Microphase Separation of Cyclic Block Copolymers of Styrene and Butadiene and of Their Corresponding Linear Triblock Copolymers

2003 ◽  
Vol 36 (1) ◽  
pp. 148-152 ◽  
Author(s):  
Yuqing Zhu ◽  
Samuel P. Gido ◽  
Hermis Iatrou ◽  
Nikos Hadjichristidis ◽  
Jimmy W. Mays
Keyword(s):  
Block Copolymers ◽  
Microphase Separation ◽  
Triblock Copolymers ◽  
Cyclic Block

Microphase Separation of Linear and Cyclic Block Copolymers Poly(styrene-b-isoprene):  SAXS Experiments

2004 ◽  
Vol 37 (5) ◽  
pp. 1843-1848 ◽  
Author(s):  
S. Lecommandoux ◽  
R. Borsali ◽  
M. Schappacher ◽  
A. Deffieux ◽  
T. Narayanan ◽  
...  
Keyword(s):  
Block Copolymers ◽  
Microphase Separation ◽  
Cyclic Block

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.

scholarly journals Quadruple Hydrogen Bond-Containing A-AB-A Triblock Copolymers: Probing the Influence of Hydrogen Bonding in the Central Block

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4705
Author(s):  
Boer Liu ◽  
Xi Chen ◽  
Glenn A. Spiering ◽  
Robert B. Moore ◽  
Timothy E. Long
Keyword(s):  
Hydrogen Bonding ◽  
Self Assembly ◽  
Microphase Separation ◽  
Triblock Copolymers ◽  
Random Copolymer ◽  
Thermomechanical Properties ◽  
Structure Property ◽  
Scanning Calorimetry ◽  
Central Block ◽  
Quadruple Hydrogen Bonding

This work reveals the influence of pendant hydrogen bonding strength and distribution on self-assembly and the resulting thermomechanical properties of A-AB-A triblock copolymers. Reversible addition-fragmentation chain transfer polymerization afforded a library of A-AB-A acrylic triblock copolymers, wherein the A unit contained cytosine acrylate (CyA) or post-functionalized ureido cytosine acrylate (UCyA) and the B unit consisted of n-butyl acrylate (nBA). Differential scanning calorimetry revealed two glass transition temperatures, suggesting microphase-separation in the A-AB-A triblock copolymers. Thermomechanical and morphological analysis revealed the effects of hydrogen bonding distribution and strength on the self-assembly and microphase-separated morphology. Dynamic mechanical analysis showed multiple tan delta (δ) transitions that correlated to chain relaxation and hydrogen bonding dissociation, further confirming the microphase-separated structure. In addition, UCyA triblock copolymers possessed an extended modulus plateau versus temperature compared to the CyA analogs due to the stronger association of quadruple hydrogen bonding. CyA triblock copolymers exhibited a cylindrical microphase-separated morphology according to small-angle X-ray scattering. In contrast, UCyA triblock copolymers lacked long-range ordering due to hydrogen bonding induced phase mixing. The incorporation of UCyA into the soft central block resulted in improved tensile strength, extensibility, and toughness compared to the AB random copolymer and A-B-A triblock copolymer comparisons. This study provides insight into the structure-property relationships of A-AB-A supramolecular triblock copolymers that result from tunable association strengths.

scholarly journals Chain elongation suppression of cyclic block copolymers in lamellar microphase-separated bulk

2004 ◽  
Vol 121 (2) ◽  
pp. 1129-1132 ◽  
Author(s):  
Y. Matsushita ◽  
H. Iwata ◽  
T. Asari ◽  
T. Uchida ◽  
G. ten Brinke ◽  
...  
Keyword(s):  
Block Copolymers ◽  
Chain Elongation ◽  
Cyclic Block

RAFT without an “R-Group”: From Asymmetric Homo-telechelics to Multiblock Step-Growth and Cyclic Block Copolymers

2021 ◽  
Vol 54 (17) ◽  
pp. 7732-7742
Author(s):  
Karen Hakobyan ◽  
Christopher S. P. McErlean ◽  
Markus Müllner
Keyword(s):  
Block Copolymers ◽  
Cyclic Block ◽  
Step Growth

Self-assembly of block copolymers into sieve-like particles with arrayed switchable channels and as scaffolds to guide the arrangement of gold nanoparticles

Nanoscale ◽  
2017 ◽  
Vol 9 (39) ◽  
pp. 15056-15061 ◽  
Author(s):  
Yun He ◽  
Yan Zhang ◽  
Nan Yan ◽  
Yutian Zhu ◽  
Wei Jiang ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Block Copolymers ◽  
Self Assembly ◽  
Triblock Copolymers ◽  
Emulsion Droplets

The unique sieve-like particles with lattice arrayed switchable channels were created via the confined self-assembly of P4VP-b-PS-b-P4VP triblock copolymers within the emulsion droplets.

Effect of Block Molecular Weight on the Mechanical Properties of PA1010-b-PEG Segmented Block Copolymers

2012 ◽  
Vol 512-515 ◽  
pp. 2127-2130
Author(s):  
Li Huo ◽  
Cai Xia Dong
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Block Copolymers ◽  
Microphase Separation ◽  
Soft Segment ◽  
Mechanical Measurements ◽  
Wide Range ◽  
Hard Block ◽  
Higher Temperature ◽  
Hard Segments

The mechanical properties were investigated of a series of PA-PEG thermalplastic elastomer based on PA1010 and polytetramethylene glycol (PEG) with varying hard and soft segment content. Dynamic mechanical measurements of these polymers have carried out over a wide range of temperatures. The block copolymers exhibit three peaks, designated as α, β and γ in the tanδ-temperature curve. The α transition shifts to higher temperature with increasing hard block molecular weight. However, at a constant hard molecular weight, the α transition shifts to higher temperature and the damping increases on increasing the soft segment molecular weight. DMA results show that the block copolymers exhibit a microphase separation structure and both soft and hard segments were found to be crystallizable. The degree of phase separation increases with increasing hard block molecular weight.

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