The effects of nano-C-S-H with different polymer stabilizers on early cement hydration

A promising approach to accelerate cement hydration known as “seeding technology” has been discovered using nano-particles to provide additional nucleation sites for growing of C-S-H. Two different types of polymer, polycarboxylate (PCE) and polysulfonate (PSE) were used as stabilizer to synthesize nano-C-S-H via co-precipitation process. The obtained C-S-H-polymer composites were characterized by means of XRD, FTIR, thermogravimetric analysis (TGA), TEM, dynamic laser scattering (DLS), and BET. DLS measurement shows that the particle size of the obtained C-S-H-polymer suspension ranges from 82.6 to 589.9 nm. The results of DLS and BET show that the particle size of the C-S-H particles synthesized using PCE polymer as stabilizer is smaller than those synthesized with PSE polymer, and hence the specific surface area is much higher. FTIR and TGA results confirm the presence of the polymers in the obtained C-S-H composites particles. XRD results indicate that the presence of the polymers reduces the crystallinity of C-S-H due to the absence of the d002 peak at 2θ of 7°. The calorimetry results show that the main hydration peak of cement is dramatically increased by the addition of the C-S-H-polymer composites. It is interestingly found that the acceleration effect of the C-S-H-polymer composites is linearly proportional to the total surface area of the nanoparticles introduced into the cement pastes. At the same time, it is found that the secondary hydration peak, usually known as the sulfate-depletion peak, is greatly advanced by addition of the C-S-H nano-particles in comparison with the blank cement paste. The acceleration effect of the nano-C-S-H is further verified in a pure C₃S system.     

Microwave Dielectric Study of Water Structure in the Hydration Process of Cement Paste

Microwave dielectric relaxation measurements, via the time-domain reflectometry method, were performed on portland cement paste for the first time, and the water structure during the hydration process was observed. The relaxation process due to the orientation of free water, which is independent of calcium silicate hydrate (C-S-H), was observed at ∼10 GHz. The relaxation strength, in proportion to the amount of free water, decreased rapidly as the curing time increased for the first three days. This change is in good agreement with that of a chemical reaction that was reported by measurements of the heat that is evolved during hydration. The free water is taken into C-S-H and is transformed to hydrated water by the hydration process. When hydration proceeds, the relaxation processes due to the orientation of the hydrated water in C-S-H occur at ∼100 MHz and 1 MHz.     

Living radical polymerization in homogeneous system with phenylazotriphenylmethane as a thermal iniferter

Summary Radical polymerization of methyl methacrylate (MMA) with phenylazotriphenylmethane (PAT) was found to give the polymer with a trityl group bonded at its -chain end which could further dissociate into propagating and trityl radicals. Therefore, it was confirmed that PAT served as a thermal iniferter for polymerization of MMA, which proceeded via a living radical mechanism, i.e. yield and molecular weight of the polymers increased with reaction time. When the polymer thus obtained was used as a polymeric iniferter for the polymerization of styrene (St), the block copolymer was obtained.     

Polymerizations with elemental sulfur: A novel route to high sulfur content polymers for sustainability,energy and defense

Recent developments in the polymerizations of elemental sulfur (S₈) to prepare high sulfur content polymers are reviewed. While the homopolymerization of S₈ via ring-opening processes to prepare high molar mass polymeric sulfur has long been known, this form of polymeric sulfur is chemically unstable and depolymerizes back to S₈. In the current report, we discuss the background into the production of sulfur via petroleum refining and the challenges associated with utilizing S₈ as a chemical reagent for materials synthesis. To circumvent these long standing challenges in working with sulfur, the use of S₈ as a reaction medium and comonomer in a process termed, inverse vulcanization, was developed to prepare chemically stable and processable sulfur copolymers. Furthermore, access to polymeric materials with a very high content of sulfur–sulfur (SS) bonds enabled for the first time the creation of materials with useful (electro)chemical and optical properties which are reviewed for use in Li–S batteries, IR imaging technology and self-healing materials.     

