Relationship between morphology structure and composition of polycaprolactone/Poly(ethylene oxide)/Polylactide copolymeric microspheres

A novel tri‐component copolymer, polycaprolactone/poly(ethylene oxide)/polylactide (PCEL) was synthesized. The effect of the chemical composition on physical properties was investigated by using NMR, differential scanning calorimetry (DSC) and X‐ray diffraction. Both the soft segment poly(ethylene oxide) (PEO) and polycaprolactone (PCL) could enhance the mobility of polymer chains and decrease the crystallizability of the copolymers. The polymeric microspheres, which are of interest for drug delivery systems, were prepared using an emulsification‐solvent evaporation technique. By scanning electron microscopy (SEM) and atomic force microscopy (AFM), the surface morphology of the microspheres was studied. It was found that the presence of PEO segment could improve the hydrophilicity of the copolymers and the morphology of the polymeric microspheres could be altered by adjusting the chemical composition. The accumulation of PEO segments on the outer surface of the polymeric microspheres was proven by X‐ray photoelectron spectroscopy (XPS). It had also been proven that the PCL segment could facilitate the movement of PEO segment to the outer surface. Copyright © 2002 John Wiley & Sons, Ltd.     

Reaction-induced microphase separation in epoxy resin containing polystyrene-block-poly(ethylene oxide) alternating multiblock copolymer

Polystyrene-block-poly(ethylene oxide) alternating multiblock copolymer (PS-alt-PEO) was synthesized with the combination of atom transfer radical polymerization (ATRP) and Huisgen 1,3-dipolar cycloaddition (i.e., click chemistry). The copolymer has been characterized by means of Fourier transform infrared spectroscopy (FTIR), ¹H nuclear magnetic resonance spectroscopy (NMR), gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). The PS-alt-PEO alternating multiblock copolymer was incorporated into epoxy resin to investigate the behavior of reaction-induced microphase separation, which has been compared to the case of the thermosets containing PS-b-PEO diblock copolymer. The morphology of epoxy thermosets containing PS-alt-PEO alternating multiblock copolymer were investigated by means of atomic force microscopy (AFM), and small-angle X-ray scattering (SAXS) and the nanostructures were detected in all the thermosetting blends investigated. In marked contrast to the case of the thermosets containing PS-b-PEO diblock copolymer, the thermosets containing PS-alt-PEO multiblock copolymer displayed disordered nanostructures, which have been interpreted on the basis of the restriction of the alternating multiblock topology of the block on the formation of the nanostructures via reaction-induced microphase separation.     

CRYSTALLIZATION AND MELTING OF POLY（ETHYLENE OXIDE） CONFINED IN NANOSTRUCTURED PARTICLES WITH CROSS-LINKED SHELLS OF POLYBUTADIENE

Small fixed aggregates of a poly(ethylene oxide)-block-polybutadiene diblock copolymer(PEO-b-PB)in THFsolution were obtained by adding a selective solvent for PB blocks,followed by cross-linking the PB shells.Themorphologies of the nanostructured particles with a cross-linked shell were investigated by atomic force microscopy andtransmission electron microscopy.The average behaviors of the PEO crystallization and melting confined within thenanostructured particles were studied by using differential scanning calorimetry experiments.For the deeply cross-linkedsample(SCL-1),the crystallization of the PEO blocks was fully confined.The individual nanoparticles only crystallized atvery low crystallization temperatures(T_cs),wherein the homogenous primary nucleation determined the overallcrystallization rate.For the lightly cross-linked sample(SCL-2),the confinement effect was T_c dependent.At T_c(?)42℃,thecrystallization and melting behaviors of SCL-2 were similar to those of the pure PEO-b-PB diblock copolymer.At T_c>42℃,SCL-2 could form PEO lamellae thicker than those of the pure PEO-b-PB crystallized at the same T_c.     

