Designed Monomers and Polymers最新文献

Novel aromatic aliphatic diacid monomer, 4 4' bis(4-carboxy methylene) biphenyl was synthesized via friedel craft acylation with acetic anhydride followed by willgerodot reaction and used in the preparation of polyamides by direct polycondensation using the Yamazaki phosphorylation reaction with commercial aromatic diamines. These polyamides were obtained in good yield with moderate-to-high-molecular-weight build up as evidenced by inherent viscosities in the range of 0.52-0.96 dlg-1. The XRD studies showed that all the polyamides were amorphous in nature and these polymers dissolved in polar aprotic solvents such as N-methyl-2-pyrrolidone(NMP),N,N-dimethylsulfoxide(DMSO), N,N-dimethyl formamide (DMF) and N,N-dimethyl acetamide. The resulting polyamides were characterized by inherent viscocity measurements, FT-IR, 1H NMR and 13C NMR spectroscopy, solubility, thermogravimetry, X-ray diffraction studies. These polyamides had glass transition temperatures between 210°C and 261°C, and their temperatures at a 10% weight loss were 620 to 710°C and 497 to 597°C in nitrogen and air atmospheres, respectively, which indicates thermally stable polymers.

The basalt fiber (BF) and polyamide 6 (PA6) reinforced HDPE composite were prepared; the effects of adding fiber, organic filler, and polar component maleic anhydride (MA) on the microstructural characteristics of composites were investigated. Microstructural characterization evidenced the binary-dispersed phase (PA6/BF) is of a core-shell structure in which the component PA6 encapsulates component BF, and the extent of encapsulates would decline with the MA adding. It is confirmed that the microstructure is related to the interfacial tension of components by the SEM observation and theoretical calculation. The effect of multi-component on the crystallization behavior of composites was investigated. Differential scanning calorimeter (DSC) analyses showed a significant change in the HDPE microstructure. It demonstrated PA6 and BF as a nucleation agent accelerated the crystallization rate under the cooling process. The corresponding crystallization kinetics and activation energy were further analyzed using the Jeziorny method, Avrami-Ozawa method, Kissinger method. The results showed MA markedly changed the crystal growth mechanism of the HDPE matrix to heterogeneous nucleation for acicular and tabular crystal growth during the annealing step. The lowest crystallinity energy and crystallinity were observed for BF/PA6/HDPE composites with 3 wt % MA. Furthermore, a clear improvement of mechanical properties (by 61%) were observed, which mechanism is discussed in detail. The mechanism of toughening is not only one, but the result of a variety of mechanisms together.

Polyurea, a controlled release material, has been widely applied in agricultural fields due to high thermal stability and low cost. In this article oxyfluorfen polyurea microcapsules suspension was successfully prepared by interfacial polymerization using diisocyanate and polyamines such as Ethylenediamine, Hexamethylenediamine, Diethylenetriamine in presence of green solvent, i.e., N,N-dimethyldecanamide. The microcapsule suspension of oxyfluorfen has not been researched yet by using solvent N,N-dimethyldecanamide and polyamines. The effect and the type of diamines on the morphology and properties of the microcapsules have been investigated. The synthesized microcapsules were characterized by scanning electron microscope, ultraviolet spectrometry, Fourier transform iInfrared spectrometer, thermogravimetric analysis and particle size analyser. The effect of the core to shell ratio on encapsulation efficiency and release kinetics were also studied. The oxyfluorfen microcapsules had an excellent encapsulation efficiency (98.2%) using EDA as the monomer and Release kinetics depended upon the type of monomers used and also on core to shell ratio used (6.5:1, 5:1, 4:1). As core to shell ratio was increased the encapsulation efficiency was found to decrease. Prepared Microcapsules when sprayed on paddy crop was found to be safe in comparison with Emulsifiable concentrate sample.

