scholarly journals Synthesis of Poly(ε-caprolactone)-Based Miktoarm Star Copolymers through ROP, SA ATRC, and ATRP

Polymers ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 858 ◽  
Author(s):  
Venkatesan Sathesh ◽  
Jem-Kun Chen ◽  
Chi-Jung Chang ◽  
Junko Aimi ◽  
Zong-Cheng Chen ◽  
...  
Keyword(s):  
Gel Permeation Chromatography ◽  
Proton Nuclear Magnetic Resonance ◽  
Atom Transfer ◽  
Force Microscopy ◽  
Radical Coupling ◽  
Flight Mass Spectrometry ◽  
Atomic Force ◽  
Star Copolymers ◽  
Miktoarm Star ◽  
Novel Strategy

The synthesis of novel branched/star copolymers which possess unique physical properties is highly desirable. Herein, a novel strategy was demonstrated to synthesize poly(ε-caprolactone) (PCL) based miktoarm star (μ-star) copolymers by combining ring-opening polymerization (ROP), styrenics-assisted atom transfer radical coupling (SA ATRC), and atom transfer radical polymerization (ATRP). From the analyses of gel permeation chromatography (GPC), proton nuclear magnetic resonance (1H NMR), and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), well-defined PCL-μ-PSt (PSt: polystyrene), and PCL-μ-PtBA (PtBA: poly(tert-butyl acrylate) μ-star copolymers were successfully obtained. By using atomic force microscopy (AFM), interestingly, our preliminary examinations of the μ-star copolymers showed a spherical structure with diameters of ca. 250 and 45 nm, respectively. We successfully employed combinations of synthetic techniques including ROP, SA ATRC, and ATRP with high effectiveness to synthesize PCL-based μ-star copolymers.

scholarly journals Miktoarm Star Copolymers Prepared by Transformation from Enhanced Spin Capturing Polymerization to Nitroxide-Mediated Polymerization (ESCP-Ŧ-NMP) toward Nanomaterials

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2392
Author(s):  
Tzu-Yao Lin ◽  
Cheng-Wei Tu ◽  
Junko Aimi ◽  
Yu-Wen Huang ◽  
Tongsai Jamnongkan ◽  
...  
Keyword(s):  
Physical Property ◽  
Water Contact ◽  
Force Microscopy ◽  
Atomic Force ◽  
Star Copolymers ◽  
Ft Ir ◽  
Miktoarm Star ◽  
The Difference ◽  
Reversible Deactivation Radical Polymerization ◽  
Nitroxide Mediated Polymerization

Reversible-deactivation radical polymerization (RDRP) serves as a powerful tool nowadays for the preparations of unique linear and non-linear macromolecules. In this study, enhanced spin capturing polymerizations (ESCPs) of styrene (St) and tert-butyl acrylate (tBA) monomers were, respectively, conducted in the presence of difunctional (1Z,1′Z)-1,1′-(1,4-phenylene) bis (N-tert-butylmethanimine oxide) (PBBN) nitrone. Four-arm (PSt)4 and (PtBA)4 star macroinitiators (MIs) can be afforded. By correspondingly switching the second monomer (i.e., tBA and St), miktoarm star copolymers (μ-stars) of (PSt)2-μ-(PtBA-b-PSt)2 and (PtBA)2-μ-(PSt-b-PtBA)2) were thus obtained. We further conducted hydrolysis of the PtBA segments to PAA (i.e., poly(acrylic acid)) in μ-stars to afford amphiphilic μ-stars of (PSt)2-μ-(PAA-b-PSt)2 and (PAA)2-μ-(PSt-b-PAA)2. We investigated each polymerization step and characterized the obtained two sets of “sequence-isomeric” μ-stars by FT-IR, 1H NMR, differential scanning calorimeter (DSC), and thermogravimetric analysis (TGA). Interestingly, we identified their physical property differences in the case of amphiphilic μ-stars by water contact angle (WCA) and atomic force microscopy (AFM) measurements. We thus proposed two microstructures caused by the difference of polymer chain sequences. Through this polymerization transformation (Ŧ) approach (i.e., ESCP-Ŧ-NMP), we demonstrated an interesting and facile strategy for the preparations of μ-stars with adjustable/switchable interior and exterior polymer structures toward the preparations of various nanomaterials.

