Synthesis of Hyperbranched Polyacrylates by a Chloroinimer Approach

Bio-Inspired Fluoro-polydopamine Meets Barium Titanate Nanowires: A Perfect Combination to Enhance Energy Storage Capability of Polymer Nanocomposites

Rapid evolution of energy storage devices expedites the development of high-energy-density materials with excellent flexibility and easy processing. The search for such materials has triggered the development of high-dielectric-constant (high-k) polymer nanocomposites. However, the enhancement of k usually suffers from sharp reduction of breakdown strength, which is detrimental to substantial increase of energy storage capability. Herein, the combination of bio-inspired fluoro-polydopamine functionalized BaTiO₃ nanowires (NWs) and a fluoropolymer matrix offers a new thought to prepare polymer nanocomposites. The elaborate functionalization of BaTiO₃ NWs with fluoro-polydopamine has guaranteed both the increase of k and the maintenance of breakdown strength, resulting in significantly enhanced energy storage capability. The nanocomposite with 5 vol % functionalized BaTiO₃ NWs discharges an ultrahigh energy density of 12.87 J cm^-3 at a relatively low electric field of 480 MV m^-1, more than three and a half times that of biaxial-oriented polypropylene (BOPP, 3.56 J cm^-3 at 600 MV m^-1). This superior energy storage capability seems to rival or exceed some reported advanced nanoceramics-based materials at 500 MV m^-1. This new strategy permits insights into the construction of polymer nanocomposites with high energy storage capability.

Mussel-inspired Fluoro-Polydopamine Functionalization of Titanium Dioxide Nanowires for Polymer Nanocomposites with Significantly Enhanced Energy Storage Capability

High-dielectric-constant polymer nanocomposites are demonstrated to show great promise as energy storage materials. However, the large electrical mismatch and incompatibility between nanofillers and polymer matrix usually give rise to significantly reduced breakdown strength and weak energy storage capability. Therefore, rational selection and elaborate functionalization of nanofillers to optimize the performance of polymer nanocomposites are vital. Herein, inspired by adhesive proteins in mussels, a facile modification by fluoro-polydopamine is employed to reinforce the compatibility of TiO₂ nanowires in the fluoropolymer matrix. The loading of 2.5 vol % f-DOPA@TiO₂ NWs leads to an ultrahigh discharged energy density of 11.48 J cm⁻³ at 530 MV m⁻¹, more than three times of commercial biaxial-oriented polypropylene (BOPP, 3.56 J cm⁻³ at 600 MV m⁻¹). A gratifying high energy density of 9.12 J cm⁻³ has also been obtained with nanofiller loading as high as 15 vol % at 360 MV m⁻¹, which is nearly double to that of pure P(VDF-HFP) (4.76 J cm⁻³ at 360 MV m⁻¹). This splendid energy storage capability seems to rival or exceed most of previously reported nano-TiO₂ based nanocomposites. The methods presented here provide deep insights into the design of polymer nanocomposites for energy storage applications.

In Situ Generated ABA Block Copolymers from CO2, Cyclohexene Oxide, and Poly(dimethylsiloxane)s

Chain-transfer polymerization reactions with siloxanes, CO₂, and cyclohexene oxide have been conducted, utilizing two β-diiminate (BDI) zinc-based catalysts, BDI^CF3(1)-ZnEt and BDI^CF3(2)-ZnEt ((BDI^CF3(1))H = [CH(CCF₃NC₆H₄-2,6-C₂H₅)₂] and (BDI^CF3(2))H = [CH(CCF₃NC₆H₄-2,6-CH(CH₃)₂)₂]). The correlation between equivalents of siloxane and the corresponding molecular masses and glass transition temperatures is exhibited. Furthermore, the in situ preparation of ABA block copolymers from carbon dioxide, cyclohexene oxide, and α,ω-bis(hydroxymethyl)poly(dimethylsiloxane)s is presented. This reaction was found to strongly relate to a robust Lewis acid catalyst like the outlined complexes. The polymer properties can be tuned by varying the amount of chain-transfer agent or changing the catalyst. The resulting polymer structures and incorporation of siloxanes were revealed by ²⁹Si NMR spectroscopy, ¹H NMR spectroscopy, ESI-MS, GPC, and DSC.