Polynorbornenes, prepared by the 'living' and 'controlled' ring-opening metathesis polymerization (ROMP) method, have emerged as a stimuli-sensitive new class of polymer carriers. Herein, we reported a novel amphiphilic diblock polynorbornene, PNCHO-b-PNTEG, containing active benzaldehyde units, which exhibited good conjugating capacity to amino-containing molecules (e.g., doxorubicin (DOX)) via the pH-sensitive Schiff base linkage. The copolymer and its conjugate with DOX, DOX-PNCHO-b-PNTEG, were adequately analyzed by various techniques including ¹H NMR, ¹³C NMR, gel permeation chromatography, etc. Especially, the formed conjugate of DOX-PNCHO-b-PNTEG could self-assemble into near-spherical micelles with the diameter of 81 ± 10 nm, and exhibit acid-triggered DOX release behavior, and the release rate could be adjusted by changing the environmental pH value. The excellent biological safety of PNCHO-b-PNTEG was further demonstrated by the results from both in vitro toxicity evaluation to murine fibroblast cells (L-929 cells) and in vivo evaluation of acute developmental toxicity and cell death in zebrafish embryos. Hence, the present polynorbornene-based PNCHO-b-PNTEG possesses great potential application as a biocompatible polymeric carrier and could be employed to fabricate various pH-sensitive conjugates.

[This corrects the article DOI: 10.1163/138577210X12634696333433.][This corrects the article DOI: 10.1163/138577211X577178.].

Introduction: This trial investigated whether a Facebook smoking cessation intervention culturally tailored to young sexual and gender minority (SGM) smokers (versus non-tailored) would increase smoking abstinence.

Methods: Participants were 165 SGM young adult US smokers (age 18-25) recruited from Facebook in April 2018 and randomized to an SGM-tailored (POP; N = 84) or non-tailored (TSP-SGM; N = 81) intervention. Interventions delivered weekly live counseling sessions and 90 daily Facebook posts to participants in Facebook groups. Primary analyses compared POP and TSP-SGM on biochemically verified smoking abstinence (yes/no; primary outcome), self-reported 7-day point prevalence abstinence (yes/no), reduction in cigarettes per week by 50+% from baseline (yes/no), making a quit attempt during treatment (yes/no), and stage of change (precontemplation/contemplation vs. preparation/action). Supplemental analyses compared POP to two historical control groups.

Results: POP participants were more likely than TSP-SGM participants to report smoking abstinence at 3 (23.8% vs. 12.3%; OR = 2.50; p = .03) and 6 months (34.5% vs. 12.3%; OR = 4.06; p < .001) and reduction in smoking at 3 months (52.4% vs. 39.5%; OR = 2.11; p = .03). Biochemically verified smoking abstinence did not significantly differ between POP and TSP-SGM at 3 (OR = 2.00; p = .33) or 6 months (OR = 3.12; p = .08), potentially due to challenges with remote biochemical verification. In supplemental analyses, POP participants were more likely to report abstinence at 3 (OR = 6.82, p = .01) and 6 (OR = 2.75, p = .03) months and reduced smoking at 3 months (OR = 2.72, p = .01) than participants who received a referral to Smokefree.gov.

Conclusions: This pilot study provides preliminary support for the effectiveness of a Facebook smoking cessation intervention tailored to SGM young adults.

Implications: SGM individuals have disproportionately high smoking prevalence. It is unclear whether smoking cessation interventions culturally tailored to the SGM community are more effective than non-tailored interventions. This pilot trial found preliminary evidence that an SGM-tailored Facebook smoking cessation intervention increased reported abstinence from smoking, compared to a non-tailored intervention.

Trial registration: NCT03259360.

A completely metal-free and environmentally friendly strategy is demonstrated for the preparation of graft copolymers by combining photoinduced Atom Transfer Radical Polymerization (ATRP) and Ring Opening Polymerization (ROP). Polymerizations are simultaneously realized in a one-pot manner. For this purpose, bare vinyl monomers, vinyl monomers with hydroxyl functional groups, and lactone monomers were simultaneously polymerized under visible light using specific catalysts. While vinyl monomers construct the main chain, the lactone monomers were polymerized from the hydroxyl functions present at the side chain. Spectral and chromatographic analyses prove that the utilized strategy is successful in the preparation of graft copolymers controlled molecular weights and narrow distributions.

