Block Copolymers in Solution

This unique text discusses the solution self-assembly of block copolymers and covers all aspects from basic physical chemistry to applications in soft nanotechnology.

Block Copolymers in Solution

This unique text discusses the solution self-assembly of block copolymers and covers all aspects from basic physical chemistry to applications in soft nanotechnology. Recent advances have enabled the preparation of new materials with novel self-assembling structures, functionality and responsiveness and there have also been concomitant advances in theory and modelling. The present text covers the principles of self-assembly in both dilute and concentrated solution, for example micellization and mesophase formation, etc., in chapters 2 and 3 respectively. Chapter 4 covers polyelectrolyte block copolymers - these materials are attracting significant attention from researchers and a solid basis for understanding their physical chemistry is emerging, and this is discussed. The next chapter discusses adsorption of block copolymers from solution at liquid and solid interfaces. The concluding chapter presents a discussion of selected applications, focussing on several important new concepts. The book is aimed at researchers in polymer science as well as industrial scientists involved in the polymer and coatings industries. It will also be of interest to scientists working in soft matter self-assembly and self-organizing polymers.

Amphiphilic Block Copolymers

It is the belief of the editors of this book that the recognition of block copolymers as being amphiphilic molecules and sharing common features with other well-studied amphiphiles will prove beneficial to both the surfactant and the ...

Amphiphilic Block Copolymers

It is the belief of the editors of this book that the recognition of block copolymers as being amphiphilic molecules and sharing common features with other well-studied amphiphiles will prove beneficial to both the surfactant and the polymer communities. An aim of this book is to bridge the two communities and cross-fertilise the different fields. To this end, leading researchers in the field of amphiphilic block copolymer self-assembly, some having a background in surfactant chemistry, and others with polymer physics roots, have agreed to join forces and contribute to this book. The book consists of four entities. The first part discusses theoretical considerations behind the block copolymer self-assembly in solution and in the melt. The second part provides case studies of self-assembly in different classes of block copolymers (e.g., polyethers, polyelectrolytes) and in different environments (e.g., in water, in non-aqueous solvents, or in the absence of solvents). The third part presents experimental tools, ranging from static (e.g., small angle neutron scattering) to dynamic (e.g., rheology), which can prove valuable in the characterization of block copolymer self-assemblies. The fourth part offers a sampling of current applications of block copolymers in, e.g., formulations, pharmaceutics, and separations, applications which are based on the unique self-assembly properties of block copolymers.

Design and Characterization of Self assembled Nanostructures of Block Copolymers in Solution

Self-assembling amphiphilic block copolymers have been studied extensively due to their ability to form a wide range of morphologies including spheres, cylinders, and vesicles.

Design and Characterization of Self assembled Nanostructures of Block Copolymers in Solution

Self-assembling amphiphilic block copolymers have been studied extensively due to their ability to form a wide range of morphologies including spheres, cylinders, and vesicles. Changing the molecular composition of the block copolymer, the relative block lengths, and the solution conditions can alter the assembly behavior. The main goal of this dissertation is to investigate the self-assembly of two different amphiphilic block copolymer systems in an effort to controllably make different assembled structures. Amphiphilic, triblock copolymers of poly(acrylic acid)- b -poly(methyl acrylate)- b -polystyrene (PAA-PMA-PS) in tetrahydrofuran (THF)/ water solvent mixtures were studied. The solution conditions and the relative block lengths were varied, and complexation with an amine counterion was used to influence the self-assembly of these materials. A variety of structures were observed including phase-separated nanoparticles, bulk-like lamellar phase separation, spherical, cylindrical, and disk-like micelles, as well as toroidal assemblies. The specific structure formed was dependent on the composition of the triblock copolymer, the amount and valency of the counterion present, and the THF to water volume ratio. The structure of polymer nanoparticles and networks formed in low water content systems was examined. The size of the nanoparticles and whether separated nanoparticles vs. an interconnected network was formed was controlled via solvent composition. Importantly, both the nanoparticles and network phases contained their own inherent nanostructure due to local phase separation of the block copolymers. This phase behavior within the nanoparticles could be tuned, i.e. porous or lamellar internal structure, by changing the valency of the amine counterion. Cryo-transmission electron microscopy (TEM), traditional TEM, and neutron scattering were used to examine these samples. In addition to these triblock copolymers, amphiphilic diblock copolypeptides of hydrophobic leucine (L) and hydrophilic lysine (K) with poly(ethylene glycol) side groups were investigated. The effect of the copolypeptide design on the resulting morphology was studied by examining diblock compositions with different block lengths and secondary structures. It was determined that the secondary structure of these peptides plays a significant role in influencing the assembly of these materials.

Kinetic Assembly of Block Copolymers in Solution Helical Cylindrical Micelles and Patchy Nanoparticles

The study shows kinetic control can be a very effective way to make novel polymeric nanostructures. Two examples discussed here are helical cylindrical micelles and patchy nanoparticles.

