Through-space conjugated polymer containing [2.2]paracyclophane and dithiafulvene units in the main chain

A new through-space conjugated polymer containing alternate [2.2]paracyclophane and dithiafulvene units was synthesized by cycloaddition polymerization of aldothioketene derived from 4,16-diethynyl[2.2]paracyclophane. The obtained polymer was soluble in common organic solvents and could form thin films. UV–vis absorption spectrum of the polymer revealed that its conjugation length increased due to the through-space interaction of the [2.2]paracyclophane units. The polymer formed a charge transfer (CT) complex with 7,7,8,8-tetracyanoquinodimethane (TCNQ) in DMSO.     

Synthesis and surface mobility of segmented polyurethanes with fluorinated side chains attached to hard blocks

Novel polyurethanes with fluorinated side chains attached to hard blocks were synthesized and characterized by NMR, mass spectroscopy, DSC and gel permeation chromatography (GPC). A unique chain extender, 3-(2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluoro-octyloxy)-propane-1,2-diol (PFOPDOL) was prepared from 3-(2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluoro-octyloxymethyl)-oxirane (PDFOMO) by reacting it with diluted perchloric acid. Poly(ether urethane)s and poly(carbonate urethane)s containing various amounts of the chain extender with fluorinated side chains were then synthesized using methylenebis(phenylene isocyanate) (MDI), polytetramethyleneoxide (PTMO), poly(1,6-hexyl-1,5-pentylcarbonate) diol (PHPCD), 1,4-butandiol (BDO) and PFOPDOL. Mechanical properties of the polyurethanes were characterized by Instron. Surface properties were characterized by X-ray photoelectron spectroscopy (XPS) and contact angle measurements. Results from GPC and Instron studies indicated that fluorinated polyurethanes with high molecular weights and good mechanical properties were obtained. Results from XPS and contact angle studies indicated that the surface of fluorinated polyurethanes were very nonpolar due to migration of fluorinated side chains to the surface.     

Chemical fixation of SO2 using norbornene with different side‐chain groups and control of the physical properties of poly(olefin sulfone)

Photoresists involving polymer solubility and degradation play a crucial role in the manufacture of integrated circuits by photolithography. Conventional photoresists typically rely on a single switching mechanism based on a change in either polarity or molecular weight of the polymer. Here we report a new type of poly(olefin sulfone) as a photoresist which overcomes the drawback of poor dry etching resistance, solubility and thermal degradation. The effects of different side‐chain groups (acetyl, acetoxy and carboxylic acid) of norbornene on the properties of poly(norbornene sulfone)s were analyzed with the aim of developing a new type of photoresist. Thermogravimetry and gel permeation chromatography results revealed that bond breaking occurred at different temperatures, because of the different side‐chain groups, and the three side‐chain groups affect the solubility and stability of the poly(norbornene sulfone)s. A novel photoresist material based on a poly(olefin sulfone) with different side‐chain groups was synthesized and its physical properties examined. © 2017 Society of Chemical Industry     

Chain length effect of alkenyl succinic anhydride on thermal and mechanical properties of the cured epoxy resins

As epoxy curing agents three alkenyl succinic anhydrides (ASA) with varying side chain length (2-octenyl, 2-dodecenyl and 2-hexadecenyl succinic anhydride) were prepared by the ene synthesis and thermal and mechanical properties of a bisphenol A epoxy resin cured with the ASA's were measured. With increase in the side chain length of the ASA the Tg, the tensile strength and the impact strength decreased. All the cured samples exhibited excellent transparency and flexibility.     

Mechanical relaxations of poly(β,L‐aspartate)s

The dynamic mechanical thermal properties of a family of poly(α‐alkyl β,L ‐aspartate)s bearing various cyclic, linear, and branched alkoxycarbonyl groups in the side chain were studied. The measurements carried out by dynamic mechanical thermal analysis (DMTA) revealed the significant influence of the constitution of the side chain on mechanical relaxation phenomena. Three relaxations were observed, which are referred to as γ, β, and α, in increasing order of temperature. The first two, γ and β, are related to the local and global motions of the side chain, respectively. Relaxation α is related to the motion of the main chain. Relaxation β, which is associated with the rotation of the side chain, is the most intense. The magnitude and temperature at which this relaxation occurs depends on the volume, the length, and the degree of branching of the ester group of the side chain. A comparison between the dynamic mechanical properties of poly(β,L ‐aspartate)s and poly(α,L ‐glutamate)s revealed that the two methylene groups spacing the ester group from the main chain provides the poly(α‐L ‐glutamate)s with greater mobility, and thus, relaxations α and β occur at lower temperatures. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 994–1003, 2006     

