Simple “On‐Demand” Production of Bioactive Natural Products

Exchange of the native promoter to the arabinose‐inducible promoter P_BAD was established in entomopathogenic bacteria to silence and/or activate gene clusters involved in natural product biosynthesis. This allowed the “on‐demand” production of GameXPeptides, xenoamicins, and the blue pigment indigoidine. The gene clusters for the novel “mevalagmapeptides” and the highly toxic xenorhabdins were identified by this approach.     

“Pore/bead” membrane for rechargeable lithium ion batteries

A special “pore/bead” membrane was prepared with a mesoporous inorganic filler (MCM‐41) and a P(VDF‐HFP) binder. The special “pore/bead” structure of the MCM‐41 filler not only enhanced the puncture strength of the membrane but also improved its ionic conductivity. The puncture strength of the dried “pore/bead” membrane (MCM‐41 : P(VDF‐HFP) = 1 : 1.5) was 18 N, and showed a slight decrease (16 N) after the membrane was wetted by liquid electrolyte. Additionally, the composite membrane showed excellent thermal dimensional stability. The composite membrane could be activated by adding 1M LiClO₄‐EC/DMC (1 : 1 by volume). The activated membrane displayed a high ionic conductivity about 3.4 × 10^?3 S cm^?1 at room temperature. Its electrochemical stability window was up to 5.3 V vs. Li/Li⁺, indicating that it was very suitable for lithium‐ion battery application. The battery assembled using the composite electrolyte also showed reasonably good high‐rate performance. The approach of preparing a “pore/bead” membrane provides a new avenue for improving both the conductivity and the mechanical strength of polymer electrolytes for lithium batteries. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Treatment of gases and dust using “droplet columns”

The properties of the air-water state diagram, representing the liquid holdups according to gas velocities, in a 0.075 m diameter column are restated. After measurement of the interfacial areas and mass-transfer coefficients, the part of the diagram corresponding to high gas velocities and low liquid contents (10 < U_G < 14 m/s and 0.005 < U_L < 0.04 m/s) was chosen for the treatment of polluted gas streams. Under these conditions, it was shown that a “droplet column” is very efficient for the treatment of gases polluted by acid vapors (SO₂, HCl) and dust (iron oxide, talc, etc.). The cost of energy appeared more favorable than for classical bubble columns.     

Construction of waste-collagen modified superfine fiber substrates based on “click” chemistry: Moisture absorption and permeability

Superfine fiber synthetic leather is a high-grade artificial leather product with numerous characteristics and advantages. However, compared with natural leather, it shows poor moisture absorption and moisture permeability, and it gives people a hot and tacky feeling; thus, the improvement of these properties has become a popular topic in the industry. In this paper, the “click” chemistry method was employed to modify the nylon fiber of the superfine fiber synthetic leather base with waste collagen to improve the moisture absorption and permeability of the superfine fiber synthetic leather base, thus enhancing the hygienic performance and wearing comfort of the end products, realizing waste recycling. This study obtained the optimal reaction conditions for the “click” modification of unfigured sea-island superfine fiber synthetic leather base with collagen methacrylamide. The characterizations by static contact angle measurements, attenuated total reflection infrared spectroscopy, and X-ray photoelectron spectroscopy analysis confirmed that collagen was successfully grafted onto the surface of the nylon fiber. Compared with the original base, the moisture absorption, and permeability of the base were improved by 602.4% and 43%, respectively. This study shows the theoretical research significance and excellent practical value for the resource utilization of skin collagen waste.     

Modeling of “living” free‐radical polymerization processes. I. Batch,semibatch, and continuous tank reactors

A comprehensive mathematical model is developed for “living” free‐radical polymerization carried out in tank reactors and provides a tool for the study of process development and design issues. The model is validated using experimental data for nitroxide‐mediated styrene polymerization and atom transfer radical copolymerization of styrene and n‐butyl acrylate. Simulations show that the presence of reversible capping reactions between growing and dormant polymer chains should boost initiation efficiency when using free nitroxide in conjunction with conventional initiator and also increase the effectiveness of thermal initiation. A study shows the effects of the value of the capping equilibrium constant and capping reaction rate constants for both nitroxide‐mediated styrene polymerization (using alkoxyamine as polymer chain seeds) and atom transfer radical polymerization of n‐butyl acrylate (using methyl 2‐bromopropionate as chain extension seeds). Also the effect of introducing additional conventional initiator into atom transfer radical polymerization of n‐butyl acrylate is studied. It is found that the characteristics of long chain growth are determined by the fast exchange of radicals between growing and dormant polymer chains. Polymerization results in batch, semibatch, and a series of continuous tank reactors are analyzed. The simulations also show that a semibatch reactor is most flexible for the preparation of polymers with controlled architecture. For continuous tank reactors, the residence time distribution has a significant effect on the development of chain architecture. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1630–1662, 2002     