Kinetic Assembly of Block Copolymers in Solution Helical Cylindrical Micelles and Patchy Nanoparticles

There is always an interest to understand how molecules behave under different conditions. One application of this knowledge is to self-assemble molecules into increasingly complex structures in a simple fashion. Self-assembly of amphiphilic block copolymer in solution has produced a large variety of nanostructures through the manipulation in polymer chemistry, assembly environment, and additives. Moreover, some reports suggest the formation of many polymeric assemblies is driven by kinetic process. The goal of this dissertation is to study the influence of kinetics on the assembly of block copolymer. The study shows kinetic control can be a very effective way to make novel polymeric nanostructures. Two examples discussed here are helical cylindrical micelles and patchy nanoparticles. Helical cylindrical micelles are made from the co-assembly of amphiphilic triblock copolymer poly(acrylic acid)- block -poly(methyl acrylate)- block -polystyrene and organoamine molecules in a mixture of tetrahydrofuran (THF) and water (H 2 O). This system has already shown promise of achieving many assembled structures. The unique aspects about this system are the use of amine molecules to complex with acid groups and the existence of cosolvent system. Application of amine molecules offers a convenient control over assembled morphology and the introduction of PMA-PS selective solvent, THF, promotes the mobility of the polymer chains. In this study, multivalent organoamine molecules, such as diethylenetriamine and triethylenetetramine, are used to interact with block copolymer in THF/water mixture. As expected, the assembled morphologies are dependent on the polymer architecture, selection and quantity of the organoamine molecules, and solution composition. Under the right conditions, unprecedented, multimicrometer-long, supramolecular helical cylindrical micelles are formed. Both single-stranded and double-stranded helices are found in the same system. These helical structures share uniform structural parameters, including the width of the micelles, width of the helix, and the pitch distance. There is no preference to the handedness, and both handednesses are observed, which is understandable since there are no chiral molecules or specific binding effects applied during the assembly. The helical structure is a product of kinetic process. Cryogenic transmission electron microscopy has been employed to monitor the morphological transformation. The study indicates there are two complicated but reproducible kinetic pathways to form the helices. One pathway involves the stacks of bended cylinders at early stages and the subsequent interconnection of these bended cylinders. Spherical micelles bud off of the interconnected nanostructure as the final step towards a defect-free helix. Another kinetic pathway shows very short helices are formed at first and aligned via head-to-tail style in the solution, and the subsequent sequential addition of these short helices results in prolonged mature helices. By using a ninhydrin-staining technique, amine molecules within the micellar corona are visualized and confirmed to preferentially locate in the inner side of the helical turns. The aggregation of amine molecules provides a strong attraction force due to electrostatic association between oppositely charged amine and acid groups and accumulation of hydrogen bonding among amine molecules to coil the cylindrical micelles into helical twisting features which are stabilized by the repulsion forces due to the chain packing frustration within the hydrophobic core, steric hindrance of amine molecules as well as the Coulomb repulsion of the excess charged amine groups. The formation mechanism of the helix offers the feasibility to manipulate the helical pitch distance and formation kinetics. The helical pitch distance can be enlarged or shrunk by varying the type and amount of amine molecules used in assembly, introducing inorganic salts, and changing pH. Luckily, the helical structure can be preserved permanently by inducing the amide reaction between amine and carboxylic acid groups. The kinetics of the helix is also subject to many factors, including used amine molecules, inorganic salts and preparation procedure. The aging time for the helix can be either reduced or prolonged. Furthermore, even though the helical formation is pathway-dependent, helical formation can still be triggered from extended cylindrical micelles or stacks of disklike micelles as long as a right condition is applied. Another strategy for kinetic assembly of block copolymer is presented as well. A novel patchy nanoparticle has been produced following this strategy. The patches are formed on the surface of polymeric colloids due to the phase separation of two chemically unlike segments. Certain level of mobility of the polymer chains is required for the blocks to segregate into patches. More importantly, the number and distribution geometry of the patches are related to the particle size. Future efforts are needed to control the particle size in order to manufacture uniform nanoparticles with desired patch patterns for the applications in nanotechnology, drug delivery and nanodevices.

Block Copolymers II

Block Copolymers II


Block Copolymers

This pioneering text provides not only a guideline for developing synthetic strategies for creating block copolymers with defined characteristics, but also a key to the relationship between the physical properties of block copolymers and ...

Block Copolymers

Polymers may be classified as either homopolymers, consisting ofone single repeating unit, or copolymers, consisting of two or moredistinct repeating units. Block copolymers contain long contiguousblocks of two or more repeating units in the same polymer chain.Covering one of the hottest topics in polymer chemistry, BlockCopolymers provides a coherent overview of the synthetic routes,physical properties, and applications of block copolymers. This pioneering text provides not only a guideline for developingsynthetic strategies for creating block copolymers with definedcharacteristics, but also a key to the relationship between thephysical properties of block copolymers and the structure anddynamics of materials. Covering features of the chemistry andphysics of block copolymers that are not found in comparable texts,Block Copolymers illustrates the structure-activity relationship ofblock copolymers and offers suggestions for the design of specificapplications. Divided into five sections–Block Copolymersincludes chapters on: Block Copolymers by Chemical Modification of PrecursorPolymers Nonlinear Block Copolymers Adsorption of Block Copolymers at Solid-Liquid Interfaces Theory of Block Copolymer Segregation Phase Transformation Kinetics Block Copolymer Morphology Block Copolymer Dynamics Polymer chemists, physicists, chemical engineers, and materialsscientists, as well as graduate students in polymer science, willfind Block Copolymers to be an invaluable text.

Block Copolymers in Nanoscience

This first book to take a detailed look at one of the key focal points where nanotechnology and polymers meet provides both an introductory view for beginners as well as in-depth knowledge for specialists in the various research areas ...

Block Copolymers in Nanoscience

This first book to take a detailed look at one of the key focal points where nanotechnology and polymers meet provides both an introductory view for beginners as well as in-depth knowledge for specialists in the various research areas involved. It investigates all types of application for block copolymers: as tools for fabricating other nanomaterials, as structural components in hybrid materials and nanocomposites, and as functional materials. The multidisciplinary approach covers all stages from chemical synthesis and characterization, presenting applications from physics and chemistry to biology and medicine, such as micro- and nanolithography, membranes, optical labeling, drug delivery, as well as sensory and analytical uses.