scholarly journals Synthesis of amphiphilic ABA triblock oligomer via ATRP and its surface properties

2017 ◽  
Vol 95 (5) ◽  
pp. 605-611 ◽  
Author(s):  
Lei Wang ◽  
Shaoqing Wen ◽  
Zhanxiong Li
Keyword(s):  
Photoelectron Spectroscopy ◽  
Microphase Separation ◽  
Gel Permeation Chromatography ◽  
Contact Angles ◽  
Chemical Compositions ◽  
Water Contact ◽  
Force Microscopy ◽  
Atomic Force ◽  
Poly Ethylene ◽  
Magnetic Resonances

A series of novel amphiphilic ABA-type poly(tridecafluorooctylacrylate)-poly(ethylene glycol)-poly(tridecafluorooctylacrylate) (henceforth referred to as p-TDFA-PEG-p-TDFA) triblock oligomers were successfully synthesized via atom transfer radical polymerization (ATRP) using well-defined Br-PEG-Br as macroinitiator and copper as catalyst. The block oligomers were characterized by Fourier transform infrared (FTIR) spectroscopy and 1H and 19F nuclear magnetic resonances (NMR). Gel permeation chromatography (GPC) showed that the block oligomers have been obtained with narrow molecular weight distributions of 1.22–1.33. X-ray photoelectron spectroscopy (XPS) was carried out to confirm the attachment of p-TDFA-PEG-p-TDFA onto the silicon substrate, together with the chemical compositions of p-TDFA-PEG-p-TDFA. The wetabilities of the oligomer films were measured by water contact angles (CAs). Water CAs of p-TDFA-PEG-p-TDFA film were measured and their morphologies were tested by atomic force microscopy (AFM). The result showed that the CAs of the oligomer films, which possess fluoroalkyl groups assembled on the outer surface, increase after heating due to the migration of fluoroalkyl groups and the resulted microphase separation of the p-TDFA-PEG-p-TDFA.

Dendrimer-Like Star-Branched Block Copolymers with Controlled Segment Sequence and their Star-Like Dendrigraft Derivatives

2014 ◽  
Vol 67 (1) ◽  
pp. 31 ◽  
Author(s):  
Chao Zhang ◽  
Junpo He
Keyword(s):  
Block Copolymers ◽  
Molecular Conformation ◽  
Coupling Reactions ◽  
Dilute Solution ◽  
Mica Substrate ◽  
Segment Sequence ◽  
Force Microscopy ◽  
Atomic Force ◽  
Star Copolymers ◽  
Grafting Reactions

Star polymers with star-like arms, namely dendrimer-like star-branched block copolymers, were synthesised by anionic polymerisation with 1,3-bis(1-phenylethenyl)benzene (MDDPE) and divinylbenzene (DVB) as the coupling agents. The segment sequence was controlled by changing the polymerisation sequences of different monomers and coupling reactions. Two types of dendrimer-like star-branched block copolymers were prepared with polyisoprene (PI) block incorporated in the interior part or on the periphery. The PI chains in the resulting star copolymers were iteratively grafted through epoxidation and grafting reactions, forming star-like dendrigraft copolymers. The molecular conformation of the products in dilute solution was analysed by static and dynamic light scattering. These products adopt large sized globular conformation in dilute solution. Atomic force microscopy shows that the star-like dendrigraft copolymers appear as collapsed spheres on mica substrate.

Synthesis and Characterization of Linear Polymers for Non-Linear Optics through Click Chemistry Route

2012 ◽  
Vol 584 ◽  
pp. 8-12 ◽  
Author(s):  
Balakrishna Kolli ◽  
Sarada P. Mishra ◽  
Mukesh P. Joshi ◽  
S. Raj Mohan ◽  
T.S. Dhami ◽  
...  
Keyword(s):  
Click Chemistry ◽  
Second Harmonic ◽  
Gel Permeation Chromatography ◽  
Linear Polymers ◽  
Linear Optics ◽  
Scanning Calorimetry ◽  
Force Microscopy ◽  
Molecular Weights ◽  
Non Linear Optics ◽  
Atomic Force

