Copolymer Solutions Research Articles

Unveiling the interaction between carbon nanodot and IR light emitting fluorescent dyes inside the confined micellar environment

In this contribution, using microwave heating of polyethylene glycol (PEG 200), we have prepared carbon nanodot (CND). It is found that in aqueous medium as well as in the micellar solutions of triblock copolymer, P123 and in anionic surface active ionic liquid (SAIL), 1-butyl-3-methylimidazolium n-octylsulfate ([C4mim][C8SO4]) the fluorescence intensity of CND gets quenched in the presence of cationic cyanine dye HITCP and cationic phenoxazine dye Nile blue (NB). Stern-Volmer constant indicates that the quenching of fluorescence intensity is more in the aqueous medium compared to P123 and [C4mim][C8SO4] i.e., (BmimOs) micelles. Time-correlated single photon counting (TCSPC) measurement reveals that the fluorescence quenching is static in nature and the quenching through Förster resonance energy transfer (FRET) process is not dominant here. Addition of both the cationic dye molecules (HITCP and NB) in CND solution generates new excited state absorption peaks in transient absorption measurement. This observation suggests that a transient species is generated through photoinduced electron transfer (PET) between the donor-acceptor pairs and this PET is responsible for the fluorescence quenching of CNDs by the dye molecules. Moreover, this electron transfer kinetics is relatively faster in bulk water compared to that inside P123 and BmimOs micelle due to the intervention of the surfactant molecules between CND and the dye molecules. Therefore, this study provides a new insight about the PET dynamics between CND and fluorescent dye molecules.

Insights on the interaction between sodium dodecyl sulfate and partially hydrolyzed microblock hydrophobically associating polyacrylamides in different polymer concentration regimes

The partially hydrolyzed microblock hydrophobically associating polyacrylamides (HMBHAPs) with different microblock lengths (NH) and some positive charges were prepared by free radical copolymerization in aqueous solution and the HMBHAPs were characterized by FTIR, 1H-NMR, ion titration, elemental analysis and thermal gravimetric analysis. Moreover, the hydrodynamic size and microtopography of HMBHAPs were also characterized by dynamic light scattering and environment scanning electron microscope. The self-association effect of HMBHAPs and the interaction between HMBHAPs and oppositely charged sodium dodecyl sulfate (SDS) in different polymer concentration regimes were investigated through the measurements involving rheology, fluorescence, conductivity and zeta potential. The results show that HMBHAPs presented different viscosity behaviors in the concentration range concerned that could be divided into three different concentration regimes, where the viscosity contribution made by association effect was significantly discrepant and enhanced with increasing microblock length. Moreover, rheological measurements indicate that, with the addition of SDS, zero-shear viscosity (η0) of HMBHAPs presented different variation trends in three polymer concentration regimes: at lower HMBHAPs concentration, the η0 of HMBHAPs/SDS system was smaller than that in absence of SDS; at moderate HMBHAPs concentration, the system viscosity increased slightly; whereas, the viscosity distinctly increased with increasing SDS concentration at higher HMBHAPs concentration. The I3/I1 and Ie/Im also demonstrated that the aforementioned viscosity behaviors were closely related to the efficiency and number of the associations, as well as the micro-block longer the association effect stronger. In addition, η0 and Ie/Im exhibited a very interesting “double peaks” phenomenon with increasing SDS, which may be interpreted by the simultaneous influence of electrostatic interaction and the association effect between cationic hydrophobic groups and anionic surfactant. The SDS amounts binded by HMBHAPs showed a slightly increasing trend as increasing polymer concentration and decreasing NH. Zeta potentials at n-octane-water interface showed a “charge reversal” phenomenon with increasing HMBHAPs concentration, which appeared earlier for longer microblock. With the addition of SDS, Zeta potential rapidly varied from an initial smaller positive charge to a greater negative charge, and the variation presented earlier with varied polymer concentration regimes and increasing NH. This result may be ascribed to the adsorption of HMBHAPs macromolecules at the oil-water interface and different inter-molecular conformations after interacting with SDS at the interface.

Ln3+-Induced Diblock Copolymeric Aggregates for Fully Flexible Tunable White-Light Materials.