Influence of side‐chain structures on the viscoelasticity and elongation viscosity of polyethylene melts

Metallocene‐catalyzed, low‐density and linear low‐density polyethylenes with similar melt indexes were used to investigate how side‐chain structures influence the elongation viscosity and viscoelastic properties. The viscoelastic properties were determined with a rotation rheometer, while the elongation viscosities were acquired by using isothermal fiber spinning. The Phan‐Thien‐Tanner (PTT) model was also used to understand how the side‐chain structure affects the elongation behavior. Experimental results demonstrate that the log G′ vs. log G″ plot can qualitatively describe the effects of the side chain branch on the rheological properties of polyethylene melts. According to the results determined by the PTT model, low‐density polyethylene (LDPE) has low elongation viscosities at high strain rates. This low elongation viscosity can be attributed to the fact that LDPE has high shear thinning behavior. The long‐chain branching tends to increase entanglements, thereby enhancing the storage modulus, elongation viscosity and shear‐thinning behaviors. Uniform side‐chain distribution lowers the entanglements, which results in a low storage modulus, elongation viscosity and shear‐thinning behavior.     

Layer‐by‐layer films based on charge transfer interaction of ϕ‐conjugated poly(dithiafulvene) and incorporation of gold nanoparticles into the films

Layer‐by‐layer (LBL) self‐assembled ultrathin films were prepared via consecutively alternating immersion of substrates into solutions of electron donor, poly(dithiafulvene) (PDF), and electron acceptor, poly(hexanyl viologen) (6‐VP). The charge transfer (CT) interaction formed at solid–liquid interfaces between the backbones of the electron acceptor and donor polymers was the driving force of the alternative deposition. The sandwich heterostructure of the LBL film led to electrical anisotropy in the directions parallel and perpendicular to the film surfaces. Incorporation of gold nanoparticles into the LBL films was investigated by reducing gold ions with the PDF layers already deposited on the film surfaces, or depositing PDF‐protected gold colloidal solution as the electron donor layers directly. The influence of the gold nanoparticles on the electrical anisotropy of the LBL films was also illustrated in this research. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1608–1615, 2007     

Syntheses and properties of polyurethanes containing side‐chain azobenzene groups

Polymers containing azobenzene groups have the characteristic reaction of photo‐induced cis–trans isomerism. The study of new materials for optical information storage has prompted making use of these photo‐isomerizations. In this study, we report the syntheses and properties of four different polyurethanes (DR‐PUns) containing azobenzene groups in the side‐chains. The structurally similar polyurethanes (DR‐PUns) were synthesized by the polycondensation reaction of Disperse Red 19 (DR 19) and four different diisocyanates in dimethylformamide. By introducing of DR 19 into the polymer, we obtained polymers containing a photochromic group in the side‐chain. The weight‐average molecular weights of the DR‐PUns were in the range 5500–12 900. The T_gs of the DR‐PUns range from 119.5 °C to 157.0 °C, depending on the structure of the diisocyanate. Optical properties and solubilities of the polyurethanes were compared. The diffraction efficiencies of films were measured as a function of the reaction time. Typically, the diffraction efficiencies of the DR‐PU1 film prepared from toluene 2,4‐diisocyanate were observed up to a level of 0.25%. For the DR‐PU1 film, the effect of the intensity of the induced laser beam on the diffraction efficiency is also discussed. © 2003 Society of Chemical Industry     

Dispersion of surface acoustic waves in polycrystalline diamond plates

Five free-standing polycrystalline diamond plates were grown by electron-assisted hot filament CVD on molybdenum using different deposition parameters. The homogeneity of the elastic properties was studied for each side of the samples by surface acoustic waves (SAWs) using pulsed laser excitation and piezoelectric detection. From the velocities of the longitudinal acoustic bulk waves (LABWs) and SAWs, values of the Poisson ratio of approximately ν=0.14±0.06 were obtained. The Young's modulus varied between E=928±40 GPa and E=1098±43 GPa. Anomalous dispersion of the SAWs on the nucleation side was observed in some samples. In addition the mean velocity of the SAWs was generally higher on the nucleation side than on the growth side. This indicates that the elastic properties changed considerably during the growth process. Measurements of the grain size by scanning electron microscopy (SEM), of the phase purity by Raman spectroscopy, and the texture by X-ray diffraction (XRD) were performed in order to estimate the contribution of different effects to the dispersion and the side dependence of the SAW velocities. In addition Fourier transform infrared (FTIR) spectroscopy was applied to study the influence of the hydrogen content.     

