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Phase Behavior of Sphere-Forming Triblock Copolymers in Films  [PDF]
Hong-Ge Tan, Qing-Gong Song, Xin-Huan Yang, Ya-Jing Deng
Open Journal of Applied Sciences (OJAppS) , 2012, DOI: 10.4236/ojapps.2012.23023
Abstract: The self-assembly of sphere-forming triblock copolymers confined between two thin homogeneous surfaces is investigated based on mean-field dynamic density functional theory. The morphologies deviating from the bulk sphere-forming phase are revealed, including cylinders oriented perpendicular to the surface, cylinders oriented parallel to the surface, perforated lamellae and lamellae by varying film thickness and surface field strength. The phase diagram of surface reconstruction is also constructed. By comparing the present phase diagram with the other relevant phase diagram for the cylinder-forming triblock copolymer film, the difference between the sphere-forming and the cylinder-forming triblock copolymer thin film is discussed.
Anionic Micelle-Forming Triblock Copolymers as Nanocontainers for Doxorubicin  [cached]
Kunitskaya L.R.,Stoika R.S.,Shlyakhtina Ye.A.,Zheltonozhskaya T.B.
Proceedings of the International Conference Nanomaterials : Applications and Properties , 2012,
Abstract: The anionic derivative of asymmetric triblock copolymer containing biocompatible chemically complementary polyacrylamide and poly(ethylene oxide) (PAAm-b-PEO-b-PAAm) was obtained. The micellization of the initial (TBC) and modified (TBC-COOH) copolymer samples in aqueous solution were investigated. Practically the same values of the critical micellization concentration and the Gibbs free micellization energy for both TBCs were found. The anticancer effects of the doxorubicin (DOX)-loaded micelles of the initial and modified triblock copolymers were studied on the tumor cells of human T-leukemia of Jurkat line, transformed leukemia of L929 line and mouse lymphatic leukemia of L1210 line. The fact of high efficacy of DOX/TBC and DOX/TBC-COOH compositions in compare with pure DOX was determined and discussed.
Effect of polymer concentration and length of hydrophobic end block on the unimer-micelle transition broadness in amphiphilic ABA symmetric triblock copolymer solutions  [PDF]
X. -G. Han,Y. -H. Ma,S. -L. Ouyang
Physics , 2013, DOI: 10.5488/CMP.16.33601
Abstract: The effects of the length of each hydrophobic end block N_{st} and polymer concentration \bar{\phi}_{P} on the transition broadness in amphiphilic ABA symmetric triblock copolymer solutions are studied using the self-consistent field lattice model. When the system is cooled, micelles are observed, i.e.,the homogenous solution (unimer)-micelle transition occurs. When N_{st} is increased, at fixed \bar{\phi}_{P}, micelles occur at higher temperature, and the temperature-dependent range of micellar aggregation and half-width of specific heat peak for unimer-micelle transition increase monotonously. Compared with associative polymers, it is found that the magnitude of the transition broadness is determined by the ratio of hydrophobic to hydrophilic blocks, instead of chain length. When \bar{\phi}_{P} is decreased, given a large N_{st}, the temperature-dependent range of micellar aggregation and half-width of specific heat peak initially decease, and then remain nearly constant. It is shown that the transition broadness is concerned with the changes of the relative magnitudes of the eductions of nonstickers and solvents from micellar cores.
Bioconjugated Pluronic Triblock-Copolymer Micelle-Encapsulated Quantum Dots for Targeted Imaging of Cancer: In Vitro and In Vivo Studies  [cached]
Liwei Liu, Ken-Tye Yong, Indrajit Roy, Wing-Cheung Law, Ling Ye, Jianwei Liu, Jing Liu, Rajiv Kumar, Xihe Zhang, Paras N. Prasad
Theranostics , 2012,
Abstract: Early in this study, CdTe/ZnS core/shell quantum dots (QDs) were encapsulated in carboxylated Pluronic F127 triblock polymeric micelle, to preserve the optical and colloidal stability of QDs in biological fluids. Folic acid (FA) was then conjugated to the surface of QDs for the targeted delivery of the QD formulation to the tumor site, by exploiting the overexpressed FA receptors (FARs) on the tumor cells. Cytotoxicity study demonstrated that the QD formulation has negligible in vitro toxicity. The in vitro study showed that the bioconjugated micelle-encapsulated QDs, but not the unconjugated QDs, were able to efficiently label Panc-1 cancer cells. In vivo imaging study showed that bioconjugated QDs were able to target tumor site after intravenous injection of the formulation in tumor-bearing mice.