In this research contribution, nano-aggregates have been fabricated by introducing lanthanide (Ln3+) ions into solutions of amphiphilic diblock copolymers of polystyrene-b-poly (acrylic acid) (PS-b-PAA). The coordination of acrylic acid segments to lanthanide cations induces diblock copolymer (BCPs) self-assembly in order to design stable white luminescent hybrid nanoparticles with fine uniform particle size. The introduction of Ln3+ ions (Eu3+ and Tb3+) bestows the micelles, precisely white light, upon excitation of 342 nm. Lanthanide coordination cross-linking of poly (acrylic acid) segments, or blocks, endows the micelles higher thermal stability than that of BCPs micelles without cross-linking. As the most important key point of this work, the regular and stable nano-particles with high emission quality can make fully flexible electroluminescent devices with self-formation or uncoordinated into polymer hosts. Instead of inorganic luminescent nanoparticles with hard cores, this method can potentially apply for fully flexible white-light emitting diodes (FFWLEDs).

Synthesis of special acrylic nanofibers as an appropriate precursor for conductive carbon nanofibers

Electrospinning technique is a significant approach used for producing special acrylic nanofibers (SANFs) through applying electrostatic field. SANFs were electrospun from polyacrylonitrile (PAN) copolymer solutions to be used as a precursor for carbon nanofibers (CNFs). The Box–Benkhen design (BBD) was used to elucidate the effects of the acrylic concentration (wt%), electrospinning voltage (kV), and spinning distance (cm) on the SANFs surface morphology and optimize these parameters. Based on BBD model the optimum SANFs diameter of 292 nm and 14.20% coefficient of variation, were collected at 9.3 wt% PAN concentration, 14 kV applied voltage, and 20 cm spinning distance. The optimized SANFs manufactured under BBD settings were specified by scanning electron microscope (SEM), mechanical tester, and differential scanning calorimeter (DSC). The optimized SANFs was stabilized in air and then carbonized in inert atmosphere at 800, 1000, and 1200 °C, respectively. The electrical conductivity of CNFs samples obtained from SANFs at 800 °C carbonization temperature is 2.31 × 10−2 S/cm, which is increased to 2.60 × 10+1 S/cm at 1200 °C. The results indicated that, the optimized SANFs possessed the most desired morphological properties, mechanical characteristics, and thermal stability; and thus they are appropriate for the development of high-performance CNFs.

