ABSTRACTWhile perfluoroalkyl acids (PFAAs), also known as C8s, are used extensively in textile repellent coatings, concerns have arisen for their carcinogenicity and hazardous effects on the environment. In this study, a novel water‐based, nonfluoro, and nanobrush textile repelling agent was prepared by conventional sol–gel chemistry using amorphous fumed silica and n‐octyltriethoxysilane as the starting materials. Minimal interaction between the designed repelling agent and marketed water‐based resins was confirmed using linear viscosity region (LVR) analysis and asymmetric‐flow field‐flow fractionation (AF4), suggesting the self‐stratification potential of the repelling agent. More specifically, the repelling agent exhibited excellent compatibility and self‐stratifying ability with a force‐emulsified acrylic‐based resin, affording a water contact angle of 104.3° when incorporated at 7% solid content. Performance tests carried out on thermoplastic polyurethane (TPU) revealed excellent adhesion (100/100) of a final formulation, and a significant increase in water contact angle from 80.1° to 103.8° after treatment. In addition, the fouling area after the removal of a submerged sample from a mixture of slurry, polymer, and oil decreased from 48 to 1% when the repelling agent was added. Moreover, the sludge‐fouling property remained unchanged after 1000 cycles of abrasion. These findings demonstrate the potential of the described nonfluoro, nanobrush repelling agent as an environmentally safe alternative for use with commercial resins, in turn realizing a fully water‐based hydrophobic coating. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48003.

We have prepared semi-interpenetrating polyacrylate networks (PA/BA-m s-IPNs) through rapid photo-polymerization of a triacrylate monomer (TMPTA) in the presence of a photomitiator (1184), a tetramercaptane transfer agent (4SH), and N-methyl-bisbenzoxazine (BA-m). Next, we prepared novel fully interpenetrating polyacrylate (PA) and polybenzoxazine (PBZ) networks (PA/PBZ f-IPNs) through thermal polymerization of the BA-m monomer at 180 degrees C for 4 h. For the PA/BA-m s-IPNs, the BA-m monomers can be frozen and dispersed in the UV-cured PA network within 5 min to inhibit macrophase separation. After thermal polymerization, the phenol units of the ring-opened PBZ segments can form a hydrogen-bonding interface with the carbonyl groups to improve the compatibility between the PBZ microdomains and the PA networks. From an analysis using Kissinger's method, the non-isothermal kinetics of the thermal polymerization for the PA/BA-m s-IPNs indicate that an increase in the PA content increased the steric hindrance of PBZ polymerization. We used DSC, TGA, and contact angle analyses to determine the glass transition temperature, thermal stability, and surface free energy, respectively, of the PA/PBZ f-IPNs. The thermal stability and surface free energy of these PA/PBZ f-IPNs display linear relationships with respect to the PBZ content. Crown Copyright (C) 2008 Published by Elsevier Ltd. All rights reserved.

Wer bietet weniger? Polybenzoxazine können niedrigere freie Oberflächenenergien aufweisen als reines Poly(tetrafluorethylen). Während der Polymerisationen wurden die Kontaktwinkel und die freien Oberflächenenergien bestimmt (siehe Beispielkurven). Diese Materialien sind billiger in der Herstellung und leichter verarbeitbar als fluorierte Polymere. Supporting Information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2001/2006/z503957_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

A series of poly(vinylphenol-co-methyl methacrylate) (PVPh-co-PMMA) block and random copolymers were prepared through anionic and free radical polymerizations, respectively, of 4-tert-butoxystyrene and methyl methacrylate and subsequent selective hydrolysis of the 4-tert-butoxystyrene protective groups. Analysis of infrared spectra suggests that the random copolymer possesses a higher fraction of hydrogen-bonded carbonyl groups and a larger interassociation equilibrium constant relative to those of a block copolymer containing similar vinylphenol content because of the different sequence distribution that may arise from the so-called intramolecular screening effect. In contrast, the glass transition temperature of the block copolymer, which has the lower polydispersity index, is higher than that of the random copolymer at the same composition.

