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From an industrial/engineering point of view, the greatest demerit of solely isosorbide (ISB)-based polycarbonate is its fragility; this is considerably overcome in this study by using a dual-diol strategy with 1,4-cyclohexanedimethanol (CHDM). A series of copolycarbonates of ISB, a bio-derived diol with a rigid heterocyclic structure, and ductile CHDM monomers with diphenyl carbonate were prepared...
The effects of sequence distribution of two types of poly(propylene-ethylene) (PP-PE) copolymers, with propylene being the dominant component, on the associated crystallization behavior have been analyzed. The average sequence lengths of the crystallizable propylene sequences in these copolymers are different, although the ethylene content was virtually identical. In one case the chain configuration...
Morphology transformations of multicompartment assemblies of polystyrene-polyisoprene-poly(2-vinylpyridine), PS-PI-P2VP, was demonstrated. As the solvent quality is continuously varied the triblock copolymer experiences transformations from core-shell-corona micelles to particles with perforated lamellae, or from multicompartment micelles into PI-perforated PS-P2VP lamellae. Such multicompartment...
The swell ratio is a key parameter characterizing the structure and properties of a hydrogel. In macroscopic gels, the swell ratio can be determined by straightforward measurements of the gel weight in the dry and hydrated states. However, measuring the swell ratio characteristic of microgels (gel particles with dimensions of 0.1–100 μm) is substantially more challenging because of their small size...
The influence of multi-walled carbon nanotubes (0–5 wt%) on the crystallization process in isotactic polypropylene has been investigated by DSC and fast scanning calorimetry. In the non-isothermal experiments the crystallization temperature shifts to higher temperatures with increasing nanotube content, αCNT, whereas the polymer crystallinity was not significantly influenced. The critical cooling...
A periodic Density Functional Theory investigation of the structural and spectroscopic properties of poly(p-phenylene terephthalamide) (PPTA), carried out by means of CRYSTAL14, is here reported, for both the three-dimensional crystal and the isolated polymer chain treated as a infinite one-dimensional crystal focusing in particular on strain-dependent Raman spectra. Parallel to the theoretical investigation,...
Fiber properties are decided by its structure, and the structure are mainly formed in the fiber drawing process. In this study, the effects of the draw ratio on the fiber structure development of polyethylene terephthalate after continuous neck-drawing were investigated using simultaneous WAXD/SAXS measurements. Low-oriented amorphous as-spun fibers were drawn to a draw ratio of 3.0–4.5, at which...
Stereocomplex mesophase is for the first time disclosed by annealing of 1:1 poly (l-lactide) (PLLA)/poly (d-lactide) (PDLA) blends just above glass transition temperature. Its structure is analogue to that of stereocomplex crystals, as a result of weak intermolecular interactions between PLLA and PDLA chains. In the limited temperature range formation of stereocomplex mesophase is enhanced with annealing...
Nanoconfinement of a polymer film affords a reduction of the glass transition temperature (Tg) and effective viscosity (ηeff). Early on, Prof. Tisato Kajiyama pioneered the idea of enhanced polymer mobility at the free surface. This concept is now well established, and accounts for the Tg and ηeff reductions of thin polymer films. To pay tribute to Prof. Kajiyama's seminal contribution, it is fitting...
Carbon dots (CDs) is an area of intense focus, currently limited to unclear photoluminescence (PL) mechanism. Much effort has been made to clarify the certain PL centers but is still fruitless. Herein, a new type of polymer carbon dots (PCDs) with absolute quantum yield as high as 44.18% was synthesized by hydrothermally crosslinking polyacrylic acid and ethylenediamine. Through carefully comparing...
Organic semiconducting/ferroelectric blend films attracted much attention due to their cross-talk-free resistive property. Blend films were fabricated from the co-dissolved solution of both semiconducting and ferroelectric components. Spinodal decomposition induced phase separation which was the key structure for determination of resistive property in such blend films. However, till now only seldom...
An atomistic molecular dynamics simulation was performed for crosslinked phenolic resins which were constructed from phenols and crosslinkers using a pseudo-reaction algorithm, in order to understand the structure-mechanical property relationships therein from an atomistic perspective. The tensile modulus was characterized from the linear elastic region of the stress-strain curves under uniaxial tensile...
This paper investigates what effect network heterogeneity has on the thermal and non-linear mechanical properties of epoxy based asymmetric double network glasses. Asymmetric Double Network epoxies were formulated using miscible stoichiometric blends of amines following a controlled three stage cure schedule. The widely different reactivities of the aromatic and aliphatic amines allows for sequential...
“Mobile” polymer brushes with self-adjustable tethering density can be found in the single crystals of amorphous-crystalline diblock copolymers in the thermodynamically stable state. In such a system, the amorphous blocks form polymer brushes on the surface of the single crystal of the crystalline blocks. Different from the common polymer brushes with fixed tethering density, of which polymers are...
Polyurethane elastomers (PUEs) based on poly(2-ethyl-1,3-hexamethylene adipate) glycol (PEHA), poly(2,4-diethyl-1,5-pentamethylene adipate) glycol (PDEPA) and poly(2-butyl-2-ethyl-1,3-trimethylene adipate) glycol (PBETA) were synthesized with 4,4’-diphenylmethane diisocyanate (MDI) and 1,4-butane diol (BD)/1,1,1-trimethylol propane (TMP). PEHA has one primary and one secondary hydroxyl groups, but...
Over and above measurements of contact angles, this article provides examples from our work that emphasize unexpected wetting behavior using the Wilhelmy Plate (WP) method. These findings either would not have been noticed by conventional sessile drop methods or might have been dismissed due to deviations associated with measurements or sample-to-sample variations in surface composition. The examples...
Molecular modeling of crosslinked polymers often follows arbitrary pathways for network generation, with different precursor topology from experimental systems. We use coarse-grained molecular simulation to study the effects of precursor choice on the predicted network structure and properties. Three sets of precursors with different molecular architectures are designed such that they would form identical...
Two kinds of new electroactive polyamides were synthesized from a novel diphenylamine-fluorene skeleton bis(ether amine) monomer “N,N-bis((4-aminophenoxy)phenyl)-2-amino-9,9-dimethylfluorene” with cycloaliphatic and aromatic dicarboxylic acids, respectively. These polyamides were highly soluble in many organic solvents and could be solution-cast into transparent and flexible films. These films were...
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