Silver-based nanoparticles and biomaterials have extensive biomedical applications owing to their unique antimicrobial properties. Thus, green and facile synthesis of such materials is highly desirable. This study reports an antibacterial hydrogel based on polyvinyl alcohol/sodium alginate network with the incorporation of silver nanoparticles (AgNPs), which is greenly synthesized by reductive metabolites obtained from the leaves of green tea. The 'flower-shape' AgNPs were acquired, it formed a mono-disperse system with a distinct uniform interparticle separation. The average size of AgNPs varied from 129.5 to 243.6 nm, which could be regulated by using different volumes of the green tea extract. Zeta potentials of the AgNPs were from -39.3 mV to -20.3 mV, indicating the moderate stability of the particles in water. In the next stage, the antibacterial polyvinyl alcohol/sodium alginate hydrogels were fabricated by incorporating prepared AgNPs. Scanning Electron Microscopy (SEM) images showed that the porous structure was obtained, and Energy Dispersive X-Ray (EDX) analysis confirmed that the AgNPs were uniformly dispersed in the polymer network. The hydrogels exhibited superior water absorption properties, which were characterized by a high swelling ratio (500-900%) and fast equilibrium. The hydrogels also exhibited good antimicrobial activity in assays with Gram-positive bacteria Escherichia coli and Gram-negative bacteria Staphylococcus aureus. To sum up, a process for the green preparation of antibacterial hydrogels based on AgNPs derived from tea leaves as a conveniently available cheap local agricultural product was established.

1'-(2-Acryloxyethyl)-3,3'-dimethyl-6-nitrospiro[2 H-1-benzopyran-2,2'-indoline] (SPA) was synthesized and grafted onto a water-soluble carboxymethyl chitin (CMCH) macromolecule to prepare a photochromic copolymer (CMCH-g-SPA). The structure of CMCH-g-SPA was characterized by Fourier-transform infrared (FT-IR) spectroscopy, thermogravimetric (TG) analysis, X-ray diffraction (XRD) analysis, water-solubility evaluation, and UV-vis spectroscopy. XRD patterns of CMCH-g-SPA revealed that grafting copolymerization disrupts the CMCH semicrystalline structure, thus improving water solubility. UV-vis spectroscopy results supported the negative photochromic behavior of the merocyanine (MC) form of CMCH-g-SPA (CMCH-g-MCA) present in a water solution of the target copolymer. In addition to high solvent polarity, the intermolecular and intramolecular electrostatic attraction between the indolenine cation and the COO^- anion were found to be influencing factors, which stabilize these MC form of spiropyran groups grafted onto CMCH. In a water solution, visible light bleaching was completed over a short period (8 minutes) under artificial visible light irradiation and the thermal coloration reaction, whose rate constant at 25 °C was 4.64 × 10^-4 s^-1, which fit the first-order reaction equation. After ten photochromic cycles in water solution, the relative absorption intensity of CMCH-g-MCA decreased by 7.92%.

A new aromatic diacid (II) was synthesized and Characterized by Spectroscopic techniques namely, FT-IR, ¹ H and ¹³ C NMR, etc. A series of aromatic aliphatic polyamides containing phenoxy s-triazine ring with methylene spacer group was synthesized from diacid (II) and various aromatic diamines by using Yamazaki Phosphorylation method. These polyamides were obtained in good yields and characterized by solubility in common organic solvent, inherent viscosity, FT-IR, X-ray diffraction analysis. All of these polyamides were found to be amorphous in morphology as indicated by XRD to posses outstanding solubilities, and to be easily dissolved in amide-type polar aprotic polar solvents. Polyamides with moderate inherent viscosity in the range 0.21 to 0.41 dL/g in N,N,dimethyl formamide solvent (DMF) at 30 ± 0.1° C. The Thermal properties of the polyamides were evaluated by Thermogravimetric analysis and Differential scanning calorimetery. These polymer shows good thermal stability with glass transition temperature (T_g) of 143-223°C and their (T_max) weight loss temperature were around 426-455°C, confirming their good thermal stability. The char yields of these polymers were given their limiting oxygen index LOI 32.3 to 37.5 5% values of polyamides; indicate these polymers also show good flame resistance. The NPs were negatively charged with a zeta potential of -24.2 to -37.9 mV indicating a good colloidal stability against aggregation.