Surface modification of cellulose with plant triglycerides for hydrophobicity

Hydrophobic cotton was achieved by surface modification of the cellulose with triglycerides from several plant oils including soybean, rapeseed, olive and coconut oils. These oils were delivered to the cellulose substrates in homogeneous solutions of ethanol or acetone as well as aqueous emulsions. Surface modification was facilitated by solvent evaporation followed by heating between 110 and 120 °C for 60 min. All oils, except for coconut, produced hydrophobic and less water-absorbing cotton, supporting the desirable role of higher unsaturation in the fatty acids to achieve crosslinked network. The most hydrophobic surfaces were obtained by the reaction with 1% soybean oil in acetone. On both bleached and scoured cotton, a water contact angle of 80° and water absorption value of 0.82 μL/mg were achieved. The acquired hydrophobicity was not only retained after water washing but also improved with subsequent exposures to elevated temperatures. The surface tension of scoured cotton cellulose was lowered from 63.81 mJ/m² to 25.74 mJ/m² when modified by soybean oil delivered in acetone, which is lower than that of poly(ethylene terephthalate). An aqueous emulsion of soybean oil also rendered the scoured cotton hydrophobic, which shows promise for a green chemistry and bio-based approach to achieve water repellency on cellulosic materials.     

Design of Polymeric Culture Substrates to Promote Proangiogenic Potential of Stem Cells

Stem cells are a promising cell source for regenerative medicine due to their differentiation and self‐renewal capacities. In the field of regenerative medicine and tissue engineering, a variety of biomedical technologies have been tested to improve proangiogenic activities of stem cells. However, their therapeutic effect is found to be limited in the clinic because of cell loss, senescence, and insufficient therapeutic activities. To address this type of issue, advanced techniques for biomaterial synthesis and fabrication have been approached to mimic proangiogenic microenvironment and to direct proangiogenic activities. This review highlights the types of polymers and design strategies that have been studied to promote proangiogenic activities of stem cells. In particular, scaffolds, hydrogels, and surface topographies, as well as insight into their underlying mechanisms to improve proangiogenic activities are the focuses. The strategy to promote angiogenic activities of hMSCs by controlling substrate repellency is introduced, and the future direction is proposed.     

Synthesis and repellent properties of vinylidene fluoride-containing polyacrylates

Fluorinated polyacrylats with side group containing vinylidene fluoride (VDF) units (CF₃(CF₂)_n (CH₂CF₂)_m, n = 3, 5; m = 1, 2) were successfully synthesized. The water and oil repellency properties of these polymers are similar to those of fluorinated polyacrylate with side group containing long perfluorooctyl group (CF₃(CF₂)₇). The thermal telomerization of CF₃(CF₂)₅I and CF₃(CF₂)₃I with vinylidene fluoride (VDF) provided CF₃(CF₂)₅CH₂CF₂I (1b) and CF₃(CF₂)₃CH₂CF₂CH₂CF₂I (1c), respectively. The addition of 1b with ethylene followed by hydrolysis gave CF₃(CF₂)₅CH₂CF₂CH₂CH₂OH (2b). Treatment of 1c with ethyl vinyl ether in the presence of Na₂S₂O₄ followed by reduction produced CF₃(CF₂)₃CH₂CF₂CH₂CF₂CH₂CH₂OH (2c). Fluoroacrylates 3b-d were prepared by acrylation of the corresponding fluoroalcohols 2b-d. The semi-continuous process emulsion co-polymerization of 3a-d with octadecyl acrylate and 2-hydroxylethyl acrylate initiated by (NH₄)₂S₂O₈ in the presence of a mixture emulsifiers of polyoxyethylene(10)nonyl phenyl ether (TX-10) and sodium lauryl sulfate provided stable latexes 4a-d, respectively. The water and oil repellency properties of 4b (R_f: CF₃(CF₂)₅CH₂CF₂) and 4c (R_f: CF₃(CF₂)₃CH₂CF₂CH₂CF₂) containing vinylidene fluoride (VDF) units were similar to those of 4a (R_f: CF₃(CF₂)₇) containing long perfluoroalkyl group and much better than those of polymer 4d (R_f: CF₃(CF₂)₃) with short perfluoroalkyl chain. Thus, polyacrylates containing vinylidene fluoride units showed promising aspects as the alternatives to the currently used water and oil repellent agents with long perfluoroalkyl chains.     

Synthesis and surface properties of microphase separated or nanostructured coatings based on hybrid and fluorinated acrylic copolymers

Coating materials characterised by intrinsic inhomogeneity or nanostructured morphology can display unique interfacial (e.g. surface and adhesion) and bulk (e.g. mechanical, thermal) properties, when heterophasic or self-segregating components are obtained by suitable design of the constitutive copolymers' structure. With the purpose of obtaining intrinsically photostable low-surface energy coating materials characterised by good penetration into porous substrates and variable response of the adhesive and polymer-air interface, fluorinated acrylic-based copolymers and water-borne acrylic-organosilane hybrids have been considered. For the latter, dispersed phase polymerisation procedures based on combined emulsion copolymerisation and hydrolysis-polycondensation of organosilane precursors have been adopted.     

