Piezoelectric
polyvinylidene fluoride (PVDF) provided an opportunity
for non-invasive in situ electrical stimulation of cell behavior,
yet its electroactive β phase was difficult to obtain due to
its instability in the molten state. Herein, polyaniline (PANI) protrusions
were in situ oxidation-polymerized on molybdenum disulfide (MoS2) nanosheets (PANI-MoS2). Then, PANI-MoS2 was introduced into laser additive-manufactured PVDF scaffolds.
On the one hand, PANI protrusions produced steric hindrance between
adjacent MoS2 nanosheets and inhibited the stacking and
aggregating of MoS2. On the other hand, PANI-MoS2 could serve as a platform to achieve interfacial polarization locking.
Specifically, Mo–S dipoles in MoS2 and π electron
clouds over the N atom in PANI locked −CH2 dipoles
in PVDF through electrostatic and hydrogen bond interactions, respectively,
which forced −CH2 to align perpendicularly to the
basal plane of MoS2 and bialy to one side of the PVDF main
chain, thereby forming a full-reverse planar zigzag configuration
of the polarized β phase and maintaining its stable existence.
The results demonstrated that the β phase of the scaffolds was
significantly increased from 43 to 90%, which resulted in an enhanced
electrical output performance. The improved electrical output greatly
promoted osteoblast-like cell proliferation and differentiation. Furthermore,
owing to the pulling-out effect of MoS2 and improved interfacial
stress transfer between MoS2 and the polymer matrix, the
mechanical properties of scaffolds were also enhanced. These findings
suggested that the piezoelectric scaffolds had great potential in
bone tissue engineering.
Two kinds of modified poly(p-phenylene benzoxazole) (PBO), the copolymer of TPA (SPBO) and p-SPBO, containing ionic groups in the macromolecular chains were obtained by copolymerization from 1,3-diamino-4,6-dihydroxybenzene dihydrochloride (DAR) and terephthalic acid (TPA), with the addition of selected amounts (1.5-5.0% molar ratio over DAR) of 5-sulfoisophthalic acid monosodium salt or sulfoterephthalic acid monopotassium salt in place of the TPA, respectively, in poly(phosphoric acid) (PPA). The resultant PBO/PPA, SPBO/PPA, and p-SPBO/PPA lyotropic liquid-crystalline solutions were spun into fibers by a dry-jet wet-spinning technique. Chemically modified PBO fibers with sulfonate salt pendants in the polymer chains were obtained for the first time. The surface wetting behavior and interfacial shear strength between the fiber and epoxy resin were investigated. The interference of sulfonate salt pendants on the crystalline morphology was measured.
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