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Orientation of polymer chains in the spherulites of polymer-small molecule inclusion compounds (IC) is an interesting issue. Two kinds of spherulite morphologies were observed in the metastable β phase of poly(ethylene oxide) (PEO)/urea IC under the same isothermal crystallization temperature. Via polarized micro-Fourier transform infrared spectroscopy and two-dimensional wide angle X-ray diffraction...
A series of random poly(hexamethylene succinate-co-hexamethylene fumarate) (PHSF) samples was synthesized through a two-step reaction process, and their properties were systematically studied using wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FTIR). The crystal modification of polyester changes from monoclinic to orthorhombic...
Stretch-induced structural changes of poly(butylene adipate) at various temperatures were systematically investigated by X-ray diffraction method. It was found that tensile deformation could lead to both occurrence of α to β and β to α crystal transition via solid–solid process. Experimental results shows that either α or β form can be adopted as the stable phase for PBA crystal depending on the competition...
Poly(vinylidene fluoride) (PVDF) ultrafiltration membranes were prepared by immersion precipitation method using poly(hydroxyethyl methacrylate)-block-poly(methyl methacrylate) grafted silica (PHEMA-b-PMMA@SiO 2 ) nanoparticles as additives. The hybrid nanoparticles were synthesized by the surface initiated atom transfer radical polymerization (SI-ATRP), and they were characterized in detail...
Inclusion complexes formed from host small molecules and guest polymers have provided a novel platform to study both the physical properties of isolated polymer chains and crystallization behavior of host molecules. In this report, we have studied the crystalline structure, melting behavior and infrared information of inclusion complexes formed between polyethylene glycol oligomers and urea molecules...
The morphology and crystalline structure of banded spherulites of poly(butylene adipate) (PBA) were investigated by polarized optical microscopy (POM), wide-angle X-ray diffraction (WAXD), atomic force microscopy (AFM) and scanning electronic microscopy (SEM). It was found that after purification and fractionation, the obtained PBA fractions with different molecular weight formed ring-banded spherulites...
Various methods were employed to study the thermal behaviors of a novel microbial polyhydroxyalkanoate (PHA) terpolyester, namely, poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) (PHBVHHx) compared with poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx). PHBVHHx showed higher crystallization rate and degree of crystallinity. PHBVHHx exhibited also different multiple melting...
Usually, amphiphilic or crystalline structure is necessary to prepare nano- or micro-structured materials with various morphologies. Racemic random polylactide (PDLLA) is completely amorphous in nature and was mainly prepared to be of spherical form for the use of sustained drug release. In this paper, we observed novel lath-, sheaf-like morphologies of PDLLA microarchitectures fabricated by the double...
Poly(methylmethacrylate) (PMMA) and polystyrene(PS)/PMMA particles with Janus-like morphology were prepared via the internal phase separation followed by extraction of hexadecane (HD) template. The internal phase separation was triggered by evaporation of dichloromethane (DCM) from the polymer/HD/DCM-in-water emulsion droplets, which led to the formation of HD/PMMA or HD/PMMA/PS microparticles. After...
The interface structure of the poly(ethylene terephthalate) (PET)/silica nanocomposites was characterized by Fourier transform infrared and solid-state nuclear magnetic resonance. Our study reveals that PET chains are grafted onto the surface of silica nanoparticles, and they form branched and lightly crosslinking structures during the polycondensation. Gel permeation chromatography measurements indicate...
Poly(vinylidene fluoride) composite membranes filled with different weight fractions of SiO 2 nanoparticles have been prepared by a blending method. Cation-exchange groups were introduced by the copolymerization of glycidyl methacrylate with divinylbenzene and subsequent sulfonation. These hybrid membranes have been characterized by Fourier-transform infrared (FTIR) spectroscopy, scanning...
Inclusion compounds formed from host small molecules and guest polymers have provided a novel platform to study the behavior of isolated polymer chains confined in nanochannels. In this article, the PEO chain conformation in the metastable poly(ethylene oxide) (PEO)–urea inclusion compound (IC) and its transition was characterized via a combination of different analytical methods. Based on the FTIR...
In this work, we show that simple dialysis of a poly(dl-lactic acid) (PLA) solution against water resulted in the spontaneous formation of PLA spheres. We observed initial formation of particles with irregular shape and large size, which then were disrupted into uniform and smooth nanospheres. Further, the formation process of PLA spheres was also investigated by dynamic light scattering technique...
Nonlinear optical response in various polyhydroxyalkanoates (PHAs) was investigated via second harmonic generation microscopy (SHGM). It was revealed that the second harmonic generation (SHG) efficiency depended on both the polymer chemical structure and the crystalline structure. Among the PHAs studied, the microbial polyesters, poly(R-3-hydroxybutyrate) (PHB) and poly(R-3-hydroxyvalerate) (PHV)...
The diffusion effects on chain extension reactions, using carboxyl-terminated polyamide12 (PA12, say CA in this paper) as a model reactant with bisoxazolines (OO), were simulated by the stochastic Monte Carlo (MC) method. The chain length dependence and detailed diffusive behavior of each chain were considered based on the reptation theory. It is found that the diffusion effects retard the progress...
The chain extension using bisoxazolines (OO) as coupling agent was studied by means of the Monte Carlo (MC) method, focusing on the reaction kinetics. A comparison between simulated results and those calculated by an improved kinetic model was made. The coupling efficiency of the chain extender, average molecular weight and molecular weight distributions (MWDs) were investigated. The results show...
Comb-shaped graft copolymers with poly(methyl acrylate) as a handle were synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization and ring-opening polymerization (ROP) techniques in three steps. First, copolymers of poly(styrene-co-chloromethyl styrene), poly(St-co-CMS), were prepared by RAFT copolymerization of St and CMS using 1-(ethoxycarbonyl)prop-1-yl dithiobenzoate...
Banded spherulites of pure poly(l-lactide) (PLLA) were observed via the ‘crystallization after annealing’ procedure, while only common spherulites were obtained via the ‘direct isothermal crystallization’ procedure. Wide angle X-ray diffraction revealed that the two types of spherulites had the same crystal lattice of α-modification. Atomic force microscopy demonstrated that the alternative negative...
Two polymerizable anionic surfactants sodium 4-(ω-acryloyloxyalkyl)oxy benzene sulfonate (SABS-n, n=8 or 10) have been successfully used in the semi-continuous emulsion copolymerization with butyl methacrylate (BMA). After generating seeding particles in an emulsion consisting SABS-8 or SABS-10 and small amount of BMA using a redox initiator ammonium persulfate (APS)/tetramethylethylenediamine (TMEDA)...
Melting and crystallization of two types of polyhydroxyalkanoates (PHAs), poly(3-hydroxybutyrate) homopolymer (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) random copolymer (PHBHHx) were studied via in situ Fourier transform infrared spectroscopy (FTIR). The absorbance variances of the crystalline and the amorphous bands revealed that melting of PHB occurred at a narrow temperature range,...
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