Ryo Yoshida

Angewandte Chemie International EditionVolume 58, Issue 30 p. 10040-10040 Author ProfileFree Access Ryo Yoshida First published: 14 February 2019 https://doi.org/10.1002/anie.201901583AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Graphical Abstract “The most important future application of my research is artificial life. The secret of being a successful scientist is having a sense of beauty …” Find out more about Ryo Yoshida in his Author Profile. Ryo Yoshida The author presented on this page has published his 10. article in Angewandte Chemie in the last 10 years: “Chemomechanical Motion of a Self-Oscillating Gel in a Protic Ionic Liquid”: T. Masuda, T. Ueki, R. Tamate, K. Matsukawa, R. Yoshida, Angew. Chem. Int. Ed. 2018, 57, 16693; Angew. Chem. 2018, 130, 16935. The work of R. Yoshida has been featured on the cover of Angewandte Chemie: “Evolved Colloidosomes Undergoing Cell-like Autonomous Shape Oscillations with Buckling”: R. Tamate, T. Ueki, R. Yoshida, Angew. Chem. Int. Ed. 2016, 55, 5179; Angew. Chem. 2016, 128, 5265. Date of birth: December 22, 1964 Position: Professor, School of Engineering, The University of Tokyo E-mail: ryo@cross.t.u-tokyo.ac.jp Homepage: http://cross.t.u-tokyo.ac.jp ORCID: 0000-0002-0558-2922 Education: 1988 BS, Waseda University, Tokyo, Japan 1993 PhD supervised by Kiyotaka Sakai, Waseda University, Tokyo, Japan (collaborative study supervised by Prof. Teruo Okano, Tokyo Women's Medical University, Tokyo, Japan) Awards: 2009 SPSJ Wiley Award, Society of Polymer Science Japan (SPSJ); 2018 New Age Technology Award, International Association of Advanced Materials Research: Design of functional polymer gels with spatio-temporal structure and development to biomimetic smart soft materials Hobbies: Playing classical and acoustic guitars The most important future application of my research is artificial life. The secret of being a successful scientist is having a sense of beauty. I get advice from Zen words. I admire laws and scenario of nature, life, and cosmos. My motto is Have originality. “Do not go where the path may lead, go instead where there is no path and leave a trail” (Ralph Waldo Emerson). Looking back over my career, I feel destiny. My favorite saying is “Let it be”. My biggest inspiration is designing a self-oscillating gel. My favorite way to spend a holiday is playing classical and acoustic guitars. My favorite name reaction is the Belousov–Zhabotinsky reaction. My science “heroes” are Albert Einstein, Erwin Schrödinger, Ilya Prigogine, Paul J. Flory, and others. The most important thing I learned from my students is the flow of time. The principal aspect of my personality is thoughtfulness. My favorite author is Steve Jobs as a creator and his way of thinking. My favorite composers and musicians are Johann Sebastian Bach, Andrés Segovia, Bon Jovi, X JAPAN, Billy Joel, Simon & Garfunkel, The Beatles, and others. My 5 top papers: 1“Comb-Type grafted Hydrogels with Rapid De-Swelling Response to Temperature Changes”: R. Yoshida, K. Uchida, Y. Kaneko, K. Sakai, A. Kikuchi, Y. Sakurai, T. Okano, Nature 1995, 374, 240. (This polymer network design to improve gel kinetics had a high impact on gel research.) 2“Self-Oscillating Gel”: R. Yoshida, T. Takahashi, T. Yamaguchi, H. Ichijo, J. Am. Chem. Soc. 1996, 118, 5134. (My first report of a novel polymer gel which autonomously swells and de-swells periodically in a closed homogeneous solution without any external stimuli—like heartbeat.) 3“Self-Walking Gel”: S. Maeda, Y. Hara, T. Sakai, R. Yoshida, S. Hashimoto, Adv. Mater. 2007, 19, 3480. (Application of the self-oscillating gel as an autonomous soft robot.) 4“Self-Beating Artificial Cells: Design of Cross-Linked Polmyersomes Showing Self-Oscillating Motion”: R. Tamate, T. Ueki, R. Yoshida, Adv. Mater. 2015, 27, 837. (One of a series of attempts to create artificial self-beating cells using the self-oscillating polymer, which would be a significant step in closing the gap between artificial and living cells.) 5“Amoeba-Like Self-Oscillating Polymeric Fluids with Autonomous Sol-Gel Transition”: M. Onoda, T. Ueki, R. Tamate, M. Shibayama, R. Yoshida, Nature Communications 2017, 15862. (A block copolymer solution that undergoes autonomous and periodic sol–gel transition under constant conditions, demonstrating strong potential to realize a type of bioinspired autonomous soft robots.) Volume58, Issue30July 22, 2019Pages 10040-10040 ReferencesRelatedInformation

Bioresorbable pH- and temperature-responsive injectable hydrogels-incorporating electrosprayed particles for the sustained release of insulin

In situ-forming injectable hydrogels are attractive delivery vehicles not only for the controlled delivery of drugs and proteins but also for the controlled the delivery of nanometer sized particles. In this study, pH- and temperature-responsive pentablock copolymers were synthesized by the conjugation reaction between carboxylic groups of oligo (serine) and alcohol groups of temperature-responsive triblock copolymers, poly (ε-caprolactone)-b-poly (ethylene glycol)-b-poly (ε-caprolactone). Owing to their pH- and temperature-responsive property, the pentablock copolymers were found to be soluble at high pH, and transformed to viscoelastic gel at the physiological condition (pH 7.4, 37 °C). Furthermore, the free-flowing pentablock copolymer sols form a stable hydrogel depot on the back of Sprague-Dawley rats. The hydrogel depot was found to be degradable in a controlled manner and bioresorbable after one month. Insulin-incorporated nanosized chitosan particles were prepared via the electrospraying method and mixed with the pentablock copolymer solution to control the release of insulin. At high pH, the negatively charged pentablock copolymers and insulin-incorporated chitosan particles form an ionic complex through electrostatic interaction. Interestingly, in physiological conditions, the complex formed a viscoelastic gel and controlled the release of insulin in a spatiotemporal-controlled manner for over one month with remarkable inhibition of first-burst of insulin. These results demonstrated that modular design of injectable smart hydrogels with chitosan particles showing great prospect to control the delivery of insulin.