The structure of benzoxazines is similar to that of phenolic resin through thermal self-curing of the heterocyclic ring opening reaction that neither requires catalyst nor releases any condensation byproduct. These polybenzoxazine resins have several outstanding properties such as high thermal stability and high glass transition temperature. To better understand the curing kinetics of this copolybenzoxazine thermosetting resin, dynamic and isothermal differential scanning calorimetry measurements were performed. Three models, the Kissinger method, the Flynn-Wall-Osawa method, and the Kamal method, were used to describe the curing process. Dynamic kinetic activation energies based on Kissinger and Flynn-Wall-Osawa methods are 72.11 and 84.06 KJ/mol, respectively. The Kamal method based on an autocatalytic model results in a total order of reaction between 2.66 and 3.03, depending on curing temperature. Its activation energy and Arrhenius preexponential are 50.3 KJ/mol and 7959, respectively. (C) 2004 Wiley Periodicals, Inc.

β-Cyclodextrin (β-CD) forms inclusion complexes (ICs) with adamantane-modified benzoxazines (2 benzoxazine and 3 benzoxazine). These benzoxazines can readily penetrate into the CD's hydrophobic cavity, causing turbidity of their solutions, from which fine crystalline powders are obtained. We characterized these complexes by powder X-ray diffraction, 13C and 13C CP/MAS NMR spectroscopies, DSC, and TGA. The X-ray diffraction and solid-state 13C CP/MAS NMR spectroscopy indicate that the IC domains of the polypseudorotaxanes maintain their channel-type structures after the ring-opening curing reactions have occurred. Furthermore, DSC measurements indicate that complexing the adamantane-modified benzoxazine units with β-CDs result in stiffer main chains and, thus, higher glass transition temperature. TGA also indicates that the inclusion complexes have enhanced its thermal stability.

We have generated porous polybenzoxazine (PBZZ) materials by using a B-a type PBZZ as the matrix and various molecular weights of poly(ε-caprolactone) (pa-PCL) as the labile constituent. The slight degree of hydrogen bonding that exists between the two polymers results in micro-phase separation without an excess degree of aggregation occurring. The porous structures form after hydrolysis of the PCL domains; we characterized them using a variety of techniques, including FT-IR spectroscopy, DSC, TGA, FE-SEM, and DEA. At 298K and 105Hz, we obtained a thin, transparent, and nanoporous film that has a very low dielectric constant (1.95).

We have prepared polystyrene/clay nanocomposites using an emulsion polymerization technique. The nanocomposites were exfoliated at up to a 3wt% content of pristine clay relative to the amount of polystyrene (PS). We used two different surfactants for the montmorillonite: the aminopropylisobutyl polyhedral oligomeric silsesquioxane (POSS) and the ammonium salt of cetylpyridinium chloride (CPC). Both surfactants can intercalate into the layers of the pristine clay dispersed in water prior to polymerization. Although the d spacing of the POSS-intercalated clay is relatively smaller than that of the CPC-intercalated clay, PS more easily intercalates and exfoliates the POSS-treated clay than the CPC-treated clay. IR spectroscopic analysis further confirms the intercalation of POSS within the clay layers. We used X-ray diffraction (XRD) and transmission electron microscopy (TEM) to characterize the structures of the nanocomposites. The nanocomposite prepared from the clay treated with the POSS containing surfactant is exfoliated, while an intercalated clay was obtained from the CPC-treated surfactant. The molecular weights of polystyrene (PS) obtained from the nanocomposite is slightly lower than the virgin PS formed under similar polymerization conditions. The value of Tg of the PS component in the nanocomposite is 8 °C higher than the virgin PS and its thermal decomposition temperature (21 °C) is also higher significantly. The presence of the POSS unit in the MMT enhances the thermal stability of the polystyrene.

The son-gel process was used to prepare a photosensitive inorganic-organic composite, silica/poly(2-hydroxymethyl methacrylate). Its nanoscale morphology was observed with field emission scanning electron microscopy at high magnifications (e.g., 160,000X). The size of the particles in the nanocomposite synthesized under various preparation conditions fell in the range of 20-50 nm. The effects of the pH, reactant composition, and solvent content in the reaction mixture on the thermal and mechanical properties of the nanocomposite were studied with thermogravimetric analysis, dynamic mechanical analysis, and thermomechanical analysis. The thermal stability of the synthesized nanocomposite could generally be improved by an increase in the molar ratio of the inorganic component, a reduction in the reaction pH, or an increase in the solvent content. (C) 2004 Wiley Periodicals, Inc.

