Effects of Hydrophobic Modifications on the Solution Self-Assembly of P(DMAEMA-co-QDMAEMA)-b-POEGMA Random Diblock Copolymers
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In this work, the synthesis and the aqueous solution self-assembly behavior of novel partially hydrophobically modified poly(2-(dimethylamino) ethyl methacrylate)-b-poly(oligo(ethylelene glycol) methyl ether methacrylatetabel) pH and temperature responsive random diblock copolymers (P(DMAEMA-co-Q6/12DMAEMA)-b-POEGMA), are reported. The chemical modifications were accomplished via quaternization with 1-iodohexane (Q6) and 1-iodododecane (Q12) and confirmed by 1H-NMR spectroscopy. The successful synthesis of PDMAEMA-b-POEGMA precursor block copolymers was conducted by RAFT polymerization. The partial chemical modification of the diblocks resulted in the permanent attachment of long alkyl chains on the amine groups of the PDMAEMA block and the presence of tertiary and quaternary amines randomly distributed within the PDMAEMA block. Light scattering techniques confirmed that the increased hydrophobic character results in the formation of nanoaggregates of high mass and tunable pH and temperature response. The characteristics of the aggregates are also affected by the aqueous solution preparation protocol, the nature of the quaternizing agent and the quaternization degree. The incorporation of long alkyl chains allowed the encapsulation of indomethacin within the amphiphilic diblock copolymer aggregates. Nanostructures of increased size were detected due to the encapsulation of indomethacin into the interior of the hydrophobic domains. Drug release studies demonstrated that almost 50% of the encapsulated drug can be released on demand by aid of ultrasonication.A unique and programmable peptide self-assembling system has been fabricated by using poly(ethylene glycol)-attached amphiphilic oligopeptide, which shows rapid self-assembly into well-organized β-sheet nanofibers in response to an enzymatic reaction.
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Molecular self-assembly is a process to obtain a well defined structure from suitable starting materials. The study of self-assembly provides a fundamental understanding of the driving forces and co-operative interaction behind these processes. Among the plenty of molecules, an amphiphilic molecule, containing both hydrophilic and hydrophobic counter parts is one of the interesting building blocks to study the self-assembly processes. In this short review, the hierarchical self-assembly of amphiphilic molecules into various supramolecular architectures such as vesicles, spheres, flowers, tubes and fibrillar networks of nano- to micrometer dimensions and gels have been discussed.
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Abstract In this study, a novel library of thermoresponsive homopolymers based on poly (ethylene glycol) (EG) (m)ethyl ether methacrylate monomers is presented. Twenty‐seven EG based homopolymers were synthesized and three parameters, the molar mass (MM), the number of the ethylene glycol groups in the monomer, and the chemistry of the functional side group were varied to investigate how these affect their thermoresponsive behavior. The targeted MMs of these polymers are varied from 2560, 5000, 8200 to 12,000 g mol −1 . Seven PEG‐based monomers were investigated: ethylene glycol methyl ether methacrylate (MEGMA), ethylene glycol ethyl ether methacrylate (EEGMA), di(ethylene glycol) methyl ether methacrylate (DEGMA), tri(ethylene glycol) methyl ether methacrylate (TEGMA), tri(ethylene glycol) ethyl ether methacrylate (TEGEMA), penta(ethylene glycol) methyl ether methacrylate (PEGMA), nona(ethylene glycol) methyl ether methacrylate (NEGMA). Homopolymers of 2‐(dimethylamino) ethyl methacrylate (DMAEMA) were also synthesized for comparison. The cloud points of these homopolymers were tested in different solvents and it was observed that it decreases as the number of EG group was decreased or the MM increased. Interestingly, the end functional group (methoxy or ethoxy) of the side group has an effect as well and is even more dominant than the number of EG groups.
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Amphiphilic peptides with or without oligoethylene glycol (OEG) chains based on 3,4-bis(benzyloxy)benzoic-linked glutamide were designed and their self-assembly was investigated. It was found that the amphiphilic peptide 3 with OEG chains could not only form stable gels in a wide range of solvents, but also showed better solubility in solvents than those without OEG chains. Fibrillar and nanotube structures were found in the gels formed and the width of the fibres could be tuned with added water content. The UV-vis and XRD results suggested that the driving forces for the peptide self-assembly were mainly intermolecular π–π and hydrogen-bonding interactions. These results provide a deeper understanding of the self-assembly mechanism and size control of nanofibrils formed by an OEG-based amphiphilic peptide.
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Abstract The construction of highly ordered organizations through self‐assembly is one of the most popular phenomena both in natural and artificial environments. Amphiphilic molecules are the most commonly used building blocks for the self‐assembly, which are conventionally known as amphiphilic low molecular weight surfactants with polar heads and nonpolar tails, or amphiphilic block copolymers (BCPs) consisting of covalently bonded hydrophilic and hydrophobic block chains. Compared with single surfactant self‐assembly system, binary amphiphiles co‐assembly systems composing of both small mass surfactants and amphiphilic BCPs feature high flexibilities and versatilities in materials designing and structure regulation, ascribing to the vast possibilities of intermolecular interactions within the systems and facile component modulations during the assembly processes. The amphiphilic features of the two kinds of molecules endow them with similar self‐assembly behaviors, while the unique and distinct characters of each kind of amphiphiles lead to various complex but highly diversified co‐assembly systems. According to the roles of the surfactant played in the co‐assembly system, in this review, we summarize the binary co‐assembly systems from three distinct types: 1) the co‐micellization system in which the surfactants are added into the BCPs assemblies as a self‐assembly assistant; 2) the co‐emulsification system in which the surfactants work as an emulsion stabilizer to assist and confine the assembly of BCPs in 3D geometries; 3) the co‐templating system where the individual micelles of both surfactant and BCPs are hierarchically arranged and distributed to guide the formation of hierarchical nanomaterials. Following this, the major potential applications of the nanomaterials synthesized from the binary amphiphiles in biological field are described. Finally, we shortly discuss the current challenges and future perspectives of the binary amphiphiles self‐assembly systems.
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Self-complementary facially amphiphilic derivatives of glycoluril are useful building blocks for hydrophobic self-assembly in water; we describe the design, synthesis and characterization of six dimeric self-assembled structures with values of KS up to 1840 M–1 in pD 7.4 buffered D2O.
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This review summarized the self-assembly of C 60 -based amphiphiles in aqueous and nonaqueous solutions and discussed the corresponding characteristics with close comparison to traditional surfactants.
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An amphiphilic metallacage with tetragonal prismatic frameworks as a hydrophobic core and pendent tri(ethylene glycol) chains as hydrophilic tails was prepared successfully and showed controllable self-assembly behaviour in water.
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In this paper, the recent development of the self-assembly of amphiphilic block copolymers in solutions were reviewed, with emphasis on new morphologyies of aggregates,such as rod, wormlike, vesicle,onion and solid onion etc. At the same time, the potential applications of the self-assembly of amphiphilic block copolymers in solutions, to light and e-lectricity ,the release of pharmacies,gene enginerring were introduced. The preparation methods of aggregates were also reviewed.
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