Facile synthesis of photolabile dendritic-unit-bridged hyperbranched graft copolymers for stimuli-triggered topological transition and controlled release of Nile red

Successive RAFT SCVP and ROP were used to generate novel hyperbranched graft copolymers with the ability for the photo-triggered degradation and accelerative release of hydrophobic dye.

Synthesis, postmodification and fluorescence properties of reduction-cleavable core-couplable miktoarm stars with a branched core

Postmodification of (PEG)_m(PCL)_n miktoarm stars with a dual-reactive branched core allowed the introduction of versatile functionalities, and the coumarin-functionalized star exhibited tunable fluorescence properties sensitive to solvent polarity and reduction stimulus.

Spectroscopic investigation on the interaction of hyperbranched poly (amine) ester with model plasma protein: effect on the structural and conformational changes

Mechanism of interaction between hyperbranched poly (amine) ester (HPAE) and bovine serum albumin (BSA) was investigated using fluorescence, synchronous fluorescence, three-dimensional fluorescence spectra, UV-Vis spectrometry and circular dichroism (CD). The structural and conformational changes of BSA induced by HPAE were also revealed in this study. Stern-Volmer analysis of fluorescence quenching showed that BSA fluorescence was statically quenched by HPAE, which implied that ground state complex formed between BSA and HPAE. Vander Waals force and hydrogen bond played major roles in the interaction of HPAE with BSA. The distance, r between the donor (BSA) and acceptor (HPAE) was calculated based on the Forster's theory of non-radiation energy transfer and was found to be 3.24 nm. Synchronous and three-dimensional fluorescence studies showed that the interaction of BSA with HPAE induced conformational changes in BSA. The secondary structural analysis by CD spectra suggested that HPAE binding induced BSA to form a more compact conformation with about 6.9% transformation of α-helix to β-sheet. Molecular model of the interaction of HPAE with BSA was also presented according to the results of this study.

Effect of branching density on avidity of hyperbranched glycomimetics for mannose binding lectin

Hyperbranched glycopolymers containing mannose units in the branch point were synthesized through the copolymerization of a mannose inimer and mannose acrylate via atom transfer radical polymerization (ATRP). Incorporating a saccharide residue at the branch point results in a closer analogue to natural branched polysaccharides. Gel permeation chromatography characterization of the polymers qualitatively indicates branching in samples from polymerizations utilizing the mannose inimer. Deprotection of the acetate protecting groups from the hyperbranched mannose polymers yields water-soluble polymers that interact with mannose binding lectin (MBL), a key protein of the innate immunity complement system. MBL interaction increases with increasing polymer molecular weight and increasing branching density. Notably, incorporating mannose into the branching repeat unit also increases the interaction of the glycopolymers with MBL compared with glycopolymers with the same branching density but with no mannose at the branch point.

Characterization of the commercial hyperbranched polyesters

In this paper, properties of the commercially available Boltorn? hydroxy-functional aliphatic hyperbranched polyesters of the second, third and fourth pseudo generation, were investigated. Beside that, samples of the third and fourth pseudo generation were fractionated using the precipitation fractionation method to obtain three fractions of each sample, which were also investigated in this paper. According to the results obtained by GPC analysis, molar mass and polydispersity of the investigated Boltorn? hyperbranched polyesters increased with increase of the pseudo generation number. Value of the limiting viscosity number of the investigated samples, determined using the viscosity measurements of dilute solutions of these polymers in N-methyl-2-pyrrolidone, increased with increase of the pseudo generation number. On the other side, value of the limiting viscosity number of the fractions decreased from the first up to the third fraction. The same trend was also observed for the values of the hydrodynamic diameter of parent samples and their fractions, determined by dynamic light scattering using N-methyl-2-pyrrolidone as solvent. The thermal properties of the investigated Boltorn? hyperbranched polyesters were determined by thermogravimetry in nitrogen atmosphere and it has been shown that thermal stability of these samples increased with increase of the pseudo generation number. End hydroxyl groups of the second and third pseudo generation samples were modified with ?-alanine to obtain hyperbranched samples soluble in water. That was fully accomplished only for the Boltorn? hyperbranched polyester of the second pseudo generation. On the other side, modified sample of the third pseudo generation was possible to dissolve in water only after adding small amount of the NaOH.