Synthesis and Micellization Behavior of Amphiphilic Block Copolymers of Poly(N-vinyl Pyrrolidone) and Poly(Benzyl Methacrylate): Block versus Statistical Copolymers (original) (raw)
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Macromolecules, 2003
Amphiphilic AB, A 1 A 2 B, and A2B block copolymers, where A ) polyisobutylene, B ) poly-(methyl vinyl ether), and the superscripts denote molecular weight asymmetry, with constant molecular weight and composition have been synthesized by living cationic polymerization. The influence of architecture on aqueous micellar properties of these block copolymers were investigated in the temperature range 20-30°C by fluorescence spectroscopy and static and dynamic light scattering (SLS and DLS). The critical micelle concentration (cmc) measured at 23°C increased in the order A 2B < A 1 A 2 B < AB. The partition equilibrium constants, Kv of pyrene, characteristic of hydrophobicity, increased in the opposite order of cmc. The hydrodynamic radii (Rh) and aggregation numbers (Nagg) of micelles remained approximately constant in the whole temperature range for A 1 A 2 B and A2B and below 25°C for AB. At ∼25°C, however, there was a sudden increase in both Rh and Nagg for AB. Below 25°C both Rh and Nagg increased in the order AB < A 1 A 2 B < A2B. The particle size distribution for all block copolymers remained narrow in the whole temperature range. The results are discussed in terms of possible morphologies.
2014
2.3.1 Theoretical estimation of polymeric micelle shape 62 2.3.2 Rheological properties of copolymer EO 38 SO 10 EO 38 Temperature and concentration scans 63 2.3.3 References 64 2.4. EO m SO n EO m copolymers: From "classical" chemotherapeutic nanocarriers to active cell-response inducers 65 2.4.1 Abstract 65 2.4.2 Introduction 65 2.4.3 Experimental section 67 2.4.3.1 Materials 67 2.4.3.2 Methods 68 2.4.4 Results and discussion 70 2.4.4.1 Solubilization capacity 70 2.4.4.2 Size distribution and physical stability of DOXO-polymeric micelles 71 2.4.4.3 In vitro release 72 2.4.4.4 Cytocompatibiity of EO 33 SO 14 EO 33 and EO 33 SO 14 EO 33 74 2.4.4.5 Inhibition of P-gp efflux pump and intracellular DOXO accumulation 75 2.4.4.6 Cellular uptke and in vitro cytotoxicity of iii DOXO-loaded polymeric micelles (P-gp evasion) 77 2.4.5 Conclusions 81 2.4.6 References 81 Chapter 3: BO n EO m EO n copolymers as nanocarriers of hydrophobic drugs 95 3.1. Aim of the work 97 3.1.1 Aim of the work 98 3.1.2 Methodology 98 3.1.3 References 100 3.2. Micellisation of triblock copolymers of ethylene oxide and 1,2-butylene oxide: Effect of BO-block length iv 3.3.5 Conclusions 133 3.3.6 References 133 3.4. Solution behavior of reverse poly(butylene oxide)-poly(ethylene oxide)-poly(butylene oxide) triblock copolymers with lengthy hydrophilic blocks 136 3.4.1 Abstract 136 3.4.2 Introduction 137 3.4.3 Experimental section 138 3.4.3.1 Materials 138 3.4.3.2 Methods 139 3.4.4 Results and discussion 141 3.4.4.1 Clouding 141 3.4.4.2 Population size distributions 142 3.4.4.3 Micellar properties 145 3.4.4.4 Rheological behavior 148 3.4.5 Conclusions 156 3.4.6 References 157 3.5. Supporting information 160 3.6. Doxorubicin-loaded micelles of reverse poly(butylene oxide)-poly(ethylene oxide)-poly(butylene oxide) block copolymers as efficient "active" chemotherapeutic agents 162 3.6.1 Abstract 162 3.6.2 Introduction 163 3.6.3 Experimental section 165 3.6.3.1 Materials 165 3.6.3.2 Methods 165 3.6.4 Results and discussion 169 3.6.4.1 Cytocompatibility of BO n EO m BO n copolymers 170 3.6.4.2 Solubilization capacity 170 3.4.4.3 Size and stability of the DOXO-loaded polymeric micelles 172 3.6.4.4 In vitro release 173 3.6.4.5 Intracellular DOXO accumulation by inhibition of Pg-P efflux pump 174 3.6.4.6.Cellular uptake of DOXO-loaded polymeric micelles (P-gp evasion) 175 3.6.5 Conclusions 180 3.6.6 References 181
Macromolecules, 2004
