Vinyl monomers bearing chromophore moieties and their polymers. VII. Synthesis,photochemical, and initiation behavior of acrylic monomers bearing phenothiazine oxide moieties and their polymers

Four acrylic monomers bearing phenothiazine oxide moieties, that is, N-acryloyl-phenothiazine-5-oxide (APTO), N-acryloyl-2-chlorophenothiazine-5-oxide (ACPTO), N-acryloyl-phenothiazine-5,5-dioxide (APTDO), and N-acryloyl-2-chlorophenothiazine-5,5-dioxide (ACPTDO) were synthesized by oxidation of corresponding N-acryloyl-phenothiazine (APT) and N-acryloyl-2-chlorophenothiazine (ACPT) using sodium perborate as an oxidant. These monomers could easily be polymerized by initiation of AIBN. The emission fluorescence spectra of the monomers and their polymers were recorded, and the results indicated that these 4 new monomers possess a fluorescence structural self-quenching effect (SSQE), as we have reported previously. Moreover, with the change of the electronic structure of sulfur atom in the phenothiazine chromophore, that is, from sulfide to sulfoxide and sulfone groups, the tendency of SSQE of these monomers is in the order of APT > APTO > APTDO. This would be ascribed mainly to the decrease of electron-donating abilities of monomers in a sequence of sulfide, sulfoxide, and sulfone groups; that is, at the sulfur atom of these monomers, APT has 2 lone-pair electrons, APTO has 1 lone-pair electrons, and APTDO completely loses its lone-pair electrons. Based on the exciplex formation, the monomers APTO, APTDO, ACPO, and ACPTDO could act as sensitizers for the photopolymerization of acrylonitrile (AN). The combination of APTO or ACPTO with organic peroxides such as BPO could also initiate the polymerization of vinyl monomers, such as AN, by redox nature. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 1191–1199, 1998     

Morphology of oligomers and their network polymers

Summary The morphology of di (4-methacryloxyethylene carbamate toluylen-2-carbamic) esters of oligoethylene glycols (OUM) with different molecular weight, of their network polymers and of model oligomers without methacrylic groups was studied. The supermolecular structure of oligomers is found to depend on molecular weight. Globular structure is typical for low molecular weight oligomers with M_n1200. The structure of crystalline samples with M= 1600–3600 is lamellar. The latter is retained on melting. It is transformed into globular structure at a temperature much higher than the melting point. A correlation exists between the morphology of polymerizable oligomers and their network polymers. The process of network formation from oligomers is extremely complicated. Irrespective of the mechanism it is influenced by MWD, FTD, intermolecular interaction and a number of other factors. The interconnection between the morphology of polymerizable oligomers and the supermolecular structure of their crosslinked polymers has not been sufficiently studied.Information about this connection facilitates phenomenological understanding of the network formation process.Presented at the 7th IUPAC Discussion Conference Polymer Networks, Karlovy Vary, CSSR, September 1980     

纳米碳管及其在聚合物中的应用

综述了聚合物基纳米碳管复合材料的制备方法及增强型、耐热型、抗静电型和电磁屏蔽型纳米碳管/聚合物复合材料的性能和应用。纳米碳管作为填料加入到聚合物中，可改善聚合物的机械性能和耐热性能，也可赋予聚合物抗静电和电磁屏蔽等新性能。随着对纳米碳管研究的不断深入，其将在物理学、化学、材料学领域尤其在纳米电子器件和复合材料领域有很大的突破。     

Polyhydroxyalkanoates,a family of natural polymers,and their applications in drug delivery

Polyhydroxyalkanoates (PHAs) are natural biopolymers produced by various microorganisms as a reserve of carbon and energy. PHA synthesis generally occurs during fermentation under nutrient limiting conditions with excess carbon. There are two main types of PHAs, short chain length PHAs (scl‐PHAs) and medium chain length PHAs (mcl‐PHAs). The mechanical and thermal properties of PHAs depend mainly on the number of carbons in the monomer unit and its molecular weight. PHAs are promising materials for biomedical applications because they are biodegradable, non‐toxic and biocompatible. The large range of PHAs, along with their varying physical properties and high biocompatibility, make them highly attractive biomaterials for use in drug delivery. They can be used to produce tablets, micro‐ and nanoparticles as well as drug eluting scaffolds. A large range of different PHAs have been explored and the results obtained suggest that PHAs are excellent candidates for controlled and targeted drug delivery systems. © 2015 Society of Chemical Industry     