Synthesis and characterization of new ferroelectric liquid‐crystalline cyclic oligosiloxanes containing methyleneoxymethylene spacers

The synthesis of side‐chain liquid‐crystalline oligocyclosiloxanes containing methyleneoxymethylene spacers, two different mesogenic cores (including biphenyl phenyl carboxylate or biphenyl fluorophenyl carboxylate groups) and chiral tails is presented. Differential scanning calorimetry, optical polarizing microscopy and X‐ray diffraction measurements reveal liquid‐crystalline properties for all of the synthesized monomers and oligomers. All cyclic oligosiloxanes exhibit enantiotropic smectic A and chiral smectic C phases. The mesogenic properties of the cyclic oligomers and side‐chain liquid‐crystalline precursor are discussed. Copyright © 2005 Society of Chemical Industry     

Microstructural Characteristic and its Relation to Mechanical Properties of Clinocardium californiense Shell

The microstructures and mechanical properties of Clinocardium californiense shell were investigated in relation to the different parts of shell. It is found that the shell can be divided into three parts, that is, the dorsal side, body part, and marginal side based on the variation of microstructures along the longitudinal cross section. Specifically, all areas exhibit a cross‐lamellar structure on the dorsal side, and a hierarchical structure comprising three layers including inner (with a cross‐lamellar structure), middle (with a complex cross‐lamellar structure), and outer (with a prismatic structure) layers was observed on the body part, whereas on the marginal side, the orientation of aragonite sheets shows an obvious deflection. The structural architecture, the dimensions of different‐order lamellae in the same kind of structure and the orientation between the indenting direction and aragonite sheet all contribute to the unique mechanical properties of this shell. It is also found that a low value of the ratio of hardness‐to‐Young's modulus (H/E) corresponds to an improved indentation toughness. The middle layer with the densest and most complicated structure on the body part shows the lowest H/E ratio and the highest hardness and Young's modulus.     

Vinyl‐addition type norbornene copolymers containing flexible spacers and sulfonated pendant groups for proton exchange membranes

Novel sulfonated poly(2‐butoxymethylenenorbornene‐co‐2‐(6‐phenoxy‐hexyloxymethylene)‐5‐norbornene [sP(BN/PhHN)] were prepared successfully through vinyl‐addition type polymerization and then sulfonated with concentrated sulfuric acid (98%) as sulfonating agent in a component solvent. The sP(BN/PhHN)‐40 with the maximal degree of sulfonation of 40% can be obtained by controlling the sulfonating reaction time from 8 to 20 h, and a proton conductivity of 3.35 × 10^?3 S/cm was achieved at 70°C. The methanol permeabilities of these membranes were in the range from 0.26 to 6.58 × 10^?7 cm²/s, which were remarkably lower than Nafion (2.36 × 10^?6 cm²/s). TEM analysis revealed that these side‐chain type membranes have a microphase separated structure composed of hydrophilic side‐chain domains and hydrophobic polynorbornene main chain domains. Sulfonated polynorbornene containing soft spacers displayed better properties, such as lower water uptake, high thermal properties, mechanical properties, and low methanol permeability. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Impact of flow-corrective insert on flow patterns in two-dimensional moving bed

This paper presents the study of the flow patterns inside a granular moving bed in a quasi-two-dimensional (2D) model of a granular moving bed filter (GMBF) vessel with vertical walls and a mass flow hopper. Fine quartz sand was chosen as the granular filter media in experiments. The related flow properties were measured by a Jenike Shear Tester. According to the flow properties of fine silica sand and Johanson's theory, a 2D moving-bed apparatus was built, with transparent walls and the flow-corrective insert to diminish the quasi-stagnant zones along the side walls. The flow patterns and velocity profiles of silica sand in the system with flow-corrective insert were studied experimentally, and the effect of the location of the flow-corrective insert on the internal flow patterns was investigated. The optimal placement of flow-corrective insert according to Johansson's theory was demonstrated to efficiently diminish the quasi-stagnant zones near the side walls. Little vertical shift of the flow-corrective insert from optimal position changed the stable and uniform mass flow pattern of moving bed into the funnel flow.     