Amphiphilic diblock copolymers with varying compositions of hydrophilic poly[bis(methoxyethoxyethoxy)phosphazene] and hydrophobic polystyrene were synthesized via the living, cationic polymerization of Cl3PdNSiMe3, using a polystyrenyl-phosphoranimine as a macroterminator. The selfassociation behavior of the block copolymers in aqueous media was investigated using fluorescence spectroscopy, transmission electron microscopy, and dynamic light scattering. The critical micelle concentrations of PS-MEEP block copolymers with molar block ratios of 1:0.37, 1:0.58, 1:0.70, and 1:0.86 were determined to be 1.8, 2.3, 10.0, and 13.6 mg/L, respectively. The mean diameters of micelles of these block copolymers were measured as 167, 168, 179, and 173 nm through dynamic light scattering. The equilibrium constants of pyrene in these micelles ranged from 5.75 × 10 5 to 7.31 × 10 4 .
Journal of Applied Polymer Science, 2017
The micellization of three tailor-made triblock copolymers, such as PB 100-P2VP 100-PEO 104 , PB 185-P2VP 108-PEO 154 , and PB 37-P2VP 115-PEO 241 , having similar total molecular weights and constant poly(2-vinylpyridine) (P2VP) sequence lengths, was investigated as a function of pH and sodium dodecyl sulfate (SDS) concentration. At pH 7 the formation of intermicellar aggregates was observed, especially for copolymers of low poly(ethylene oxide) (PEO) content. A pH decrease from 7 to 3 leads to a particle size increase due to the electrostatic repulsion of the protonated P2VP chains. The influence of the PEO sequence length was also observed for zeta potential values. At pH 3, in the absence of SDS, core-shell-corona micelles are formed whereas in the presence of small amount of SDS (degree of neutralization DN 5 0%-50%), a complex is formed between SDS and the protonated P2VP which leads to the shrinkage of the shell and thus to a decrease of the micellar sizes. For higher DN values, the micellar sizes increase due to the formation of large agglomerates and a transition occurs from a monomodal to a bimodal size distribution. Furthermore, it turned out that secondary aggregation, such as intermicellar aggregation, can completely be avoided if the degree of polymerization (DPn) of the water-soluble block is significantly higher than the DPn of the water-insoluble sequence. V
Significance of Amphiphilic Block Copolymer Micelles and its Characteristics
"Amphiphilic block copolymers (ABCs) have been used broadly in pharmaceutical applications. One of the most widely used drug delivery systems is the self assembly of ABCs carriers in micelle forms in aqueous environment. Block copolymers have low toxicity and due to their nontoxic properties and surface-activity they have found application in the areas of biomaterials, protein separation, drug delivery and cardiovascular therapeutics and as industrially important surfactants. ABCs micelles have been the focus of research for the last many decades. Research in the field has been increasingly focused on achieving enhanced stability of the micellar assembly, prolonged circulation times and controlled release of the drug for optimal targeting. Dr. Tejas Joshi""Significance of Amphiphilic Block Copolymer Micelles and its Characteristics"" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-1 | Issue-5 , August 2017, URL: http://www.ijtsrd.com/papers/ijtsrd2316.pdf Article URL: http://www.ijtsrd.com/chemistry/physical-chemistry/2316/significance-of-amphiphilic-block-copolymer-micelles-and-its-characteristics/dr-tejas-joshi"
University of Groningen Polystyrene-Poly ( sodium methacrylate ) Amphiphilic Block Copolymers
2018
Three well-defined polystyrene−poly(sodium methacrylate) amphiphilic block copolymers characterized by different molecular architecture (diblock, triblock, and fourarm star) have been synthesized by ATRP. The rheology of their water solutions has been evaluated by measuring dynamic moduli and shear viscosity at different concentrations. All polymers show remarkable thickening properties and a sol−gel transition at low concentration (0.1 wt %). Above the gel concentration the solutions are shear thinning without an apparent Newtonian plateau. The observed viscosity profile can be interpreted in terms of percolation theory applied to highly stretched polymeric micelles, which start to contract above the percolation threshold. An interesting correlation between solution viscosity and concentration of hydrophilic block (defined here as “arm concentration”) has been observed, giving indirect evidence for the arrangement of the polymers into micelles. The influence of ionic strength and p...