Click chemistry is used for synthesizing polymers for second order NLO study. The molecular weights found by gel-permeation chromatography (GPC), were in the range of 7000-55000 g/mol. Differential scanning calorimetry shows glass transition temperature (Tg) above 120 oC. From electronic spectra order parameter of the poled films were calculated to be 0.1-0.5. The change in surface morphology after poling was checked by atomic force microscopy. By using a pulsed Nd:YAG laser (1064nm), the second harmonic generation (SHG) intensity was measured. The SHG intensity was also studied as a function of against temperature and time respectively.

scholarly journals Fabrication and Nanoscale Properties of PEDOT:PSS Conducting Polymer Nanospheres

2021 ◽  
Author(s):  
Matteo Sanviti ◽  
Angel Alegria ◽  
Daniel E Martínez-Tong
Keyword(s):  
Physical Properties ◽  
Spherical Shape ◽  
Step Method ◽  
Force Microscopy ◽  
Styrene Sulfonate ◽  
Electrically Conducting ◽  
Atomic Force ◽  
One Step ◽  
Novel Strategy ◽  
Poly Styrene Sulfonate

<div><div><div><p>Electrically conducting nanospheres of poly-(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) with tailored size, were prepared by a one-step method. To fabricate the nanostructures, PEDOT:PSS was dissolved in ethylene glycol using a novel strategy and the solution was precipitated in deionized water. The proposed fabrication route allowed to obtain a water-based dispersion of monodisperse nanospheres with good optical properties. To determine physical properties of the nanospheres, we followed a nanoscale approach, using Atomic Force Microscopy (AFM). Our nanoscale mechanical and electrical investigations showed that the nanospheres preserved good physical properties, compared to the commercial product. Moreover, the local studies indicated that the confinement imposed by the spherical shape can lead into a different arrangement of the PSS and PEDOT phases. In particular, we envisaged nanospheres composed by a PEDOT-rich surface, responsible for the good electrical conductivity of the nanostructures.</p></div></div></div>

scholarly journals New Strategy for Inducing Surface Anisotropy in Polyimide Films for Nematics Orientation in Display Applications

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 3107
Author(s):  
Elena-Luiza Epure ◽  
Iuliana Stoica ◽  
Raluca Marinica Albu ◽  
Camelia Hulubei ◽  
Andreea Irina Barzic
Keyword(s):  
Liquid Crystals ◽  
Surface Anisotropy ◽  
Polyimide Films ◽  
Alignment Layer ◽  
Display Devices ◽  
Force Microscopy ◽  
Atomic Force ◽  
New Strategy ◽  
Great Relevance ◽  
Novel Strategy

The operability of liquid crystal displays is strongly impacted by the orientation aspects of nematics, which in turn are affected by the alignment layer surface features. In this work, two polyimide (PI) structures are obtained based on a cycloaliphatic dianhydride and aromatic or aliphatic diamines with distinct flexibility. The attained PI films have high transmittance (T) for visible radiations, i.e., at 550 nm T > 80%. Here, a novel strategy for creating surface anisotropy in the samples that combines rubbing with a cloth and stretching via pressing is reported. Birefringence and atomic force microscopy (AFM) scans reveal that the generated orientation of the chains is affected by the chemical structure of the polymer and order of the steps involved in the surface treatment. Molecular modeling computations and wettability tests show that the PI structure and produced surface topography are competitive factors, which are impacting the intensity of the interactions with the nematic liquid crystals. The achieved results are of great relevance for designing of reliable display devices with improved uniform orientation of liquid crystals.

scholarly journals Micromechanism of the Dispersion Behavior of Polymer-Modified Rejuvenators in Aged Asphalt Material

2018 ◽  
Vol 8 (9) ◽  
pp. 1591 ◽  
Author(s):  
Mingyu Zhao ◽  
Fan Shen ◽  
Qingjun Ding
Keyword(s):  
Asphalt Binder ◽  
Gel Permeation Chromatography ◽  
Force Microscopy ◽  
Atomic Force ◽  
Dispersion Behavior ◽  
Dispersion Agent ◽  
Resistance To Deformation ◽  
Aged Asphalt ◽  
Dispersal Behavior ◽  
Pavement Engineering

