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Difunctional glycidyl azide polymer (GAP) is an energetic binder promising for propellant formulations. The multifunctional fluorine‐containing GAP has been synthesized to enhance its mechanical properties. This work outlined multifunctional GAP partially grafted with 1,2,3‐triazole‐5‐(α‐hydroxyl)‐fluorinated polyether (GAP‐g‐3F) synthesized by thermal and catalyst‐free azide‐alkyne cycloaddition reaction, in which the azide groups were from GAP and electron‐deficient alkynes from β‐propargyl‐α‐hydroxyl poly (tri‐fluoropropane glycidyl ether) (PHP3F). PHP3F was synthesized via the typical cationic ring‐opening polymerization of 2‐((2,2,2‐trifluoroethoxy) methyl) oxirane and propargyl alcohol as the initiator. The chemical structures, molecular weight, and thermal properties were characterized by FTIR, NMR, GPC, DSC, and TGA, respectively. HNMR results showed that 8 % of total azide groups in GAP were grafted. GAP‐g‐3F had a slightly higher glass transition temperature than that of GAP. The results of TGA showed that GAP‐g‐3F had suitable thermal decomposition resistance up to 200 °C. The thermal properties, mechanical properties, cross‐linking network structures, and microstructures of the polyurethane networks cured with hexamethylene diisocyanate trimer as a crosslinking agent were determined and compared by TGA, universal tensile test, swelling measurement, and SEM, respectively. The initial decomposition temperature of GAP‐g‐3F‐based polyurethane networks (GAP‐g‐3F‐PU) was around 220 °C, thus meeting the requirements for propellants. In addition, GAP‐g‐3F‐PU exhibited superior mechanical properties, showing an almost twelvefold increase in tensile strength to 16.9 MPa compared with difunctional GAP‐PU with 1.4 MPa tensile strength. The results of the swelling measurement revealed that the GAP‐g‐3F‐PU sample showed a higher crosslinking density in comparison to the GAP‐PU sample. SEM results indicated that the multifunctional fluorine‐containing GAP could enhance compatibility between the soft and hard segments of polyurethanes, leading to a decrease in their separation degree. This finding showed that the synthesis of a multifunctional GAP partially grafted with fluorinated polyether via a triazole ring may be a promising solution to decrease the separation degree increase of PUs, thereby improving the mechanical properties. [ABSTRACT FROM AUTHOR]

This contribution reports the efficient conversion of γ‐valerolactone and its derivatives, abundant but unexplored renewable feedstocks, into sustainable and degradable polythioesters via the establishment of the first isomerization‐driven ring‐opening polymerizations (IROPs) of corresponding thionolactone intermediates. The key to this success relies on the development of a new simple and robust [Et3O]+[B(C6F5)4]− cationic initiator which possesses high activity, exclusive selectivity, living nature, and broad scope of thionolactones. A complete inversion of configuration during IROP of enantiopure γ‐thionovalerolactone is also disclosed, affording isotactic semicrystalline polythioesters (Tm=87.0 °C) with mechanical property compared well to the representative commodity polyolefins. The formation of a highly crystalline supramolecular stereocomplex with enhanced thermal property (Tm=117.6 °C) has also been revealed. [ABSTRACT FROM AUTHOR]

This contribution reports the efficient conversion of γ‐valerolactone and its derivatives, abundant but unexplored renewable feedstocks, into sustainable and degradable polythioesters via the establishment of the first isomerization‐driven ring‐opening polymerizations (IROPs) of corresponding thionolactone intermediates. The key to this success relies on the development of a new simple and robust [Et3O]+[B(C6F5)4]− cationic initiator which possesses high activity, exclusive selectivity, living nature, and broad scope of thionolactones. A complete inversion of configuration during IROP of enantiopure γ‐thionovalerolactone is also disclosed, affording isotactic semicrystalline polythioesters (Tm=87.0 °C) with mechanical property compared well to the representative commodity polyolefins. The formation of a highly crystalline supramolecular stereocomplex with enhanced thermal property (Tm=117.6 °C) has also been revealed. [ABSTRACT FROM AUTHOR]

• Synthesis of biobased polyamide 4 by anionic polymerization of 2-pyrrolidone. • Preparation of nanofibers by electrospinning and their characterization. • Test of degradation of nanofibers in water environment for a long period. • Nanofiber layers are hydrolytically stable. Based on renewable raw materials, polyamide 4 has excellent mechanical properties, high hydrophilicity, and cotton-like water sorption. The problem is its low thermal stability near its melting point, which does not allow melt processing. With the development of the technology of electrostatic spinning of polymers from solutions, the attention of researchers has returned to polyamide 4. In this work, nanofiber layers of polyamide 4 with molar masses of 18,000 and 280,000 g/mol and diameters of 350 ± 60 and 270 ± 10 nm, respectively, were prepared by electrostatic spinning from a mixed solution of formic acid and dichloromethane. Subsequently, the layers were subjected to degradation in phosphate buffer at 37 and 60 °C. The electrostatic spinning process was shown to result in a decrease in the molar mass of the samples. During degradation in buffer at pH 7.4, the molar mass does not change significantly, but there is a change in the structure of the nanofibrous layers by bonding of the fibers, especially for low molecular weight PA4. In contrast to other studies, polyamide 4 is hydrolytically stable even in the form of nanofiber layers. [ABSTRACT FROM AUTHOR]

