Biodegradable Interpolyelectrolyte Complexes Based on Methoxy Poly(ethylene glycol)-b-poly(alpha,L-glutamic acid) and Chitosan

We synthesized methoxy poly(ethylene glycol)-b-poly(alpha,L-glutamic acid) (mPEGGA) diblock copolymer by ring-opening polymerization of N-carboxy anhydride of gamma-benzyl-L-glutamate (NCA) using amino-terminated methoxy polyethylene glycol (mPEG) as macroinitiator. Polyelectrolyte complexation between mPEGGA as neutral-block-polyanion and chitosan (CS) as polycation has been scrutinized in aqueous solution as well as in the solid state.

The influence of variant PE-b-PEO segments on physical properties of LLDPE graft copolymers

A method was adopted to fix a series of polymers of PE-b-PEO with different PEO/PE segments on the chains of LLDPE. Maleic anhydride (MA) reacting with hydroxyl group of PE-b-PEO (mPE-b-PEO) was used as the intermediate. The structures of intermediates and graft copolymers were approved by H-1 NMR and FTIR. XPS analysis revealed a great amount of oxygen on the surface of grafted copolymers although the end group of PEO was fixed on the LLDPE chains through MA. Thermal properties of the graft copolymers as determined by differential scanning calorimetry (DSC) showed that PE segments in the grafted monomers could promote the heterogeneous nucleation of the polymer, increase T., and crystal growth rate.

Guest inducing p-sulfonatocalix[4] arene into three-dimensional capsule architecture and a mixed A-B double layer framework

The reactions of sodium p-sulfonatocalix[4]arene (Na5L) and terbium/europium(III) chloride in the presence of pyrazine-N,N'-dioxide (PNNO) in aqueous solutions gave the crystalline complexes 1 and 2. Both structures contain molecular capsules of p-sulfonatocalix[4] arene with PNNO as guest molecules in the cavity of the calix[4]arenes. The molecular capsules are connected through sodium and terbium (or europium) centers forming a three-dimensional framework.

Crystallization and morphology of poly(ethylene oxide-b-lactide) crystalline-crystalline diblock copolymers

The crystallization behaviors and morphology of asymmetric crystalline-crystalline diblock copolymers poly(ethylene oxide-lactide) (PEO-b-PLLA) were investigated using differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD), and microscopic techniques (polarized optical microscopy (POM) and atomic force microscopy (AFM)). Both blocks of PEO5-b-PLLA(16) can be crystallized, which was confirmed by WAXD, while PEO block in PEO5-b-PLLA(30) is difficult to crystallize because of the confinement induced by the high glass transition temperature and crystallization of PLLA block with the microphase separation of the block copolymer.

Molecular weight dependence of phase Behavior of PEO/P(EO-b-DMS) blends: Application of Sanchez-Lacombe lattice fluid theory

Molecular weight dependence of phase separation behavior of the Poly (ethylene oxide) (PEO)/Poly(ethylene oxide-block-dimethylsiloxane) (P(EO-b-DMS)) blends was investigated by both experimental and theoretical methods. The cloud point curves of PEO/P(EO-b-DMS) blends were obtained by turbidity method. Based on Sanchez-Lacombe lattice fluid theory (SLLFT), the adjustable parameter, epsilon*(12)/k (quantifying the interaction energy between different components), was evaluated by fitting the experimental data in phase diagrams. To calculate the spinodals, binodals, and the volume changes of mixing for these blends, three modified combining rules of the scaling parameters for the block copolymer were introduced.

The phase behavior of comblike block copolymer A(m+1)B(m)/homopolymer A mixtures

The phase behaviors of comblike block copolymer A(m+1)B(m)/homopolymer A mixtures are studied by using the random phase approximation method and real-space self-consistent field theory. From the spinodals of macrophase separation and microphase separation, we can find that the number of graft and the length of the homopolymer A have great effects on the phase behavior of the blend. For a given composition of comblike block copolymer, increasing the number of graft does not change the macrophase separation spinodal curve but decreases the microphase separation region. The addition of a small quantity of long-chain homopolymer A increases the microphase separation of comblike block copolymer/homopolymer A mixture.

Hybridization of poly(4-vinyl pyridine)-b-polystyrene-b-poly(4-vinyl pyridine) aggregates in dioxane/water solution

Self-assembly of binary blends of two triblock copolymers of poly(4-vinyl pyridine)-b-polystyrene-b-poly(4-vinyl pyridine), i.e., P4VP(43)-b-PS260-b-P4VP(43) (P1) and P4VP(43)-b-PS366-b-P4VP(43) (P2), in dioxane/water solution was studied. These two triblock copolymers individually tend to form vesicles (P2) and cylindrical micelles (P1) in dilute solution. It was found that copolymer components in the blend, sample preparation method, and annealing time had significant effect on hybridization aggregate morphology. By increasing P1 content in the copolymer blends, fraction of looped and stretched cylinders increased, while fraction of bilayers decreased. Nearly no bilayer was observed when P1 content was above 85 wt%.