We have successfully synthesized a novel benzoxazine ring-containing polyhedral oligomeric silsesquioxane (BZ-POSS) monomer by two routes: (1) hydrosilylation of a vinyl-terminated benzoxazine using the hydro-silane functional group of a polyhedral oligomeric silsesquioxane (H-POSS) and (2) reaction of a primary amine-containng POSS (Amine-POSS) with phenol and formaldehyde. The benzoxazine-containing POSS (BZ-POSS) monomer can be copolymerized with other benzoxazine monomers through ring-opening polymerization under conditions similar to that used for polymerizing pure benzoxazines. Thermal properties of these POSS-containing organic/inorganic polybenzoxazine nanocomposites have been improved over the pure polybenzoxazine analyzed by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The BZ-POSS monomer is poorly miscible with the benzoxazine monomer and tends to aggregate and forms its own domains, both before and after polymerization. At a higher BZ-POSS content, gross aggregation occurs and results in a lower than expected improvement in the thermal properties.

Two novel structures of adamantane-modified benzoxazines were synthesized from 4-(1-adamantyl)-phenol through the incorporation of adamantane as a pendant group into the polybenzoxazine backbone. Both H-1-NMR and Fourier transform infrared spectra were used to characterize these structures. The rigid structure of the adamantane tended to hinder the chain mobility (boat anchor effect) and substantially enhanced the thermal properties, including the glass-transition temperature and decomposition temperature, especially for poly(6-adamantyl-3-methyl-3,4-dihydro-2H-1,3-benzoxazine). In the poly(6-adamantyl-3-phenyl-3,4-dihydro-2H-1,3-benzoxazine) system, however, the opposite result for the glass-transition temperature was observed and it was interpreted as lower crosslinking density. The phenyl group was bulkier than the methyl group, and the movement of the molecular chain was hindered between bridging points during the curing process; this resulted in a lower crosslinking density and a lower glass-transition temperature than those of poly(6-adamantyl-3-methyl-3,4-dihydro-2H-1,3-benzoxazine). (C) 2004 Wiley Periodicals, Inc.

It is well-known that low dielectric materials are used as insulating materials, and the incorporation of fluorinated substitutes into polymer is able to decrease its dielectric constant because of small dipole and the low polarizability of the C–F bond. In this study, a novel structure of the fluorinated benzoxazine (F-1 benzoxazine) has been synthesized by incorporating the trifluoromethyl groups into the monomer, and its structure has also been characterized by 1H NMR, 19F NMR and FT-IR. Further, we have prepared the fluorinated copolybenzoxazine (B-a/F-1=1/1) with substantially reduced dielectric constant at K=2.36. In addition, this fluorinated copolybenzoxazine possesses high glass transition temperature and high thermal stability, which is suitable for high temperature operation for certain special processes of interlayer dielectrics.

The thermal properties and hydrogen bonding behavior of B-a type polybenzoxazine (PBZZ)/PVP blends were investigated by DSC and FTIR. The DSC result shows a single Tg over the entire compositions and a large positive deviation based on Kwei equation was observed in the Tg versus composition diagram, implying that strong hydrogen bonding interaction exists between PBZZ and PVP segments. The strength of hydrogen bonding interaction is in the order of inter-association between the hydroxyl group of PBZZ and the carbonyl group of PVP (KA=594Lmol−1)>self-association between the hydroxyl group of pure PBZZ (KB=72.6Lmol−1)>inter-association between the hydroxyl and the Mannich-based bridge of pure PBZZ (KC<10Lmol−1). Good correlation between DSC and FTIR analysis were observed.

3-Epitacamonine and 14-epitacamonine have been synthesized starting from the dinitrile 3. The synthetic route was designed on the basis of symmetric considerations which emphasized the establishment of the relative configuration in two of the three stereocenters.

ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTTotal Synthesis of (±)-Nudenoic AcidTse-Lok Ho and Chun-Yuan SuView Author Information Department of Applied Chemistry, National Chiao Tung University, Hsinchu, Taiwan, Republic of China Cite this: J. Org. Chem. 2000, 65, 11, 3566–3568Publication Date (Web):May 11, 2000Publication History Received19 January 2000Published online11 May 2000Published inissue 1 June 2000https://pubs.acs.org/doi/10.1021/jo0000729https://doi.org/10.1021/jo0000729brief-reportACS PublicationsCopyright © 2000 American Chemical SocietyRequest reuse permissionsArticle Views1157Altmetric-Citations12LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-AlertscloseSupporting Info (1)»Supporting Information Supporting Information SUBJECTS:Alcohols,Anions,Mixtures,Rearrangement,Sesquiterpenes Get e-Alerts