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Using atomic force microscopy (AFM), we measured friction between an AFM tip and a polystyrene surface at 25°C, as a function of the sliding velocity and the applied normal load, both in air and under vacuum conditions. The objective was to analyze the influence of humidity on the frictional behavior of polystyrene. Our experimental results as a function of sliding velocity revealed a logarithmic...
In a previous study the effect of compositional variations on the equilibrium swelling of co-polymer hydrogels designed and synthesized from N-isopropylacrylamide (NIPAAm) and vinyl iminodiacetic acid (VIDA) monomers was investigated [Iyer G, Tillekeratne LMV, Coleman MR, Nadarajah A. Polymer, in this issue, doi:10.1016/j.polymer.2008.06.037]. The gels have both thermally responsive swelling and metal...
A series of poly(ether ketone) copolymers were prepared by nucleophilic aromatic polymerization reactions of the AB monomer 4-fluoro-4′-hydroxybenzophenone, 1, and the AB 2 monomer bis(4-fluorophenyl)-(4-hydroxyphenyl)phosphine oxide, 2, in the presence of 3 or 5mol% of a highly reactive core molecule, tris(3,4,5-trifluorophenyl)phosphine oxide (B 3 ), 4. All of the copolymers prepared...
A novel fluorene-based copolymer with aza-15-crown-5 as pendant group was synthesized by Suzuki-coupling reaction, and characterized by 1 H NMR, 13 C NMR, EA, and GPC. The polymer was brightly blue emissive in common organic solvents, such as CHCl 3 , CH 2 Cl 2 , and THF. Fluorescent titration experiments carried out in THF–MeOH system indicate that the polymer...
We present an efficient method for direct determination of the excess free energy ΔF of a nanoparticle inserted into a polymer brush. In contrast to Widom's insertion method, the present approach can be efficiently implemented by Monte Carlo or Molecular Dynamics methods also in a dense environment. In the present investigation the method is used to determine the free energy penalty ΔF(R, D) for placing...
Chain topology strongly affects the static and dynamic properties of polymer melts and polymers in dilute solution. For different chain architectures, such as ring and linear polymers, the molecular size and the diffusion behavior are different. To further understand the chain topology effect on the static and dynamic properties of polymers, we focus on the tadpole polymer which consists of a cyclic...
This paper describes the thermal properties, morphologies, and interactions within the binary and ternary blends of poly(methyl methacrylate) (PMMA), octa(phenol)octasilsesquioxane (OP-POSS), and LiClO 4 . In the binary PMMA/OP-POSS blends, the OP-POSS molecules tend to aggregate and result in a decrease (19°C) in the glass transition temperature. In the ternary PMMA/LiClO 4 /OP-POSS...
A novel highly effective low temperature route to synthesis of perinone type compounds, namely pyrroloperimidines, based on catalytic cyclization reaction of amic acids was developed. According to this route a series of perinones with polymerizable double carbon–carbon bond were synthesized and their free radical copolymerizations with styrene and methyl methacrylate were investigated. It was shown...
An amorphous polyamide (a-PA) and three organoclays, M 3 (HT) 1 , M 2 (HT) 2 and (HE) 2 M 1 T 1 , were melt processed to explore the effect of the organoclay structure on the extent of exfoliation and properties of these nanocomposites. Wide angle X-ray scattering, transmission electron microscopy, and stress–strain behavior were used to determine...
The alkylammonium surfactants used to form commercial organoclays are known to begin to degrade at temperatures below the typical melt processing temperatures of some polymers. In this study, the thermal stability and degradation of various surfactants and their corresponding organoclays were investigated. Several factors, such as surfactant type and excess surfactant in the organoclay, that affect...
Oxidative electropolymerization of aniline (Ani) in phosphoric acid (H 3 PO 4 ) on composite 2B pencil graphite was accomplished using selected inorganic salts as supporting electrolytes. These salts determined the degree of conductivity of polyaniline (PAni) formed. The conductivity was in the order of CaCl 2 >KCl>ZnCl 2 >ZnSO 4 >Ca 3 (PO...
A disparate polymerization technique is utilized for preparing versatile block copolymers from poly(trimethylene carbonate) (poly(TMC)). In this study, 4-(chloromethyl)benzyl alcohol (CBA) is used for the disparate polymerization. The hydroxyl group of CBA is involved in ring-opening polymerization and the benzyl chloride group is involved in incorporating dithiocarbamate for pseudo-living radical...
Electrically conductive polypropylene (PP)/multi-walled carbon nanotube (MWCNT) composites containing electrically inert particulate filler calcium carbonate (CaCO 3 ) have been prepared in a rotational rheometer. A significant reduction in electrical resistivity was found with the addition of CaCO 3 . The concept of effective concentration of MWCNTs is proposed to quantitatively evaluate...
Copolymer hydrogels were synthesized from N-isopropylacrylamide (NIPAAm) and vinyl iminodiacetic acid (VIDA) monomers, incorporating thermally responsive swelling and metal affinity properties. Compared to pure NIPAAm hydrogels, the copolymer hydrogels showed significantly increased swelling due to the hydrophilic VIDA groups while still retaining their sharp phase transition behavior. However, excessive...
Contribution of conformational isomerization to polymer tacticity has been studied in free radical polymerization of (−)-menthyl 2-acetamidoacrylate with azo initiators. It has been demonstrated that the chain end of the growing polymer radical, which is generated from the s-trans and s-cis conformers of monomer, produces stereoselectively new R and S configurational quaternary carbons, respectively,...
The present contribution describes the preparation and characterization of polymer–clay nanocomposite gels and films containing poly(ethylene oxide) and various ratios of Laponite and Montmorillonite. The aim is to understand how clays with different chemistry, sizes and surface areas interact with each other and affect the structure and characteristics of polymer based nanocomposites in the form...
This paper reports the preparation of a MAMA-SG1 (BlocBuilder™) derived alkoxyamine bearing a N-succinimidyl (NHS) ester group 1, valuable for functional and advanced polymer synthesis. This alkoxyamine was exploited following two strategies: (i) a post-functionalization approach based on the transformation of α-NHS chain ends of polymers previously obtained by nitroxide mediated polymerization (NMP)...
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