Synthesis and micellization behavior of stimuli-responsive polypeptide hybrid triblock copolymer
JingYi Rao,ZhiYuan Zhu,ShiYong Liu
Chinese Science Bulletin , 2009, DOI: 10.1007/s11434-009-0244-x
Abstract: Polypeptide hybrid triblock copolymer, poly(L-glutamic acid)-b-poly(propylene oxide)-b-poly (L-glutamic acid) (PLGA-b-PPO-b-PLGA), was synthesized by the ring-opening polymerization of benzyl-L-glutamic N-carboxyanhydride (BLG-NCA) using poly(propylene glycol) bis(2-aminopropyl ether) as initiator, followed by the subsequent deprotection step. The obtained double hydrophilic triblock copolymer exhibits “schizophrenic” micellization behavior in aqueous solution upon dually playing with solution pH and temperature. The multi-responsive micellization behavior of this polypeptide hybrid triblock copolymer has been thoroughly investigated by 1H NMR, laser light scattering (LLS), temperature-dependent optical transmittance, and circular dichroism spectroscopy (CD).
Synthesis and micellization behavior of stimuli-responsive polypeptide hybrid triblock copolymer

JingYi Rao,ZhiYuan Zhu,ShiYong Liu,

科学通报(英文版) , 2009,
Abstract: Polypeptide hybrid triblock copolymer, poly(L-glutamic acid)-b-poly(propylene oxide)-b-poly (L-glutamic acid) (PLGA-b-PPO-b-PLGA), was synthesized by the ring-opening polymerization of benzyl-L-glutamic N-carboxyanhydride (BLG-NCA) using poly(propylene glycol) bis(2-aminopropyl ether) as initiator, followed by the subsequent deprotection step. The obtained double hydrophilic triblock copolymer exhibits “schizophrenic” micellization behavior in aqueous solution upon dually playing with solution pH and temperature. The multi-responsive micellization behavior of this polypeptide hybrid triblock copolymer has been thoroughly investigated by 1H NMR, laser light scattering (LLS), temperature-dependent optical transmittance, and circular dichroism spectroscopy (CD). Supported by the National Natural Science Foundation of China (Grant Nos. 20534020, 20674079, and 20874092)
Poly(ethylene glycol)-poly(tetrahydrofuran)-poly(ethylene glycol) triblock copolymer : Synthesis, crystallization behavior and novel morphology
W. W. Fan,X. D. Fan,W. Tian,X. Q. Liao
eXPRESS Polymer Letters , 2013, DOI: 10.3144/expresspolymlett.2013.39
Abstract: Poly(ethylene glycol)-poly(tetrahydrofuran)-poly(ethylene glycol) (PEG-PTHF-PEG) triblock copolymer was synthesized by ring-opening polymerization of ethylene oxide using sodium alcoholate of PTHF as the macroinitiator. Its crystallization behavior and formation mechanisms of different crystal structures were studied. The study showed that the molecular weight of PEG-PTHF-PEG exhibited a significant effect on its crystallization: that is, with the increase of the copolymer’s molecular weight, the crystallizability of PTHF blocks decreased gradually, which led to the transition of copolymer from crystalline-crystalline to crystalline-amorphous. By adjusting the total molecular weight of triblock copolymer, the crystallization process can be effectively controlled, and as a result, different spherulite structures were obtained. Particularly, when PTHF blocks became amorphous, novel double concentric spherulites were observed. The morphological structures were studied by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), polarized optical microscopy (POM), and its crystalline process was investigated.
Experimental Studies of the Jamming Behaviour of Triblock Copolymer Solutions and Triblock Copolymer-Anionic Surfactant Mixture  [PDF]
Rajib Basak,Nabaneeta Mukhopadhyay,Ranjini Bandyopadhyay
Physics , 2010,
Abstract: Photon correlation spectroscopy and rheological measurements are performed to investigate the microscopic dynamics and mechanical responses of aqueous solutions of triblock copolymers and aqueous mixtures of triblock copolymers and anionic surfactants. Increasing the concentration of triblock copolymers results in a sharp increase in the magnitude of the complex moduli characterising the samples. This is understood in terms of the changes in the aggregation and packing behaviours of the copolymers and the constraints imposed upon their dynamics due to increased close packing. The addition of suitable quantities of an anionic surfactant to a strongly elastic copolymer solution results in a decrease in the complex moduli of the samples by several decades. It is argued that the shape anisotropy and size polydispersity of the micelles comprising mixtures cause dramatic changes in the packing behaviour, resulting in sample unjamming and the observed decrease in complex moduli. Finally, a phase diagram is constructed in the temperature-surfactant concentration plane to summarise the jamming-unjamming behaviour of aggregates constituting triblock copolymer-anionic surfactant mixtures.
