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Transamidation between PA1012 and PA612 was investigated with combination techniques including differential scanning calorimetry (DSC), rheometry, nuclear magnetic resonance (NMR) and variable-temperature Fourier transform infrared spectroscopy (VT-FTIR). Based on the increase of storage modulus with sweep time, the presence of reactive chain ends were proved, promoting chain growth in either polyamide...
We report the synthesis and photovoltaic properties of a donor–acceptor polymer, poly(naphthobisthiadiazole-triphenylamine) [poly(NTD-TPA)], which consists of TPA as a donor unit and NTD as a stronger acceptor than benzothiadiazole. This polymer had an absorption edge at wavelengths up to 610 nm. The optimized bulk-heterojunction (BHJ) organic photovoltaic (OPV) cell using poly(NTD-TPA) and [6,6]-phenyl...
The first normal stress difference (N1) of lyotropic liquid crystalline solutions of poly(p-phenylene terephthalamide) (PPTA) in sulfuric acid was studied by rheometric measurements. For the first time, a negative value range of N1 was observed for the solutions in a high shear rate range. N1 showed a non-monotonic dependence on the shear rate when the PPTA/sulfuric-acid solution was in the nematic...
A novel method for synthesizing a microsponge polyimide (PI) film with excellent thermal stability, chemical resistance, and heat insulation performance was developed. The synthesized microsponge PI film has open cells with sizes between 1 and 10 μm and a porosity of 76%. Furthermore, the film contains several layers overlapping in multiple grid structures, which complicates the heat transfer paths...
A series of random hyperbranched linear polyethylene (RHBLPE), which represents a completely new type of polyethylene, was synthesized through a single step polymerizing process of ethylene by an α-diiminonickel complex pre-catalyst. The molecular weights, branching architectures, chemical compositional distributions as well as the crystallization behavior of these RHBLPEs were carefully investigated...
Pressure dependence of various phase transitions for the miscible block copolymer (BCP) blends was evaluated by depolarized light scattering (DPLS) and small-angle neutron scattering (SANS) measurements, in which the blends consist of a polystyrene-b-poly(n-butyl methacrylate) (PS-b-PnBMA) and a deuterated polystyrene-b-poly(n-hexyl methacrylate) (dPS-b-PnHMA). Excellent baroplasticity was observed...
The principal purpose in this paper is to present a combined experimental and analytical study to understand the mechanical behavior of polycarbonate (PC) under a wide range of temperatures (−40 °C to 100 °C) and strain rates (0.001 up to 5000 s−1). Firstly, the experiments were conducted to obtain stress-strain response from low to high rates and temperatures. Then a robust physically consistent...
A novel CO2 adduct has been synthesised from a branched polyethyleneimine with polypropylene glycol (PPG) side chains and can serve as an alternative to traditional polyurethane blowing agents, such as hydrochloroflourocarbons and hydrofluorocarbons, which cause ozone depletion and/or global warming. The CO2 adduction trapped 13.8 wt% of CO2, forming alkylammonium carbamates in the main chains. Therefore,...
Betaine ester-shell functionalized hyperbranched polyethylenimines (BEHPEI) were synthesized by Menschutkin reaction between per-N-methylated polyethylenimine (MeHPEI) and alkyl bromoacetate. BEHPEI could play dual antimicrobial roles that were, the betaine ester-shell acted as contact-based antibacterial polycations and the drug-loaded BEHPEI could controllably release the drugs due to the cleavage...
The correlation between rheological behavior and time evolution of the phase separation patterns was investigated in the epoxy/thermoplastic blends. Before and during the induction period of phase separation, the storage and loss modulus initially increased with epoxy curing reaction and the concentration fluctuation. At the late stage of phase separation, the modulus values also increased and showed...
The microsphere of poly(methyl methacrylate) (PMMA)/graphene composite, having a core–shell structure, is effectively prepared by Pickering suspension polymerization using a water-dispersible sulfonated graphene alone as a Pickering stabilizer. This is the first case where a graphene is designed as a Pickering stabilizer for suspension polymerization. The sulfonated graphene is prepared using a novel...
Crystallization behaviors and kinetics of iPP in an in-situ prepared isotactic polypropylene/graphene (iPP/G) composites were studied in this paper. In samples used in this study, the graphene fillers were well dispersed, and the interfacial adhesion exhibited enhanced features between graphene and iPP components. The thermal stability of the composites was improved by about 100 °C compared to the...
The morphology of a series of poly(butylene terephthalate) (PBT)/fatty acid dimer diol (FADD)-based copolyesters prepared by solid-state modification (SSM) was studied. It was shown that in copolyesters containing less than 10 wt% FADD two different phases, i.e. a PBT crystalline phase and a PBT-rich amorphous phase, are present. The FADD residues were more or less homogeneously distributed throughout...
Poly(methyl methacrylate) (PMMA) monoliths with a three-dimensional continuous interconnected porous structure in a single piece were fabricated via thermally induced phase separation (TIPS) by utilizing unique cosolvency toward PMMA. We found that PMMA was soluble in a mixture of non-solvents (ethanol and water) at 60 °C. Cooling the solution resulted in formation of a monolith having interconnected...
Although recent experiments concerning shear effects on crystallization in polymer melts are inclined to support the oriented network model, two important questions still remain open: the effect of polydispersity on shish formation and the growth mechanism of shish. In this work, a narrowdisperse poly(ethylene oxide) (PEO) is chosen as a model system to clarify the role of polydispersity for shish...
Gel spun polyacrylonitrile/carbon nanotube (PAN/CNT) composite fibers have been produced, and the stress-induced G′ Raman band shifts in the CNTs have been monitored to observe stress transfer during fiber strain. Improvements in CNT quality, CNT dispersion, and post-processing fiber drawing are shown to increase the stress transfer from the matrix to the CNT. Radial breathing mode (RBM) intensity...
The rheological properties of polybutadiene (PB)/polyisoprene (PI) in the unstable and metastable regions under oscillatory shear flow has been studied. Based on the shear quench experiment, it showed that the time dependent storage modulus G′ initially increased and then decreased with time in the unstable region. The concentration fluctuation led to the increasing part and the coarsening of the...
Thin hydrogel films attached to a rigid substrate can only swell along the direction perpendicular to the substrate, which generates compressive stress within the gel. When the stress is sufficiently large, the free surface of the gel will locally buckle and fold against itself to form various wrinkling patterns. Here we show that hydrogen-bonded layer-by-layer (LBL) films of poly(vinyl pyrrolidone)...
Carbonization at high temperature can significantly increase the conductivity of polyaniline nanofibers (PANF) but the created carbonized surface is too hydrophobic for Pt-loading. Sulfonic acid groups are then grafted on the carbonized PANF by ultra-sonication in concentrated sulfuric acid to increase the surface hydrophilicity and Pt-loading. The obtained sulfonated carbonized PANF was found to...
This study introduces a useful approach for fabrication of hollow-structured hydrogel microparticles and for encapsulation of biomacromolecules in the hollow core of the particles. Monodisperse hollow-structured poly(vinyl amine) hydrogel particles were fabricated without using templates that combines the dispersion polymerization and the sequential hydrolysis/crosslinking. The hydrogel shell showed...
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