Low dielectric photoinduced patterned materials have attracted extensive attention owing to their potential applications in integrated circuits and semiconductor devices. In this work, we synthesized a low dielectric polymer that can be used for photolithography. The monomer, 1-(4-vinylphenyl)-2-(4-benzocyclobutenyl)ethene (DVB-S-BCB), was synthesized from divinylbenzene (DVB) and 4-bromobenzocyclobutene (4-BrBCB) using the Heck reaction. Subsequently, P-DVB based on DVB-S-BCB was prepared by anionic polymerization. As the structure comprised thermally curable benzocyclobutene (BCB) groups and photocurable vinyl groups (UV/Thermal dual curing structure), P-DVB has been used for high-performance negative photosensitive resin with 2,6-bis(4-azidobenzylidene) cyclohexanone (BAC) as a photoinitiator. Photolithography was carried out using a 365-nm UV light source to obtain various patterns, and the research results indicate that photosensitive resins exhibit stable patterning processes at different curing stages. Besides, the cured P-DVB exhibited high thermal stability (T 5% above 420 °C in N 2), low dielectric constant (2.55 at 10 MHz), low dielectric loss (1.56 × 10−3 at 10 MHz), and excellent mechanical performance. These properties make P-DVB a potential photoresist that can be widely used as interconnected dielectrics. P-DVB containing vinyl groups and benzocyclobutene groups was synthesized by anionic polymerization. This resin exhibits low D k and high-resolution photo-imageable dielectric performance. Therefore, it is expected to be used for integrated circuits and semiconductor devices. [Display omitted] • Rapid synthesis of photosensitive resins with photo-thermal curing structures on a large scale, and at low cost. • Have high-resolution photo-imageable and process flexibility (spin coating or dry film, patterning, developing). • UV/Thermal double cured structure gives excellent mechanical properties, low dielectric properties and low CTE. • Widely used in high-density, low-power packages such as WLP, RDL, TSV, etc., promoting integration and miniaturization. [ABSTRACT FROM AUTHOR]

Copolymerization of diallylamine (DAA) and itaconic acid (IA) was synthesized using benzoyl peroxide as a free radical initiator, in dioxane as the solvent. The composition of the copolymer was determined by the nitrogen content using Edx. The solubility of the copolymer was also investigated. The water solubility of the synthesized copolymer depends on the comonomers' ratio. The structure of the copolymer was confirmed by 13C-NMR spectroscopy. To increase the water insolubility of the copolymers, and keep their hydrophilicity, the copolymer was allowed to react with chitosan to form a superabsorbent polymeric material (SP). The structure of the synthesized superabsorbent was confirmed using 13C-NMR spectroscopy. The thermal property of the (SP) was also investigated by TGA. The investigation of the chitosan-based superabsorbent, as water-retaining agents, was studied. The results revealed that the superabsorbent polymers exhibited a good swelling ability and salt tolerance. [ABSTRACT FROM AUTHOR]

UV‐initiated cationic frontal polymerization is exploited as a solvent‐free, extremely fast, and low‐temperature technique to obtain epoxy‐based adhesives. Epoxy formulations are prepared by blending commercial resins at different weight ratios and adding photo and thermal initiators at different percentages. In addition, the influence of other critical parameters, including the joint thickness, the nature of the adherends, and the temperature, is studied. As the reaction front is thermally sustained, the boundary conditions play a key role during the curing process and heat dissipation through the adherends in particular. The thermal properties of the epoxy formulation are studied through differential scanning calorimetry analysis, and the joint strengths are investigated by carrying out single lap off‐set shear tests under compression. The results demonstrate the feasibility of obtaining joints by means of the radical induced cationic frontal polymerization of the epoxy adhesives, which exhibit comparable epoxy group conversion and mechanical performances to the ones cured by traditional energy‐intensive techniques. [ABSTRACT FROM AUTHOR]

Preparing an epoxy resin with biomass resources as an alternative for bisphenol A is significant for sustainable and renewable development under great pressure of limited fossil resources and urgent environmental issues. Herein, we synthesized an epoxy oligomer P-DBP-EP-n derived from biomass magnolol through an efficient one-step glycidylation. P-DBP-EP-n exhibited a low viscosity of 11.7 Pa·s at room temperature, endowing it with excellent processability as diglycidyl ether of bisphenol A (DGEBA) and magnolol-based epoxy monomer EDBP. Then P-DBP-EP-n was cured with a diamine curing agent, 4,4'-diaminodiphenyl methane (DDM), and following thermal addition polymerization of allyl units. Compared with DGEBA/DDM and EDBP/DDM, P-DBP-EP-n/DDM possessed a higher glass transition temperature (Tg) (304 to 167 and 226 °C), implying distinguished heat resistance. Furthermore, the tensile properties and notched impacted strength of P-DBP-EP-n/DDM were better than EDBP/DDM (20.7 to 19.4 MPa, 2.0 to 1.6 GPa, and 2.5 to 2.0 kJ/m²). The initial degradation temperature and char residue of P-DBP-EP-n/DDM were 421 °C and 35.2%, with a 13.5 and 101% increase compared with those of DGEBA/DDM, respectively. Additionally, P-DBP-EP-n/DDM displayed outstanding flame retardancy with V-0 rate for the vertical burning test and limiting oxygen index value of 47.7%, which was almost twice as much as that of DGEBA/DDM. This study offers a promising and feasible pathway to obtain a fully bio-based epoxy resin substituted for petroleum-based DGEBA with distinguished processability, heat resistance, and flame retardancy. Comprehensive properties of the bio-based thermosets are expected to be further regulated by the thermal addition polymerization of allyl units. [ABSTRACT FROM AUTHOR]

In the available research, firstly a new 3-acetamido phenyl acrylate (APhA) monomer and a novel copolymer containing acetamido phenyl group were synthesized. 3-acetamido phenyl acrylate (APhA) monomer was acquired by the reaction of acryloyl chloride and N-(3-hydroxyphenyl) acetamide. 3-acetamido propyl methacrylate (AAPMA) monomer was prepared in our previous study. A series of copolymers were prepared using these monomers in different mole ratios by free-radical polymerization method at 70 °C The structure of P(AAPMA-co-APhA) copolymer systems was characterized by FT-IR and NMR techniques. Thermal characteristics of P(AAPMA-co-APhA) copolymers were evaluated through thermogravimetric analysis (TGA) and differential scanning calorimeter (DSC) in an N2 atmosphere. Due to the presence of the amide group, we can say that the polymer with the least weight loss and the highest residue percentage at 500 °C is poly(APhA). AC electrical conductivity and dielectric and electrical parameters were analyzed in a range of 100 Hz–20 kHz frequency. The dielectric constant values of poly(AAPMA-co-APhA0.63) and P(AAPMA-co-APhA0.30) were 4.98 and 4.57 respectively. According to the results, the dielectric value decreased as the APhA units increased. [ABSTRACT FROM AUTHOR]