Bioassay-Guided Isolation of Iridoid Glucosides from Stenaria nigricans,Their Biting Deterrence against Aedes aegypti (Diptera: Culicidae), and Repellency Assessment against Imported Fire Ants (Hymenoptera: Formicidae)

In our natural product screening program, we screened natural products for their repellency and toxicity against insect vectors. Methanolic extract of aerial parts of Stenaria nigricans (Lam.), with no published chemistry, was tested for repellency against mosquitoes and imported hybrid fire ants. Methanolic extracts showed biting deterrence similar to DEET (N,N-diethyl-3-methylbenzamide) against Aedes aegypti L. Based on this activity, the crude extract was fractionated into chloroform, ethyl acetate, and methanol subfractions. The active methanolic subfraction was further fractionated into 13 subfractions. These fractions were tested for their biting deterrence against Ae. Aegypti. Active subfractions were further characterized to identify the compounds responsible for this activity. Four undescribed iridoid glucosides (1–4) and three previously reported compounds (5–7) were isolated from active subfractions and tested for their biting deterrent activity. Based on BDI values, compounds 2, 3, 6, and 7, with biting deterrence similar to DEET, showed the potential to be used as repellents against mosquitoes. In an in vitro digging bioassay, none of these compounds showed any repellency against hybrid imported fire ants at a dose of 125 µg/g. This is the first report of biting deterrence and repellency of S. nigricans extract and its pure compounds, iridoid glucosides against mosquitoes and imported fire ants. Further studies will be conducted to explore the repellent potential of these compounds in different formulations under field conditions.     

含氟共聚乳液改善浸渍滤纸抗水抗油性的研究

用核/壳乳液聚合工艺,通过改变单体组成、设计乳胶粒子的形态结构和在乳胶粒子的壳层中引入含氟丙烯酸酯单体,制备具有核/壳结构的含氟丙烯酸酯的共聚乳液。并通过FTIR1、3C-NMR、TEM等手段对共聚乳液的化学结构以及乳胶粒子形态结构进行了表征。同时研究了含氟单体种类和用量、乳化剂种类以及单体加料方式对其聚乳液性能以及浸渍滤纸抗水/油性的影响。     

Identification of insecticidal constituents of the essential oils of Dahlia pinnata Cav. against Sitophilus zeamais and Sitophilus oryzae

The aim of this research was to determine the chemical composition of the essential oils of Dahlia pinnata, their insecticidal activity against Sitophilus zeamais and Sitophilusoryzae and to isolate insecticidal constituents. Based on bioactivity-guided fractionation, active constituents were isolated and identified as d-limonene, 4-terpineol and α-terpineol. Essential oils and active compounds tested exhibited contact toxicity, with LD₅₀ values ranging from 132.48 to 828.79 μg/cm² against S. zeamais and S. oryzae. Essential oils possessed fumigant toxicity against S. zeamais and S. oryzae with LC₅₀ from 14.10 to 73.46 mg/L. d-Limonene (LC₅₀ = 4.55 and 7.92 mg/L) showed stronger fumigant toxicity against target insects. 4-Terpineol (88 ± 8%) and d-limonene (87 ± 5%) showed the strongest repellency against S. zeamais and S. oryzae, respectively. The results indicate that essential oils and insecticidal constituents have potential for development into natural fumigants, insecticides or repellents for control of the stored-product insect pests.     

Fumigant and repellent activities of essential oil extracted from Artemisia dubia and its main compounds against two stored product pests

The major chemical constituents of the essential oil extracted from Artemisia dubia wall. ex Bess. (Family: Asteraceae) were found as terpinolene (19.02%), limonene (17.40%), 2,5-etheno[4.2.2]propella-3,7,9-triene (11.29%), isoelemicin (11.05%) and p-cymene-8-ol (5.93%). Terpinolene and limonene were separated as main components from the essential oil. The essential oil showed fumigant toxicity against Tribolium castaneum and Liposcelis bostrychophila with LC₅₀ values of 49.54 and 0.74 mg/L, respectively. The essential oil and isolated compounds of A. dubia showed repellency activities against both insects. Terpinolene and limonene showed the fumigant toxicity against T. castaneum. Terpinolene showed obvious fumigant toxicity against L. bostrychophila. The results indicated that the essential oil of A. dubia had potential to be developed into natural insecticides for controlling stored product pests.     

Fluorinated modification of hyperbranched polyesters used for improving the surface property of UV curing coatings

The commercial hyperbranched aliphatic polyols (Hn) were modified by thioglycolic acid (TA) and hexafluorobutyl acrylate (HFBA) or dodecafluoroheptyl methacrylate (DFHMA) to prepare a series of fluorinated hyperbranched polyesters. For comparison, a linear fluorinated polymer, poly(n-BMA-co-DFHMA), was synthesized through the copolymerization of n-butyl methacrylate (BMA) and DFHMA. The molecular structures were characterized by ¹H NMR spectroscopic analysis. The synthesized polymers were incorporated into UV-curable formulations as additives, and exposed to a UV lamp. After UV curing, the wettability of the films was investigated by contact angle measurement with water and 1-bromonaphthalene. The results showed that both the hydrophobicity and oleophobicity were greatly enhanced. Moreover, the fluorinated hyperbranched polymers possessed better water and oil repellency than the copolymer poly(n-BMA-co-DFHMA) at a very low concentration. The surface F/C ratio values of the cured films were detected by XPS analysis, and the film with TAH20-DFHMA showed the highest F/C ratio value, indicating its most efficient aggregation effect at the film surface.