Efficient synthesis of zwitterionic sulfobetaine group functional polyurethanes via “click” reaction

A novel polyurethane material containing zwitterionic sulfobetaine groups has been synthesized using the copper‐catalyzed 1,3‐dipolar cycloaddition (azide‐alkyne click chemistry). A standard two‐step polyaddition method was used to produce the well‐defined polyurethane based on polycarbonatediol (PCDL) with alkyne groups. These polyurethanes containing alkyne units were then efficiently clicked using 3‐((2‐azidoethyl)dimethylammonio)propane‐1‐sulfonate (DMPS‐N₃). The novel PU material was characterized by ¹H NMR, Fourier transform infrared (FTIR) spectrometer, gel permeation chromatography (GPC), elemental analysis, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA). This facile “click” reaction provides a useful tool for the development of novel functional polyurethanes for biomedical applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

“Click” Polymer‐Supported Palladium Nanoparticles as Highly Efficient Catalysts for Olefin Hydrogenation and Suzuki Coupling Reactions under Ambient Conditions

Complexation of palladium(II) acetate [Pd(OAc)₂] or dipotassium tetrachloropalladate [K₂PdCl₄] to “click” polymers functionalized with phenyl, ferrocenyl and sodium sulfonate groups gave polymeric palladium(II)‐triazolyl complexes that were reduced to “click” polymer‐stabilized palladium nanoparticles (PdNPs). Transmission electron microscopy (TEM) showed that reduction using sodium borohydride (NaBH₄) produced PdNPs in the 1–3 nm range of diameters depending on the nature of the functional group, whereas slow reduction using methanol yielded PdNPs in the 22–25 nm range. The most active of these PdNPs (0.01% mol Pd), stabilized by poly(ferrocenyltriazolylmethyl)styrene, catalyzed the hydrogenation of styrene at 25 °C and 1 atm hydrogen, with turnover numbers (TONs) of 200,000. When stabilized by the water‐soluble poly(sodium sulfonate‐triazolylmethyl)styrene, the PdNPs (0.01% mol Pd) catalyze the Suzuki–Miyaura coupling between iodobenzene (PhI) and phenylboronic acid [PhB(OH)₂] in water/ethanol (H₂O/EtOH) at 25 °C with TONs of 8,200. This high catalytic activity is comparable to that obtained with “click” dendrimer‐stabilized PdNPs under ambient conditions.     

Synthesis and characterization of the new cellulose derivative films based on the hydroxyethyl cellulose prepared from esparto “stipa tenacissima” cellulose of Eastern Morocco. II. Esterification with acyl chlorides in a homogeneous medium

Esparto “Stipa tenacissima” cellulose esters derivatives: HECA‐COO? C₄H₈? COOC₂H₅, HECA‐COO? C₈H₁₆? COOC₂H₅, and HECA‐COO? C₆H₄? COOC₂H₅ were successfully prepared in Tetrahydrofuran (THF)/triethylamine system with a degree of substitution (DS), respectively, DS_AD‐Et=0.32, DS_SB‐Et=0.22, and DS_TRP‐Et=0.50 using hydroxyethyl cellulose acetate (HECA; DS_AC=0.50) as intermediate product, and we avoided the drawbacks of cellulose solubility. The structural modifications were investigated using Fourier transform infrared spectroscopy (FTIR), Proton nuclear magnetic resonance (¹H‐NMR), Carbon‐13 nuclear magnetic resonance (¹³C‐NMR), and Distortionless Enhancement by Polarization Transfer 135° (DEPT‐135). The results from these analyses revealed the presence of the characteristic groups indicating that the grafting reaction was successful. The crystallinity and the structure order changes during the esterification reactions were recorded by X‐ray diffraction (XRD), it is found that the crystallinity degree decrease from 63.1% for Esparto “Stipa tenacissima” cellulose to 27.74% for HECA. The thermal stability of the esterified and unmodified cellulose samples was studied by thermogravimetric analysis (TGA)‐differential thermal analysis (DTA); the modified HECA exhibits a decrease in thermal stability relatively to the unmodified HECA, and this may be related to the groups grafted. The resulted cellulose esters HECA‐P_x (x = 1, 2, or 3) were soluble in THF and present an amorphous structure justified by XRD spectra. It was noted by TGA‐DTA analysis that the cellulose esters with low melting range were proved as thermoplastic polymers. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis and Characterization of Segmented Block Copolymers Based on Hydroxyl‐Terminated Liquid Natural Rubber and α,ω‐Diisocyanato Telechelics