Phase behavior and hydrogen bonding in biomembrane mimicing polyurethanes with long side chain fluorinated alkyl phosphatidylcholine polar head groups attached to hard block

To achieve a good biocompatibility, two sets of novel segmented polyurethanes, namely, poly(ether urethane)s and poly(carbonate urethane)s, with long side chain fluorinated alkyl phosphatidylcholine polar head groups attached to hard block have been synthesized recently in our laboratory by using a new diol with a long side chain fluorinated alkyl phosphatidylcholine polar head group 2-[2-[2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9-hexadecafluoro-10-ethoxy-decyloxy]-N-(2-hydroxy-1-hydroxymethyl-1-methyl-ethyl)-acetamide] phosphatidylcholine, HFDAPC as an extender. These novel polyurethanes have shown a potential to be used as bio-membrane mimicry. In this article we investigated the phase behavior of these materials by Instron, DSC, DMA, and AFM because the phase behavior has a great effect on the surface properties thus the biological-related perspective. T_g decreases first then increases for the poly(carbonate urethane)s, but increases first then decreases for the poly(ether urethane)s with an increasing in fluorinate phosphatidylcholine content. On the other hand, the tensile modulus was found decrease for the poly(carbonate urethane)s but increase for the poly(ether urethane)s with an increasing in fluorinate phosphatidylcholine content. It was found via AFM that the phase separation increases in poly(ether urethane)s but phase mixing increases in poly(carbonate urethane)s, with increasing content of fluorinated phosphatidylcholine side chain. The interaction between hard and soft segment, particularly, the hydrogen bonding was investigated by FTIR. The effect of fluorinated phosphatidylcholine side group on the phase separation of polyurethane was discussed and compared with that of fluorinated polyurethanes containing only fluorinated side chains. Our result demonstrated how the phase behavior of polyurethanes could be controlled by tailoring the interaction between hard and soft segment.     

Structural effects of pendant groups on thermal and electrical properties of polyimides

Two series of aromatic polyimides containing various‐sized alkyl side groups were synthesized by thermal imidization of the poly(amic acid)s prepared from the polyaddition of benzophenonetetracarboxylic dianhydride and hexafluoro‐isopropylidene bis(phthalic anhydride) with 4,4′‐methylenedianiline, 4,4′‐methylene‐bis(2,6‐dimethylaniline), 4,4′‐methylene‐bis(2,6‐diethylaniline), and 4,4′‐methylene‐bis(2,6‐diisopropylaniline). The extent to which alkyl substitutes affect the thermal properties of polyimides was examined by differential scanning calorimetry, thermomechanical analyzer, and thermogravimetric analysis techniques. The analytical results demonstrated that the incorporation of alkyl moieties causes a moderate increase in the coefficient of thermal expansion and a slight decrease in thermal stability. Notably, all polymers had a decomposition temperature exceeding 500°C. The glass transition temperature increases markedly when hydrogen atoms at ortho positions on aniline rings are replaced with methyl groups, but decreases with growing alkyl side group size. The dielectric measurements show that the polymer possessing a large alkyl side group would have the lower dielectric value. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4672–4678, 2006     

Studying the effects of chain extenders chemical structures on the adhesion and mechanical properties of a polyurethane adhesive

Chain extenders including diethanol amine (DEA) and 2-cyano-N,N-bis-hydroxyethyl acetamide (CNBA) were utilized to enhance the adhesion and mechanical properties of a polyurethane (PU) adhesive. The adhesion and mechanical properties of the adhesives were studied by peel test, tensile test and dynamic thermal analysis (DMTA) respectively. Results revealed that both chain extenders (DEA and CNBA) increased peel test modulus. The cross-linking density and toughness of the adhesive were significantly increased using chain extenders. Results showed that chain extender without side chain (DEA) could improve the adhesion and mechanical properties of the adhesive greater than chain extender with aliphatic side group (CNBA).     