Calcium Silicate Hydrates Studied by Small-Angle Neutron Scattering (SANS)

Small-angle neutron scattering (SANS) was used to study calcium silicate hydrate (C-S-H) formed via pozzolanic reaction between calcium oxide and ultrafine silica in water or polymer solutions at a temperature of 20°C. The SANS profile of this product was consistent with a structure that consisted of platelets with maximum diameters of ∼20 nm (± 5 nm) in the x – y plane, which was similar to a structure that had been deduced in previous work via X-ray diffractometry. The presence of two different types of superplasticizer in solution (at a concentration of 10 g/L) had no significant effect on its formation kinetics or its SANS profile.     

Synthesis of Reactive Polymeric Dyes as Textile Auxiliaries

New polymeric materials containing amino‐substituted azobenzene chromophores and reactive functional groups and characterized by some hydrophilicity were prepared with the aim of investigating alternative textile dyeing routes. The indicated materials were obtained either by copolymerization of suitable monomers or by modification of preformed polymers. In both cases commercial 4‐amino‐2′,3‐dimethylazobenzene (FG) was used as chromogenic compound. According to the first synthetic strategy, the methacrylamido derivative of FG was copolymerized by free radical initiation with different monomers, such as methyl methacrylate, glycidyl methacrylate, N‐tert‐butylacrylamide, methacrylic acid, N‐vinyl‐2‐pyrrolidinone, and vinyl acetate. Reaction of FG with preformed polymers containing epoxy groups generally afforded crosslinked materials. On the other hand, low FG loading extents were recorded by amidation of polymers containing carboxylic groups. Indeed, almost quantitative conversions were obtained only in the reaction of FG with anhydride containing polymers. The chemical structure, molecular weight properties, and the physical‐chemical characteristics of all synthesized polymeric dyes were thoroughly investigated. Some very preliminary dyeing tests of different cloth types with the prepared polymeric dyes were also performed.

UV absorption spectrum of poly(FGMAA) and poly(FGMAA‐co‐MMA) in chloroform at 25 °C (FGMAA = 4‐methacrylamido‐2′,3‐dimethylazobenzene).     

Development of antimicrobial aminoacid-modified bisphenol-A formaldehyde resin and its transition-metal complexes

A polymeric ligand (BFG), containing glycine moiety was synthesized by the polycondensation reaction of bisphenol-A and formaldehyde with amino acid (glycine) in alkaline medium. The polymer–metal complexes were synthesized with transition metal ions. The polymer and its metal complexes were characterized by elemental analysis and other spectroscopic techniques. The analytical data revealed that the coordination polymers of Cr(III), Co(II), and Ni(II) were coordinated with two water molecules, which are further supported by FTIR spectra and TGA data. The amino acid was found to act as bidentate ligand toward metal ions via the nitrogen of the NH group and carboxyl oxygen of the respective amino acid. The in-vitro preliminary antimicrobial activities of all the synthesized polymers were investigated against some bacteria and fungi. The polymer–metal complexes showed excellent antimicrobial activities against both types of microorganisms. Interestingly the polymeric ligand was found antimicrobial in nature but less effective as compared the polymer–metal complexes. On the basis of the antimicrobial behavior, these polymers hold potential in their application as antifungal and antifouling coating materials in medical devices as well as antimicrobial packaging material.     