超分子聚合物及其在涂层材料中的应用

基于非共价相互作用形成的超分子聚合物具有许多特殊的性能,它主要包括配位聚合物、π-π堆积聚合物和氢键结合聚合物3类.具有脲基嘧啶酮(Upy)四重氢键识别基元的超支化聚合物显示了优良的涂层性能,并且随着温度升高,熔体黏度迅速降低,这类聚合物适合用作热熔型涂层材料.     

NLO active Pd(II)-based organometallic side-chain polymers with C,N or N,O-chelating chromophoric ligands

Three organometallic homopolymers and three copolymers have been obtained, by reacting, respectively, cyclopalladated dinuclear complexes with a polymeric backbone, and by radical copolymerization of cyclopalladated acrylic monomers and methyl methacrylate. Taking into account thermal behaviour and solubility, the copolymers, which display good second order nonlinear optical activity, seem to be the most promising for applications within the new metallated macromolecules. Macroscopic nonlinear optical coefficients d₃₃ have been determined on spin-coated corona-poled thin films by means of Second Harmonic Generation (SHG) measurements at the wavelength of 1064 nm.     

Modified phenylquinoxaline-containing polymers and materials on their basis

The latest data concerning the modification of polymers containing phenylquinoxaline cycles and the manufacture of polymer materials on their basis are systematized. It has been shown that the design of silicon-and fluorine-containing and sulfated poly(phenylquinoxalines) makes it possible to significantly improve the processability of polymers and the performance characteristics of the related materials.     

Monolayer film behavior of polymers and their mixtures

The monomolecular film behavior of polyvinyl acetate (PVAc), polyethyl acrylate (PEA) and mixtures of these ranging in concentration ratio of PEA to PVAc from 0.008 to 11.301 has been studied using a Langmuir-type filmbalance over an aqueous 0.01N HCl substrate. Hysteresis was observed in the compression–expansion cycle for PVAc. A discussion of polymer–polymer interaction in a mixed monomolecular film at an interface is presented. The extent of this interaction for films comprising PVAc and PEA has been determined in terms of deviations of the film area from the ideal behavior. The data on the film areas of PVAc and PEA are discussed in terms of the molecular orientation of these polymers on the surface. A simple equilibrium thermodynamic treatment is applied to the data on mixed monolayer films. The implications resulting from this study are discussed.     

New photoinitiating systems and photoactive polymers and their applications

Two new types of photoinitiating systems based on transition metal carbonyls [mainly Mn₂(CO)₁₀ and Re₂(CO)₁₀] and free from abstractable halogen atoms are described. The first consists of a low concentration (typically ～0.1 mol 1^?1) of a fluoro-olefin, together with the metal carbonyl. Quantum yield data for photoinitiation by a number of these systems are presented; Re₂(CO)₁₀ is generally more active than Mn₂(CO)₁₀ and quantum yields near unity are obtainable. Polymers prepared with the aid of these initiators carry terminal groups in which the metal atom is covalently bound to the polymer chain through a fluoro-olefin unit. In the second type no halogen is present. The additive employed with the metal carbonyl is (a) acetylene or an acetylene derivative (e.g. acetylene dicarboxylic acid); or (b) an olefinic derivative carrying electron-attracting groups (e.g. diethyl fumarate). Mechanistically these photoinitiators resemble those based on fluoro-olefins; high quantum yields of initiation may be obtained and terminal groups containing covalently bound metal atoms are present in the polymers. Polymers prepared with either type of photoinitiator behave as macromolecular thermal initiators at higher temperatures (e.g. 100°C) and furnish a convenient route to block copolymers. A third type of photoinitiator, based on a vanadium (V) chelate, is also discussed. Chelates such as V^V OQ₂or, where Q represents 8-quinolyloxo, have been shown to photolyse by scission of (OR). If R is a side chain attached to a polymer molecule, photolysis yields a macroradical capable of initiating grafting reactions. The behaviour and applications of these photoactive polymers are described.     

