Structural Diversity and Phase Behavior of Brush Block Copolymer Nanocomposites

Brush block copolymers (BBCPs) exhibit attractive features for use as templates for functional hybrid nanomaterials including rapid ordering dynamics and access to broad ranges of domain sizes; however, there are relatively few studies of the morphology of the BBCPs as a function of their structural variables and fewer still studies of BBCP composite systems. Here we report the structural diversity and phase behavior of one class of BBCP nanocomposites as a function of the volume fractions of their components and the side chain symmetry of the BBCPs. We conducted a systematic investigation of gold nanoparticle (NP) (∼2 nm) assembly in a series of poly­(<i>tert</i>-butyl acrylate)-<i>block</i>-poly­(ethylene oxide) (P<i>t</i>BA-<i>b</i>-PEO) BBCPs with a fixed side chain length of P<i>t</i>BA (<i>M</i>_n = 8.2 kg/mol) but with different PEO brush lengths (<i>M</i>_n = 5.0, 2.0, or 0.75 kg/mol) as well as volume fractions (<i>f</i>_PEO = 0.200–0.484). The gold NPs are selectively incorporated within the PEO domain via hydrogen bond interactions between the 4-mercaptophenol ligands of the gold NPs and the PEO side chains. A number of morphological transitions were observed and were dependent on the total volume fraction (<i>f</i>_NP/PEO) of NPs and PEO domain. Symmetric or asymmetric lamellar morphologies of NP arrays were readily created through simple variation of <i>f</i>_NP/PEO. Interestingly, a lamellar structure was obtained at a small <i>f</i>_NP/PEO of only 0.248 for nanocomposites based on BBCPs with comparable side chain lengths (MW_PEO/MW_PtBA = 0.63). In contrast, NP morphological transitions from wormlike through cylindrical to lamellar structures were observed with the increase of <i>f</i>_NP/PEO for nanocomposites based on BBCPs with a large difference in side chain length (MW_PEO/MW_PtBA = 0.09). Highly deformed cylinders were observed in the cylindrical morphology as clearly identified by high angle annular dark field (HAADF) scanning transmission electron microscopy (STEM) tomography. This work represents a starting point for understanding BBCP composite phase behavior, and it provides new insight toward strategies for control over the microstructure of NP arrays assembled in BBCP templates, which is essential for functional materials design

Controlled Supramolecular Self-Assembly of Large Nanoparticles in Amphiphilic Brush Block Copolymers

To date the self-assembly of ordered metal nanoparticle (NP)/block copolymer hybrid materials has been limited to NPs with core diameters (<i>D</i>_core) of less than 10 nm, which represents only a very small fraction of NPs with attractive size-dependent physical properties. Here this limitation has been circumvented using amphiphilic brush block copolymers as templates for the self-assembly of ordered, periodic hybrid materials containing large NPs beyond 10 nm. Gold NPs (<i>D</i>_core = 15.8 ± 1.3 nm) bearing poly­(4-vinylphenol) ligands were selectively incorporated within the hydrophilic domains of a phase-separated (polynorbornene-<i>g</i>-polystyrene)-<i>b</i>-(polynorbornene-<i>g</i>-poly­(ethylene oxide)) copolymer via hydrogen bonding between the phenol groups on gold and the PEO side chains of the brush block copolymer. Well-ordered NP arrays with an inverse cylindrical morphology were readily generated through an NP-driven order–order transition of the brush block copolymer

THE DEVELOPMENT OF THE TECHNOLOGICAL BASES FOR OBTAINING AND PROCESSING OF THE BASE THERMOPLASTIC BUTADIEN-NITRIL ELASTOMERS

The object of investigation: the butadien-nitril rubber, polyvinylchloride, polystirol, polycarbonate, ABC-plastics, polyamide, acetylcellulose, polypropylene. The theoretical justification has been given, the mathematical model of the quality of the base materials, the mathematical model of optimization of the modified thermoplastic elastomers recipe have been developed, the influence of the fillers and plastificators of the different nature on the consumers properties of the base materials has been developed, the method of prognosing of the materials technological properties has been developed. Offered has been the method of the &quot;dynamic&quot; vulcanization, with the aid of which the base materials have been received, and it allows to reduce the time of the vulcanization by 5 times and to reduce the electric power consumption. The recipes of the cast compositions, posessing the improved values of the operating and consumer properties, the modes and the parameters of the processing of the base materials, the multiple use of the obtained alloys have been offered. The base polymer materials of the new type for casting under pressure have been introduced in practiceAvailable from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio

High Temperature Thermoplastic Elastomers Synthesized by Living Anionic Polymerization in Hydrocarbon Solvent at Room Temperature

We present the synthesis and characterization of a new class of high temperature thermoplastic elastomers composed of polybenzofulvene–polyisoprene–polybenzofulvene (FIF) triblock copolymers. All copolymers were prepared by living anionic polymerization in benzene at room temperature. Homopolymerization and effects of additives on the glass transition temperature (<i>T</i>_g) of polybenzofulvene (PBF) were also investigated. Among all triblock copolymers studied, FIF with 14 vol % of PBF exhibited a maximum stress of 14.3 ± 1.3 MPa and strain at break of 1390 ± 66% from tensile tests. The stress–strain curves of FIF-10 and 14 were analyzed by a statistical molecular approach using a nonaffine tube model to estimate the thermoplastic elastomer behavior. Dynamic mechanical analysis showed that the softening temperature of PBF in FIF was 145 °C, much higher than that of thermoplastic elastomers with polystyrene hard blocks. Microphase separation of FIF triblock copolymers was observed by small-angle X-ray scattering, even though long-range order was not achieved under the annealing conditions employed. In addition, the microphase separation of the resulting triblock copolymers was examined by atomic force microscopy