[Display omitted] An efficient synthesis of the new star-shaped polymer with azido-containing oligomer rays is based on construsion of these rays on the β-cyclodextrin nitrate core employing 3,3-bis(azidomethyl)oxetane as the key reactant. The formation of star-shaped structure was proved. Thermal and optical properties of the synthesized polymers were assessed. [ABSTRACT FROM AUTHOR]

Model PCL homopolymers (anionic polymerization) were synthetized and chemically functionalized with anhydrides to improve their bio-activity. Modified polyesters were used to fabricate highly porous PCL membranes by leaching technique, reaching porosities values up to 86.1%. Microstructural characterization revealed that chemical modification did not affect thermal properties and mechanical stabilities of PCL membranes. In vitro assays were carried out by soaking samples in simulated body fluid (SBF) solution. By SEM-EDX and TGA analyses, it was observed that modified polyesters exhibited a hydroxyapatite layer over polymeric surfaces, with calcium/phosphorous ratio of 1.58, close to the value reported by literature for hard tissue. [ABSTRACT FROM AUTHOR]

In this study, 2-(bis(cyanomethyl)amino)-2-oxoethyl acrylate (CMA2OEA) monomer, which does not exist in the literature, was synthesized and characterized. Elemental analysis technique, along with classical spectroscopic methods such as FTIR, 1H and 13C NMR, is used in the characterization of the monomer. Further, homopolymer of the CMA2OEA monomer [poly(CMA2OEA)] is synthesized by free radical chain polymerization reaction. Homopolymer synthesized is also characterized by spectroscopic techniques and thermal characterization is investigated by TGA/DTA/DTG thermal analysis methods. [ABSTRACT FROM AUTHOR]

Polystyrene (PS) has low impact strength and also shows poor strain hardening. In this work, poly(styrene–butadiene–styrene) triblock copolymer (SBS) was solution- and melt-blended with PS in the presence of a free-radical polymerization initiator, dicumyl peroxide (DCP), to enhance PS's thermal stability, mechanical properties, impact resistance, and strain hardening. The solution-blended PS/SBS containing 0.1% DCP annealed at 180 °C showed strong strain hardening, but the melt-blended PS/SBS annealed at the same temperature and time showed poor strain hardening. The change in the blending temperature, DCP concentration, and PS-to-SBS ratio had minimal effect on the strain hardening of melt-blended PS/SBS. The tensile strength increased with an increase in the concentration of DCP up to 0.1%, and beyond that level, the tensile strength started decreasing. The impact resistance considerably improved with an increase in the SBS loading in the PS matrix, and the enhancement was more than double of the impact resistance shown by the neat PS. [ABSTRACT FROM AUTHOR]

The elastic constants and vibrational contributions to thermal properties of three polymerizing liquids were investigated by using the available hypersonic velocity measured by Brillouin light scattering in real time. During the addition polymerization to a molecular network structure, Poisson’s ratio υPoisson decreases approximately according to exp[-(ktpolym)]n, where both k and n are composition dependent. The Debye frequency increases and the corresponding heat capacity, energy, and entropy approaching a limiting value. υPoisson of the vitrified polymer continues to decrease but much more slowly, indicating its continued slow polymerization and structural relaxation with time. In the potential energy landscape interpretation, a polymerizing liquid’s state point continuously shifts to another landscape’s more curved, deeper minima. [ABSTRACT FROM AUTHOR]

Oligo(spiroorthocarbonate)s 1, which were synthesized by the polycondensation of pentaerythritol derivatives with tetraethylorthocarbonate, were employed as comonomers in the cationic polymerization of epoxide initiated by sulfonium salt. In the copolymerization, the spiroorthocarbonate moiety of 1 underwent double ring‐opening reaction, leading to the efficient diminution of the volume shrinkage upon the copolymerization. Thermal properties of the resulting networked polymers were evaluated by TGA. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1564–1568 [ABSTRACT FROM AUTHOR]

Combination of anionic and ring opening metathesis (ROMP) polymerizations is conducted for the synthesis of different series of brush polymers adopting the macromonomer methodology. Specifically, poly( tert-butoxystyrene) (P tBOS), polystyrene (PS), and poly(ethylene oxide) (PEO) macromonomers, having end norbornene groups, are prepared by anionic polymerization techniques and suitable termination reactions or functional anionic initiators. These macromonomers are either homopolymerized or copolymerized by ROMP employing Ruthenium Grubbs catalysts of the 1st or 3rd generation leading to the formation of polymer brushes. Using this synthetic approach, P tBOS polymacromonomers, P tBOS-PEO block and random copolymacromonomers, and P tBOS-PS random copolymacromonomers are prepared. Acidic hydrolysis of the tert-butoxy groups of the P tBOS brushes affords the corresponding polyhydroxystyrene (PSOH) brushes. Subsequent activation of the hydroxyl groups upon reaction with triphenylmethyl potassium and addition of ethylene oxide lead to the formation of PEO brushes on the PSOH brushes (brush on brush structures). These materials are thoroughly characterized by size exclusion chromatography, and 1H-NMR spectroscopy. The thermal properties are studied by differential scanning calorimetry, thermogravimetric analysis , and differential thermogravimetry. [ABSTRACT FROM AUTHOR]

1,6-hexanediol diacrylate (HDDA) single crystal was grown by slow cooling method. The grown crystal was characterized by single crystal X-ray diffraction, and it showed that HDDA crystallizes in the triclinic system with space group P-1. The cell parameters are a = 6.4885 (9) Å, b = 6.945 (2) Å, c = 7.4890 (12) Å, α = 96.43 (2) °, β = 98.369 (13) °, γ = 109.96 (2) ° and Z = 1. The thermal properties of the HDDA was studied by differential scanning calorimetry (DSC) and showed just one crystalline form existed. A modelization method to judge the possibility of photoinitiating free-radical chain-reaction polymerization in crystal region was established based on the single crystal data, with which the polymerize possibility of HDDA in crystal region was studied. [ABSTRACT FROM AUTHOR]

