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Zhang R.,Key Laboratory of Functional Polymer Materials | Wang X.,Nanjing University of Technology | Sun P.,Key Laboratory of Functional Polymer Materials | Lv W.,Petrochina | And 2 more authors.
European Physical Journal E | Year: 2015

Abstract.: In this work, the effect of poly(ethylene oxide) (PEO) molecular weight in blends of epoxy (ER) and PEO on the miscibility, inter-chain weak interactions and local dynamics were systematically investigated by multi-frequency temperature modulation DSC and solid-state NMR techniques. We found that the molecular weight (Mw) of PEO was a crucial factor in controlling the miscibility, chain dynamics and hydrogen bonding interactions between PEO and ER. A critical PEO molecular weight (Mcrit) around 4.5k was found. PEO was well miscible with ER when the molecular weight was below Mcrit, where the chain motion of PEO was restricted due to strong inter-chain hydrogen bonding interactions. However, for the blends with high molecular weight PEO (Mw > Mcrit), the miscibility between PEO and ER was poor, and most of PEO chains were considerably mobile. Finally, polarization inversion spin exchange at magic angle (PISEMA) solid-state NMR experiment further revealed the different mobility of the PEO in ER/PEO blends with different molecular weight of PEO at molecular level. Based on the DSC and NMR results, a tentative model was proposed to illustrate the miscibility in ER/PEO blends. Graphical abstract: [Figure not available: see fulltext.] © 2015, EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg. Source


Liu J.,Key Laboratory of Functional Polymer Materials | Liu G.,Key Laboratory of Functional Polymer Materials | Zhang M.,Peking Union Medical College | Sun P.,Nankai University | Zhao H.,Key Laboratory of Functional Polymer Materials
Macromolecules | Year: 2013

Materials with asymmetric structures are attractive for wide applications in chemistry and materials science. Two-dimensional Janus disks or nanosheets are particularly appealing because of the unique shape and the distinctive self-assembled structures. A facile and versatile method for the synthesis of amphiphilic Janus Laponite disks is proposed in this paper. Positively charged PS spheres were prepared by ATRP emulsion polymerization. Upon addition of aqueous dispersion of negatively charged Laponite disks into PS emulsions, the nanosized disks were adsorbed onto the surface of PS particles via electrostatic interaction. One side of a Laponite disk touches the surface of a colloidal particle, and the other side faces the medium. After addition of positively charged polymeric micelles or quaternized poly(2-(dimethylamino)ethyl methacrylate) (q-PDMAEMA) chains into the aqueous dispersions of the colloidal particles, the micelles or polymer chains were immobilized onto the Laponite disks, and Janus disks were produced on particle templates. After centrifugation and redispersion of the colloidal particles into a good solvent, amphiphilic Janus Laponite disks with PS chains on one side and hydrophilic q-PDMAEMA or polymeric micelles on the other side were obtained. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) were used to characterize the Janus disks. Self-assembly of the Janus disks at liquid-liquid interface and in selective solvents was investigated. Similar to small molecular surfactants, the amphiphilic Janus disks can self-assemble at liquid-liquid interface, resulting in a decrease of the interfacial tension and emulsification of oil droplets in water. In a THF-methanol mixture at a volume ratio of 1:6, PS brushes on the Janus disks collapse forming two-layer face-to-face stacks. The distinctive self-assembled structures were analyzed by TEM and AFM. © 2013 American Chemical Society. Source


Wen J.,Hebei University of Technology | Yuan L.,Key Laboratory of Functional Polymer Materials | Yang Y.,Hebei University of Technology | Liu L.,Nankai University | Zhao H.,Key Laboratory of Functional Polymer Materials
ACS Macro Letters | Year: 2013