Coordination polymers of Zn(II) and N,N'-bis (carboxymethyl) dithiooxamide

Summary Coordination polymers were synthesized using N,N'-Bis (carboxymethyl) dithiooxamide (NN' CMDTO) and Zinc(II) salts. The complexes were characterized by elemental analyses, IR spectral studies, TGA and viscosity measurements. In the proposed structures the ligand was supposed to be coordinated to metal through sulphur and oxygen.     

Dynamic mechanical,thermal, electrical and tensile properties of 1,4-diaminopiperazine polymers and their metal chelates

The properties and performance of 1,4-diaminopiperazine polymers and their metal chelates were studied. The polymeric chelates were semiconducting, stronger and more flexible, and had greater thermal stability and lower transition (relaxation) temperatures than the parent polymers.     

Hydrophobically associating polymers and their interactions with rod-like micelles

Several families of anionic and cationic hydrophobically associating acrylamide-based copolymers have been synthesized. This study focuses on the characterization in aqueous environments of water-soluble copolymers in which low levels of alkyl, i.e. methylene, units are incorporated into the polymer chain structure. These hydrophobic monomers have built-in surfactant character; therefore, no non-polymerizable surfactants are required in the preparation of these copolymer materials. These hydrophobically associating copolymers are shown to possess both polyelectrolyte and hydrophobic character, especially as the ionic strength of the solution is varied. The results confirm that, even at low concentrations of hydrophobe (typically ≤ 1 mol%), interesting solution properties are observed, i.e. enhanced rheology as compared to its non-associating parent, marked time-dependent rheology at low shear rates, ‘anti-polyelectrolyte effect’ in high-ionic-strength solutions and the ability to interact preferentially with hydrophobically associating rod-like micelles. These latter materials are capable of forming highly viscoelastic solutions themselves. The rheological properties of these latter solution mixtures are very sensitive to the fraction of each component in the mixture and to the length of the alkyl chain copolymerized into the acrylamide chain backbone.     

聚合物及其复合材料的摩擦学研究进展

聚合物及其复合材料是一类重要的耐磨材料,在工程中有重要的应用价值。其磨损类型根据用途主要有滑动摩擦磨损型、气蚀磨损型和冲蚀磨损型等。主要对其磨损类型及相应的磨损机理进行了介绍。     

Annealing effects of polymers and their underlying molecular mechanisms

This paper indicates that changes in chain mobility, heat capacity, WAXS crystallinity, SAXS long period, SAXS peak intensity, specific volume and morphology as a function of increasing temperature, occur in three fairly distinct annealing ranges (I, II and III) that are more or less the same for all crystallized polymers with a lamellar morphology. It is shown that none of the proposed molecular models to date, including the well-known fold surface premelting model, can satisfactorily account for all the experimental data. However, a new molecular interpretation, based primarily on electron microscopy and SAXS studies of changes such as lateral ‘melting’ from edges of microparacrystallites (mPC) within the lamellae seen at the annealing temperatures can account for the data. With our new molecular interpretation, the effect of temperature increase is established to result in a slight breakup of the laterally aligned mPC within the lamellae at low annealing temperatures in range I, and selective lateral ‘melting’ of the exposed mPC and recrystallization at higher annealing temperatures in ranges II and III, with the recrystallization being very limited in range III. Annealing effects seen in cold- or hot-drawn polymers with a fibrillar morphology can also be readily accounted for by this very general molecular mechanism occurring in the same annealing temperature ranges.     

Recent advances in vegetable oil-based polymers and their composites

The development of viable alternatives to petroleum-based polymeric materials is a compelling contemporary challenge attributable to environmental concerns and the effects of fluctuating oil prices. Triglycerides, the primary components of vegetable oils, are an abundant, renewable, and widely investigated alternative feedstock for polymeric materials. Efforts are made on a global scale to develop innovative technologies to transform these natural resources into novel monomers and polymers. Some of these technologies have already generated competitive industrial products with properties comparable to conventional petrochemical polymers. Fillers and fibers have also been incorporated into these bio-based polymer matrices to improve the physical and thermal-mechanical properties of the resulting composite materials. The development of multifunctional composite materials facilitates the application of these materials in new areas, e.g., sensors, structural parts, medical device, construction units, flame retardant parts. This article reviews recent advances in polymeric materials from vegetable oils in terms of preparation, characterization, and properties. Nano-composites and fiber reinforced composites based on bio-polymers matrices will also be reviewed. This chapter will conclude with an overview of current and potential future applications of these materials in packaging, automotive, construction, electrical, and medical devices.     