Diblock/Triblock Structural Transition and Sol-Gel Transition of Peptide/PEG Diblock Copolymer Having a Terminal Terpyridine Group Induced by Complexation with Metal Ion  [PDF]
Satoshi Tanimoto,Yasushi Nakamura,Hitoshi Yamaoka,Yoshitsugu Hirokawa
International Journal of Polymer Science , 2010, DOI: 10.1155/2010/294790
Abstract: Terpyridine-polyethyleneglycol-block-polyleucine block copolymer (tpy-PEG-PLeu) was synthesized by a ring-opening polymerization of L-leucine -carboxyanhydride. The copolymer complexed with ion and its aqueous solution showed a purple color as a result of the complexation. This complexation caused the diblock/triblock structural transition of the copolymer. The change of the aggregation behavior caused by the structural transition was observed by a dynamic light scattering apparatus. The diblock tpy-PEG-PLeu copolymer formed a micelle in the aqueous solution. On the other hand, the triblock-type copolymer, after the complexation, formed the micelle structures and huge aggregates, which is considered to be a network structure. The complexation of the diblock tpy-PEG-PLeu copolymer with Fe ion is consequently considered to be a trigger of the gelation. 1. Introduction The chloroform solution of the ABA-type triblock copolymer which consists of a polyleucine (PLeu) chain as the A segment and a polyethylene glycol (PEG) as the B segment has been reported to show a thermoresponsive sol-gel transition [1]. This sol-gel transition was not observed on the solution system of AB-type block copolymer having the same components. These results were attributed to the difference in the aggregation behavior between the AB-type and the ABA-type block copolymers. Since the two polyleucine segments of the triblock copolymer behave as the junction point due to the hydrophobic interaction to string the many copolymers together, the ABA-type triblock copolymer in the solution can form the network structure, resulting in the formation of the gel. On the other hand, the AB-type diblock copolymer could not form the gel like the ABA-type [2]. On the basis of the facts mentioned above, we would like to propose the novel sol-gel transition system made up of the AB-type diblock copolymer as a basic material. In this study, the terminal functionalized AB-type diblock copolymer consisting of PEG and polyleucine segments was synthesized. A terpyridine, which was known to make a complex with metal ion [3–6], was employed as a terminal functional group. The terminal functionalized AB-type diblock copolymer consisting of PEG and polyleucine segments and having the terpyridine group (tpy) at the end of PEG is, hereafter, referred to as tpy-PEG-PLeu. When the divalent metal ion is added to the solution of the tpy-PEG-PLeu, the metal ion should behave as the terminal connector of the diblock copolymer and make the tpy-PEG-PLeu into the ABA-type triblock copolymer. Therefore, the addition of
Self-consistent field theoretic simulations of amphiphilic triblock copolymer solutions: Polymer concentration and chain length effects  [PDF]
X. -G. Han,Y. -H. Ma
Physics , 2014, DOI: 10.5488/CMP.17.23604
Abstract: Using the self-consistent field lattice model, polymer concentration $\bar{\phi}_{{P}}$ and chain length $N$ (keeping the length ratio of hydrophobic to hydrophilic blocks constant) the effects on temperature-dependent behavior of micelles are studied, in amphiphilic symmetric ABA triblock copolymer solutions. When chain length is increased, at fixed $\bar{\phi}_{{P}}$, micelles occur at higher temperature. The variations of average volume fraction of stickers $\bar{\phi}_\textrm{co}^\textrm{s}$ and the lattice site numbers $N_\textrm{co}^\textrm{ls}$ at the micellar cores with temperature are dependent on $N$ and $\bar{\phi}_{{P}}$, which demonstrates that the aggregation of micelles depends on $N$ and $\bar{\phi}_{{P}}$. Moreover, when $\bar{\phi}_{{P}}$ is increased, firstly a peak appears on the curve of specific heat $C_V$ for unimer-micelle transition, and then in addition a primary peak, the secondary peak, which results from the remicellization, is observed on the curve of $C_V$. For a long chain, in intermediate and high concentration regimes, the shape of specific heat peak markedly changes, and the peak tends to be a more broad peak. Finally, the aggregation behavior of micelles is explained by the aggregation way of amphiphilic triblock copolymer. The obtained results are helpful in understanding the micellar aggregation process.
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