Synthesis and characterization of nano Ag end capped L-cysteine bridged diblock copolymer

The target of the present investigation is synthesis and characterization of an amphiphilic diblock copolymer with antibacterial property. Ring opening polymerization (ROP) of ε-caprolactone (CL) and tetrahydrofuran (THF) was carried out under inert atmosphere by using L-cysteine as a bridging agent in the presence of stannous octoate (SO) as a catalyst. The nano silver end capped diblock copolymer was synthesized by in situ method. Thus obtained nano silver end capped L-cysteine bridged diblock copolymer was characterized by various analytical methods like Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, circular dichroism (CD), fluorescence spectroscopy, gel permeation chromatography (GPC), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM) and zeta potential. The antimicrobial property of the nano silver end capped diblock copolymer against e-coli was tested.     

Binary blends based on poly(vinyl chloride) and multi-block copolymers containing poly(ϵ-caprolactone) and poly(ethylene glycol) segments

Binary blends based on poly(vinyl chloride) (PVC) were prepared both by casting from tetrahydrofuran (THF) and by mixing in the melt form, in a discontinuous mixer, PVC and multi-block copolymers containing poly(ϵ-caprolactone) (PCDT) and poly(ethylene glycol) (PEG) segments. PCDT-PEG copolymers were synthesized using a polycondensation reaction where the α,ω-bis-chloroformate of an oligomeric poly(ϵ-caprolactone) diol terminated (PCDT) and oligomeric PEG were employed as macromonomers. For comparison purposes, blends PVC with starting oligomers as well as with mixtures containing a typical low molecular plasticizer, dioctylphthalate (DOP), were also prepared. The copolymer miscibility was studied by differential scanning calorimetry (DSC) and FT-IR spectroscopy. The blend morphology was investigated by polarized light microscopy (PLM). A higher miscibility with PVC was observed for copolymers compared to PEG.     

Cylindrical micelles from the aqueous self-assembly of an amphiphilic poly(ethylene oxide)-b-poly(ferrocenylsilane) (PEO-b-PFS) block copolymer with a metallo-supramolecular linker at the block junction

A supramolecular AB diblock copolymer has been prepared by the sequential self-assembly of terpyridine end-functionalized polymer blocks by using Ru(III)/Ru(II) chemistry. By this synthetic strategy a hydrophobic poly(ferrocenylsilane) (PFS) was attached to a hydrophilic poly(ethylene oxide) (PEO) block to give an amphiphilic metallo-supramolecular diblock copolymer (PEO/PFS block ratio 6:1). This compound was used to form micelles in water that were characterized by a combination of dynamic and static light scattering, transmission electron microscopy, and atomic force microscopy. These complementary techniques showed that the copolymers investigated form rod-like micelles in water; the micelles have a constant diameter but are rather polydisperse in length, and light scattering measurements indicate that they are flexible. Crystallization of the PFS in these micelles was observed by differential scanning calorimetry, and is thought to be the key behind the formation of rod-like structures. The cylindrical micelles can be cleaved into smaller rods whenever the temperature of the solution is increased or they are exposed to ultrasound.     

Annealing effect on performance and morphology of photovoltaic devices based on poly(3‐hexylthiophene)‐b‐poly(ethylene oxide)

Novel block copolymers, poly(3‐hexylthiophene)‐b‐poly(ethylene oxide) (P3HT‐b‐PEO) were synthesized via Suzuki coupling reaction of P3HT and PEO homopolymers. The copolymers were characterized by NMR, gel permeation chromatography, differential scanning calorimeter, and UV–vis measurements. A series of devices based on the block copolymers with a fullerene derivative were evaluated after thermal or solvent annealing. The device using P3HT‐b‐PEO showed higher efficiency than using P3HT blend after thermal annealing. Phase‐separated structures in the thin films of block copolymer blends were investigated by atomic force microscopy to clarify the relationship between morphologies constructed by annealing and the device performance. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Iodine-transfer polymerization and CuAAC “click” chemistry: A versatile approach toward poly(vinylidene fluoride)-based amphiphilic triblock terpolymers