Graphene and graphene oxide and their uses in barrier polymers

Currently, there is great interest in graphene‐based devices and applications because graphene has unique electronic and material properties, which can lead to enhanced material performance. Graphene may be used in a wide variety of potential applications from next‐generation transistors to lightweight and high‐strength polymeric composite materials. Graphene, which has atomic thickness and two‐dimensional sizes in the tens of micrometer range or larger, has also been considered a promising nanomaterial in gas‐ or liquid‐barrier applications because perfect graphene sheets do not allow diffusion of small gases or liquids through its plane. Recent molecular simulations and experiments have demonstrated that graphene and its derivatives can be used for barrier applications. In general, graphene and its derivatives can be applied via two major routes for barrier polymer applications. One is the transfer or coating of few‐layered, ultrathin graphene and its derivatives, such as graphene oxide (GO) and reduced graphene oxide (rGO), on polymeric substrates. The other is the incorporation of fully exfoliated GO or rGO nanosheets into the polymeric matrix. In this article, we review the state‐of‐the‐art research on the use of graphene, GO, and rGO for barrier applications, including few‐layered graphene or its derivatives in coated polymeric films and polymer nanocomposites consisting of chemically exfoliated GO and rGO nanosheets, and their gas‐barrier properties. As compared to other nanomaterials being used for barrier applications, the advantages and current limitations are discussed to highlight challenging issues for future research and the potential applications of graphene/polymer, GO/polymer, and rGO/polymer composites. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39628.     

Hydrothermal syntheses and crystal structures of PbII coordination polymers based on a N,O-donor ligand

In this article, four new lead(II) coordination polymers based on a N,O-donor ligand 2′-(1 H-1,3,7,8-tetraaza-cyclopenta[l]phenanthren-2-yl)biphenyl-2-carboxylic acid (HL) have been hydrothermally synthesized, namely, [PbL₂]·2H₂O (1), [PbL₂]·2H₂O·CH₃CH₂OH (2), [Pb₅L₂(m-BDC)₄]·3H₂O (3) and [Pb₂L₂(p-BDC)] (4), where m-BDC = 1,3-benzenedicarboxylate and p-BDC = 1,4-benzenedicarboxylate. Compound 1 shows a 2D bilayer structure, which is further extended into a 3D supramolecular structure through π–π stacking interactions. Compound 2 shows a 3D supramolecular structure based on a zero-dimensional molecule by π–π stacking interactions of neighboring molecules. Compound 3 shows a 2D layer structure. Compound 4 displays a 1D chain-like structure, which is then stacked by π–π interactions to result in a 2D supramolecular structure. Solid-state luminescent spectra of four lead(II) complexes indicate intense fluorescent emissions.     

Synthesis, characterization and third-order non-linear optical properties of novel fluorene monomers and their cross-conjugated polymers

We designed and synthesized two novel fluorene monomers of D-A-D (donor-acceptor-donor) type (M1 and M2), and their two corresponding polymers (PM1 and PM2) and a copolymer (CPM). These high molecular weight, film-forming polymers were obtained from metal-free, superacid-catalyzed reactions of the monomers with N-phenylisatin. The cubic NLO response (χ⁽³⁾) for these new compounds, in solid thin films, was measured through the use of third-harmonic generation (THG) Maker-Fringes technique at IR wavelengths given values of the order of 10⁻¹² esu from which, the corresponding second hyperpolarizabilities (γ) were estimated to be of the order of 10⁻³³ esu for monomers and 10⁻³¹ esu for polymers. Second hyperpolarizabilities have also been estimated theoretically at B3LYP/6-31G(d) level of theory in gas phase and related with the electronic structure of the synthesized molecules.