ABSTRACT During the last years, the field of drug delivery has experienced a growing interest toward the so-called thermo-responsive polymers: synthetic materials that, due to the specific hydrophilic-lipophilic balance of their repeating units, exhibit a lower critical solution temperature (LCST) in water associated to a characteristic coil-globule transition. In this work, thermo-responsive amphiphilic block copolymers are synthesized via reversible addition-fragmentation transfer (RAFT) polymerization starting from thermo-responsive monomers and a hydrophobic biodegradable macromonomer, oligo(caprolactone)methacrylate (CL3MA), produced via ring opening polymerization (ROP). The obtained copolymers exhibit an interesting self-assembly behavior leading to nanoparticles (NPs) as long as temperature is kept below the LCST. Otherwise, once this value is overcome, the destabilization of the NPs causes the formation of hydrophobic superstructures that enhance the release of an entrapped lipophilic drug. This characteristic behavior has been systematically studied and related to the copolymer structure. In particular, the self-assembly behavior as well as temperature-triggered NP destabilization have been related to the relative length of the two blocks constituting the copolymers and to their hydrophilic-lipophilic balance (HLB). Finally, the efficacy of the thermo-responsive triggered drug release has been tested in the case of Paclitaxel (PTX). © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 2919-2931 [ABSTRACT FROM AUTHOR]

This study aims at physicochemical properties of thermo- and pH/CO2-responsive cyclic homopolymers. Three examples of cyclic poly(2-(dimethylamino)ethyl methacrylate)s (PDMAs) are synthesized by combining the reversible addition-fragmentation chain transfer process and the Diels-Alder ring-closure reaction. After cyclization, the glass transition temperature significantly increases (Δ Tg = 51.8-59.7 °C) due to the different configurational entropy and end groups, and the maximum decomposition temperature to lose the pendent groups is drastically decreased from 309 to 278 °C. Effects of polymerization degree, polymer concentration, additive of NaCl, and pH/CO2 on lower critical solution temperature behaviors of PDMA aqueous solutions are investigated. The cloud points ( Tc) of ring PDMAs are usually higher than their linear precursors, and the Δ Tc values obtained under a fixed condition can reach up to 20.7 °C, revealing the crucial role of the topology effect. This study paves the way for unique properties and applications of smart cyclic polymers and their derivatives. [ABSTRACT FROM AUTHOR]

A series of poly(polyethylene glycol n -alkyl ether vinyl ether)s (PC m E n VEs) with various lengths of alkyl chains and polyethylene glycol spacers as side chain (m = 16,18; n = 1,2) were synthesized via two steps. First, monomers-ethylene glycol hexadecyl ether vinyl ether (C 16 E 1 VE), ethylene glycol octadecyl ether vinyl ether (C 18 E 1 VE), diethylene glycol hexadecyl ether vinyl ether (C 16 E 2 VE) and diethylene glycol octadecyl ether vinyl ether (C 18 E 2 VE) were synthesized by a modified Williamson etherification. Then, four new types of phase change materials were successfully fabricated by a living cationic polymerization. Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) were employed to characterize their composition, thermal properties and crystallization behavior. The results show that, the side chains of PC 16 E 1 VE, PC 18 E 1 VE, PC 16 E 2 VE and PC 18 E 2 VE are in a hexagonal lattice, and the onset temperatures for melting of PC 16 E 1 VE, PC 18 E 1 VE, PC 16 E 2 VE and PC 18 E 2 VE are 39.8 °C, 37.4 °C, 51.0 °C and 48.9 °C, the onset temperatures for crystallization are 36.7 °C, 35.2 °C, 47.4 °C and 46.3 °C, respectively. The enthalpy changes of PC 18 E 1 VE, PC 16 E 2 VE and PC 18 E 2 VE are higher than 100 J/g; on the contrary, it is 96 J/g for PC 16 E 1 VE. The enthalpy decrease is no more than 11% after 10 heating and cooling cycles. The 5 wt% mass loss temperatures of PC 18 E 1 VE, PC 16 E 2 VE and PC 18 E 2 VE are higher than 300 °C; on the contrary, it’s 283 °C for PC 16 E 1 VE. Using a weak polarity, flexible alkyl ether chain (-OCH 2 CH 2 O-) as a spacer to link the main chain and side chain is conducive to the crystallization of the alkyl side chain. These new phase change materials can be applied in heat storage, energy conservation, and environmental protection. [ABSTRACT FROM AUTHOR]

The free radical polymerization characteristics of various vinylated melamine derivatives, cross linking and linear, were analysed by GC/MS and HPLC/PDA measurements. Special attention was put on the general progress of the polymerization as well as on the opportunity for copolymerizations with common monomers like methyl methacrylate and styrene. In order to retrieve thermal properties of the (co)polymers also larger scale polymerizations have been done, showing that thermal stability can be increased by incorporation of vinylmelamines. Also the glass transition temperature can be increased linearly by increasing amounts of vinyl pentamethylmelamine in styrene and methyl methacrylate copolymers. [ABSTRACT FROM AUTHOR]

The present study demonstrates the hydrophobic effect of poly(electrolyte) multilayer films when they are alkyl-grafted and complexed or not with surfactants. For this purpose, sodium hydrophobically modified poly(acrylates) (PAC n Na, n = 10, 18) or their anionic complexes with alkyltrimethylammonium bromides (C x TAB, x = 10, 12, 14, 18), and the cationic poly(diallyldimethyldiammonium chloride) (PDDAMAC) are assembled by layer-by-layer deposition on a glass substrate. Contact angle (CA) measurements reveal that films constructed with PAC n Na-C x TAB/PDADMAC are superior water repellants than those of PACnNa/PDADMAC. For example, the highest CA is obtained for the PAC 18 Na-C 18 TAB/PDADMAC. Moreover, it has been observed that the CA increases with the alkyl chain length of PAC n Na and of surfactant. The film roughness and thickness have the same trend as wettability. Thinner and less coarse films are obtained by NaCl addition, as witnessed by SEM and AFM. [ABSTRACT FROM AUTHOR]