This study presents the synthesis and properties of linear PVDF-based amphiphilic triblock terpolymers with PS and PEO, [PVDF-b-PS-b-PEO], by adopting a procedure that involves: (a) iodine-transfer polymerization (ITP) of VDF with 1-iodoperfluorohexane (C₆F₁₃I) serving as chain-transfer agent (CTA) to afford C₆F₁₃-PVDF-I, (b) ITP of styrene with the C₆F₁₃-PVDF-I macromolecular-CTA to obtain C₆F₁₃-PVDF-b-PS-I diblock copolymer, (c) end-group exchange from iodo- to azido-group by nucleophilic substitution reaction with NaN_3, and (d) copper-catalyzed azide-alkyne cycloaddition (CuAAC) with alkyne-terminated PEO to achieve C₆F₁₃-PVDF-b-PS-b-PEO triblock terpolymers. The ¹H and ¹⁹F NMR spectroscopy confirmed the presence of all blocks, while gel permeation chromatography traces showed the living nature of ITP technique. The self-assembly of these terpolymers was investigated in films (atomic force microscopy and DSC), as well as in aqueous and organic solvents (DLS). The analysis of crystalline phases based on the FTIR spectroscopy indicated the conversion of PVDF α-phase into α + β-phases and β + γ-phases upon the incorporation of PS and PEO blocks, respectively. The synthesized amphiphilic copolymers were evaluated (fluorescence spectroscopy) as carriers of small hydrophobic molecules in water. © 2019 Wiley Periodicals, Inc. J. Polym. Sci. 2020 , 58, 163–171     

核磁共振谱研究PAA-F108-PAA 嵌段共聚物的胶束化行为

采用原子转移自由基聚合伴随水解的方法合成了聚丙烯酸-聚醚嵌段共聚物(PAA-F108-PAA), 并通过氢核磁共振波谱和二维核Overhauser效应谱(2D NOE)研究了温度、 羧酸基团中和度(α)及盐浓度对PAA-F108-PAA嵌段共聚物在水溶液中胶束化行为的影响. 结果表明, PAA-F108-PAA分子的临界胶束化温度受α影响较小, 受盐的种类和浓度影响较大. 当α=0.14(0.01 mol/L KCl)时, 在6 ℃条件下, PAA-F108-PAA分子处于塌缩状态, 而在60 ℃条件下, 聚氧化丙烯(PPO)链段发生疏水聚集形成胶束的核, PAA链段与PEO链段相互作用形成胶束的壳; 当α=0.80(0.01 mol/L KCl)时, 在6 ℃条件下, PAA-F108-PAA分子处于相对伸展状态, 而在60 ℃条件下, PPO链段仍发生疏水聚集形成胶束的核, PEO与PAA彼此分离形成胶束的壳. 增加KCl的浓度至1 mol/L, PAA-F108-PAA分子的临界胶束化温度显著降低, KCl对PPO和PEO链段都表现出脱水作用. 但KI的浓度增加至1 mol/L时, PAA-F108-PAA分子的临界胶束化温度仅略微增加, KI对PPO链段表现出脱水作用, 而对PEO链段表现出增溶作用.     

Langmuir monolayer and Langmuir–Blodgett films of amphiphilic triblock copolymers with water-soluble middle block

Langmuir monolayers and Langmuir–Blodgett (LB) film morphology of amphiphilic triblock copolymers are studied using surface pressure-area measurements and atomic force microscopy (AFM), respectively. The triblock copolymers are composed of long water-soluble poly(ethylene oxide) (PEO) chains as middle block with very short poly(perfluorohexylethyl methacrylate) (PFMA) end blocks. The surface pressure-area isotherms show phase transitions in the brush regime. This phase transition is due to a rearrangement of PFMA block at the air–water interface. It becomes more significant with increasing PFMA content in the copolymer. LB films transferred at low surface pressures from the air–water interface to hydrophilic silicon substrates show surface micelles in the size range of 50–100 nm. A typical crystalline morphology of the corresponding PEO homopolymer is observed in LB films of copolymers with very short PFMA blocks, transferred in the brush region at high surface pressure. This crystallization is hindered with increasing PFMA content in the copolymer.     

