TY - JOUR
T1 - Tuning quaternary ammonium ionomer composition and processing to produce tough films
AU - Khan, Wayz R.
AU - Murdakes, Nick
AU - Cornelius, Chris J.
N1 - Funding Information:
This work was possible due to funding by a grant from the Nebraska Center for Energy Sciences Research at the University of Nebraska-Lincoln enabled major portions of this work.
Publisher Copyright:
© 2018
PY - 2018/4/25
Y1 - 2018/4/25
N2 - Multi-block and random quaternary ammonium poly (arylene ether sulfone) copolymer ionomers were synthesized using sequential reactions. Ionomer film processing involved two separate methods: heterogeneous-conversion and solution-casting a pseudo-solution. Film hydroxyl conductivity, water swelling, and tensile strength were dependent upon the hydrophilic and hydrophobic block-length. 1H nuclear magnetic resonance was used to evaluate brominated multi-block poly (arylene ether sulfone) composition, degree of functionalization (DF), and ion-exchange capacity (IEC). In general, multi-block ionomer hydroxyl conductivity was greater than its randomly functionalized counterpart at a similar IEC. Multi-block ionomer films with largest hydrophilic block length exhibited a hydroxide conductivity of 49.8 mS/cm. However, the equivalent random copolymer's conductivity was 1.02 times lower with a water uptake of 223 wt%, which were 190% higher than its multi-block counterpart. This was attributed to ion-clustering improvements, which is not present in a random ionomer. Equivalent copolymer ionomers had a percolation threshold associated with excessive swelling when its IEC exceeded 2.02 meq/g. In contrast to the random ionomer, the maximum swelling observed for the multi-block copolymers was 33.6% at an IEC of 2.86 meq/g. This swelling suppression at high IEC was attributed to the sequential hydrophilic-hydrophobic block architecture. Moreover, the solution-cast multi-block ionomer was found to possess the highest toughness of 1185 × 104 J/m3, which was 237% greater than its heterogeneous counterpart. These results suggest that block length and ionomer processing play a critical role in controlling swelling, improving mechanical strength, and enhancing ion transport.
AB - Multi-block and random quaternary ammonium poly (arylene ether sulfone) copolymer ionomers were synthesized using sequential reactions. Ionomer film processing involved two separate methods: heterogeneous-conversion and solution-casting a pseudo-solution. Film hydroxyl conductivity, water swelling, and tensile strength were dependent upon the hydrophilic and hydrophobic block-length. 1H nuclear magnetic resonance was used to evaluate brominated multi-block poly (arylene ether sulfone) composition, degree of functionalization (DF), and ion-exchange capacity (IEC). In general, multi-block ionomer hydroxyl conductivity was greater than its randomly functionalized counterpart at a similar IEC. Multi-block ionomer films with largest hydrophilic block length exhibited a hydroxide conductivity of 49.8 mS/cm. However, the equivalent random copolymer's conductivity was 1.02 times lower with a water uptake of 223 wt%, which were 190% higher than its multi-block counterpart. This was attributed to ion-clustering improvements, which is not present in a random ionomer. Equivalent copolymer ionomers had a percolation threshold associated with excessive swelling when its IEC exceeded 2.02 meq/g. In contrast to the random ionomer, the maximum swelling observed for the multi-block copolymers was 33.6% at an IEC of 2.86 meq/g. This swelling suppression at high IEC was attributed to the sequential hydrophilic-hydrophobic block architecture. Moreover, the solution-cast multi-block ionomer was found to possess the highest toughness of 1185 × 104 J/m3, which was 237% greater than its heterogeneous counterpart. These results suggest that block length and ionomer processing play a critical role in controlling swelling, improving mechanical strength, and enhancing ion transport.
KW - Hydroxyl conductivity
KW - Multiblock ionomer
KW - Swelling and film strength
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U2 - 10.1016/j.polymer.2018.03.028
DO - 10.1016/j.polymer.2018.03.028
M3 - Article
AN - SCOPUS:85044097657
VL - 142
SP - 99
EP - 108
JO - Polymer
JF - Polymer
SN - 0032-3861
ER -