Arene-functionalized polyisocyanides: photophysics of well-defined homopolymers and block copolymers for efficient light harvesting

1995 ◽  
Vol 73 (11) ◽  
pp. 2101-2101 ◽  
Author(s):  
Bo Hong ◽  
Mary A. Fox
Keyword(s):  
Electron Transfer ◽  
Block Copolymers ◽  
Diblock Copolymer ◽  
Diblock Copolymers ◽  
Triblock Copolymers ◽  
Ion Pairs ◽  
Energy Migration ◽  
Excimer Emission ◽  
Transfer Energy ◽  
Exciplex Formation

Steady-state and time-resolved fluorescence spectroscopy of the homopolymers and di- and triblock copolymers of 2-naphthylethylisocyanide (7), 9-anthrylethylisocyanide (10), and 2-phenanthrylethylisocyanide (11) exhibit emission from the isolated chromophores, i.e., naphthyl, anthryl, or phenanthryl, upon excitation at 284 or 354 nm. The absence of excimer emission in the fluorescence spectra of all these homopolymers is indicative of a rigid polymeric backbone. Fluorescence quenching in diblock copolymers containing a dimethylaniline donor block and a naphthalene or anthracene acceptor block takes place through directional energy migration to the acceptor–quencher interface. The migrating excited state is then quenched at the interface either by photoinduced electron transfer in the anthracene–dimethylaniline diblock copolymer or by exciplex formation in the naphthalene–dimethylaniline diblock copolymer. Upon incorporation of an intervening block derived from pentamethylphenylethylisocyanide 8, exciplex formation is suppressed in the related triblock copolymer. Transient absorption spectra of this family of di- and triblock copolymers reveal the formation of radical ion pairs, with a lifetime of 1.1 μs in the anthracene–dimethylaniline diblock copolymer. Keywords: electron transfer, energy migration, excimer emission, polyisocyanides, block copolymers.

Photophysical Properties and Performance of Semiconducting Block Copolymers

2012 ◽  
Vol 568 ◽  
pp. 376-379
Author(s):  
Li Guo ◽  
Yong Guo Zhang ◽  
Jian Qiang Hu
Keyword(s):  
Electron Transfer ◽  
Block Copolymers ◽  
Diblock Copolymer ◽  
Photophysical Properties ◽  
Phenylene Vinylene ◽  
Donor Acceptor ◽  
And Performance

The covalent incorporation of C60 into one block of a poly(1,4-(2,5-dioctyloxy)phenylene vinylene)-based diblock copolymer resulted in a donor–acceptor diblock copolymer, which demonstrated a very efficient electron transfer upon excitation of the PPV block. The strong quenching of the photoluminescence from the PPV block indicated an efficient electron transfer at the donor–acceptor interface.

Block Copolymers Poly(2,6-dimethyl-1,4-phenylene oxide)-poly(6-hexanelactam). Preparation and Composition

1993 ◽  
Vol 58 (11) ◽  
pp. 2574-2582 ◽  
Author(s):  
Jaroslav Stehlíček ◽  
Rudolf Puffr
Keyword(s):  
Molecular Weight ◽  
Block Copolymers ◽  
Diblock Copolymer ◽  
Anionic Polymerization ◽  
Diblock Copolymers ◽  
Toluene Solution ◽  
Low Molecular Weight ◽  
Phenylene Oxide ◽  
End Groups ◽  
Tolylene Diisocyanate

Poly(2,6-dimethyl-1,4-phenylene oxide)-poly(6-hexanelactam) diblock copolymers were prepared from low-molecular weight poly(2,6-dimethyl-1,4-phenylene oxide) by transforming its phenolic end groups via the reaction with 2,4-tolylene diisocyanate and 6-hexanelactam to polymeric initiators and the subsequent anionic polymerization of 6-hexanelactam. The polymerization of 6-hexanelactam was carried out in bulk or toluene solution. The content of the 6-hexanelactam homopolymer was estimated by TLC showing that the pure diblock copolymer can be prepared in toluene. The reason for relatively low yields is discussed.

