Phosphinated phenols from acid‐fragmentation of bisphenols and their unsymmetrical diamine derivatives for copolyimides

Four novel diamines (9–12) were prepared by a two‐step procedure from phosphinated phenols (1–4) that were prepared from acid‐fragmentation of four bisphenols, including bisphenol A, 4,4′‐isopropylidenebis(2,6‐dimethylphenol), cis(4‐hydroxyphenyl)cyclohexane, and 9,9′‐bis(4‐hydroxyphenyl)fluorene, followed by nucleophilic addition of 9,10‐dihydro‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO). Copolyimides based on (9–12) /4,4′‐diaminodiphenyl ether (ODA)/dianhydride were prepared. The structure‐property relationship on the copolyimides was discussed. Due to the structural similarity, (9) /ODA‐based copolyimides were compared with (10) /ODA‐based copolyimides, while (11) /ODA‐based copolyimides were compared with (12) /ODA‐based copolyimides. The dimethyl substitutents cause (10) /ODA‐based copolyimides to display higher T_g, modulus, dimensional stability, contact angle, and better solubility than (9) /ODA‐based copolyimides. (12) /ODA‐based copolyimides that exhibit fluorene moieties display higher T_g and thermal stability, but a lower contact angle and poorer solubility than (11) /ODA‐based copolyimides that exhibit cyclohexane moieties. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 390–400     

Thiol‐ene photopolymerization for efficient curing of vinyl esters

Monomers for radical photopolymerization based on vinyl esters (VEs) have recently been identified as suitable alternatives to (meth)acrylates on account of their low irritancy and cytotoxicity. The drawback of most VEs with abstractable hydrogens is their relatively low reactivity compared with (meth)acrylates. Within this article, we proved by photo‐differential scanning calorimetry measurements and real‐time Fourier transform infrared spectroscopy that the thiol‐ene concept is able to improve the photoreactivity of these VEs to a large extent to a level between those of acrylates and methacrylates. Other VEs have now a reactivity of at least the level of similar acrylates. Mechanical properties as determined by Dynamic Mechanical Analysis and Charpy impact tests showed significant toughening of these materials. Furthermore, we were able to confirm low toxicity of all components by osteoblast cell culture experiments. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Photocrosslinked co-networks from glycidylmethacrylated gelatin and poly(ethylene glycol) methacrylates

Biopolymer-based systems with adjustable macroscopic properties that can be varied in a wide range using only small changes in chemical composition are promising candidates for biomaterial-induced autoregeneration. Glycidylmethacrylated gelatin is photopolymerized with the addition of PEG mono- or dimethacrylate to form co-networks in pH = 7.4 PBS. The degree of swelling (Q) and water uptake (H) in PBS at 37 °C are tailorable for PEGDMA co-networks (Q ≈ 250-650 vol%), while the storage modulus of swollen networks at 3 °C can be adjusted by the PEG(D)MA content (G' = 0.7-145 kPa). Indirect cytotoxicity tests on ethylene oxide sterilized films show non-toxic responses for the homonetwork and all but one PEGDMA-containing co-networks materials.     

Synthesis of n‐alkyl methacrylate polymers with pendant carbazole moieties and their derivatives

New methacrylate monomers with carbazole moieties as pendant groups were synthesized by multistep syntheses starting from carbazoles with biphenyl substituents in the aromatic ring. The corresponding polymers were prepared using a free‐radical polymerization. The novel polymers contain N‐alkylated carbazoles mono‐ or bi‐substituted with biphenyl groups in the aromatic ring. N‐alkyl chains in polymers vary by length and structure. All new polymers were synthesized to evaluate the structural changes in terms of their effect on the energy profile, thermal, dielectric, and photophysical properties when compared to the parent polymer poly(2‐(9H‐carbazol‐9‐yl)ethyl methacrylate). According to the obtained results, these compounds may be well suited for memory resistor devices. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 70–76     

Thermoresponsive self-assembly of short elastin-like polypentapeptides and their poly(ethylene glycol) derivatives

Short polypeptides with four pentad repeats, (VPGVG)(4) and (VPAVG)(4), were synthesised by manual fluorenylmethoxycarbonyl/tert-butyl (Fmoc/t-Bu) solid phase peptide synthesis using a convergent approach. In the next step, the peptides were coupled via their N-terminus with activated semi-telechelic poly(ethylene glycol) O-(N-Fmoc-2-aminoethyl)-O'-(2-carboxyethyl)undeca(ethylene glycol) (Fmoc-PEG-COOH) to yield monodisperse Fmoc-PEG-peptide diblock copolymer. Both the presence of the terminal hydrophobic Fmoc group and the hydrophilic PEG chain in the copolymers were shown to play a crucial role in their self-associative behaviour, leading to reversible formation of supramolecular thermoresponsive assemblies. The peptides and their PEG derivatives were characterised by HPLC, NMR and MALDI-TOF MS. The associative behaviour of the peptides and their PEG derivatives was studied by dynamic light scattering, MAS NMR and phase contrast microscopy. [image: see text]     