In situ preparation of hydroxyapatite composites into hydrolyzed polyacrylamidesolution and methylene blue dye retention

Four composites of hydroxyapatite/hydrolyzed polyacrylamide (HAP/HPAM-n) were prepared using an in situ wet chemical method. The synthesis was performed by preparing a suspension of calcium in a copolymer solution having a known HPAM concentration. Phosphoric acid was added dropwise to each suspension to obtain HAP/HPAM-n composites. The effect of initial copolymer amount on the composite properties was investigated using XRD, FTIR, TGA, and SEM/EDS analysis. The obtained results were compared to the HAP sample synthesized under the same conditions and without copolymer. HPAM amount in the composite affects the retention of methylene blue (MB) dye. The result shows that the increase of HPAM in the material leads to the increase of the dye retention capacity. Therefore, the composite prepared with a higher copolymer amount was selected to study the effects of different parameters on the dye removal including contact time, concentration, pH, temperature, and composite regenerations. We deduce in this work that the composite HAP/HPAM-75 is a good candidate for MB dye retention from aqueous solution with a maximum removal capacity of 435.6 mg g$^{-1}$ and the possibility of its reuse for several times.

Temperature-Induced Re-Entrant Morphological Transitions in Block-Copolymer Micelles.

Using a combination of a mean-field theoretical method and the numerical Scheutjens-Fleer self-consistent field approach, we predict that it is possible to have re-entrant morphological transitions in nanostructures of diblock copolymers upon variation in temperature-mediated solubility of the associating blocks. This peculiar effect is explained by the different rates in variation of the density of the collapsed core domains and the corresponding interfacial energy as a function of the temperature. The theoretical findings are supported by existing experimental observations of reversed sequences of the morphological transitions occurring upon temperature variation in solutions of amphiphilic block copolymers.

Luminol‐Pendant Chemiluminescent Polymethacrylamide‐Based Polymers for Peroxide Sensing in Live Cell Imaging.

AbstractThe present study aims at the development of luminol pendant functionalized chemiluminescent polymethacrylamides, for sensing and imaging applications. Luminol functionalized poly(methacrylamide) homopolymer was synthesized by the post‐polymerization modification of poly(methacryloyl chloride), (PMC) with luminol. Luminol based methacrylamide monomer (LUME) was synthesized using a simple Schotten‐Baumann type reaction between methacryloyl chloride and luminol. LUME was copolymerized with hydroxyethyl methacrylate (HEMA) using SET‐LRP (Single Electron Transfer‐ Living Radical Polymerization), a controlled radical polymerization technique. Luminol functionalized homo (PML) and copolymer (PHL) were having excellent solubility in basic medium as well as polar solvents like as dimethyl sulfoxide and dimethyl formamide. Basic solutions of both PML and PHL copolymers were tested for their chemiluminescent sensing of hydrogen peroxide using graphene oxide (GO) as a catalyst. Chemiluminescence intensity was found to be varying linearly with an increase in the concentration of hydrogen peroxide for both these polymers. Upto 1 μM of peroxide can be sensed even with a very dilute solution of PML (1.8x10−11M) and PHL (2x10−8M).These chemiluminescent polymethacrylamides were also studied for peroxide sensing in live cells.

Quantitative Grafting for Structure-Function Establishment: Thermoresponsive Poly(alkylene oxide) Graft Copolymers Based on Hyaluronic Acid and Carboxymethylcellulose.