Mixed Co/Fe oxide nanoparticles in block copolymer micelles

Small iron oxide and Co-doped iron oxide nanoparticles (NPs) were synthesized in a commercial amphiphilic block copolymer, poly(ethylene oxide)-b-poly(methacrylic acid) (PEO 68-b-PMAA8), in aqueous solutions. The structure and composition of the micelles containing guest molecules (metal salts) or NPs (metal oxides) were studied using transmission electron microscopy, dynamic light scattering, X-ray photoelectron spectroscopy, and X-ray powder diffraction. The enlarged micelle cores after incorporation of metal salts are believed to be formed by both PMAA blocks containing metal species and penetrating PEO chains. The nanoparticle size distributions in PEO 68-b-PMAA8 were determined using small-angle X-ray scattering (SAXS) in bulk. Two independent methods for SAXS data interpretation for comprehensive analysis of volume distributions of metal oxide NPs showed presence of both small particles and larger entities containing metal species which are ascribed to organization of block copolymer micelles in bulk. The magnetometry measurements revealed that the NPs are superparamagnetic and their characteristics depend on the method of the NP synthesis. The important advantage of the PEO 68-b-PMAA8 stabilized magnetic nanoparticles described in this paper is their remarkable solubility and stability in water and buffers.     

Nanostructures and surface dewettability of epoxy thermosets containing hepta(3,3,3-trifluoropropyl) polyhedral oligomeric silsesquioxane-capped poly(ethylene oxide)

Hepta(3,3,3-trifluoropropyl) polyhedral oligomeric silsesquioxane (POSS)-capped poly(ethylene oxide) (PEO) was synthesized via the reaction of hydrosilylation between hepta(3,3,3-trifluoropropyl)hydrosilsesquioxane and allyl-terminated PEO. The POSS-capped PEO was characterized by means of Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy. The organic-inorganic amphiphile was incorporated into epoxy resin to prepare the organic-inorganic nanostructured thermosetting composites. The morphology of the hybrid composites was characterized with field emission scanning electronic microscopy (FESEM) and transmission electronic microscopy (TEM). The formation of nanostructures was addressed on the basis of miscibility and phase behavior of the sub-components (viz. POSS and PEO chains) of the organic-inorganic amphiphile with epoxy after and before curing reaction. The static contact angle measurements indicate that the organic-inorganic nanocomposites displayed a significant enhancement in surface hydrophobicity as well as reduction in surface free energy. The atomic force microscopy (AFM) showed that there is significant migration of the POSS moiety at the surface of the thermosets. The improvement in surface properties was ascribed to the enrichment of the POSS moiety on the surface of the nanostructured thermosets, which was evidenced by X-ray photoelectron spectroscopy (XPS).     

Effect of Surface‐Hydroxylated CdS Nanoparticles on the Morphological Transformation of Polystyrene‐block‐Poly(ethylene oxide) Thin Films

Summary: Polystyrene‐block‐poly(ethylene oxide) (SEO) block copolymer thin films, in which CdS clusters have been sequestered into the PEO domains of the SEO block copolymers, are found to induce the morphological transformation of PEO from cylinders to spheres, as shown by using atomic force microscopy (AFM), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). This transformation is caused by the presence of hydrogen‐bonding interactions between surface‐hydroxylated CdS and PEO, as confirmed by nuclear magnetic resonance (NMR) studies.

Morphological transformation of PEO cylinders into CdS/PEO spheres by hydrogen‐bonding interactions between surface‐hydroxylated CdS and PEO.     