Polymeric materials as anion-exchange membranes for alkaline fuel cells

After summarizing the different fuel cells systems, including advantages and drawbacks, this review focuses on the preparation of copolymers and polymeric materials as starting materials for solid alkaline fuel cells membranes. The requirements for such membranes are also summarized. Then, different strategies are given to synthesize anion-exchange polymeric materials containing cationic (especially ammonium) groups. The first pathway focuses on heterogeneous membranes that consist in: (i) polymer blends and composites based on poly(alkene oxide)s and hydroxide salts or polybenzimidazole doped with potassium hydroxide, (ii) organic–inorganic hybrid membranes especially those synthesized via a sol–gel process, and (iii) (semi)interpenetrated networks based on poly(epichlorhydrine), poly(acrylonitrile) and polyvinyl alcohol for example, that have led to new polymeric materials for anion-exchange membranes. The second and main part concerns the homogeneous membranes divided into three categories. The first one consists in materials synthesized from (co)polymers obtained via direct (co)polymerization, for example membranes based on poly(diallyldimethylammonium chloride). The second pathway concerns the modification of polymeric materials via radiografting or chemical reactions. These polymeric materials can be hydrogenated or halogenated. The radiografting of membranes means the irradiation via various sources – electron beam, X and γ rays, ⁶⁰Co and ¹³⁷Cs that lead to trapped radicals or macromolecular peroxides or hydroperoxides, followed by the radical graft polymerization of specific monomers such as chloromethyl styrene. The third route deals with the chemical modifications of commercially available hydrogenated aliphatic and aromatic (co)polymers, and the syntheses of fluorinated (co)polymers such as carboxylic and sulfonic perfluoropolymers. In addition, several approaches for the crosslinking of above-mentioned polymeric materials are also reported as this process enhances the properties of the resulting membranes. Moreover, electrochemical and thermal properties of various above ionomers are given and discussed.     

Methacrylate based side chain liquid crystalline polymers with pendant cholesterol group: Preparation and investigation of electrical conductivity mechanism

Methacrylate based side‐chain liquid crystalline polymers (SCLCP) bearing cholesterol pendant moieties with various lengths of aliphatic spacer were synthesized and their electrical conductivity mechanism was studied for their possible applications in elastic microelectronic devices. All the polymers exhibited liquid crystalline behavior of broken focal‐conic fan texture of smectic phase. The dielectric properties of polymers were investigated by impedance spectroscopic technique in the frequency range of 100 Hz to 15 MHz at room temperature. Alternating current (AC) conductivity ( ) of the liquid crystalline polymeric films was observed to vary with angular frequency, ω as ω^S with s < 2. Detailed conductivity analysis revealed that the conductivity of the polymeric films follows quantum mechanical tunneling and correlated barrier hoping conductivity mechanisms at low frequency regime, whereas it obeys super linear power law and direct current conductivity mechanisms at high frequency region. The investigation of the SCLC polymeric films helped to propose a model system for their possible potential applications. In the light of this study, the SCLC polymers will be employed as the gate insulator for organic field effect transistor applications, such as large area flexible arrays or as other advanced microelectronic devices that have superior performance. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45207.     

Composition and Morphology of Hydrated Tricalcium Silicate

Hardened C₃S paste cured for 1 year at 20°C was examined to confirm the composition and the morphology of hydrated tricalcium silicate. A new technique was used in which the samples for scanning electron microscopy (SEM) and electron probe microanalysis (EPMA) were etched in 1% HNO₃-alcohol or in glycerol-alcohol (4:6 by volume). After the surface was etched in 1% HNO₃-alcohol, SEM clearly showed the difference in texture in the outer and inner C-S-H products. The existence of a zonal texture within the inner C-S-H products was shown, in addition to the unreacted core; particles 0.1 to 0.2 μm in diameter were observed. After free CH extraction with glycerol-alcohol, two new types of C-S-H grains could be identified. One type has a smooth surface, which seems to be produced from C₃S grains trapped within the growing CH crystals in the early stage of hydration, the C/S mol ratio for these being >3. The other type is covered with many acicular outer C-S-H gel hydration products and has a C/S mol ratio >3.     

Using hydrophilic polymers to control nutrient release

Using diverse technological approaches, many types of delivery devices have been used to supply plant nutrients at a controlled rate in the soil. One new approach is the use of hydrophilic polymers as carriers of plant nutrients. These polymers may be generally classified as 1) natural polymers derived from polysaccharides, 2) semi-synthetic polymers (primarily cellulose derivatives), and 3) synthetic polymers. By controlling the reaction conditions when forming the polymers, various degrees of cross-linking, anionic charge, and cationic charge can be added, thereby changing their effectiveness as fertilizer carriers.When fertilizer-containing solutions are mixed with hydrophilic polymers to form a gel prior to application in the soil, the release of soluble nutrients can be substantially delayed compared with soluble fertilizer alone. The effectiveness of a specific controlled-release polymeric system is determined in part by its specific chemical and physical properties, its biodegradation rate, and the fertilizer source used. Addition of some polymers with nutrients has been shown to reduce N and K leaching from well-drained soils and to increase the plant recovery of added N, P, Fe, and Mn in some circumstances     