A series of thermoresponsive graft copolymers, gelling at physiological conditions in aqueous solution and cell growth media, have been synthesized using quantitative coupling between a small set of amino-functionalized poly(alkylene oxide) copolymers (PAO) and the carboxylate of the biologically important polysaccharides (PSa) carboxymethylcellulose and the less reactive hyaluronate. Quantitative grafting enables the establishment of structure-function relationship which is imperative for controlling the properties of in situ gelling hydrogels. The EDC/NHS-mediated reaction was monitored using SEC-MALLS, which revealed that all PAOs were grafted onto the PSa backbone. Aqueous solutions of the graft copolymers were Newtonian fluids at room temperatures and formed reversible physical gels at elevated temperatures which were noncytotoxic toward chondrocytes. The established structure-function relationship was most clearly demonstrated by inspecting the thermogelling strength and the onset of thermogelling in a phase diagram. The onset of the thermogelling function could be controlled by the global PAO concentration, independent of graft ratio.

Effect of Ca2+ on viscosity and microstructure of water‐soluble triblock terpolymer used as thicker in the hydraulic fracturing

ABSTRACTCa2+ tolerance of water‐soluble polyacrylamide is a key problem in application fields. It is urgent to make the mechanism of between the polyacrylamide and Ca2+ clear. A terpolymer polyacrylamides including the sulfonate group with different monomer concentrations is synthesized. The effect of the CaCl2 concentration on the rheological properties is measured by a rheological rheometer. The zeta potential of the copolymer solution is obtained by a zeta potentiometer to learn about the electrical characteristics of the copolymers in solution. The microcosmic shape of the copolymer aqueous solution is investigated by a laser particle analyzer and an environmental scanning electron microscope. The results show that more sulfonate groups on the molecule can enhance the salt tolerance of the polyacrylamide. Sulfonate groups can weaken the effect of Ca2+ on the copolymer through the formation of complexes, whereas the self‐aggregation process of the copolymer cannot be stopped at high Ca2+ concentrations. This study provides theoretical guidance to elucidate the influencing rules and mechanism of calcium salt on the polyacrylamide containing a sulfonate group, which can be helpful for polyacrylamide modification and can improve the application of polyacrylamide under the condition of higher salt concentration. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47539.

Evaluation of the resistance to bacterial growth of star-shaped poly(ε-caprolactone)-co-poly(ethylene glycol) grafted onto functionalized carbon nanotubes nanocomposites

Nanocomposites of functionalized carbon nanotubes (CNTsf) as nanofillers, and a copolymer of star-shaped poly(ε-caprolactone) (stPCL) and poly(ethylene glycol) (PEG) as a polymeric matrix were synthesized, characterized, and their resistance to the growth of Staphylococcus aureus and Pseudomonas aeruginosa was evaluated. CNTsf contain hydroxyl, carboxyl and acyl chloride groups attached to their surface. Nanocomposites were prepared by mixing CNTsf to a solution of stPCL-PEG copolymer. Raman and FT-IR spectroscopies confirm the functionalization of carbon nanotubes (CNTs). Star-shaped PCL-PEG copolymer was characterized by Gel permeation chromatography (GPC), and 1H-NMR and 13C-NMR spectroscopies. X-ray photoelectron spectroscopy (XPS) shows that CNTsf are grafted to the stPCL-PEG copolymer. Crystallization behavior of the nanocomposites depends on the amount of CNTsf used in their preparation, detecting nucleation (nanocomposites prepared with 0.5 wt.% of CNTsf) or anti-nucleation (nanocomposites prepared with 1.0 wt.% of CNTsf) effects. Young’s Moduli and thermal stability of nanocomposites were higher, but their resistence to the proliferation of Staphylococcus aureus and Pseudomonas aeruginosa was lower than the observed for their pure polymer matrix.

Thermoresponsive Pentablock Copolymer on Silica: Temperature Effects on Adsorption, Surface Forces, and Friction.

