Morphology Control Of Poly Research Articles

Morphology control of poly(lactic) acid/polypropylene blend composite by using silanized cellulose fibers extracted from coir fibers

Morphology control of poly(lactic) acid/polypropylene blend composite by using silanized cellulose fibers extracted from coir fibers

Preparation and Morphology Control of Poly(ionic liquid) Particles.

Poly(ionic liquid)s (PILs) are prepared by the polymerization of ionic liquid (IL) monomers that have polymerizable groups on their cationic or anionic component. PILs also share many of the characteristic properties of ILs and can be used in various materials such as CO2 sorbents, polymer electrolytes, dispersants, and microwave-absorbing materials. In this feature article, we survey our research, focusing on the preparation of PILs in the particulate state (PIL particles) and on the morphological control of the PIL particles, including (1) the preparation of PIL particles by dispersion polymerization and emulsion polymerization, (2) control of the morphology of composite particles consisting of a PIL and poly(methyl methacrylate) (PMMA), (3) the preparation of hollow particles with a PIL shell, and (4) the preparation of PIL particles containing reduced graphene oxide (rGO). The size of the obtained PIL particles could be controlled through a modification of the synthesis conditions and the mode of polymerization (i.e., dispersion polymerization or emulsion polymerization). The obtained PIL particles maintained the characteristic properties of the corresponding ILs; moreover, the solubility of the PIL particles could be easily modified by changing their counteranion. Using seeded polymerization, we prepared PMMA/PIL composite polymer particles and subsequently demonstrated that their morphology can be manipulated to yield a core-shell or Janus structure. Hollow particles consisting of a PIL shell were also prepared, and modification of the polarity and penetration behavior of the shell through anion exchange was demonstrated.

Morphology Control of Poly(styrene-block-dimethylsiloxane) by Simple Blending with Trimethylsilylated Silicate Nanoparticles.

Trimethylsilylated silicate nanoparticle (termed MQ resin, combining M Me3SiO1/2 and Q SiO4/2 units)/poly(styrene-block-polydimethylsiloxane) (PS-PDMS, 31K-15K, polydispersity PD = 1.15, weight-average molecular weight Mw = 45.5K) blends behave similarly to block copolymers with different PS/PDMS ratios. MQ is localized in the PDMS phase virtually extending the volume fraction in the block copolymer. This allows for microdomain morphology control beyond what can be achieved with the starting block copolymer. Synthesizing siloxane-containing block copolymers targeted at certain equilibrium morphologies can be time-consuming and in some cases technically challenging. This work shows that MQ is a robust morphology modifier, not limited by the occurrence of surface segregation and the high diffusion rates typically associated with homopolymer modification, as confirmed by looking at the PDMS/PS-PDMS reference. The convenient and robust structure control MQ nanoparticle modification of PS-PDMS provides could overcome one of the hurdles to adoption of block copolymer lithography.

Morphology control of poly(3-hexylthiophene)-b-poly(ethylene oxide) block copolymer by solvent blending

The use of mixed solvents provided an effective way to control the self-assembly behavior and photophysical properties of a conjugated rod–coil block copolymer, poly(3-hexylthiophene)-b-poly(ethylene oxide) (P3HT-b-PEO). It was shown that the balance between the π–π stacking of the P3HT and microphase separation of the copolymer could be dynamically controlled and shifted by solvent blending. Depending on the mixed solvent ratio (i.e., chloroform/methanol, anisole/chloroform, or anisole/methanol), the copolymer chains experienced different kinetic pathways, yielding a series of nanostructures such as disordered wormlike pattern, densely packed nanofibrils, and isolated nanofibrils. With the varying solvent selectivity, the P3HT-b-PEO chains displayed a hybrid photophysical property depending on the competition between intrachain and interchain excitonic coupling, resulting in the transformation between J- and H-aggregation. Overall, this work offered an effective way to demonstrate the correlation and transformation between π–π stacking of P3HT and microphase separation, and how the conformation of P3HT chains influenced the photophysical properties of the copolymer during solvent blending. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 544–551

Characterization and morphology control of poly(p-phenylenediamine) nanofibers: A novel, simple and highly selective fluorescent probe for thiols

In this paper, the poly(p-phenylenediamine) (PpPD) nanofibers were synthesized via chemical oxidation polymerization of p-phenylenediamine (pPD) monomers by (NH4)2S2O8 (APS) at room temperature. The control of morphological was discussed with scanning electron microscope (SEM). It is spectacular that the PpPD nanofibers show high-efficiency effects in enhancing the fluorescence intensity of thiols. 1H NMR study showed that the possible mechanism is the hydrogen bonds between polymer and thiols. This paper also analyzes the mechanism of fluorescence synergistic effect of the PpPD with the theoretical calculations. This new method may be applied to the actual test. The measuring method is simple, efficient, pollution-free, low-cost and sensitive.