Thermodynamics of Calcium Silicate Hydrates and Their Solutions

The solution that surrounds hydrating cement particles contains dissolved species which are important in the overall process. A method, based on the Gibbs-Duhem equation for a three-component system, has been developed for computing the composition of one phase from values for its equilibrium solubility in a second phase. The method has been used to compute the CaO:SiO₂ ratio for two types of calcium silicate hydrate (C-S-H) gel, one of which is thought to form from hydrating tricalcium silicate (Ca₃SiO₅), and the other by precipitation from appropriate solutions. The results agree well with measured values reported in the literature. They have also been used to help define the probable composition of the C-S-H layer which forms on tricalcium silicate surfaces during the early stages of hydration when the reaction is slow. A chemical potential phase diagram is constructed from which thermodynamic quantities can be computed directly. The free energies of formation have been estimated for two types of C-S-H formed from CaO, SiO₂, and H₂O, These results provide insight into the structure and composition of C-S-H, which is the most abundant product in portland cement systems.     

Some New Organometallic Polyamides based on Ferrocene

Three new polyamides containing ferrocene units in the main chain were synthesized via low temperature polycondensation route, reacting 1,1′-ferrocenedicarboxylic acid chloride with three different types of aromatic diamines. The products were characterized by their solubilities, elemental analysis, FTIR spectral analysis, differential scanning calorimetry, thermogravimetry and viscosity measurements. The glass transition temperatures of the polymers were found by DSC curves and the activation energies of pyrolysis were estimated from TG curves applying Horowitz and Metzger method. Among these, polyamide P-1 (prepared from 4-(4-aminophenyloxy)phenyl-4-aminobenzamide) was found soluble in some of the organic solvents at room temperature but has poor thermal stability. Polyamide P-2 (prepared from 1,2-di(para-aminophenyloxy)ethylene) was soluble on heating and is thermally stable. However, all of these were also miscible with concentrated H₂SO₄ forming red coloured solutions.

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Graphical Abstract Ferrocenedicarbonyl chloride was reacted with three different types of aromatic diamines via solution polycondensation to get three new polyamides. Two of which were soluble in some organic solvents. The resulting polymers were characterized by their solubilities, viscosity measurements, elemental analysis, FTIR spectroscopy, differential scanning calorimetric and thermogravimetric studies.

     

粉煤灰源C-S-H吸附U(Ⅵ)性能及机理

以粉煤灰铝回收过程的脱硅液为原料,通过控制钙硅摩尔比的常规沉淀法制备得到大比表面积介孔C-S-H（401 m²·g^-1）,系统研究了初始浓度、投加量、pH和离子强度对C-S-H吸附U（Ⅵ）过程的影响,以及吸附的热动力学特征,并评价了C-S-H去除实际含铀废水中毒性金属的性能。结果表明,通过控制合成条件实现了低品质硅钙渣向高附加值吸附材料的转变。0.75 g·L^-1 C-S-H在pH 2仍具有较高的平衡吸附容量（q_e=67.9 mg·g^-1）,在富含CO₃^2-的碱性溶液中UO₂（H₂O）₅²⁺转变为UO₂（CO₃）₃^4-不利于带负电的C-S-H表面吸附U（Ⅵ）。当C-S-H投加量升高至2～5 g·L^-1,材料对U（Ⅵ）的吸附去除效率即能维持在相对较高水平（C[U（Ⅵ）]_initial=500 mg·L^-1,去除率88.3%～93.5%）,吸附可在数小时内达到平衡,符合拟二级动力学模型和两阶段Weber-Morris方程模型,吸附等温线符合Langmuir模型,吸附机理主要为离子交换（84.6%）和表面络合。材料对含铀废水中的U、Zn、Hg、Mn和Cd均表现出良好的吸附去除性能,因而C-S-H可成为在废水毒性金属去除方面极具应用前景的材料。     

