In this study, we synthesized a low-molecular-weight polytyrosine (PTyr) through living ring-opening polymerization of the α-amino acid-N-carboxyanhydride and then blended it with poly(4-vinylpyridine) (P4VP) homopolymer in N,N-dimethylformamide (DMF) and MeOH solutions, thereby controlling the miscibility behavior and secondary structures of the PTyr. Infrared spectroscopy revealed that the PTyr/P4VP mixture featured strong hydrogen bonds between the OH groups of PTyr and the pyridyl groups of P4VP. Differential scanning calorimetry revealed that the glass transition temperatures of the PTyr/P4VP complexes formed from MeOH solutions were higher than those of the corresponding PTyr/P4VP miscible blends obtained from DMF solutions. The behavior of the PTyr/P4VP blends obtained after evaporation of the DMF solutions was consistent with separated random coils of the PTyr chains. The increased degree of hydrogen bonding within the PTyr/P4VP complexes formed from MeOH solutions resulted in interpolymer complex aggregates; the corresponding enhanced intermolecular hydrogen bonding of PTyr with P4VP resulted in β-sheet conformations for PTyr, as evidenced from Fourier transform infrared spectroscopy, solid state nuclear magnetic resonance spectroscopy, and wide-angle X-ray diffraction analyses. This model, which takes advantage of the well-defined secondary structures (α-helices, β-sheets) of PTyr, can, therefore, be used to identity the behavior of separated coils and aggregated chains in polymer blend and complex systems.

A flexible PVDF/PMLG energy harvester captures electromechanical energy and its energy conversion efficiency was up to three times higher than individual PVDF and PMLG.

In this study, we examined the electrical energy conversion and mechanical characteristics of piezoelectric fibers of the synthetic polypeptide poly(g-benzyl-L-glutamate) (PBLG), prepared through cylindrical nearfield electrospinning (CNFES) of a uniform macromolecular solution of PBLG in CH 2 Cl 2 . A high electric field (from 5 Â 10 6 to 1.5 Â 10 7 V m À1 ) provided the electrostatic force to pull the polymer solution into a Taylor cone, from which the PBLG fibers were electrospun, yielding piezoelectric PBLG fibers highly oriented in an a-helical conformation, as determined through Fourier transform infrared spectroscopic analysis. The orientation of the a-helical conformation of these polypeptide fibers was greater than those of other polymer piezoelectric materials; indeed, micro-tensile testing revealed that the Young's modulus and tensile stress of the fibers were 3.64 GPa and 60.54 MPa, respectively, greater than those of the typical piezoelectric polymer poly(vinylidene difluoride). The voltage outputs of single piezoelectric fibers reached as high as 89.14 mV with 8 MU resistance, with a maximum power output of 138.42 pW. PBLG piezoelectric fibers directly patterned on a cicada wing, with an interdigitated electrode for energy harvesting and a vibrational frequency of approximately 10-30 Hz, produced voltages ranging from 7.64 to 14.25 mV; such systems have potential applications as sensors and harvesters.

In this study, the influence of the functional groups by the diblock copolymers of poly(styrene-b-4-vinylpyridine) (PS-b-P4VP), poly(styrene-b-2-vinylpyridine) (PS-b-P2VP), and poly(styrene-b-methyl methacrylate) (PS-b-PMMA) on their blends with octa-functionalized phenol polyhedral oligomeric silsesquioxane (OP-POSS) nanoparticles (NPs) was investigated. The relative hydrogen bonding strengths in these blends follow the order PS-b-P4VP/OP-POSS > PS-b-P2VP/OP-POSS > PS-b-PMMA/OP-POSS based on the Kwei equation from differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopic analyses. Small-angle X-ray scattering and transmission electron microscopic analyses show that the morphologies of the self-assembly structures are strongly dependent on the hydrogen bonding strength at relatively higher OP-POSS content. The PS-b-P4VP/OP-POSS hybrid complex system with the strongest hydrogen bonds shows the order-order transition from lamellae to cylinders and finally to body-centered cubic spheres upon increasing OP-POSS content. However, PS-b-P2VP/OP-POSS and PS-b-PMMA/OP-POSS hybrid complex systems, having relatively weaker hydrogen bonds, transformed from lamellae to cylinder structures at lower OP-POSS content (<50 wt%), but formed disordered structures at relatively high OP-POSS contents (>50 wt%).