Nanoscale patterning of two metals on silicon surfaces using an ABC triblock copolymer template

Patterning technologically important semiconductor interfaces with nanoscale metal films is important for applications such as metallic interconnects and sensing applications. Self-assembling block copolymer templates are utilized to pattern an aqueous metal reduction reaction, galvanic displacement, on silicon surfaces. Utilization of a triblock copolymer monolayer film, polystyrene-block-poly(2-vinylpyridine)-block-poly(ethylene oxide) (PS-b-P2VP-b-PEO), with two blocks capable of selective transport of different metal complexes to the surface (PEO and P2VP), allows for chemical discrimination and nanoscale patterning. Different regions of the self-assembled structure discriminate between metal complexes at the silicon surface, at which time they undergo the spontaneous reaction at the interface. Gold deposition from gold(III) compounds such as HAuCl4(aq) in the presence of hydrofluoric acid mirrors the parent block copolymer core structure, whereas silver deposition from Ag(I) salts such as AgNO3(aq) does the opposite, localizing exclusively under the corona. By carrying out gold deposition first and silver second, sub-100-nm gold features surrounded by silver films can be produced. The chemical selectivity was extended to other metals, including copper, palladium, and platinum. The interfaces were characterized by a variety of methods, including scanning electron microscopy, scanning Auger microscopy, X-ray photoelectron spectroscopy, and atomic force microscopy.     

温敏梳状嵌段共聚物对PS微球阻抗蛋白吸附作用的研究

采用可逆加成断裂链转移聚合(RAFT)方法和大分子单体技术,制备了温敏性聚N-异丙基丙烯酰胺(PNIPAM)-聚乙烯基吡咯烷酮(PVP)与PNIPAM-聚氧化乙烯(PEO)梳状嵌段共聚物,这些共聚物具有PVP或PEO支链.以溶菌酶为蛋白模型研究了所得共聚物对聚苯乙烯(PS)微球表面蛋白吸附的抑制作用.通过絮凝实验、激光散射法表观粒径测定、电泳迁移率测定及蛋白吸附量的定量数据比较了不同梳状结构的抗蛋白吸附效果.结果表明,预吸附梳状嵌段共聚物可有效阻抗蛋白吸附,亲水支链增加阻抗性能提高,即使环境温度高于PNIPAM的相转变温度也能阻抗蛋白吸附.透射电镜和共聚物胶体粒径测试表明,梳状嵌段共聚物阻抗蛋白吸附的机制是预吸附后PVP或PEO亲水支链在微球表面形成了阻隔层.通过PS微球的变温絮凝实验可评价预吸附聚合物的抗蛋白吸附性能,快速获得定性结果.     

Composites comprising CdS nanoparticles and poly(ethylene oxide): optical properties and influence of the nanofiller content on the thermal behaviour of the host matrix

Tri-n-octylphosphine oxide-capped CdS nanoparticles were synthesized with the cadmium(II) complex of thiocarbohydrazide as a precursor. Nanocomposites were prepared by mixing a toluene solution of poly(ethylene oxide) (PEO) and the obtained CdS nanoparticles. The ultraviolet-visible spectroscopy measurements showed a blue shift of the onset of optical absorption, compared to bulk CdS, which confirmed the presence of nanostructured CdS. A transmission electron microscopy micrograph of the nanocomposite depicted that the nanoparticles are well dispersed in the PEO matrix. Differential scanning calorimetry analysis revealed hindered crystallization of PEO in the presence of CdS nanoparticles. It was also found that increasing the nanoparticle content led to the shift of the onset of decomposition of the matrix towards higher temperature.     

Nanostructured thermoset epoxy resin templated by an amphiphilic poly(ethylene oxide)‐block‐poly(dimethylsiloxane) diblock copolymer

An amphiphilic poly(ethylene oxide)‐block‐poly(dimethylsiloxane) (PEO–PDMS) diblock copolymer was used to template a bisphenol A type epoxy resin (ER); nanostructured thermoset blends of ER and PEO–PDMS were prepared with 4,4′‐methylenedianiline (MDA) as the curing agent. The phase behavior, crystallization, hydrogen‐bonding interactions, and nanoscale structures were investigated with differential scanning calorimetry, Fourier transform infrared spectroscopy, transmission electron microscopy, and small‐angle X‐ray scattering. The uncured ER was miscible with the poly(ethylene oxide) block of PEO–PDMS, and the uncured blends were not macroscopically phase‐separated. Macroscopic phase separation took place in the MDA‐cured ER/PEO–PDMS blends containing 60–80 wt % PEO–PDMS diblock copolymer. However, the composition‐dependent nanostructures were formed in the cured blends with 10–50 wt % PEO–PDMS, which did not show macroscopic phase separation. The poly(dimethylsiloxane) microdomains with sizes of 10–20 nm were dispersed in a continuous ER‐rich phase; the average distance between the neighboring microdomains was in the range of 20–50 nm. The miscibility between the cured ER and the poly(ethylene oxide) block of PEO–PDMS was ascribed to the favorable hydrogen‐bonding interaction. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3042–3052, 2006     