Polymer, 2011
Amphiphilic block copolymers with various chain lengths of poly(n-butyl methacrylate) blocks (PBMA) and poly(N-acryloylmorpholine) blocks (PAM) were prepared by RAFT polymerization. Packing parameter of block polymers in water (b < 0.2) indicated the formation of core-corona structures, which was further confirmed from a difference between core-and corona-forming chain surface areas. Hydrodynamic micellar size was related with the numbers of BMA (N BMA ) and AM (N AM ), and their ratios (N BMA / N AM ). With increasing N BMA /N AM value, the polymer aggregation numbers and inner core sizes increased, while the critical micelle concentrations, the corona thickness, and the second virial coefficient of block copolymer micelles decreased. These properties changed with increasing N BMA /N AM value resulted in a linear increase in corona chain unit density (r AM ) that limited chain mobility. Thus, the interaction between the micelles and serum protein at low r AM disappeared at a higher value. Consequently, both micellar properties and biocompatible effect can be regulated by tailoring the block compositions of amphiphilic polymers.
Polymers
Self-assembly of amphiphilic block copolymers display a multiplicity of nanoscale periodic patterns proposed as a dominant tool for the ‘bottom-up’ fabrication of nanomaterials with different levels of ordering. The present review article focuses on the recent updates to the self-association of amphiphilic block copolymers in aqueous media into varied core-shell morphologies. We briefly describe the block copolymers, their types, microdomain formation in bulk and micellization in selective solvents. We also discuss the characteristic features of block copolymers nanoaggregates viz., polymer micelles (PMs) and polymersomes. Amphiphilic block copolymers (with a variety of hydrophobic blocks and hydrophilic blocks; often polyethylene oxide) self-assemble in water to micelles/niosomes similar to conventional nonionic surfactants with high drug loading capacity. Double hydrophilic block copolymers (DHBCs) made of neutral block-neutral block or neutral block-charged block can transform on...
Temperature and Salt-Induced Micellization of Some Block Copolymers in Aqueous Solution
Micellization of three commercial samples of ethylene oxide (EO)-propylene oxide (PO) (PEO-PPO-PEO) triblock copolymers (pluronics) P65 (EO 25 PO 30 EO 25 , mw PPO = 1750, %PEO = 50), P85 (EO 25 PO 40 EO 25 , mw PPO = 2250, %PEO = 50), and F88 (EO 102 PO 40 EO 102 , mw PPO = 2250, %PEO = 80) in aqueous sodium chloride solution (0-3 M) was examined by cloud point, surface tension, dye spectral change, fluorescence, and viscosity measurements over a temperature range of 25-50°C. Salt-induced micellization and micelle growth were observed.
Macromolecules, 2009
We report the synthesis of a series of amphiphilic molecular building blocks that can be self-assembled at the air-water interface to form two-and three-dimensional nanostructures with tunable optoelectronic properties. Compression of these molecular building blocks using the Langmuir-Blodgett method gives rise to monolayer and multilayer thin films with different packing densities and electronic properties that are tunable due to varying π-π (hydrophobic) interactions. Depending on the noncovalent interaction between chromophores, we observe a transition toward denser packing with increasing number of phenylene ethynylene repeat units. Additionally, we use quantumchemical simulations to help determine the excited-state electronic structure, intermolecular interactions, and packing trends. Our results demonstrate that the interplay between dipole-dipole and π-π interactions dominates the formation of thin films with various packing densities and determines the associated optical properties.