Four new vanadium oxyfluorides (VOFs), Sr4V3O5F13 (1), Pb7V4O8F18 (2), Pb2VO2F5 (3), and Pb2VOF6 (4), have been synthesized under mild hydrothermal conditions. The choice of starting reagents, AF2 or A(CH3CO2)2·xH2O (A = Pb, alkaline earth), determined the oxidation states of vanadium in the final products. The reaction of V2O5 with AF2 leads, consistently, to the formation of V(v) compounds, while the use of A(CH3CO2)2·xH2O results in V(iv) containing compounds, suggesting that the acetate species behaves as an effective mild reducing agent. The crystal structures, characterized by single crystal X-ray diffraction, revealed that the compounds exhibit various anionic VOF building blocks, including dimeric and trinuclear units, as well as one-dimensional chains. All compounds contain fluorine atoms that are not bonded to the vanadium atoms, which are located between two-dimensional layers consisting of corner- or edge-shared FA3 or FA4 polyhedra that separate the vanadium containing building blocks. The magnetic susceptibility data for 4 were measured as a function of temperature, yielding an effective magnetic moment of 1.72 μB that confirms the presence of V(iv). UV-vis reflectance and thermal properties were also characterized. [ABSTRACT FROM AUTHOR]

• Effect of replacing MgO by Nb 2 O 5 in the parent Na-Ca-P-Al-O glass system is studied. • Al suppresses Nb and accelerates Mg release process from the glasses into PBS. • Al and Mg addition decreases while Nb increases the polymerization of glass network. • Al and Nb contents control the glass transition temperature. • Glass thermal stability is highly correlated only with the Nb content. In vitro dissolution, structure, and thermal properties of the glass series Na 2 O-MgO CaO Nb 2 O 5 -Al 2 O 3 -P 2 O 5 were studied. The dissolution behavior in phosphate-buffered saline (PBS) confirmed the potential bioactive properties of tested glasses. The dissolution process was found to depend on the Al, Nb, and Mg contents. Al, respectively, suppresses the Nb and accelerates the Mg release process from the glasses. Moreover, Al stays highly bonded in the phosphate network during 14 days of immersion. In all glasses, the phosphate network was found to be highly disrupted and built mostly of Q1 units. Al and Mg addition decreases the polymerization of the glass network. The Nb addition effect was found to be the opposite. Thermal properties were correlated mostly with the Nb and Al contents. However, the fragility index of glasses increases with the content of P and Al. [ABSTRACT FROM AUTHOR]

A finite element numerical model is proposed in this paper to predict the effective thermal conductivity of polytetrafluoroethylene (PTFE) composites based on the Fourier’s law of heat conduction. The reliability of the numerical model is verified using the comprehensive experimental results and theoretical models presented by predecessors. A systematic study is conducted through numerical simulation to examine the impact of graphite particle size, volume fraction, and distribution style on the thermal conductivity of PTFE composites. A prediction model of the thermal conductivity of carbon fibers reinforced PTFE composites is introduced. The results of the prediction model agree well with experimental data. A trade off between the volume fractions of graphite particles and carbon fibers is conducted. And the optimum volume fraction matching is 17.76 and 10% for graphite particles and carbon fibers, respectively. [ABSTRACT FROM AUTHOR]

Abstract: A comprehensive survey of the recent developments on the synthesis, properties and applications of silicone containing copolymers is provided. Influence of ( R2Si O ) backbone composition on the physicochemical properties of silicone copolymers, such as thermal transitions, solubility parameter and surface tension is discussed. Preparation and properties of well-defined α,ω-reactive organofunctionally terminated (telechelic) silicone oligomers and their utilization in the preparation of a wide range of block and segmented copolymers through step-growth, anionic, ring-opening and living free-radical polymerization techniques are provided. Use of silicone oligomers in the modification of polymeric network structures is also discussed. Special emphasis is given to the discussion of the effect of silicone oligomer and organic segment structure and molecular weight on the morphology and surface and bulk properties of the resultant silicone containing copolymers and networks. [Copyright &y& Elsevier]

ABSTRACT The cationic polymerization of dimethylketene is achieved in dichloromethane at −30 °C, using a stoichiometric mixture of aluminum bromide (AlBr3) and tetra- n-butylammonium bromide ( n-Bu4N+Br−) as initiator. Characterizations by 1H and 13C NMR show that the resulting polymers have a perfect polyketonic microstructure. Capillary viscosity, DSC, and SEC analysis show that for a constant monomer/initiator ratio, polymers synthesized in the presence of tetra- n-butylammonium bromide are more crystalline and have better properties than those produced only with AlBr3. Melting temperatures, inherent viscosities and average molecular weights are systematically higher. A good linearity is observed between ln (inherent viscosity) versus ln [ABSTRACT FROM AUTHOR]

ABSTRACT The benzoxazines of three naturally occurring phenylpropanoid phenols: ferulic, coumaric, and phloretic acids, and their esters are described. Benzoxazines with conjugated unsaturated chains exhibit unusual poor thermal stability and degrade partially at the polymerization temperature making necessary the use of a catalyst (BF3.Et2O) to low the polymerization temperature and prevent degradation. Polybenzoxazines are prepared thermally and characterized by DSC and TGA techniques. The resulting materials have superior Tgs when compared with those prepared from an unsubstituted monofuctional benzoxazine due to the additional crosslinking through the ester and carboxylic moieties. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4894-4903 [ABSTRACT FROM AUTHOR]