Tobermorite/jennite- and tobermorite/calcium hydroxide-based models for the structure of C-S-H: applicability to hardened pastes of tricalcium silicate, β-dicalcium silicate, Portland cement, and blends of Portland cement with blast-furnace slag, metakaolin, or silica fume

The purpose of this article is to discuss the applicability of the tobermorite-jennite (T/J) and tobermorite-‘solid-solution’ calcium hydroxide (T/CH) viewpoints for the nanostructure of C-S-H present in real cement pastes. The discussion is facilitated by a consideration of the author's 1992 model, which includes formulations for both structural viewpoints; its relationship to other recent models is outlined. The structural details of the model are clearly illustrated with a number of schematic diagrams. Experimental observations on the nature of C-S-H present in a diverse range of cementitious systems are considered. In some systems, the data can only be accounted for on the T/CH structural viewpoint, whilst in others, both the T/CH and T/J viewpoints could apply. New data from transmission electron microscopy (TEM) are presented. The ‘inner product’ (Ip) C-S-H in relatively large grains of C₃S or alite appears to consist of small globular particles, which are ≈4-8 nm in size in pastes hydrated at 20 °C but smaller at elevated temperatures, ≈3-4 nm. Fibrils of ‘outer product’ (Op) C-S-H in C₃S or β-C₂S pastes appear to consist of aggregations of long thin particles that are about 3 nm in their smallest dimension and of variable length, ranging from a few nanometers to many tens of nanometers. The small size of these particles of C-S-H is likely to result in significant edge effects, which would seem to offer a reasonable explanation for the persistence of Q⁰(H) species. This would also explain why there is more Q⁰(H) at elevated temperatures, where the particles seem to be smaller, and apparently less in KOH-activated pastes, where the C-S-H has foil-like morphology. In blended cements, a reduction in the mean Ca/Si ratio of the C-S-H results in a change from fibrillar to a crumpled-foil morphology, which suggests strongly that as the Ca/Si ratio is reduced, a transition occurs from essentially one-dimensional growth of the C-S-H particles to two-dimensional; i.e., long thin particles to foils. Foil-like morphology is associated with T-based structure. The C-S-H present in small fully hydrated alite grains, which has high Ca/Si ratio, contains a less dense product with substantial porosity; its morphology is quite similar to the fine foil-like Op C-S-H that forms in water-activated neat slag pastes, which has a low Ca/Si ratio. It is thus plausible that the C-S-H in small alite grains is essentially T-based (and largely dimeric). Since entirely T-based C-S-H is likely to have different properties to C-S-H consisting largely of J-based structure, it is possible that the C-S-H in small fully reacted grains will have different properties to the C-S-H formed elsewhere in a paste; this could have important implications.     

Formation of microporous polymeric membranes via thermally induced phase separation: A review

A review of recent research related to microporous polymeric membranes formed via thermally induced phase separation (TIPS) and the morphologies of these membranes is presented. A summary of polymers and suitable diluents that can be used to prepare these microporous membranes via TIPS are summarized. The effects of different kinds of polymer materials, diluent types, cooling conditions, extractants and additive agents on the morphology and performance of TIPS membranes are also discussed. Finally new developments in TIPS technology are summarized.

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Studies on the crystalline intercalate formed by poly(ethylene oxide) and two different kinds of guest molecules

Summary The intercalate with poly(ethylene oxide) as the host compound and dichlorobenzene/dibromobenzene as the guest compounds (PEO-PDCL/PDBB) was studied by the aid of DSC, WAXD, and ¹³C CP/MAS NMR. No selectivity was observed during the intercalating process of poly(ethylene oxide) (PEO) with p-dichlorobenzene (PDCL) and p-dibromobenzene (PDBB). The orientated PDCL and PDBB molecules are randomly distributed in the benzenic layers between PEO sheets. With increasing PDBB molar fraction, the melting point of the intercalate rises up. WAXD results indicate that the size of orthorhombic crystal cells of PEO-PDCL/PDBB intercalates enlarges as PDBB molar fraction increases. Thereby, It is possible to control the size of crystal cell via adjusting PDBB content in the PEO-PDCL/PDBB intercalates. The ¹³C CP/MAS NMR experiments imply that the carbons of PEO chains in the PEO-PDCL/PDBB intercalate are in the same chemical environment. This again supports that neither PDCL nor PDBB has priority in interacting with PEO. Received: 9 August 2001/Revised version: 13 September 2001/ Accepted: 17 September 2001     

