Polar Aprotic Solvents Disrupt Interblock Hydrogen Bonding and Induce Microphase Separation in Double Hydrophilic Block Copolymers of PEGMA and PAAMPSA

2008 ◽  
Vol 41 (12) ◽  
pp. 4069-4070 ◽  
Author(s):  
Tracy L. Bucholz ◽  
Yueh-Lin (Lynn) Loo
Keyword(s):  
Hydrogen Bonding ◽  
Block Copolymers ◽  
Microphase Separation ◽  
Aprotic Solvents ◽  
Double Hydrophilic Block Copolymers

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.

Nucleobase-Containing Block Copolymers Having a High Interaction Parameter by Complementary Hydrogen Bonding

2021 ◽  
Author(s):  
Nari Shin ◽  
Seonghyeon Ahn ◽  
Eunsoel Kim ◽  
Eun Young Kim ◽  
So Yeong Park ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Block Copolymers ◽  
Interaction Parameter ◽  
High Interaction

Combining block copolymers and hydrogen bonding for poly(lactide) toughening

RSC Advances ◽  
2014 ◽  
Vol 4 (26) ◽  
pp. 13266 ◽  
Author(s):  
Paula A. Delgado ◽  
Marc A. Hillmyer
Keyword(s):  
Hydrogen Bonding ◽  
Block Copolymers

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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