Abstract: Poly [2-(cinnamoyloxy)ethyl methacrylate-co-octamethacryl-POSS] nanocomposites were synthesized from octamethacryl-POSS and 2-(cinnamoyloxy)ethyl methacrylate (CEM) by free radical polymerization. The chemical structures and morphologies of these nanocomposites were determined by FTIR, 29Si NMR, energy-dispersive spectroscopy (EDS), X-ray powder diffraction (XRD), and scanning electron microscopy (SEM) techniques. The XRD data showed that the materials were amorphous in nature, indicating that POSS formed an aggregate instead of a crystalline form in the polymer matrix. The POSS-CEM nanocomposites exhibited high thermal stability. Excitation and emission of the CEM-incorporated POSS nanocomposites, studied in the solid state, exhibited blue emission with CIE (x, 0.178; y, 0.137) coordinates, in addition to an emission intensity that increased with increasing CEM (monomer) concentration. [Copyright &y& Elsevier]

This investigation reports a comparative study of poly(2-ethylhexyl acrylate) (PEHA) prepared via atom transfer radical polymerization (ATRP), reverse atom transfer radical polymerization (RATRP) and conventional free radical polymerization (FRP). The molecular weights and the molecular weight distributions of the polymers were measured by gel permeation chromatography (GPC) analysis. Structural characterization of the polymers was carried out by H NMR and MALDI-TOF-MS analyses. Thermal properties of the polymers were evaluated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The polymerization results and the thermal properties of PEHAs prepared via ATRP, RATRP and FRP were compared. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

ABSTRACT Structural isomers of thermo-oxidatively stable poly(carborane-siloxane-arylacetylene) (PCSAA), namely, m-PCSAA and p-PCSAA, were synthesized by the reaction of the dimagnesium salts of m-diethynylbenzene or p-diethynylbenzene with 1,7-bis(chlorotetramethyldisiloxyl)- m-carborane. The developed polymers have exceptional thermo-oxidative properties similar to their diacetylene counterpart poly(carborane-siloxane-acetylene), PCSA. Thermal treatment of either of the PCSAAs results in a fully crosslinked thermoset by 500 °C resulting from the cycloaddition reactions involving the acetylene and aryl functionalities and subsequent formation of bridging disilylmethylene entities as discerned from Fourier transform infrared, 13C and 29Si solid-state NMR, and XPS studies. X-ray diffraction analysis revealed that the thermosets obtained from p-PCSAA possess enhanced crystallinity when compared to that obtained from m-PCSAA possibly due to more efficient packing interactions of the p-diethynylbenzene groups during thermoset formation. The presence of the aryl groups in the backbone of the PCSAAs' chains appeared to have enhanced the storage and bulk moduli of their thermosets when compared to the thermoset of PCSA. Dielectric studies of m-PCSAA and p-PCSAA revealed segmental relaxation peaks, α, above their glass transition temperatures with p-PCSAA exhibiting a broader peak with a slower relaxation rate than m-PCSAA. © 2013 Wiley Periodicals, Inc.† J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2638-2650 [ABSTRACT FROM AUTHOR]

In this work, we studied the thermal characterization of block copolymers based on ε-caprolactone. The copolymers were obtained by anionic polymerization techniques, using different co-monomers such as styrene (S) and dimethylsiloxane (DMS). Synthesized copolymers were characterized by H-nuclear magnetic resonance, size exclusion chromatography, and Fourier transform infrared spectroscopy. Isothermal crystallization was performed by differential scanning calorimetry (DSC), and Avrami's theory was employed in order to obtain kinetics parameters of interest, such as the half-life for the crystallization process ( t), the bulk crystallization constant ( k), and the Avrami's exponent ( n). The spherulitic growth was measured by polarized optical microscopy in order to determine the crystallization behavior. Poly(ε-caprolactone) block (PCL) crystallization was analyzed by considering the physico-chemical characteristics of the neighboring block, PS or PDMS. The chemical nature of the neighbor block in the PCL-based copolymer affects the kinetics parameters of Avrami's equation, as can be deduced by comparing the values obtained for pure PCL and the studied block copolymers. On the other hand, the apparent thermal degradation activation energies E for PCL and block copolymers were determined by Ozawa's method. The incorporation of PDMS instead of PS improves the stability of the resulting copolymer, as it was observed by thermogravimetric analysis. [ABSTRACT FROM AUTHOR]

Abstract: The paper reports the synthesis of new silsesquioxanes with methacrylate and/or vinyl units, obtained by combining the sol–gel technique with radical polymerization in the presence of 2,2′-azobis(2-methylpropionitrile) as initiator and a cationic surfactant, cetyltrimethylammonium bromide. The thermal behaviour was investigated through simultaneous thermogravimetric and differential scanning calorimetry analysis (TG/DSC) coupled on-line with Fourier transform infrared spectroscopy (FTIR) and mass spectrometry (MS), as well as by pyrolysis and gas chromatography–mass spectrometry (GC–MS). The aim of the investigation consists in drawing useful information on the influence of both chemical structure and chain end double bonds and silanol units on the resistance of such compounds against thermal degradation. [Copyright &y& Elsevier]

Polylactide grafted starch (starch- g-PLA) was successfully synthesized via anionic swollen grafting polymerization. The swelling of starch was proved effective to facilitate the grafting reaction. The product with grafting percentage up to 376 % was obtained when optimized the experimental condition. The structure of grafted product was confirmed by Fourier transform infrared spectra and nuclear magnetic resonance spectroscopy. The modified starch has favorable thermal stability below 200 °C according to derivative thermogravimetric analysis. The thermal property of the starch- g-PLA attested that the grafted products have great potential melt blending with PLA and starch. Graphical Abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The use of commercially available hyperbranched poly(ethyleneimine)s (Lupasol™, BASF) as polymeric modifiers in diglycidyl ether of bisphenol A thermosetting formulations using 1-methylimidazole (MI) as anionic initiator has been studied. Poly(ethyleneimine)s can get incorporated into the network structure by condensation of amine and epoxy groups. The excess, over-stoichiometric epoxy groups can undergo anionic homopolymerization initiated by MI. The thermal, dynamomechanical, and mechanical properties of the resulting materials have been determined using DSC, thermomechanical analysis (TMA), dynamomechanical analysis (DMA), and mechanical testing. The effect of the different amine modifiers on the MI networks, determined by their structure, is complex. Low initiator content and high molecular weight modifiers create significant mobility restrictions, which have a strong effect on the glass transition temperature and the apparent crosslinking density of the cured materials. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012 [ABSTRACT FROM AUTHOR]