Synthesis, characterization, morphology control of poly (p-phenylenediamine)-Fe3O4 magnetic micro-composite and their application for the removal of Cr2O72− from water

In this paper, poly (p-phenylenediamine)-Fe3O4 (PpPD-Fe3O4) magnetic micro-composite was synthesized via chemical oxidation polymerization of p-phenylenediamine (pPD) monomers with (NH4)2S2O8 (APS) and Fe(NO3)3 at room temperature. The results demonstrated that the morphologies of this magnetic micro-composite were varied by tuning the consistence of Fe(NO3)3 in solution. The structures, morphologies and properties of the composites were characterized with IR, Raman spectroscopy, XRD, X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), and flame atomic absorption spectrometry (FAAS). This magnetic composite showed excellent ability on absorption of Cr2O72−. This magnetic composite is low cost, easy to operate and separate from solution. The mechanism research shows that the chemical adsorption and physical adsorption exist at the same time in adsorption process.

Morphosynthesis of poly(ether ketone) by reaction-induced crystallization during polymerization

Morphology control of poly(ether ketone) (PEK) was examined by using the crystallization during the nucleophilic aromatic substitution reaction of potassium salt of 4-fluoro-4′-hydroxybenzophenone. Polymerizations were carried out at 290°C. The PEK was obtained as precipitates and its morphology was highly influenced by the polymerization condition such as the solvent, the concentration and the polymerization time. High crystalline spindle-like crystals were obtained by the polymerization in diphenyl sulfone (DPS) at a concentration of 5.0% for 2h with the yield of 86%. The average length and width were 1.4μm and 300nm respectively, and the maximum thickness was 130nm. The surface was not smooth and it was hilly. The spindle-like crystal was likely consisted of multilayered lamellae comprised of the microcrystallites. The molecules were oriented perpendicular to the lamella. The polymerization in DPS at a higher concentration of 10.0% afforded the networks of nanofibres, of which the diameter was 100–250nm. The obtained PEK precipitates possessed excellent thermal properties.

Morphology control of poly[2-(perfluorooctyl)ethyl acrylate-co-tert-butyl acrylate] by pressure in supercritical carbon dioxide

The morphology control was attained in supercritical carbon dioxide (scCO2) for poly[2-(perfluorooctyl)ethyl acrylate (POA)-co-tert-butyl acrylate (TBA)] random copolymers with POA/TBA molar ratios of 9:1, 8:2, 7:3, 6:4, 5:5, and 4:6. The copolymers showed a different solubility and morphology in scCO2 depending on the POA/TBA ratio. There was a tendency that the copolymers with a lower TBA content, such as 9:1, 8:2, and 7:3, showed a higher solubility in scCO2 and formed a fiber-like structure in the heterogeneous state below their cloud point. On the other hand, the copolymers with the higher TBA contents of 6:4, 5:5, and 4:6 provided micrometer-sized spherical particles. Furthermore, the morphology was controlled by the CO2 pressure because the fiber-like morphology for the copolymer with the 6:4 ratio changed to spherical by decreasing the CO2 pressure.

Micro-flowers of poly( p-phenylene pyromelliteimide) crystals

Morphology control of poly( p-phenylene pyromelliteimide) (PPPI) crystals was examined using reaction-induced crystallization of oligomers during solution polymerization of self-polymerizable N-(4′-aminophenyl)-3-carboxyl-4-alkoxycarbonylphthalimide. Micro-flowers of the PPPI needle-like crystals were formed in which the needle-like crystals grew radially from the center part as petals. The molecules aligned regularly along the long axis of the needle-like crystal. The structure of alkoxy group in the monomer and the monomer concentration influenced the size of the needle-like crystals, and their average length and width were changeable from 640 nm to 1.69 μm and from 110 nm to 210 nm, respectively. The average thickness was 20 nm. The obtained micro-flowers possessed high crystallinity and exhibited excellent thermal stability.

Device Performance and Polymer Layer Morphology in Polymer Bistable Device (PBD): The Control of Physicochemical Properties of Solvent

The surface morphology control of poly(N-vinyl carbazole) (PVK) layer for the improvement of polymer bistable devices (PBDs) performance was investigated based on the simultaneous consideration of the compatibility of polymer with solvent and the polymer ordering behavior during the solvent evaporation by introducing the bisolvent system of chloroform and 1,1,2,2-tetrachloro-ethane (TCE). It was confirmed by ultra violet (UV)-vis spectroscopy that PVK has significantly higher compatibility with chloroform than TCE. On the other hand, atomic force microscope (AFM) revealed that the chloroform/TCE = 9/1 bisolvent led to the improved film morphology (the surface roughness of 0.190 nm) than chloroform, because the presence of TCE representing slower evaporation rate contributed to the enhancement of PVK ordering and arrangement during the solvent evaporation for the film formation. The great correlation was made between the film morphology properties and I-V characteristics of PBDs. The PBDs with PVK layer cast from the chloroform/TCE = 9/1 bisolvent showed dramatically improved bistability characteristics (Vth approximately equal to 2 V and Ion/Ioff ratio > 10(3)).