Summary: Segmented block copolymers, consisting of non‐polar soft segments from hydroxyl‐terminated liquid natural rubber (HTNR) and polar hard segments from α,ω‐diisocyanato telechelics obtained by “criss‐cross”‐cycloaddition, have been synthesized. The block copolymer formation took place under relatively mild reaction conditions at 80 °C in dichloroethane in the presence of dibutyltin dilaurate as a catalyst. The resulting block copolymers were characterized by spectroscopic techniques (¹H NMR, FTIR, UV‐vis spectroscopy) as well as GPC for molar mass determination. The block copolymers were compression molded in a hot stage press, and the resulting samples were characterized by DSC and stress‐strain measurement. The solubility and phase morphology of the materials have also been studied.

Segmented block copolymer from HTNR and α,ω‐diisocyanato telechelics     

Hg(II) removal with polyacrylamide grafted crosslinked poly(vinyl chloride) beads via surface‐initiated controlled/“living” radical polymerization

Polyacrylamide grafted crosslinked poly (vinyl chloride) beads (PAM‐PVC) were prepared by the surface‐initiated controlled/“living” radical polymerization (SI‐CLRP) methodology from the crosslinked poly(vinyl chloride) beads with surface modification with diethyldithiocarbamyl groups under UV irradiation. The macroiniferter, diethyldithiocarbamyl crosslinked poly(vinyl chloride) beads (DEDTC‐PVC) were prepared by the reaction of the surface C? Cl groups with sodium N,N‐diethyl dithiocarbamate. The “grafting from” polymerization exhibited some “living” polymerization characteristics and the percentage of grafting (PG%) increased linearly with polymerizing time and achieved 47.6% after 6 h UV irradiation. The beaded polymer with polyacrylamide surface was also characterized with Fourier transform infrared (FTIR) and scanning electron microscope (SEM). Its adsorption property for Hg(II) ion was also investigated preliminarily. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:3385–3390, 2006     

Electrospinning of Poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) nanofibers with feature surface microstructure

The development of surface microstructure with specific features in electrospun nanofibers has attracted more and more attention in recent years. In this article, a common biological polyester, poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) was electrospinning into nanofibers with “coral‐like” surface microstructure by a conventional‐electrospinning setup. The effect of the process parameters on the microstructure in electrospun nanofibers were investigated via a series of experiments. The formation mechanism of this feature structure and cytotoxicity assays of PHBV membrane were also discussed. The water contact angle of the electrospun PHBV membrane was higher than that of the PHBV cast film due to a very‐rough fiber surface including porous beads when PHBV was electrospun from the concentration of 4 wt %. Because of special hole shape and size distribution, the physical structure of surface of PHBV electrospun fibers offered it special properties, such as specific‐surface area, hydrophilic–hydrophobic properties, adhesion properties of cells and biological substances, etc. The demonstrated method of form coral structure would contribute to the areas such as filtration, sensor, tissue engineering scaffolds, and carriers of drugs or catalysis. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Polymerization of methyl methacrylate with a thermal iniferter: Diethyl 2,3‐dicyano‐2,3‐di(p‐tolyl)succinate

A hexa‐substituted ethane type compound, diethyl‐2,3‐dicyano‐2,3‐di(p‐tolyl)succinate (DCDTS), was successfully synthesized and used for initiation of methyl methacrylate (MMA) polymerization. The reaction demonstrated the characteristics of a “living” polymerization; i.e., both the yield and the molecular weight of the resulting polymers increased linearly with increasing reaction time, the molecular‐weight distribution of PMMA obtained was ～1.60 and almost unaffected by the conversion, and the resultant polymer can be chain extended by adding fresh MMA. End group analysis of the resultant PMMA confirmed that DCDTS behaves as a thermal iniferter for MMA polymerization. A block copolymer was prepared from the resultant PMMA, which contains a hexa‐substituted C? C bond functional end group. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2566–2572, 2001     

Crosscultural comparison of color terms and preference of persimmon‐dyed fabric,Galchon