Shape amphiphiles with distinct shapes and amphiphilic properties can be used as fundamental building blocks in the fabrication of novel structures and advanced materials. In this research synthesis and self-assembly of monotethered single-chain nanoparticle shape amphiphiles are reported. Poly(2- (dimethylamino)ethyl methacrylate)-block-polystyrene (PDMAEMA-b-PS) was synthesized by two-step reversible addition-fragmentation chain transfer (RAFT) polymerization. The PDMAEMA blocks were intramolecularly cross-linked by 1,4-diiodobutane (DIB) at significantly low concentrations, and PS-tethered PDMAEMA single-chain nanoparticles were prepared. Gel permeation chromatograph, 1H NMR and transmission electron microscopy results all indicated successful synthesis of the structures. The controlled self-assembly of the shape amphiphiles in selective solvents was investigated. Depending on the size of the single-chain nanoparticles, the shape amphiphiles self-assemble into strawberry-like micelles, a structure with single-chain nanoparticles in the corona and PS in the core, or vesicles in aqueous solutions. Similar to the self-assembled structures in aqueous solution, the morphology of the aggregates in methanol changes from micellar structure to vesicular structure with the decrease of the PDMAEMA single-chain nanoparticles size. In cyclohexane, the shape amphiphiles self-assemble into bunchy micelles with single-chain nanoparticles in the cores and linear PS in the coronae. © 2013 American Chemical Society. Source


Chen H.,Tsinghua University | Zheng Y.,Tsinghua University | Tian G.,Dalian Medical University | Tian Y.,Dalian Medical University | And 8 more authors.
Nanoscale Research Letters | Year: 2012

Three types of nanoparticle formulation from biodegradable PLGA-TPGS random copolymer were developed in this research for oral administration of anticancer drugs, which include DMAB-modified PLGA nanoparticles, unmodified PLGA-TPGS nanoparticles and DMAB-modified PLGA-TPGS nanoparticles. Firstly, the PLGA-TPGS random copolymer was synthesized and characterized. DMAB was used to increase retention time at the cell surface, thus increasing the chances of particle uptake and improving oral drug bioavailability. Nanoparticles were found to be of spherical shape with an average particle diameter of around 250 nm. The surface charge of PLGA-TPGS nanoparticles was changed to positive after DMAB modification. The results also showed that the DMAB-modified PLGA-TPGS nanoparticles have significantly higher level of the cellular uptake than that of DMAB-modified PLGA nanoparticles and unmodified PLGA-TPGS nanoparticles. In vitro, cytotoxicity experiment showed advantages of the DMAB-modified PLGA-TPGS nanoparticle formulation over commercial Taxotere® in terms of cytotoxicity against MCF-7 cells. In conclusion, oral chemotherapy by DMAB-modified PLGA-TPGS nanoparticle formulation is an attractive and promising treatment option for patients. © 2010 Chen et al. Source


Li T.,Key Laboratory of Functional Polymer Materials | Li T.,Nankai University | Han L.,Nankai University | Zhu L.,Key Laboratory of Functional Polymer Materials | Zhu L.,Nankai University
Lizi Jiaohuan Yu Xifu/Ion Exchange and Adsorption | Year: 2013

The derivatives of cholic acid, methyl 3α,7α,12α-trimethacryloyl-β-cholancate (CAME3MA) and 2'-methacryloxyloxyethyl-3α,7α, 12α-trimethacryloyloxy-β-cholan-24-ate (CAGE4MA) were prepared. The curing kinetics of CAME3MA and CAGE4MA were studied separately by DSC under non-isothermal conditions and compared with the curing kinetics of CAGE2MA. The DSC curves of the non-isothermal curing of the three curing systems were similar. At the same heating rate, the peak temperature of the DSC curves increased as the number of C=C in the compounds increased. Because of the differences in the molecular structure of CAGE2MA, CAME3MA and CAGE4MA, Ea and InA of the curing systems calculated by Kissinger method were different and the changing trend was CAGE2MA>CAGE4MA>CAME3MA. It was easier for CAGE2MA to form intermolecular hydrogen bonding than the other two systems, so that the Ea of CAGE2MA was the highest among the 3 systems. Source

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