The adsorption of hydrophilic or amphiphilic multiblock copolymers provides a powerful means to produce well-defined "smart" surfaces, especially if one or several blocks are sensitive to external stimuli. We focus here on an A-B-A-B-A copolymer, where A is a cationic poly((3-acrylamido-propyl)-trimethylammonium chloride) (PAMPTMA) block containing 15 (end blocks) or 30 (middle block) repeat units and B is a neutral thermosensitive water-soluble poly(2-isopropyl-2-oxazoline) (PIPOZ) block with 50 repeat units. X-ray reflectivity and quartz crystal microbalance with dissipation monitoring were employed to study the adsorption of PAMPTMA15-PIPOZ50-PAMPTMA30-PIPOZ50-PAMPTMA15 on silica surfaces. The latter technique was employed at different temperatures up to 50 °C. Surface forces and friction between the two silica surfaces across aqueous pentablock copolymer solutions at different temperatures were determined with the atomic force microscopy colloidal probe force and friction measurements. The cationic pentablock copolymer was found to have a high affinity to the negatively charged silica surface, leading to a thin (2 nm) and rigid adsorbed layer. A steric force was encountered at a separation of around 3 nm from hard wall contact. A capillary condensation of a polymer-rich phase was observed at the cloud point of the solution. The friction forces were evaluated using Amontons' rule modified with an adhesion term.

ОСАДОВА КОПОЛІМЕРИЗАЦІЯ 4-ВІНІЛПІРИДИНУ ЗІ СТИРОЛОМ

The determination of the copolymers of 4-vinylpyridine with styrene copolymers real composition, formed under the conditions of precipitation copolymerization in CCl4, is described. For this, 4-vinylpyridine with styrene was copolymerized in different ratios. The composition of the obtained copolymers was determined according to 1H NMR spectroscopy. A comparison of the real copolymers composition with the theoretically calculated ones was performed as well. The copolymerization of styrene with 4-vinylpyridine was carried out in sealed ampoules in argon medium. Solutions of a concentration of 1.02 mol/l in CCl4 were prepared. The initiator azobisisobutyronitrile in the amount of 0.00106 mol/l was added. The copolymerization was carried out in a thermostat C1823 at T = 75 ± 0.5°C. The copolymerization time was 3 hours. The original ratio of monomers (4-vinylpyridine:styrene) = 6:1; 5:1; 4:1; 3:1; 2:1; 1:2; 1:3; 1:4; 1:5; 1:6. The composition of the obtained copolymers was determined according to 1H NMR spectroscopy. It was determined that copolymers of 4-vinylpyridine with styrene obtained by precipitation copolymerization in CCl4 were enriched by 4-vinylpyridine bonds. On the contrary, the calculation of the instant composition of the copolymers according to the literature shows that under the conditions of classical copolymerization in 4-vinylpyridine solution is less active than styrene. We calculated the theoretical relative constants of copolymerization of styrene with 4-vinylpyridine: r1 = 1.97; r2 = 0.93. Therefore, under the conditions of classical copolymerization in solution 4-vinylpyridine is less active than styrene (r2 < r1). It was also found out that for the original molar content of styrene if it is greater than 0,85, it is not possible to synthesize by means of precipitation polymerization into CCl4 the copolymers of 4-vinylpyridine:styrene.

The Influence of Composition of Thermo- and pH-Sensitive Copolymers of N-(3-(Diethylamino)propyl)-N-methylacrylamide and N,N-Diethylacrylamide on Their Behavior in Aqueous Solutions

Buffer solutions of random copolymers of N-(3-(diethylamino)propyl)-N-methylacrylamide and N,N-diethylacrylamide containing 7.5 and 5.0 mol % units of N-(3-(diethylamino)propyl)-N-methylacrylamide with molecular masses of 3.07 × 104 and 1.45 × 104, respectively, have been studied by methods of light scattering and turbidimetry. The synthesis of copolymers has been performed via reaction of poly(acryloyl chloride) with N,N-diethyl-N′-methyl-1,3-propanediamine and diethylamine. Aqueous solutions have been studied in the concentration range of 0.0003–0.04 g/cm3 at pH 7.0–13.0. The intensities of scattered light I and optical transmittance I* have been measured. Phase separation temperatures have been determined. The results obtained have been compared with the data for a copolymer of the same structure, but with 20 mol % N-(3-(diethylamino)propyl)-N-methylacrylamide units. It has been shown that the characteristics of aqueous solutions of copolymers depend on their composition. An increase in the fraction of N-(3-(diethylamino)propyl)-N-methylacrylamide leads to formation of aggregates in the copolymer solutions and to a gain in the phase separation temperatures.

