We herein report
the synthesis and characterization of dual stimuli-responsive poly(2-iso-propyl-2-oxazoline)-block-poly(2-acrylamido
glycolic acid) (PiPrOx-b-PAGA) double
hydrophilic block copolymers (BCPs) by an effective combination of
ring-opening and reversible addition–fragmentation chain transfer
(RAFT) polymerization. The resulting materials are responsive toward
several external triggers: (1) the PiPrOx segment
undergoes a coil-to-globule transition upon heating above the cloud
point temperature (T
CP), (2) the PAGA
block chelates M2+ metal ions and provides straightforward
access to nanostructured hybrid materials, and (3) prolonged heating
above the T
CP for PiPrOx
enables crystallization-driven solution self-assembly (CDSA) toward
anisotropic micelles and superstructures. We are further able to show
that the cloud point temperature (T
CP)
of PiPrOx-b-PAGA micelles can be
tuned from ∼30 to 68 °C by varying either the BCP composition
(PiPrOx to PAGA ratio) or by the amount of metal
ions being present. The different aggregates were characterized by
transmission electron microscopy (TEM), wide-angle X-ray scattering
(WAXS), and dynamic light scattering (DLS). Our results indicate that
micellar size, shape, and T
CP are closely
connected to BCP composition and the nature of chelated metal ions.
In our opinion, such inorganic–organic hybrid materials are
of interest with regard to (photo)catalysis, as sensors, or as potential
drug delivery systems.
In this work, we present an ew synthetics trategy for fourfold-substituted perylene monoimides via tetrabrominated perylene monoanhydrides. X-ray diffraction analysis unveiled the intramolecular stacking orientation between the substituents and semicircular packing behavior.W eo bserved the remarkable influence of the substituent on the longevity and nature of the excited state upon visible light excitation.I nt he presenceo fp oly(dehydroalanine)-graftpoly(ethylene glycol)g raft copolymers as solubilizing template, the chromophores are capable of sensitizing [Mo 3 S 13 ] 2À clustersi na queous solution for stable visible light driven hydrogen evolution over three days.
Three triggers result in two measurable outputs from polymeric sensors: multiresponsive polyampholytic graft copolymers respond to pH‐value and temperature, as well as the type and concentration of metal cations and therefore, allow the transformation of external triggers into simply measurable outputs (cloud point temperature (TCP) and surface plasmon resonance (SPR) of encapsulated silver nanoparticles). The synthesis relies on poly(dehydroalanine) (PDha) as the reactive backbone and gives straightforward access to materials with tunable composition and output. In particular, a rather high sensitivity toward the presence of Cu2+, Co2+, and Pb2+ metal cations is found.
An effective strategy to enhance the performance of inorganic semiconductors is moving towards organic‐inorganic hybrid materials. Here, we report the design of core–shell hybrid materials based on a TiO2 core functionalized with a polyampholytic (poly(dehydroalanine)‐graft‐(n‐propyl phosphonic acid acrylamide) shell (PDha‐g‐PAA@TiO2). The PDha‐g‐PAA shell facilitates the efficient immobilization of the photosensitizer Eosin Y (EY) and enables electronic interactions between EY and the TiO2 core. This resulted in high visible‐light‐driven H2 generation. The enhanced light‐driven catalytic activity is attributed to the unique core–shell design with the graft copolymer acting as bridge and facilitating electron and proton transfer, thereby also preventing the degradation of EY. Further catalytic enhancement of PDha‐g‐PAA@TiO2 was possible by introducing [Mo3S13]2− cluster anions as hydrogen‐evolution cocatalyst. This novel design approach is an example for a multi‐component system in which reactivity can in future be independently tuned by selection of the desired molecular or polymeric species.
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