Effect of random midblock sequencing on the morphological characteristics of symmetric A(A/B)B triblock copolymers

1994 ◽  
Vol 52 ◽  
pp. 450-451
Author(s):  
Jonathan H. Laurer ◽  
Richard J. Spontak ◽  
Steven D. Smith ◽  
Arman Ashraf
Keyword(s):  
Diblock Copolymer ◽  
Diblock Copolymers ◽  
Triblock Copolymers ◽  
Morphological Characteristics ◽  
Morphological Features ◽  
Limited Attention ◽  
Composition Gradient ◽  
Molecular Architecture ◽  
Species Introduction ◽  
Morphological Behavior

Significant efforts have been put forth to elucidate the morphological features of strongly-segregated AB diblock copolymers, in which contiguous sequences of A and B monomers are incompatible and order into periodic morphologies. In this regime, interactions between chemically dissimilar blocks are repulsive, and the interphase separating adjacent microdomains is relatively narrow. While the properties of a diblock copolymer can be modified without changing monomer species, introduction of random A/B sequencing into the molecular architecture has received limited attention. The morphological features of diblock copolymers possessing one A/B block have been previously examined, and Smith et al. are currently exploring the morphological behavior of "random" diblock copolymers with two A/B blocks of differing composition. In this work, TEM is used to discern the morphologies of copolymers in which an A/B segment is incorporated between the endblocks (see Fig. 1). Tapered copolymers, wherein the A/B segment possesses a composition gradient, as well as non-tapered copolymers, are considered.

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.

Mechanical and Structural Consequences of Associative Dynamic Cross-Linking in Acrylic Diblock Copolymers

2019 ◽  
Author(s):  
Jacob Ishibashi ◽  
Yan Fang ◽  
Julia Kalow
Keyword(s):  
Block Copolymers ◽  
Rheological Properties ◽  
Diblock Copolymers ◽  
Cross Linking ◽  
Statistical Copolymer

<p>Block copolymers are used to construct covalent adaptable networks that employ associative exchange chemistry (vitrimers). The resulting vitrimers display markedly different nanostructural, thermal and rheological properties relative to those of their statistical copolymer-derived counterparts. This study demonstrates that prepolymer sequence is a versatile strategy to modify the properties of vitrimers.</p>

scholarly journals Dissipative Particle Dynamics Study on Interfacial Properties of Symmetric Ternary Polymeric Blends

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1516
Author(s):  
Dongmei Liu ◽  
Kai Gong ◽  
Ye Lin ◽  
Tao Liu ◽  
Yu Liu ◽  
...  
Keyword(s):  
Interfacial Tension ◽  
Chain Length ◽  
Triblock Copolymer ◽  
Diblock Copolymers ◽  
Triblock Copolymers ◽  
Dissipative Particle Dynamics ◽  
Interfacial Properties ◽  
Particle Dynamics ◽  
Polymeric Blends ◽  
Polymer Component

We investigated the interfacial properties of symmetric ternary An/AmBm/Bn and An/Am/2BmAm/2/Bn polymeric blends by means of dissipative particle dynamics (DPD) simulations. We systematically analyzed the effects of composition, chain length, and concentration of the copolymers on the interfacial tensions, interfacial widths, and the structures of each polymer component in the blends. Our simulations show that: (i) the efficiency of the copolymers in reducing the interfacial tension is highly dependent on their compositions. The triblock copolymers are more effective in reducing the interfacial tension compared to that of the diblock copolymers at the same chain length and concentration; (ii) the interfacial tension of the blends increases with increases in the triblock copolymer chain length, which indicates that the triblock copolymers with a shorter chain length exhibit a better performance as the compatibilizers compared to that of their counterparts with longer chain lengths; and (iii) elevating the triblock copolymer concentration can promote copolymer enrichment at the center of the interface, which enlarges the width of the phase interfaces and reduces the interfacial tension. These findings illustrate the correlations between the efficiency of copolymer compatibilizers and their detailed molecular parameters.

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