Fabrication and morphology control of poly(methyl methacrylate) hollow structures via coaxial electrospinning

AbstractA modified electrospinning method known as coaxial electrospinning was used to fabricate poly(methyl methacrylate) (PMMA) hollow structures. In this study to understand morphology control, the effect of processing parameters such as concentration of polymer sheath solution, size of core/sheath capillaries, feed rate, and applied voltage had been evaluated. Morphological observations via scanning electron microscope (SEM) revealed that via the control of polymer concentration within the sheath solution, morphologies such as hollow particles and fibers could be obtained. With the use of fine core/sheath capillaries, micron hollow fibers with walls of less than 20 nm were obtained. This study has demonstrated how the investigated processing parameters have a direct influence on the structures and how these parameters have supported the notion that effective encapsulation process is the key to the dual layer bicomponent structures. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Morphology control of poly(2,2′-phenylene-5,5′-bibenzimidazole) by reaction-induced crystallization during polymerization

Morphology control of polybenzimidazoles was examined by reaction-induced phase separation during polymerization. Polymerizations of 3,3′-diaminobenzidine with terephthalic acid or diphenyl terephthalate were carried out in poor solvents. The morphology of the precipitated poly[2,2′-(1,4-phenylene)-5,5′-bibenzimidazole] (PpBBI) was significantly influenced by the polymerization conditions, and the aggregates of nano-scale PpBBI fibers were obtained by the polymerization at a concentration of 3–5% and 320–350°C in dibenzyltoluene. The average diameter of the fibers was ca. 50nm and inherent viscosities of the precipitates were 0.35–0.58dLg−1. They possessed high crystallinity and thermal stability. The oligomers were precipitated first by the reaction-induced crystallization to form the highly crystalline lath-like crystals at an initial stage of polymerization. Then the lath-like crystals were split into disentangled aggregates of fine fibers with maintaining the high crystallinity. The polymerization mainly proceeded when the oligomers were registered into the crystals. The obtained aggregates of nano-scale fibers could be recognized as nonwoven fabrics. Morphology control of poly[2,2′-(1,3-phenylene)-5,5′-bibenzimidazole] was also examined and particles were mainly formed.

Morphology control of poly(vinylidene fluoride) thin film made with electrospray

Thin polymer films of poly(vinylidene fluoride) were prepared with electrospray. Effects of solvent, initial spray concentration, temperature, solution conductivity, and polymer size on the film morphology were studied with AFM. The two main factors controlling polymer film morphology are the droplet size of the spray and the viscosity of the solution at deposition. These factors determine the flow of the polymer-solvent mixture over the substrate, the density of the film, and its smoothness. The solvent is a key parameter of the entire process. It affects spray stability, polymer solubility, droplet size of the spray, and viscosity of the solution at deposition. Solvents with a low vapor pressure provide a wider window for optimization of other parameters and are therefore preferred over solvents with high vapor pressure. The viscosity at deposition is mainly controlled with the initial spray concentration, polymer size, temperature, and droplet size. The droplet size is best controlled by the conductivity of the solution and the flow rate of the spray.

Morphology Control of Poly(p-mercaptobenzoyl) by Modification of Oligomer End-group

Influence of acyl end-group of oligomers on morphology of poly(p-mercaptobenzoyl)(PMB) was examined by the polymerization of S-acyl-4-mercaptobenzoic acids having the different acyl groups and their dimers in liquid paraffin at 260–300 °C. The polymerization of S-acetyl-4-mercaptobenzoic acid afforded PMB whiskers, whereas the polymerization of S-propionyl-4-mercaptobenzoic acid, S-butyryl-4-mercaptobenzoic acid and S-valeryl-4-mercaptobenzoic acid yielded PMB microspheres. The microspheres were formed by the liquid–liquid phase separation of oligomers induced by the longer acyl end-groups than acetyl group of the oligomers due to the reduction of freezing point of oligomers. In contrast to this, the polymerizations of their dimers afforded needle-like and slab-like crystals instead of microspheres. In these polymerizations, the crystallization was induced due to the increase of the molecular weight of the phase-separated oligomers, leading to the increase of the freezing point of oligomers. The morphology of PMB could be controlled by the chemical modification of oligomer end-groups.

Morphology Control of Poly(p-phenylene pyromelliteimide) by Means of Self-Assembling Polymerization

Morphology Control of Poly(<i>p</i>-phenylene pyromelliteimide) by Means of Self-Assembling Polymerization