hydrophobic polymers and their nanocomposites. The compatibility of industrial
polymers with nanoparticles of various types has been a major topic of materials
science in recent decades. Macromolecules as one of the components in hybrid
materials or nanocomposites can be either inactive or active in terms of photochemistry. Common technical polymers or biopolymers are typical examples of photoinactive substances. In this case, the photoactivity is achieved by the addition of
photoactive components or by modifying either layered particles or the polymer with
photoactive moieties. The presence of chromophore or luminophore groups in the
chains of polymers usually plays a minor role in their chemical and physical
properties. The presence of luminophore labels mostly does not affect the binding
of a polymer to nanoparticles, because only low contents of such groups are needed
for an optical or photophysical activity of the material [71]. One of the challenges of
using polymer nanocomposites as optical materials is their transparency in the
relevant range of the electromagnetic spectrum [74]. The protecting role of the
polymer and nanoparticles in such materials is very important, especially with
dyes that are sensitive to oxidation or humidity [74, 75].
Polymer nanocomposites can be prepared by traditional routes; the most common
method of synthesis is the mixing of a polymer with nanoparticles by the adsorption
of macromolecules from their solutions or melt extrusion. In a few cases, polymerization from monomers was also performed. An example is the polymerization of
styrene, which together with R6G and a polymerization initiator was pre-intercalated
in an organically modified fluoro-mica [76]. The final composite materials exhibited
improved thermal and chemical stability and energy migration [76]. In another
study, the degree of polymerization influenced the properties of the dye component
in the material. In situ polymerization leading to the formation of poly(norbornene)
affected the molecular aggregation of oxazine 1 and FRET between oxazine 1 monomers and J-aggregates [59]. In another study, the presence of an inert and photochemically inactive polymer suppressed the molecular aggregation of the dye and
significantly improved the photoactivity of the composite [60].
Polyelectrolytes in LbL Assemblies
Polyelectrolytes can significantly alter their surface charge, depending on the density
of the charged groups in the polymer chains and the charge distribution on the
surface of the modified particles. Polyelectrolytes have been applied in numerous
works, many dealing with the synthesis of photoactive LbL films [40, 77]. For
example, the anionic block copolymer poly(tert-butyl acrylateco-ethyl acrylate-comethacrylic acid) was deposited alternatively with LDH nanosheets to form an LbL
film [78]. The polymer phase formed multicomponent micelles carrying the complex
of Zn
II (8-hydroxyquinolate) 2 and a merocyanine dye. Different types of FRET were
observed in this film: zero-dimensional FRET inside the micelles and
two-dimensional between the micelles [78]. In another study, FRET was used as a
very effective method for monitoring changes in photoactive substances during the
deposition of LbL assemblies [40]. The films were based on a layered silicate, a
228
J. Bujdák
polymers with nanoparticles of various types has been a major topic of materials
science in recent decades. Macromolecules as one of the components in hybrid
materials or nanocomposites can be either inactive or active in terms of photochemistry. Common technical polymers or biopolymers are typical examples of photoinactive substances. In this case, the photoactivity is achieved by the addition of
photoactive components or by modifying either layered particles or the polymer with
photoactive moieties. The presence of chromophore or luminophore groups in the
chains of polymers usually plays a minor role in their chemical and physical
properties. The presence of luminophore labels mostly does not affect the binding
of a polymer to nanoparticles, because only low contents of such groups are needed
for an optical or photophysical activity of the material [71]. One of the challenges of
using polymer nanocomposites as optical materials is their transparency in the
relevant range of the electromagnetic spectrum [74]. The protecting role of the
polymer and nanoparticles in such materials is very important, especially with
dyes that are sensitive to oxidation or humidity [74, 75].
Polymer nanocomposites can be prepared by traditional routes; the most common
method of synthesis is the mixing of a polymer with nanoparticles by the adsorption
of macromolecules from their solutions or melt extrusion. In a few cases, polymerization from monomers was also performed. An example is the polymerization of
styrene, which together with R6G and a polymerization initiator was pre-intercalated
in an organically modified fluoro-mica [76]. The final composite materials exhibited
improved thermal and chemical stability and energy migration [76]. In another
study, the degree of polymerization influenced the properties of the dye component
in the material. In situ polymerization leading to the formation of poly(norbornene)
affected the molecular aggregation of oxazine 1 and FRET between oxazine 1 monomers and J-aggregates [59]. In another study, the presence of an inert and photochemically inactive polymer suppressed the molecular aggregation of the dye and
significantly improved the photoactivity of the composite [60].
Polyelectrolytes in LbL Assemblies
Polyelectrolytes can significantly alter their surface charge, depending on the density
of the charged groups in the polymer chains and the charge distribution on the
surface of the modified particles. Polyelectrolytes have been applied in numerous
works, many dealing with the synthesis of photoactive LbL films [40, 77]. For
example, the anionic block copolymer poly(tert-butyl acrylateco-ethyl acrylate-comethacrylic acid) was deposited alternatively with LDH nanosheets to form an LbL
film [78]. The polymer phase formed multicomponent micelles carrying the complex
of Zn
II (8-hydroxyquinolate) 2 and a merocyanine dye. Different types of FRET were
observed in this film: zero-dimensional FRET inside the micelles and
two-dimensional between the micelles [78]. In another study, FRET was used as a
very effective method for monitoring changes in photoactive substances during the
deposition of LbL assemblies [40]. The films were based on a layered silicate, a
228
J. Bujdák