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Effect of the isothermal crystallization method on amorphous block copolymers of aromatic polyamides and their packing behavior in two‐dimensional films for screening of potential crystallization ability

The crystalline packing of polymers with high tendencies to form amorphous materials has been attained by controlling intermolecular interactions. Block copolymers of aromatic polyamides in which hydrogen‐bonding moieties are sparing and mostly substituted easily form amorphous materials because of steric hindrance and weak intermolecular affinities. Block copolymers of aromatic polyamides synthesized from 4‐(N‐methylamino)benzoic acid, terephthalic acid chloride, and poly(propylene glycol)bis(2‐aminopropyl ether) are commonly amorphous, regardless of unit length. Despite these copolymers not having distinct hydrophobic groups along the alkyl chain, aromatic rings in the same plane could be packed by π–π stacking by the method of two‐dimensional interfacial molecular films. The hard segment responsible for the c‐axis length increased the tilted angle depending on the chain length; as a result, the chain length was not dependent on the long spacing value. Actually, the layered period in organized films of aromatic polyamides did not depend on the segment length and always indicated a constant value. Isothermal crystallization was attempted for block copolymers of aromatic polyamides exhibiting potential packing ability by the method of organized molecular films. The analyzed glass transition temperature of the oligomer corresponding only to the block unit was adopted as the crystallization temperature. All amorphous polyamides used in this study crystallized after 24 h. A monoclinic packing structure and interactions between the few remaining hydrogen‐bonding moieties were suggested by a reciprocal lattice analysis. POLYM. ENG. SCI., 2017. © 2017 Society of Plastics Engineers

Authors:   Yusaku Shidara, Takeru Yunoki, Shuntaro Miura, Yuji Shibasaki, Atsuhiro Fujimori
Journal:   Polymer Engineering and Science
Year:   2017
Pages:   n/a
DOI:   10.1002/pen.24812
Publication date:   20-Dec-2017
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