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T. Onodera et al.
mechanism could be basically applied to produce the other kinds of hybridized NCs
such as polyalkylthiophene (PAT) core-platinum (Pt) hybridized NCs [20].
On the other hand, Ag core-PDA shell-type hybridized NCs were also produced
by using co-reprecipitation and microwave-irradiation method [21]. In this case, the
acetone solution of DA monomer was quickly injected into an aqueous dispersion
liquid of Ag NPs, and then DA NCs as a shell were formed well on the surface of
Ag NPs as a core. DA shell was converted to PDA shell by UV-irradiation.
In this chapter, a new type of hybridized PDA nanocrystal fibers (NCFs) [22] as a
core with gold (Au) NPs as a shell have been created, and nanostructural correlation
of optical properties will be discussed in detail. Interestingly, silica thin layer was
introduced experimentally between PDA core and Au shell so as to possibly control
LSPR effect from Au NPs [23].
13.2 Hybridized Polydiacetylene Nanocrystal Fibers
13.2.1 Preparation of PDA Nanocrystal Fibers
As described in the previous 13.1.2, it is possible to control the morphology of
organic NCs by suitably optimizing the reprecipitation conditions. In the case of
PDA NCs, the crystal size decreases in general with decreasing the concentration of
injected DA-acetone solution [10–12]. On the other hand, the added surfactant and
temperature of poor medium would affect remarkably the shape [22]. Actually, the
formation of PDA NCFs was confirmed by SEM (JEOL: JSM-6700F) observation
(Fig. 13.1). The two kinds of surfactants (SDS: sodium dodecyl sulfate, and CTAB:
hexadecyl trimethyl ammonium bromide) were employed and added to DA-acetone
solution in advance, and subsequently the injection was performed at the elevated
temperature (60 °C) of water medium. The typical diameter is ca. 30–50 nm and the
counter length is more than several μm in any resulting PDA NCFs. On the other
hand, only PDA NCs were produced around and/or below at room temperature, even
though the surfactants were co-existed.
The formation mechanism of PDA NCFs is speculated as follows [10–12]. Probably, amorphous NPs of DA is formed at the initial stage just after injection at the
elevated temperature. These amorphous DA NPs are stabilized by the added surfactants, and then the delay in nanocrystallization would occur in individual amorphous
DA NPs. Meanwhile, amorphous DA NPs are crystallized to form DA NCs with
the elapsed time. At the next stage, already-formed DC NCs may act as a nucleus
and/or a kind of substrate, and then another amorphous DA NPs are adsorbed on
the facet surface of DA NCs. The adsorbed DA NPs are immediately crystallized
through homo-epitaxial-like crystal growth. Consequently, this repetition process
could provide one-dimensional DA NCFs, which are solid-state polymerized as usual
to produce PDA NCFs. The crystal lattice structure of PDA NCFs was the same as
that of PDA NCs by the measurements with powder XRD patterns (Bruker: D8
T. Onodera et al.
mechanism could be basically applied to produce the other kinds of hybridized NCs
such as polyalkylthiophene (PAT) core-platinum (Pt) hybridized NCs [20].
On the other hand, Ag core-PDA shell-type hybridized NCs were also produced
by using co-reprecipitation and microwave-irradiation method [21]. In this case, the
acetone solution of DA monomer was quickly injected into an aqueous dispersion
liquid of Ag NPs, and then DA NCs as a shell were formed well on the surface of
Ag NPs as a core. DA shell was converted to PDA shell by UV-irradiation.
In this chapter, a new type of hybridized PDA nanocrystal fibers (NCFs) [22] as a
core with gold (Au) NPs as a shell have been created, and nanostructural correlation
of optical properties will be discussed in detail. Interestingly, silica thin layer was
introduced experimentally between PDA core and Au shell so as to possibly control
LSPR effect from Au NPs [23].
13.2 Hybridized Polydiacetylene Nanocrystal Fibers
13.2.1 Preparation of PDA Nanocrystal Fibers
As described in the previous 13.1.2, it is possible to control the morphology of
organic NCs by suitably optimizing the reprecipitation conditions. In the case of
PDA NCs, the crystal size decreases in general with decreasing the concentration of
injected DA-acetone solution [10–12]. On the other hand, the added surfactant and
temperature of poor medium would affect remarkably the shape [22]. Actually, the
formation of PDA NCFs was confirmed by SEM (JEOL: JSM-6700F) observation
(Fig. 13.1). The two kinds of surfactants (SDS: sodium dodecyl sulfate, and CTAB:
hexadecyl trimethyl ammonium bromide) were employed and added to DA-acetone
solution in advance, and subsequently the injection was performed at the elevated
temperature (60 °C) of water medium. The typical diameter is ca. 30–50 nm and the
counter length is more than several μm in any resulting PDA NCFs. On the other
hand, only PDA NCs were produced around and/or below at room temperature, even
though the surfactants were co-existed.
The formation mechanism of PDA NCFs is speculated as follows [10–12]. Probably, amorphous NPs of DA is formed at the initial stage just after injection at the
elevated temperature. These amorphous DA NPs are stabilized by the added surfactants, and then the delay in nanocrystallization would occur in individual amorphous
DA NPs. Meanwhile, amorphous DA NPs are crystallized to form DA NCs with
the elapsed time. At the next stage, already-formed DC NCs may act as a nucleus
and/or a kind of substrate, and then another amorphous DA NPs are adsorbed on
the facet surface of DA NCs. The adsorbed DA NPs are immediately crystallized
through homo-epitaxial-like crystal growth. Consequently, this repetition process
could provide one-dimensional DA NCFs, which are solid-state polymerized as usual
to produce PDA NCFs. The crystal lattice structure of PDA NCFs was the same as
that of PDA NCs by the measurements with powder XRD patterns (Bruker: D8