利用MALDI-TOF质谱技术研究MPEG-b-PCL两嵌段共聚物的嵌段长度及嵌段分布

利用基质辅助激光解吸电离飞行时间质谱(MALDI-TOFMS)结合源后分解(PSD)技术对甲氧基封端的聚乙二醇-b-聚己内酯(MPEG-b-PCL)两嵌段共聚物进行了结构分析.根据得到的MALDI-TOFMS谱图和PSD碎片信息清晰地确定了嵌段共聚物的嵌段长度和嵌段分布.结果表明,采用MALDI-TOFMS结合PSD技术研究这类嵌段共聚物链结构非常有效.这为更好地认识和应用这类嵌段共聚物提供了重要的依据,同时也建立了分析这类嵌段共聚物的方法.

温度敏感性PNIPAM-b-PZLL-b-mPEG三嵌段共聚物的合成与自组装研究

通过大分子引发剂引发ε-苄氧羰基-L-赖氨酸-N-羧酸酐(Lys-NCA)开环聚合和大分子缩合的方法合成了聚(N-异丙基丙烯酰胺)-b-聚(ε-苄氧羰基-L-赖氨酸)-b-聚乙二醇单甲醚三嵌段共聚物(PNIPAM-b-PZLL-b-mPEG).用GPC和1H-NMR对其结构进行了表征.用芘荧光探针法证明了该三嵌段聚合物形成胶束的性质并测定了临界胶束浓度(CMC).动态光散射(DLS)研究表明,在固定PNIPAM-b-PZLL链段长度的情况下,mPEG分子量为2000时,胶束在温度高于临界溶解温度(LCST)时发生聚集,mPEG分子量为5000时,胶束在LCST以上没有发生聚集.

PS-b-P4VP/CoSm杂化材料的制备及其磁性能

用溶液相金属盐沉积法在苯乙烯与4-乙烯基吡啶嵌段共聚物(PS-b-P4VP)胶束中制备了平均直径为12 nm的PS-b-P4VP/Co、PS-b-P4VP/CoSm(nCo∶nSm=3.8∶1,13.0∶1)、PS-b-P4VP/Sm纳米粒子。胶束溶液通过高温回流使磁性成核粒子和磁性金属原子的流动能力和扩散能力提高而获得尺寸均一的颗粒。

齐聚[3,2-b]并二噻吩的合成、表征及其在有机薄膜晶体管中的应用

通过Stille偶联反应合成了5,5″-二辛基-2,2′∶5′2″-三联[3,2-b]并二噻吩,并对该化合物的物理化学性质以及真空蒸镀薄膜的结构和形貌进行了详细表征.以这一化合物作为半导体层、采用顶电极结构制备了有机薄膜晶体管,并对薄膜生长基底温度做了优化,发现基底温度为100℃时器件性能最好,迁移率达到0.13 cm2/V.s,开关比为7×103,阈值电压为-19V.

Dendritic Superstructures and Structure Transitions of Asymmetric Poly(L-lactide-b-ethylene oxide) Diblock Copolymer Thin films

The evolution of morphologies of isothermally crystallized thin films with different thicknesses of poly(L-lactide-bethylene oxide) diblock copolymer was observed by optical microscopy (OM) and atomic force microscopy (AFM). Dendritic superstructures stacked with lamellae were investigated in thin films with similar to 200 nm to similar to 400 nm thickness. The lamellar structure was a lozenge- or truncated-lozenge-shaped single crystal of PLLA confirmed by AFM observations. The contour of the dendritic superstructures is hexagonal, and two types of sectors, [110] and [100], can be classified in terms of the chain-folding and crystal growth directions. These phenomena Are due to the interplay of the crystallization of the PLLA block, the microphase separation of the block copolymer, and the effect of the film thickness.

Study of morphology and phase diagram of the H-shaped (AC)B(CA) ternary block copolymers using self-consistent field theory

By using a combinatorial screening method based on the self-consistent field theory (SCFT) for polymer systems, the micro-phase morphologies of the H-shaped (AC)B(CA) ternary block copolymer system are studied in three-dimensional (3D) space. By systematically varying the volume fractions of the components A, B, and C, six triangle phase diagrams of this H-shaped (AC)B(CA) ternary block copolymer system with equal interaction energies among the three components are constructed from the weaker segregation regime to the strong segregation regime, In this study, thirteen 3D micro-phase morphologies for this H-shaped ternary block copolymer system are identified to be stable and seven 3D microphase morphologies are found to be metastable.

Nucleation in A/B/AB blends: Interplay between microphase assembly and macrophase separation

We study the interplay between microphase assembly and macrophase separation in A/B/AB ternary polymer blends by examining the free energy of localized fluctuation structures (micelles or droplets), with emphasis on the thermodynamic relationship between swollen micelles (microemulsion) and the macrophase-separated state, using self-consistent field theory and an extended capillary model. Upon introducing homopolymer B into a micelle-forming binary polymer blend A/AB, micelles can be swollen by B. A small amount of component B (below the A-rich binodal of macrophase coexistence) will not affect the stability of the swollen micelles. A large excess of homopolymer, B, will induce a microemulsion failure and lead to a macrophase separation.