and P2 or the casting solvent for coated silica. When a silica dispersion in perfluoromethylcychohexane (C₇F₁₄) was cast, films of coated silica that had P1 weight fractions of 25, 50, and 75% were all superhydrophobic because the particle surfaces were enriched by PFOEMA, which was selectively soluble in C₇F₁₄

Fluorinated Raspberry-like Polymer Particles for Superamphiphobic Coatings

Raspberry-like (RB) polymer particles were prepared, fluorinated, and cast onto glass plates to yield highly water- and oil-repellant superamphiphobic particulate coatings. To procure the RB particles, glycidyl-bearing 212 and 332 nm particles (abbreviated as <i>s</i>-GMA and <i>l</i>-GMA, respectively) were first prepared via surfactant-free free radical emulsion polymerization. Reacting the glycidyl groups of the <i>l</i>-GMA particles with 2,2′-(ethylenedioxy)­bis­(ethylamine) (EDEA) produced large amine-functionalized particles (<i>l</i>-NH₂). The <i>l</i>-NH₂ particles were then reacted with an excess of the <i>s</i>-GMA particles to create RB particles. For surface fluorination, the residual glycidyl groups of the smaller <i>s</i>-GMA particles surrounding the central <i>l</i>-NH₂ core of the RB particles were first converted to amino groups by reaction with EDEA. The purified amino-bearing particles were subsequently reacted with an excess of a statistical copolymer poly­(2-(perfluorooctyl)­ethyl methacrylate-<i>co</i>-glycidyl methacrylate), P­(FOEMA-<i>co</i>-GMA). Casting these particles onto glass plates yielded particulate films that exhibited static contact angles of 165 ± 2°, 155 ± 3°, 152 ± 4°, and 143 ± 1° and droplet rolling angles of <1 °, <1 °, 7 ± 2°, and 13 ± 2° for water, diiodomethane, corn-based cooking oil, and hexadecane droplets, respectively. These results demonstrated that this practical bottom-up approach could be used to produce superamphiphobic coatings

Mesogen-Driven Formation of Triblock Copolymer Cylindrical Micelles

Evidences were gathered to support mesogen-driven formation of cylindrical micelles from BCF and ACF triblock copolymers. Here A, B, C, and F denote poly­(acrylic acid), poly­(<i>tert</i>-butyl acrylate), poly­(2-cinnamoyloxylethyl methacrylate), and the liquid crystalline poly­(perfluorooctylethyl methacrylate) block, respectively. At room temperature (21 °C) in all tested solvents that were selective for the A or B blocks, three of the four copolymers with various compositions formed exclusively cylindrical micelles possessing an F core, a C shell, and an A or B corona. Our further analyses indicated that the F core chains were almost fully stretched, and the C shell chains were compressed relative to their unperturbed dimensions. These abnormal chain packing motifs suggest that the need to form a liquid crystalline F phase in the cores dictated micelle formation and prevailed over the needs of the shell chains to achieve their normal stretched conformations. A subsequent wide-angle X-ray scattering study of the dried cylindrical micelles confirmed smectic A phase formation for the F blocks at room temperature. The smectic A to isotropic phase transition upon raising temperature was detected by a differential scanning calorimeter for the dry cylindrical micelles and by ¹⁹F NMR for the solvated micelles. This smectic A to isotropic phase transition was accompanied by a morphological transformation from cylindrical micelles at room temperature to other morphologies at 70 °C. More interestingly, this cylinder to vesicle conversion could be cycled repeatedly by temperature cycling for one ACF sample

Polygonal Micellar Aggregates of a Triblock Terpolymer Containing a Liquid Crystalline Block

Block copolymers self-assemble in block-selective solvents into diverse nanometer-sized micellar aggregates (MAs). Understanding the formation mechanisms of these morphologies is challenging but important for the design and synthesis of block copolymer architectural materials. Here we report our discovery that polygonal or enclosed cylindrical MAs bearing sharp bends can be formed from a triblock terpolymer containing a liquid crystalline block. We propose that the sharp bends are formed mainly to enable approximately straight sides in which the liquid crystalline packing of the core block is facilitated and the cylinder bending energy is reduced. However, this energy reduction is counteracted by an energy increase due to the concentration of smectic edge dislocations at the vertices. Thus, polygonal MAs are formed only when the toroidal MAs are sufficiently small and the cylinders experience significant bending. We theoretically estimate critical toroidal size below which the transition from round toroids to polygons occurs. This estimated size agrees with our experimental observations, supporting our hypothesis and analysis

Silicone-Infused Antismudge Nanocoatings

A polyurethane-based NP-GLIDE coating that bears on its surface and in its interior <b>n</b>ano-<b>p</b>ools of a <b>g</b>rafted <b>l</b>iquid <b>i</b>ngredient for <b>d</b>ewetting <b>e</b>nablement is obtained from casting and curing a film comprising a triisocyanate, a polyol (P1), and a graft (<i>g</i>) copolymer of P1 and poly­(dimethyl­siloxane) (P1-<i>g</i>-PDMS). A silicone-infused NP-GLIDE (SINP-GLIDE) PU coating is obtained from cocasting the NP-GLIDE precursors with a free silicone oil (SO) or SO mixture (SOs). This paper reports the preparation of the novel SINP-GLIDE coatings and discusses the effect of changing the amount and type of the infused SO as well as the coating formation conditions on their optical clarity. Also reported are the contact and sliding angles of various test liquids on the NP-GLIDE and SINP-GLIDE coatings, and the data variation trends are rationalized using existing theories. Further, the stable water sliding performance of the SINP-GLIDE coatings under simulated raining and other conditions is demonstrated. The improved and stable water sliding performance of the SINP-GLIDE coatings facilitates their practical applications

Tunable Ultrathin Membranes with Nonvolatile Pore Shape Memory

The concept of a responsive nanoporous thin-film gel membranes whose pores could be tuned to a desired size by a specific “molecular signal” and whose pore geometry becomes “memorized” by the gel is reported. The ∼100 nm thick membranes were prepared by dip-coating from a solution mixture of a random copolymer comprising responsive and photo-cross-linkable units and monodisperse latex nanoparticles used as a sacrificial colloidal template. After stabilization of the films by photo-cross-linking the latex template was removed, yielding nanoporous structures with a narrow pore size distribution and a high porosity. The thin-film membranes could be transferred onto porous supports to serve as tunable size-selective barriers in various colloids separation applications. The pore dimensions and hence the membrane’s colloidal-particle-size cutoff were reversibly regulated by swelling–shrinking of the polymer network with a specially selected low-molar-mass compound. The attained pore shape was “memorized” in aqueous media and “erased” by treatment in special solvents reverting the membrane to the original state