Incorporation effects of fluorinated side groups into polyimide membranes on their physical and gas permeation properties

The effects of incorporation of fluorinated alkyl side groups into polyimide membranes were investigated in terms of their physical and gas permeation properties. Four polyimides with fluorinated side groups and four polyimides without the side groups were prepared by polycondensation of 2‐(perfluorohexyl)ethyl‐3, 5‐diamino benzoate (PFDAB) and m‐PDA with four aromatic dianhydrides (6FDA, ODPA, BTDA, and PMDA), respectively. It was found that the incorporation of fluorinated side groups into the polyimide membranes decreased their surface free energies (T_gs), solubility parameters, and fractional free volume (FFV)s and therefore, enhanced the permeabilities for CO₂, O₂, N₂, and CH₄ gases but reduced the selectivities for CO₂/ CH₄, O₂ /N₂, CO₂/N₂ gas pairs depending upon the structure of dianhydride monomers. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2756–2767, 2000     

Poly(2‐oxazoline)s: A comprehensive overview of polymer structures and their physical properties

Poly(2‐oxazoline)s (PAOx) are of increasing importance for a wide range of applications, mostly in the biomedical field. This review describes the synthesis of 2‐oxazoline monomers and their cationic ring‐opening polymerization, and gives a comprehensive overview of all reported PAOx homopolymers. In the second part of the review, the polymer properties of these PAOx homopolymers with varying side‐chain structures are discussed. Altogether, this review intends to serve as an encyclopedia for poly(2‐oxazoline)s enabling the straightforward selection of a polymer structure with the desired properties for a certain application. © 2017 Society of Chemical Industry     

Synthesis, characterization and liquid-crystal-aligning properties of novel aromatic polypyromellitimides bearing (n-alkyloxy)biphenyloxy side chains

Novel aromatic polypyromellitimides bearing (n-alkyloxy)biphenyloxy side chains were prepared by two-step polycondensation of 1,4-phenylenediamine (PDA) and biphenyl-4,4′-diamine (BZ) with 3,6-bis[4′-(n-alkyloxy)biphenyl-4-oxy]pyromellitic dianhydrides (C_mB-PMDAs, m = 6, 8, 10, 12), which had been synthesized by the nucleophilic substitution of N,N′-diphenyl-3,6-dibromopyromellitimides with sodium 4-(n-alkyloxy)biphenoxides. Inherent viscosities of the poly(amic acid)s were in the 0.26-0.62 dL/g range. Poly{1,4-phenylene-3,6-bis[4′-(n-alkyloxy)biphenyl-4-oxy]pyromellitimide}s (C_mB-PPIs) and poly{4,4′-biphenyl-3,6-bis[4′-(n-alkyloxy)biphenyl-4-oxy]pyromellitimide}s (C_mB-BPIs) obtained in films by thermal imidization of the corresponding poly(amic acid)s were characterized by FT-IR spectroscopy and elemental analysis, and their crystalline structure and thermal properties were measured and discussed with respect to the side chain length. After the polyimide films were surface-treated by rubbing with velvet fibers, standard liquid crystal (LC) cells containing 4-cyano-4′-n-pentylbiphenyl (5CB) were fabricated and their LC-aligning properties were investigated in terms of pretilt angle. The pretilt angles were remarkably affected by side chain length and on surface of the polyimides with m = 6 and 8 LCs aligned parallel to the rubbing direction while on surface of the polyimides with m = 10 and 12 they aligned nearly or completely vertical to the rubbing direction.     

Influence of Macromolecular Brushes with Polyimide Backbones and Poly(methyl methacrylate) Side Chains on Structure,Physical, and Transport Properties of Polyphthalamide

Composite films based on polyamide (poly(m-phenylene-iso-phthalamide)) (PA) and a brush-like polymer with polyimide (PI) backbone and side poly(methyl methacrylate) chains (PI-PMMA) were prepared by mixing individual solutions of PA and PI-PMMA and subsequent film casting. Macromolecular brushes with the same backbone length and density of side chains but with various lengths of side PMMA chains were synthesized via activator generated by electron transfer atom transfer radical polymerization. Interactions between PA and PI-PMMA, as well as distribution of PI-PMMA filler inside the PA matrix, were studied by viscometry, dynamic light scattering, differential scanning calorimetry, scanning electron microscopy, and IR spectroscopy. The mechanical properties of polymer samples were also investigated. Microphase separation was revealed in PA/PI-PMMA films. The length of side chains influences interactions between PA and PI-PMMA. At the same time, the degree of reduction in the rigidity parameters and in the elasticity parameter depends on the side chain length. Diffusion membranes were prepared on the basis of compositions with the best mechanical properties; these membranes proved to be highly efficient in pervaporation of methanol–hexane mixture. It was established that the fluxes and separation factors of the studied membranes are several times higher as compared to the corresponding characteristics of known commercial membranes. POLYM. ENG. SCI., 60:481–490, 2020. © 2019 Society of Plastics Engineers