Polymer-modified rejuvenator has a different composition and dispersion behavior to traditional rejuvenators. The objective of this study was to investigate the micromechanism of polymer-modified rejuvenators on the behavior of aged asphalt binder. Firstly, gel permeation chromatography (GPC) analysis was conducted to determine the dispersion effectiveness. Secondly, the dispersal behavior of polymer-modified rejuvenators was studied by means of atomic force microscopy (AFM) and scanning electron microscopy (SEM). Rheological, toughness-tenacity, and force–ductility analyses of the rejuvenated asphalt binder were additionally performed. The results indicate that the contacted asphaltenic micelles in aged asphalt binder were dispersed by dispersion agent in the polymer-modified rejuvenator, and that the dispersion ability of the polymer-modified rejuvenator was promoted to the commercial rejuvenator level. Additionally, the polymer-modified rejuvenator was found to improve the rejuvenated asphalt binder’s resistance to deformation, through the formation of polymeric network structures in the asphalt binder. The results may be used to improve the performance of rejuvenated asphalt binder in recycled-pavement engineering.

Electrostatic Effect on Jump-to-Contact and Atom Transfer Between AFM Tip and Substrate

2004 ◽  
Author(s):  
M. C. Cheng ◽  
J. L. Lai ◽  
C. K. Sung ◽  
H. M. Tai
Keyword(s):  
Morse Potential ◽  
Md Simulation ◽  
Atom Transfer ◽  
Force Microscopy ◽  
Atomic Force ◽  
Electrostatic Effect ◽  
Close Relationship ◽  
Simulation Results ◽  
Fcc Structure ◽  
Adhesive Forces

Dynamics of atoms around the interface of tip and substrate has close relationship to adhesive forces. This paper investigates the interactive behaviors by utilizing molecular dynamic (MD) simulation with the consideration of external applied electrostatic (ES) field between the atomic force microscopy (AFM) tip and substrate, which are both coated with gold. Morse potential was employed herein for modeling the energy between the atoms on the tip and substrate. The simulation model is composed of the gold-coated parts of the AFM tip and substrate, which are connected to the rest parts of the AFM tip and substrate, respectively, by the use of boundary conditions. The gold atoms were arranged in order according to face centric cubic (FCC) structure. The tip with the pyramidal shape was formed from 664 gold atoms while the substrate with cuboid shape was constructed from 2400 gold atoms. Simulation results show that both jump-to-contact interactions and the atom transfer increase as a result of enhancing the bias voltage between the tip and the substrate. The results agree well with experimental observation and also have the same trend as the experiment.

scholarly journals Structural characterization of polysaccharide from jujube (Ziziphus jujuba Mill.) fruit

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Xiaolong Ji ◽  
Yanqiu Cheng ◽  
Jingyuan Tian ◽  
Siqi Zhang ◽  
Yongshuai Jing ◽  
...  
Keyword(s):  
High Performance ◽  
Gel Permeation Chromatography ◽  
Structural Features ◽  
Resonance Spectroscopy ◽  
Acidic Polysaccharide ◽  
Force Microscopy ◽  
Atomic Force ◽  
Ziziphus Jujuba ◽  
Ft Ir ◽  
Fast Flow

Abstract Background Jujube (Ziziphus jujuba Mill.) fruit is one of the largest productions in China and its increasing production has drawn considerable attention from researchers. Polysaccharide is one of the most abundant components of jujube, and it represents a major group of biolotegically active constituents. This study intended to investigate the special structure of a homogeneous acidic polysaccharide (PZMP4) produced from Ziziphus Jujuba cv. Muzao fruit using novel methods, including DEAE-Sepharose Fast Flow and Sephacryl S-300 column chromatography. Results The structure of PZMP4 was determined via high-performance gel permeation chromatography (HPGPC), gas chromatography (GC), Fourier transform infrared spectroscopy (FT-IR), methylation analysis, nuclear magnetic resonance spectroscopy (NMR), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The results reveal that PZMP4 with a molecular weight of 27.90 kDa was composed of rhamnose, arabinose, mannose, glucose, galactose, and galacturonic acid at a ratio of 2.32:2.21:0.22:0.88:2.08:8.83. Advanced structural analysis revealed a netted structure with molecular aggregates of PZMP4. Structural features demonstrated that the basic backbone of PZMP4 appeared to mainly consist of (1→4)-linked GalpA with three branches bonded to O-3 of (1→3)-linked Araf, (1→2)-linked Rhap, and terminated with GalpA. Conclusions PZMP4’s unique structure could imply distinct bioactivities and have considerable utilization in functional food. Graphic abstract

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