Surface modification of sendust powders prepared by ball milling

Fe75Si15Al10 alloy was produced by ball milling the elemental powder mixture under argon atmosphere. Surface modification of the powder particles was carried out via wet ball milling in organosilicon block copolymer (“Lestosil SM”) and surfactant (sodium dodecyl sulfate) solutions. The produced materials were characterized by means of scanning electron microscopy, X-ray diffraction and Mossbauer spectroscopy. The interaction of modifying agents with particles surface was evaluated by the analysis of the modified surface layers of the particles by X-ray photoelectron spectroscopy.

Depletion driven self-assembly of block copolymer solutions by homopolymers.

The addition of a non-adsorbing homopolymer to a block copolymer solution provides a convenient strategy for regulating its self-assembly. We systematically investigate the depletion effect from a homopolymer on the morphologies of AB diblock and BAB triblock copolymers in selective solvents. Increasing the homopolymer content results in larger spherical micelles, and the curvature of micelles is proportional to the square of homopolymer concentrations. A high enough homopolymer concentration may transfer micelles into vesicles. A deep analysis shows that the depletion effect produces attractive interaction between hydrophilic B blocks as well as their contraction on the micellar surface. The size of triblock copolymer micelles is not affected by homopolymers significantly, and spherical-to-wormlike micelle transition occurs at high homopolymer contents. These results have important applications for the precise design of self-assembled nanostructures of copolymer systems.

Integrated Kinetic Monte Carlo–Structure–Rheology Model for Solution Copolymerization of Ethylene and α-Olefins

An integrated Kinetic Monte Carlo–structure–rheology model is developed for polyolefins produced using solution copolymerization of ethylene and α-olefins. The proposed algorithm is completely firs...

A Novel Biodegradable and Thermosensitive Poly(Ester-Amide) Hydrogel for Cartilage Tissue Engineering.

Thermosensitive hydrogels are attractive alternative scaffolding materials for minimally invasive surgery through a simple injection and in situ gelling. In this study, a novel poly(ester-amide) polymer, methoxy poly(ethylene glycol)-poly(pyrrolidone-co-lactide) (mPDLA, P3L7) diblock copolymer, was synthesized and characterized for cartilage tissue engineering. A series of amphiphilic diblock copolymers was synthesized by ring-opening polymerization of mPEG 550, D,L-lactide, and 2-pyrrolidone. By dynamic light scattering analysis and tube-flipped-upside-down method, viscoelastic properties of the mPDLA diblock copolymer solution exhibited sol-gel transition behavior as a function of temperature. An in vitro degradation assay showed that degradation acidity was effectively reduced by introducing the 2-pyrrolidone monomer into the polyester hydrogel. Besides, mPDLA exhibited great biocompatibility in vitro for cell encapsulation due to a high swelling ratio. Moreover, cell viability and biochemical analysis proved that the mPDLA hydrogel presented a great chondrogenic response. Taken together, these results demonstrate that mPDLA hydrogels are promising injectable scaffolds potentially applicable to cartilage tissue engineering.

Improve the practicability of calcium aluminate phosphate cement as well cement: The application of amphoteric ion polymer as retarder

The thickening performance of calcium aluminate phosphate cement (CAPC) just can be improved by several kinds of compound retarders. However, in order to achieve the expected thickening time, the optimal proportion of each component must be controlled strictly, which seriously affects the practicability of CAPC. Therefore, the amphoteric ion polymer (ASDA) synthesized by the solution copolymerization among 2-acrylamido-2-methyl propane sulfonic acid (AMPS), sodium p-styrenesulfonate (SSS), diallyl dimethyl ammonium chloride (DMDAAC), itaconic acid (IA) is proposed as the retarder for CAPC in this paper. First, the molecular structure of ASDA is designed according to the action and failure mechanism of conventional Portland cement retarder in CAPC. And then the retarding effect and mechanism of ASDA in CAPC is researched. Finally, the basic properties of CAPC with ASDA as well cement are evaluated. Results show that the retarding effect of ASDA is excellent at middle temperature range. And CAPC with ASDA possesses superior right angle thickening performance. Although the early compressive strength is weak, the long term compressive strength of CAPC with ASDA just declines slightly. Furthermore, rheology, stability and free water of CAPC with ASDA still meet the demand of cementing engineering.