This crosscultural study was aimed at correlating color emotions and preference for persimmon‐dyed cotton fabrics known as Galchon. Cotton fabrics were dyed with persimmon powder, in a range of shades, and in some cases were also iron mordanted. Textile and fashion students from Jeju National University in Korea and North Carolina State University (NCSU) in USA participated in the visual assessment of dyed samples and were asked to scale their visual experience and state their emotion and preference for the terms “Bright,” “Heavy,” “Soft,” “Strong,” “Deep,” and “Like.” Korean observers used “Strong” for iron‐mordanted Galchon, and American observers did not associate “Bright” or “Deep” with weakly dyed fabrics. In addition to the subjective terms described, the color preference for samples was quantified using their CIE colorimetric attributes. For Korean observers, the results indicate a correlation between L^* and “Bright,” whereas for Americans a stronger correlation was obtained against “Soft.” American observers' results also show a relationship between C^* and the term “Warm,” especially for dyeings of Galchon at high concentrations. It was also found that iron mordanting affected responses from both groups but only influenced the color preference of Korean observers. © 2015 Wiley Periodicals, Inc. Col Res Appl, 40, 592–604, 2015     

A cross‐cultural colour‐naming study. Part I: Using an unconstrained method

Colour naming by panels of British and Taiwanese subjects (speaking English and Mandarin, respectively) was used to study colour categorization, and the results applied to investigate differences of usage between the two languages. Fifty British and 40 Chinese subjects took part in experiments using an unconstrained method with 200 ISCC‐NBS colour samples. Data analysis was performed to calculate the frequency and codability of each colour name in each group and subgroup. These names were then grouped using 7‐category and 4‐category methods to find the culture and gender differences. It was confirmed that the 11 basic names found by Berlin and Kay were the most widely used for both languages. The results showed a close agreement between the two languages in terms of colour categories, but a large discrepancy in the use of secondary names due to cultural differences. The cross‐cultural comparison revealed a clear pattern of the linkage between language and concepts of colour. © 2001 John Wiley & Sons, Inc. Col Res Appl, 26, 40–60, 2001     

“Living”/controlled polymerization of methyl acrylate mediated by dithiocarbamates under γ‐ray irradiation

γ‐Ray initiated reversible addition–fragmentation chain transfer (RAFT) polymerizations of methyl acrylate (MA) were investigated in bulk using five different dithiocarbamate structures, 2‐phenyl‐benzoimidazole‐1‐carbodithioic acid benzyl ester ( 1b ), 2‐methyl‐benzoimidazole‐1‐carbodithioic acid benzyl ester ( 1c ), 2‐pheny‐indole‐1‐cardithioic acid benzyl ester ( 1d ), 2‐(carbazole‐9‐carbothioylsulfanyl)‐2‐methyl‐propionic acid ester ( 1e ), and carbazole‐9‐carbodithioic acid naphthalene‐1‐ylmethyl ester ( 1f ), as RAFT agents. The experiment results showed that MA polymerized in a controlled way under a low irradiation dose rate, i.e., first‐order kinetic plots, the experimental molecular weights increased linearly with monomer conversions. The polydispersity indices of polymers generally remained at a relatively low value (lower than 1.4). The effect of irradiation dose on the polymerization results was investigated. The obtained polymers were characterized with ¹H NMR and GPC. Chain‐extension reaction was also successfully carried out using the obtained polymer as the macro‐RAFT agent and styrene as the second monomer. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1769–1775, 2007     

Tailor‐Made Functional Polymethacrylates with Dual Characteristics of Self‐Healing and Shape‐Memory Based on Dynamic Covalent Chemistry

New shape memory polymers with self‐healing behavior are obtained by thermoreversible Diels–Alder (DA) cross‐linking of a furfuryl group‐containing star‐block copolymer with 1,1′‐(methylenedi‐4,1‐phenylene)bismaleimide. The star‐block copolymer consisting of a 3‐arm polycaprolactone (PCL) core and a polyfurfuryl methacrylate shell is synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization. For this, a 3‐arm macro‐RAFT agent based on PCL is converted with an appropriate amount of furfuryl methacrylate in the presence of a radical initiator. Films of the DA network are partly insoluble at ambient temperatures. After annealing at 120 °C the films become completely soluble because of the progressing retro‐DA reaction. Evaporation of the solvent and subsequent annealing at 60 °C restores the original insoluble state of the material. By means of a scratch test and tensile tests on cut and subsequently mended samples it is shown that the retro‐DA reaction facilitates self‐healing. Additionally, the films show pronounced shape memory effects with reasonable shape recovery and fixity ratios, which are attributed to the melting and crystallization of the PCL phase.