酶促开环聚合合成双亲性H型嵌段共聚物及其自组装

通过固定化酶Novozyme435（NV435）催化聚乙二醇（PEG）开环聚合己内酯（CL）得到端基带有羟基的ABA型三嵌段聚合物,用2,2-二氯代乙酰氯将聚合物的端羟基功能化形成H型大分子引发剂,在CuCl／HMTETA体系中引发4-乙烯基吡啶（4VP）进行原子转移自由基聚合反应（ATRP）,得到了具有两亲性的H型五嵌段聚合物（PVP）2-b—PCL-b．PEG-PCL-（PVP）2,用红外光谱（FT IR）,核磁共振（^1H NMR）,凝胶渗透色谱（GPC）对其结构与分子量及其分子量分布进行了表征,结果表明：H型五嵌段聚合物分子量46121g／mol,分子量分布1．30．并利用动态光散射（DLS）和原子力显微镜（AFM）对聚合物在水溶液中的自组装行为进行了研究,H型嵌段聚合物的胶束呈球形结构,平均直径为70nm左右．     

Effect of chain lengths of PEO-PPO-PEO on small unilamellar liposome morphology and stability: an AFM investigation

The morphology and stability of small unilamellar egg yolk phosphatidylcholine (EggPC) liposomes modified with the Pluronic copolymer (poly (oxyethylene)-poly (oxypropylene)-poly (oxyethylene) (PEO-PPO-PEO)) with different compositions on mica surface have been investigated using atomic force microscopy. Morphology studies reveal significant morphological changes of liposomes upon incorporating the Pluronic copolymer. Bilayers are observed for Pluronic with small hydrophilic (PEO) chain lengths such as L81 [(PEO)2(PPO)40(PEO)2] and L121 [(PEO)4(PPO)60(PEO)4]; bilayer and vesicle coexistence is observed for P85 [(PEO)26(PPO)39.5(PEO)26] and F87 [(PEO)61.1(PPO)39.7(PEO)61.1]; and stable vesicles are observed for F88 [(PEO)103.5(PPO)39.2(PEO)103.5], F127 [(PEO)100(PPO)65(PEO)100], and F108 [(PEO)132.6(PPO)50.3(PEO)132.6]. The micromechanical properties of Pluronic-modified EggPC vesicles were studied by analyzing AFM approaching force curve. The bending modulus (k(c)) of the Pluronic-modified EggPC vesicles increased several-fold compared with that of the pure EggPC vesicles. The significant difference is due to the enhanced rigidity of the EggPC vesicles as a result of the incorporation of PPO molecules and PEO chains. Based on the analysis of onset point by AFM and diameters of vesicles by light scattering, it was concluded that the favorable model to describe the polymer-bilayer interaction is the membrane-spanning model.     

Functionalized nanoporous thin films from metallo-supramolecular diblock copolymers

A polystyrene-[Ni(2+)]-poly(ethylene oxide) metallo-supramolecular block copolymer (PS-[Ni(2+)]-PEO), where -[ is a terpyridine, is used to create nanoporous thin films with free terpyridine ligands homogenously distributed on the pore walls. The PS-[Ni(2+)]-PEO block copolymer is synthesized by a two step assembly process, and is then self-assembled into a thin film in order to obtain PEO cylinders oriented perpendicularly to the film surface. The supramolecular junction is opened by exposing the film to an excess of a competing ligand, and the free PEO block is then rinsed away by a selective solvent. The presence of the terpyridines on the pore walls is evidenced by fluorescence spectroscopy after formation of a fluorescent complex with an europium salt.