Thermomechanical properties and phase structure of epoxy/silica nano‐hybrid materials constructed from a linear silicone oligomer

Epoxy‐grafted silicone oligomer (ESO), which has a linear silicone chain in the backbone moiety, was synthesized from a trifunctional alkoxysilane via a sol–gel reaction. Characterization of ESO was performed with ¹H and ²⁹Si NMR, Fourier transform infrared, and gel permeation chromatography. The number‐average molecular weight of ESO was 3300. By adding the silicone oligomer as the inorganic source in the curing process of the epoxy resin, novel epoxy/silica hybrid materials were prepared. It was observed by transmission electron microscope that fine silica‐rich domains of about 5‐nm diameter were uniformly dispersed in the cured epoxy matrix. Thermomechanical properties of the hybrid materials were also investigated. The storage modulus in the rubbery region and the peak area of the tan δ curve at the glass‐transition region increased and decreased, respectively, with the hybridization of the silica network. The mobility of the epoxy network chains should be considerably suppressed by the hybridization with the silica network. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1631–1639, 2005     

Combination of radical and cationic photoprocesses for the single‐step synthesis of organic‐inorganic hybrid films

Nanocomposite materials prepared from radically photocurable hybrid sol–gel precursors have been widely developed within the last decade, especially to devise novel optical devices and coatings. For their synthesis, a preferential route has involved in the successive sol–gel process of acrylate trialkoxysilane precursors followed by radical photopolymerization. In contrast, this work presents an original one‐step synthesis based on the association of two different photoinitiators (PIs) in the same formulation: the photolysis of a hydroxyphenylketone (radical PI) affords polyacrylate chains while that of a diaryl iodonium salt (cationic PI) generates powerful superacids catalyzing the sol–gel reactions of the alkoxy functions. The behavior of methacrylate and acrylate trimethoxysilane precursors was compared to highlight the effect of the organic moiety functionality on the reaction kinetics (Fourier transform infrared spectroscopy) and the film microstructure (¹³C and ²⁹Si solid‐state nuclear magnetic resonance). Interestingly, evidence of local organization in these hybrid films was also given by X‐ray analysis. In a last part, their thermomechanical properties were discussed thoroughly using a range of techniques: DSC, scratch‐resistance test, nanoindentation. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4150–4158, 2010     

New benzodithiophene‐ and benzooxadiazole/benzothiadiazole‐based donor–acceptor π‐conjugated polymers for organic photovoltaics

A new set of push‐pull type 2D‐conjugated polymers (P1–P4) were designed and synthesized where A1, A2 (oxygen analogues) and A3, A4 (sulfur analogues) are electron deficient units used as co‐monomers. On introduction of new repeating units into the polymer backbone, significant changes were observed in optoelectronic properties. Furthermore, the heteroatom exchange in new repeating units has also brought notable changes in photophysical properties, in particular P1 and P2 (oxygen analogues) showed bathochromic shift in UV‐vis absorption spectra and deeper HOMO energy levels than P3, P4 (sulfur analogues). Interestingly P1, P3 absorption spectra shows a vibronic shoulder (659, 652 nm) peak in lower energy region, and this might originated from non‐covalent interactions between the electron rich and electron deficient units. In addition, the systematic investigation of these polymers with additive and solvent treatment, yielded in enhanced power conversion efficiency of 4.29% for P3‐based devices in bulk heterojunction organic solar cells. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2668–2679     

Preparation,structure, and property of polyoxymethylene/carbon nanotubes thermal conducive composites