Polymer-clay nanocomposites have been prepared by free radical and RAFT polymerizations. To investigate the effects of nanoclay content and its modification system on the kinetics of polymerization, two different commercial grades of clay including Na-MMT and Cloisite 30B have been used and a method has been developed for further modification of Na-MMT with two commercial modifiers containing either a long organic chain or a vinyl group. Also, kinetics of free radical and RAFT polymerizations of both styrene and methyl methacrylate in the presence of these nanoclays was studied. Morphology of the nanocomposites has been studied by XRD and the results have been assessed with TEM observations. Exfoliated structure was obtained for the nanocomposites with 1 wt.% of vinyl-containing clays. Thermogravimetric behavior of the nanocomposites has been studied by TGA. Incorporation of clays has resulted in an evident increase in thermal stability of both polymers. [ABSTRACT FROM AUTHOR]

Abstract: Objective of the present work was the development of a strategy for the synthesis of semi-interpenetrating networks (semi-IPN) based on chitosan and poly(methacrylamide) under physiological conditions. Free radical polymerization of methacryloylglycylglycine (MAGG) in the presence of chitosan and ethylene glycol dimethacrylate as the crosslinker was performed. Chitosan and poly(MAGG) hydrogels having different composition and amount of crosslinker were prepared. The presence of the two polymeric components in the polymer bulk was confirmed by fourier transform infrared spectroscopy (FTIR); thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to further substantiate the structural feature of the semi-IPN hydrogels. Finally, degradation behavior promoted by lysozyme demonstrated that there was 60%, 68% and 76% of degradation of the semi-IPN hydrogel with 8%, 4% and 2% of crosslinker respectively in 28 days. The preliminary investigations of the prepared materials suggest their suitability for applications in tissue engineering and controlled release of bioactive agents. [Copyright &y& Elsevier]

Abstract: Sodium alginate/sodium montmorillonite hybrid films were prepared by casting from the suspension of sodium alginate and different clay samples. Clay samples had been modified with a cationic surfactant, a cationic polymer, and a small polar molecule, respectively. Benzethonium chloride, polyethyleneimine and urea were used as clay modifiers. The composite films begin to disintegrate at a higher temperature and with less weight loss than the pure alginate films. This suggests an enhancement of the film thermal stability due to the modification of the alginate with clay samples. [Copyright &y& Elsevier]

Highly dehydrated gold foil-coated Selemion AMV exhibited large bending under electrical stimulation. It bore a relatively well-controllable bending characteristic by the control of electrical stimulation. Conventional ionic polymer-metal composite bending mechanisms could not explain its bending behavior. We speculated that Joule heat played a central role in the bending induction. Employing the classical lamination theory, the influence of Joule heat on its bending behavior was theoretically investigated. The results calculated roughly agreed with the experimental results. Hence, we concluded that the Joule heat was the primary cause of bending induction. [ABSTRACT FROM AUTHOR]

Abstract: This work reports the preparation and study of poly(vinyl chloride) (PVC) with medium and high molecular weight using a Living Radical Polymerization (LRP) method in aqueous systems. The synthesis of ultra thermal stable PVC that falls outside the typical values known for the PVC industry is presented and PVC thermal stability is evaluated using a standard industrial method. The results presented in this manuscript suggest that the single electron transfer–degenerative transfer mediated living radical polymerization (SET–DTLRP) mechanism is the main factor influencing the thermal stability, since the polymerization temperature has no detectable effect on this property. In contrast to the Free Radical Polymerization (FRP), where low temperatures lead to PVC with high thermal stability that corresponds to a high molecular weight polymer, the polymerization temperature in SET–DTLRP (range 21–42°C) has no detectable effect on the thermal stability of PVC. The final molecular weight is defined by the [monomer]0/[initiator]0 ratio (degree of polymerization). The PVC synthesis reported in this manuscript was carried out in a 150L pilot reactor, which represents a reliable approach in terms of hydrodynamic conditions, when compared with those at the industrial scale. [Copyright &y& Elsevier]

Poly(N-isopropyl acrylamide) or pNIPAM is a thermoresponsive polymer that is widely studied for use in bioengineering applications. The interest in this polymer lies in the polymer’s unique capability to undergo a sharp property change near physiological temperature, which aids in the spontaneous release of biological cells from substrates. Currently, there are many methods for depositing pNIPAM onto substrates, including atom-transfer radical polymerization (ATRP) and electron beam ionization. Each method yields pNIPAM-coated substrates with different surface characteristics that can influence cell behavior. In this work, we compare two methods of pNIPAM deposition: plasma deposition and codeposition with a sol−gel. The resulting pNIPAM films were analyzed for use as substrates for mammalian cell culture based on surface characterization (XPS, ToF-SIMS, AFM, contact angles), cell attachment/detachment studies, and an analysis of exocytosis function using carbon-fiber microelectrode amperometry (CFMA). We find that although both methods are useful for the deposition of functional pNIPAM films, plasma deposition is much preferred for cell-sheet engineering applications because of the films’ thermoresponse, minimal change in cell density, and maintenance of supported cell exocytosis function. [ABSTRACT FROM AUTHOR]

