A hydrolysis-resistant amide-linkage heterofunctional initiator was synthesized and used successfully for polymerization of well-defined rod-coil block copolymers poly(N-isopropylacrylamide)-b-poly(Z-L-lysine) (PNIPAm-b-PZLys) by combination of atom transfer radical polymerization (ATRP) and amine hydrochloride mediated ring-opening polymerization (ROP). The ATRP of NIPAm was carried out at 0°C using CuBr/Me 6 TREN complex in 2-propanol and resulted in narrow polydispersity and high monomer conversion. The amine hydrochlorides have replaced the primary amine in the PNIPAm macroinitiator resulting in a well-controlled ROP of N ε -(carbobenzoxy)-L-lysine N-carboxyanhydride in DMF at 20°C. These amphiphilic block copolymers are able to form universal micelle morphologies of spherical micelles, wormlike micelles, and vesicles by varying the polymer compositions and the helicogenic common solvents. From synchrotron SAXS, WAXS, and TEM results, the PNIPAm-b-PZLys microphase self-assembly morphology in solid state is a hierarchical lamellar-inhexagonal structure. After the protective ε-benzyloxycarbonyl group is removed, the dual stimuli-responsive behaviors of the PNIPAm-b-PLys investigated by nuclear magnetic resonance spectroscopy in aqueous solution resulted in either coil-to-helix or coil-globule transition by changing the environmental condition of elevating the temperature or increasing the pH value.

We report the syntheses of azido-and acetylene-functionalized poly(N-isopropylacrylamide) (PNIPAm) copolymers and their use in the fabrication of ultrathin thermoresponsive microcapsules through direct covalent layer-by-layer (LbL) assembly using click chemistry. The clickable copolymers poly [Nisopropylacrylamide-co-(trimethylsilyl)propargylacrylamide] and poly(N-isoropylacrylamide-co-3-azideopropylacrylamide) were prepared through atom transfer radical polymerization (ATRP) at 0 °C using a synthesized dansyl-labeled initiator and the CuBr/Me 6 TREN (hexamethylated tris[2-(dimethylamino)ethyl] amine) catalyst complex in 2-propanol. After removing the protective trimethylsilyl groups, these clickable PNIPAm copolymers assemble alternately onto azido-modified silica particles in aqueous media through click reactions catalyzed by copper sulfate and sodium ascorbate. After removing the template, the microcapsules remained stable because of the presence of the covalently bonded triazole units; the microcapsules exhibited thermoresponsive and thermoreversible swelling/deswelling behaviors upon changing the temperature of the medium. Adjusting the number of clickable functionalities resulted in changes to the degree of cross-linking, thereby allowing control over the surface morphology and thickness of the covalently stabilized PNIPAm multilayer thin films. The microcapsules fabricated close to the lower critical solution temperature of PNIPAm exhibited extremely low surface roughnesses and thick multilayer films as a result of their compact chain conformation in aqueous solution, leading to tighter packing of the PNIPAm structure. We further postfunctionalized the surface of the multilayer thin film through click reactions with an azido-modified lissamine rhodamin dye to demonstrate the feasibility of further modification with potentially useful functionalities. Finally, preliminary study on the permeability of microcapsules was presented by using different molecular weigh tetramethylrhodamine isothiocyanate (TRITC)-labeled dextran and rhodamine 6G as probe molecules, and the results revealed that the microcapsules with tighter packing wall are selectively permeable to molecules and show potential applications for the encapsulation of a variety of materials.

The development of flexible electronics for wearable or implantable devices has become an exciting research area in recent years. With the transition from rigid to flexible devices, polymeric materials, in particular the fossil-based PET, have been extensively used as the device substrate. For the environmental sustainability reason, biobased products have drawn much attention as a green replacement for fossil-based polymers. In this work, poly(ethylene furanoate) (PEF), a 100% biobased polyester, was utilized to replace PET as the substrate, and the biopolymer, deoxyribonucleic acid (DNA), was applied as the active layer to form the all-polymer resistive switching memory devices that are fully solution processable. The devices demonstrated the writeonce-read-many-times (WORM) memory behavior with a low threshold voltage of approximately −2 V, an ON/OFF current ratio as high as 10 4 , and a data retention time over 10 4 s. No noticeable degradation was observed under bending with various radius of curvature and after 1000 cycles of bending, suggesting an excellent endurance against severe and repeated deformation.

Exploiting biomass has raised great interest as an alternative to the fossil resources for environmental protection. In this respect, polyethylene furanoate (PEF), one of the bio-based polyesters, thus reveals a great potential to replace the commonly used polyethylene terephthalate (PET) on account of its better mechanical, gas barrier, and thermal properties. Herein, a bio-based, flexible, conductive film is successfully developed by coupling a PEF plastic substrate with silver nanowires (Ag NWs). Besides the appealing advantage of renewable biomass, PEF also exhibits a good transparency around 90% in the visible wavelength range, and its constituent polar furan moiety is revealed to enable an intense interaction with Ag NWs to largely enhance the adhesion of Ag NWs grown above, as exemplified by the superior bending and peeling durability than the currently prevailing PET substrate. Finally, the efficiency of conductive PEF/Ag NWs film in fabricating efficient flexible organic thin-film transistor and organic photovoltaic (OPV) is demonstrated. The OPV device achieves a power conversion efficiency of 6.7%, which is superior to the device based on ITO/PEN device, manifesting the promising merit of the bio-based PEF for flexible electronic applications.

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