Polyoxymethylene (POM)/multiwalled carbon nanotubes (MWNTs) nanocomposites were prepared through a simple solution‐evaporation method assisted by ultrasonic irradiation. To enhance the dispersion of MWNTs in POM, MWNTs were chemically functionalized with PEG‐substituted amine (MWNT‐g‐PEG), which exhibited strong affinity with POM due to their similar molecular structure. The thermal conductivity and the mechanical properties of the composites were investigated, which showed that the thermal conductive properties of POM were improved remarkably in the presence of MWNTs, whereas reduced by using MWNT‐g‐PEG due to the heat transport barrier of the grafted‐PEG‐substituted amine chain. A nonlinear increase of the thermal conductivity was observed with increasing MWNTs content, and the Maxwell‐Eucken model and the Agari model were used for theoretical evaluation. The relatively high effective length factor of the composite predicted with mixture equation indicated that there were few entangles of MWNTs for the samples of MWNT‐g‐PEG in the composites. The mechanical strength of the composites can be improved remarkably by using suitable content of such functionalized MWNTs, and with the increase of the aliphatic chain length of PEG‐substituted amine, the toughness of the composites can be enhanced. Transmission electron microscope result indicated that MWNT‐g‐PEG exhibited strong affinity with POM and a good dispersion of MWNTs was achieved in POM matrix. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 905–912, 2010     

Preparation of photocrosslinked sol‐gel composites based on urethane‐acrylic matrix,silsesquioxane sequences,TiO2, and Ag/Au Nanoparticles for use in photocatalytic applications

An acid urethane oligodimethacrylate based on poly(ethylene glycol) was synthesized and used in the preparation of hybrid composites containing silsesquioxane sequences and titania domains formed through sol‐gel reactions along with silver/gold nanoparticles (Ag/Au NPs) in situ photogenerated during the UV‐curing process. The photopolymerization kinetics studied by Fourier transform infrared spectroscopy and photoDSC showed that the photoreactivity of the investigated formulations depends on the amount of titanium butoxide (5–20 wt %) added in the system subjected to UV irradiation. The introduction of 1 wt % AgNO₃/AuBr₃ in formulations slightly improved the degree of conversion but diminished the polymerization rates. The formation of hybrid materials comprising predominantly amorphous TiO₂/SiO₂ NPs, with or without Ag/Au NPs, was confirmed through specific analyses. The evaluation of photocatalytic activity demonstrated that the synthesized hybrid films are suitable for the complete removal of organic pollutants (phenolic compounds) from water under UV irradiation (200–350 min) at low intensity (found in the solar radiation). © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1189–1204     

Green synthesis of Ni‐Cu‐Zn ferrite nanoparticles using tragacanth gum and their use as an efficient catalyst for the synthesis of polyhydroquinoline derivatives

Ni_0.35Cu_0.25Zn_0.4Fe₂O₄ MNPs were synthesized using tragacanth gum as biotemplate and Metals nitrate as the metal source by the sol–gel method. The sample was characterized by powder X‐ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), vibrating sample magnetometer (VSM), scanning electron microscopy (SEM) and energy dispersive X‐ray analysis (EDX). The nanoparticles exhibit ferromagnetic behaviour at room temperature, with a saturation magnetization of 52.76 emu/g and a coercivity of 80.14 Oe. Thereupon, Ni‐Cu‐Zn ferrite nanoparticles as an efficient catalyst was used for the synthesis of polyhydroquinoline derivatives via multi‐component reactions under microwave irradiation. Simple work‐up, mild reaction conditions, short reaction times, use of an economically convenient catalyst, and excellent product yields are the advantageous features of this method. The catalyst could easily be recycled and reused few times without noticeable decrease in catalytic activity.     

Highly active,thermo‐responsive polymeric catalytic system for reuse in aqueous and organic CuAAC reactions

Tris‐(benzyltriazolylmethyl)amine (TBTA) has been immobilized onto a styrenic monomer and subsequently copolymerized with N‐isopropyl acrylamide (NIPAM) to afford catalytically active thermo‐responsive copolymers for copper assisted click chemistry. P(TBTA‐co‐NIPAM) copolymers were synthesized with incorporation of between 2 and 10 ligand units per chain and tuneable molecular weight (28–148 kDa). A combination of ¹H NMR spectroscopy, size exclusion chromatography (SEC) and elemental analysis (EA) confirmed the controlled synthesis of these polymers and allowed for quantification of the degree of TBTA‐functionalized monomer incorporation. After loading with copper(I) bromide, this homogeneous catalyst system was added to a water/ethyl acetate two‐phase system. Using this biphasic system aqueous click reactions could be performed at room temperature, while organic click chemistry could be performed above the cloud point temperature of the catalyst system. The polymer catalyst system could be regenerated via extraction by making use of its lower critical solution temperature (LCST)‐behavior, and then reused for further copper(I) catalyzed azide‐alkyne cycloaddition (CuAAC) reactions. While a reduced catalytic activity is observed as a result of copper leaching in aqueous click reactions, the recycling experiments in the organic phase demonstrated that this copolymer supported system allows for efficient recycling and reuse. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011