Chapter 9 Reversible Photoinduced Birefringence in Epoxy Polymers, Block Copolymers and Nanostructured Thermosetting Systems Containing Azobenzene Groups

2016 ◽  
pp. 295-336
Author(s):  
Raquel Fernández
Keyword(s):  
Block Copolymers ◽  
Epoxy Polymers ◽  
Photoinduced Birefringence ◽  
Azobenzene Groups

Photo-Induced Optical Anisotropy and Morphological Study in Azobenzene Containing Block Copolymers

2012 ◽  
Vol 714 ◽  
pp. 43-50
Author(s):  
Raquel Fernández ◽  
Iñaki Zalakain ◽  
José Angel Ramos ◽  
Loli Martin ◽  
Iñaki Mondragon
Keyword(s):  
Block Copolymers ◽  
Microphase Separation ◽  
Covalent Attachment ◽  
Nanostructured Systems ◽  
One Step ◽  
Covalently Linked ◽  
Epoxy Matrices ◽  
Epoxy Groups ◽  
Azobenzene Groups ◽  
Thermosetting Epoxy

In this work, different types of nanostructured systems containing azobenzene groups were studied. With that aim, firstly, novel azo-functionalised block copolymers (BCP) were synthesized from epoxidized poly (styrene-b-butadiene-b-styrene) (SBS) modified with azobenzene units by one-step facile reaction between the epoxy groups and an azo-amine. The epoxy/amine reaction was verified by Fourier transform infrared spectroscopy. In addition, the effect of covalent attachment of the azobenzene moieties was investigated by analyzing the morphology and the optical anisotropic response of the resulting azo-containing BCP, with respect to solution mixing of the azobenzene as a guest in the BCP host without chemical bonding. On the other hand, epoxidized SBS was also used as template for the generation of nanostructured thermosetting epoxy matrices with azobenzene groups covalently linked. This BCP can self-assemble in the epoxy matrix to produce microphase-separated domains, thanks to the selective segregation of polystyrene blocks due to reaction induced microphase separation. In this case, the influence of the azobenzene content and the amount of epoxidized SBS on the generated morphologies and the photo-induced anisotropy was studied.

scholarly journals Photoresponsive polymers with multi-azobenzene groups

2019 ◽  
Vol 10 (32) ◽  
pp. 4389-4401 ◽  
Author(s):  
Shaodong Sun ◽  
Shuofeng Liang ◽  
Wen-Cong Xu ◽  
Guofeng Xu ◽  
Si Wu
Keyword(s):  
Photoinduced Birefringence ◽  
Potential Applications ◽  
Azobenzene Groups

Photoresponsive polymers with multi-azobenzene groups are reviewed and their potential applications in photoactuation, photo-patterning, and photoinduced birefringence are introduced.

scholarly journals RELAXATION PROPERTIES OF COMPOSITE MATERIALS BASED ON MIXTURES OF EPOXY POLYMERS AND THERMOPLASTIC ELASTOMERS

2020 ◽  
pp. 85-95
Author(s):  
Y. Kochergin ◽  
Tatyana Grigorenko ◽  
V. Zolotareva
Keyword(s):  
Molecular Weight ◽  
High Temperature ◽  
Block Copolymers ◽  
Thermoplastic Elastomer ◽  
Thermoplastic Elastomers ◽  
Relaxation Processes ◽  
Polybutylene Terephthalate ◽  
Dynamic Mechanical ◽  
Epoxy Polymers ◽  
Polytetramethylene Oxide

The influence of thermoplastic elastomers, which are two-block statistical block copolymers based on polybutylene terephthalate and polytetramethylene oxide with a different ratio of rigid and elastic blocks, on the static and dynamic mechanical properties of epoxy polymers is studied. The initial compounds for the synthesis of block copolymers are dimethyl terephthalate, 1,4-butanediol and polytetramethylenoxide with a molecular weight of 2000. The tetrabutoxide is used as catalyst. The process of interaction of the initial components is carried out in two stages, the reaction of transesterification and copolycondensation is consistently carried out. The composition of BSP is set by the ratio of initial reagents. The total molecular weight of block copolymers is 30–40 thousand. The method of dynamic mechanical analysis shows that the introduction of modifiers leads to a decrease in molecular mobility in a wide temperature range from low-temperature (at 220K) to high-temperature (at 380K) relaxation transitions. The magnitude of the effect depends on the ratio of rigid and flexible blocks in the block copolymer. It is assumed that the decrease in the tangent of the angle of mechanical losses at temperatures below the glass transition temperature and especially in the region of the β-transition, may be associated with the slowdown of relaxation processes at the interface of the epoxide matrix with rigid blocks of thermoplastic elastomer. The observed effects in the region of high-temperature transition may be associated with the restriction of freedom of conformational rearrangements near the interface of the epoxy polymer with polybutylene terephthalate and polytetramethylene oxide blocks and an increase in the cross-linking density of the epoxy. A noticeable decrease in the magnitude and creep rate of epoxy composites is found when thermoelastoplast is introduced.

Self-Assembly of Hydrogels From Elastin-Mimetic Block Copolymers

2002 ◽  
Vol 724 ◽  
Author(s):  
Elizabeth R. Wright ◽  
R. Andrew McMillan ◽  
Alan Cooper ◽  
Robert P. Apkarian ◽  
Vincent P. Conticello
Keyword(s):  
Block Copolymers ◽  
Self Assembly ◽  
Triblock Copolymers ◽  
Variable Temperature ◽  
Inverse Temperature ◽  
Temperature Transition ◽  
Scanning Calorimetry ◽  
Design Synthesis ◽  
Inverse Temperature Transition ◽  
Functional Biomaterials

AbstractTriblock copolymers have traditionally been synthesized with conventional organic components. However, triblock copolymers could be synthesized by the incorporation of two incompatible protein-based polymers. The polypeptides would differ in their hydrophobicity and confer unique physiochemical properties to the resultant materials. One protein-based polymer, based on a sequence of native elastin, that has been utilized in the synthesis of biomaterials is poly (Valine-Proline-Glycine-ValineGlycine) or poly(VPGVG) [1]. This polypeptide has been shown to have an inverse temperature transition that can be adjusted by non-conservative amino acid substitutions in the fourth position [2]. By combining polypeptide blocks with different inverse temperature transition values due to hydrophobicity differences, we expect to produce amphiphilic polypeptides capable of self-assembly into hydrogels. Our research examines the design, synthesis and characterization of elastin-mimetic block copolymers as functional biomaterials. The methods that are used for the characterization include variable temperature 1D and 2D High-Resolution-NMR, cryo-High Resolutions Scanning Electron Microscopy and Differential Scanning Calorimetry.

Use of Nonionic Block Copolymers in Vaccines and Therapeutics

1998 ◽  
Vol 15 (2) ◽  
pp. 89-142 ◽  
Author(s):  
Mark J. Newman ◽  
Jeffrey K. Actor ◽  
Mannersamy Balusubramanian ◽  
Chinnaswamy Jagannath
Keyword(s):  
Block Copolymers
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