Soluble semi-conductive chelate polymers containing Cr(III) in the backbone: Synthesis, characterization, optical, electrochemical, and electrical properties

Soluble kinds of coordination polymers containing Cr(III) ion in the backbone were synthesized. Structures of the polymers were characterized by FT-IR, UV-vis, ¹H and ¹³C NMR, and size exclusion chromatography (SEC). Thermal degradation data were obtained by TG-DTA and DSC techniques. Cyclic voltammetry (CV) measurements were carried out and the HOMO-LUMO energy levels and electrochemical band gaps were calculated. Additionally, the optical band gaps (E_g) were determined by using UV-vis spectra of the materials. Electrical conductivity measurements of doped (with iodine) and undoped polymers related to temperature were carried out by four-point probe technique using a Keithley 2400 electrometer. Measurements were made by using the polymeric films deposited on ITO glass plate by dip-coating method. Also, absorption spectra of doped polymeric films were recorded by a single beam spectrophotometer showing that doping procedure causes shifting in absorption spectra. Their abilities of processing in gas sensors were also discussed. According to obtained results the synthesized chelate polymers are semi-conductors having polyconjugated structures. Also, P-2 is the most electro-conductive polymer among the synthesized, while P-1 is the most thermally stable one.     

Environmentally Friendly Cross-Linked Antifouling Coatings Based on Dual Antimicrobial Action

The synthesis of environmentally friendly antimicrobial polymeric coatings, especially in the case of aquaculture, that inhibit the growth of bio-deposits is a very important issue that will contribute to the cost reduction of nets’ cleaning process as well as the protection of the submarine wealth from the biostatic substances used so far. In the present work, the antimicrobial polymers P(SSAmC₁₆-co-VBCHAMx) and the terpolymer P(SSAmC₁₆w-co-VBCHAMx-co-GMAy) were synthesized, bearing quaternary ammonium compounds, electrostatically bound and covalently attached at the same polymer chain. The combination of the two types is of particular importance, as it can provide effective antimicrobial polymeric materials with self-polishing capabilities as a result of the released nature of the antimicrobial, in combination with the permanent local action of the immobilized species. The cross-linking reaction of the terpolymer P(SSAmC₁₆w-co-VBCHAMx-co-GMAy) with the homopolymer polyacrylic acid (PAA) was tested at 120 °C in terms of the equivalent ratio between epoxy and carboxyl groups. The synthesized polymers were further used for the coating of aquaculture nets and tested in terms of antifouling efficiency in lab and scale-up conditions. Uncoated nets were also used in all applications for comparison reasons. The coated nets performed efficiently for 35 days in lab-scale and 66 days in scale-up conditions, showing a high antifouling activity in both fields compared to the uncoated nets.     

A facile strategy for preparation of single-chain polymeric nanoparticles by intramolecular photo-crosslinking of azide polymers

A series of well-defined azide polymers, poly(styrene-co-4-vinylbenzyl azide) with different content of azide groups, were synthesized by RAFT polymerization. The single-chain polymeric nanoparticles were then facilely prepared via single polymer chain collapse and intramolecular crosslinking reaction of the azide polymer in a dilute solution at room temperature under UV irradiation within several minutes. The polymeric nanoparticles were characterized with ¹H NMR, GPC, DSC, TEM and DLS measurements, and the mean diameter of the nanoparticles was evaluated to be 5.5 ± 0.8 nm in the dry state. Furthermore, the polymeric nanoparticles containing azide groups were successfully used to prepare the single-chain polymeric fluorescent nanoparticles via click reaction with N-propargyl carbazole.