We carried out the anionic polymerization of styrene derivatives containing the triphenylamine moieties, 4,4′-vinylphenyltriphenylamine (A) and 4,4′-vinylphenyl-N,N-bis(4-tert-butylphenyl)benzenamine (B), with a variety of initiators in tetrahydrofuran (THF) at −78 °C. The anionic polymerization of Awas performed with sec-butyllithium, sec-butyllithium with additives, and (diphenylmethyl)potassium in THF at −78 °C. In all cases, an intermolecular side reaction took place between the polymer chains during polymerization. In contrast, the anionic polymerization of Bwas carried out successfully with sec-butyllithium and potassium naphthalenide in THF at −78 °C for 0.5 h without any observed intermolecular side reaction. Well-defined poly(B)s with predictable molecular weights and narrow molecular weight distributions (Mw/Mn= 1.05−1.11) were obtained. The sequential block copolymerization of Bwith styrene and 2-vinylpyridine was attempted subsequently, and the well-defined block copolymers, polystyrene-b-poly(B) and poly(B)-b-poly(2-vinylpyridine), were synthesized quantitatively. The solubilities as well as the thermal and optical properties of the resulting poly(B) were investigated. [ABSTRACT FROM AUTHOR]

Abstract: Poly(benzyl methacrylate)-magnesium phyllosilicate nanocomposites were synthesized using a novel in situ intercalative ambient temperature atom transfer radical polymerization (ATATRP). The organic moiety in the synthesized magnesium phyllosilicate was modified to initiate ATRP, in the presence of Cu(I)/PMDETA. Exfoliation was achieved and this process was rapid. The anchoring efficiency of the polymer chains on the organically modified phyllosilicate increased with silicate loading. This route to nanocomposite preparation is expected to be general and viable, and superior in comparison to the melt mixing route which did not result in the formation of a nanocomposite in these systems. [Copyright &y& Elsevier]

Novel hybrid materials of the PB-b-P(o-Bn-L-Tyr) and PI-b-P(o-Bn-L-Tyr) type (where PB: 1,4/1,2-poly(butadiene), PI: 3,4/1,2/1,4-poly(isoprene) and P(o-Bn-L-Tyr): poly(ortho-benzyl-L-tyrosine)) were synthesized through anionic and ring-opening polymerization under high-vacuum techniques. All final materials were molecularly characterized through infrared spectroscopy (IR) and proton and carbon nuclear magnetic resonance (1H-NMR, 13C-NMR) in order to confirm the successful synthesis and the polydiene microstructure content. The stereochemical behavior of secondary structures (α-helices and β-sheets) of the polypeptide segments combined with the different polydiene microstructures was also studied. The influence of the α-helices and β-sheets, as well as the polydiene chain conformations on the thermal properties (glass transition temperatures, thermal stability, α- and β-relaxation) of the present biobased hybrid copolymers, was investigated through differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and dielectric spectroscopy (DS). The obtained morphologies in thin films for all the synthesized materials via atomic force microscopy (AFM) indicated the formation of polypeptide fibrils in the polydiene matrix. [ABSTRACT FROM AUTHOR]

Abstract: Polyesteramides derived from the cyclic monomers ε-caprolactam and ε-caprolactone have been synthesized by the anionic polymerization and characterized. ε-Caprolactam magnesium bromide was employed as unique initiator giving high yield of copolymer across the whole range of monomer concentrations at 150°C. Owing to a variation of the content of ester and amide component in polyesteramide backbone a large variety of materials having diverse physico-chemical and mechanical properties have been prepared. Materials prepared were examined for mechanical characteristic. Thermal properties were characterized using DSC, temperature modulated DSC, Hi-ResTM TGA and DMA. Viscosity measurements were employed for molecular characterization. [Copyright &y& Elsevier]

Abstract: The copolymerization of a DGEBA epoxy resin and a bislactone was studied using different anionic initiators. In the previous work, the kinetics of the process was studied and the differences were observed which could affect the thermal and mechanical properties of the materials. In the present work, the thermo-mechanical properties of these materials have been investigated. An important influence of the final curing temperature on the thermal properties of the materials was detected. The addition of bislactone improved the thermal degradation of the materials due to the introduction of ester groups into the network, which in turn allowed partial or complete recovery and reworkability of the coated material via hydrolysis of the thermoset. In addition, the materials exhibited superior flexibility and toughness, in comparison to the pure DGEBA material. [Copyright &y& Elsevier]

Thermal properties and structure of initial and distorted phases of crystals K2KWO3F3, (NH4)2KWO3F3, (NH4)3WO3F3, Cs2NH4WO3F3 and Cs2KWO3F3 were studied to reveal the effect of cationic substitution on disordering and stability of cubic Fm3m phase. It was found that the nature of phase transitions depends on the shape of cation in 8c position. [ABSTRACT FROM AUTHOR]

Abstract: This work reports the synthesis of several copolymers of poly(vinyl chloride)-b-poly(n-butyl acrylate)-b-Poly(vinyl chloride) prepared by single electron transfer/degenerative chain transfer mediated living radical polymerization (SET-DTLRP) in a two step process: first, a bifunctional macroinitiator of α,ω-di(iodo)poly(butyl acrylate) [α,ω-di(iodo)PBA] was synthesized by SET-DTLRP in water at 30°C. The obtained macroinitiator was further reinitiated also by SET-DTLRP leading to the formation of the desired product. Several copolymers were synthesized in a 5L pilot reactor with different molecular weights and relative amounts of PBA and PVC. The possibility of synthesizing flexible materials made of PVC without using normal free plasticizes is extremely important for the industry. After processing the materials in a two-roll mill laboratorial equipment, the block copolymers were characterized concerning thermal and mechanical. The materials characterized in this study were prepared in a 5L pilot reactor under similar conditions to be used in industrial scale. [Copyright &y& Elsevier]

Abstract: The cationic polymerization and physicochemical properties of a biobased epoxy resin, epoxidized castor oil (ECO), initiated by N-benzylpyrazinium hexafluoroantimonate (BPH) and N-benzylquinoxalinium hexafluoroantimonate (BQH) as thermally latent catalysts were studied. As a result, BPH and BQH show an activity at different temperatures in the present systems. The cured ECO/BPH system showed a higher glass transition temperature, a lower coefficient of thermal expansion, and higher thermal stability factors than those of the ECO/BQH system. On the other hand, the mechanical properties of the ECO/BQH system were higher than those of the ECO/BPH system. These have been attributed to the differences in crosslinking level of cured resins, which were induced by the different activity of the latent catalysts. [Copyright &y& Elsevier]