scholarly journals Dextran-Coated Latex Nanoparticles via Photo-RAFT Mediated Polymerization Induced Self-Assembly

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4064
Author(s):  
Valeria Lizeth Romero Castro ◽  
Brahim Nomeir ◽  
Ana Andreea Arteni ◽  
Malika Ouldali ◽  
Jean-Luc Six ◽  
...  
Keyword(s):  
Self Assembly ◽  
Diblock Copolymers ◽  
Chain Transfer ◽  
Degree Of Polymerization ◽  
Amphiphilic Copolymers ◽  
Shell Nanoparticles ◽  
Transmission Electron Microscopy Analysis ◽  
Hydroxypropyl Methacrylate ◽  
Electron Microscopy Analysis

Polysaccharide coated nanoparticles represent a promising class of environmentally friendly latex to replace those stabilized by small toxic molecular surfactants. We report here an in situ formulation of free-surfactant core/shell nanoparticles latex consisting of dextran-based diblock amphiphilic copolymers. The synthesis of copolymers and the immediate latex formulation were performed directly in water using a photo-initiated reversible addition fragmentation chain transfer-mediated polymerization induced self-assembly strategy. A hydrophilic macromolecular chain transfer-bearing photosensitive thiocarbonylthio group (eDexCTA) was first prepared by a modification of the reducing chain end of dextran in two steps: (i) reductive amination by ethylenediamine in the presence of sodium cyanoborohydride, (ii) then introduction of CTA by amidation reaction. Latex nanoparticles were then formulated in situ by chain-extending eDexCTA using 2-hydroxypropyl methacrylate (HPMA) under 365 nm irradiation, leading to amphiphilic dextran-b-poly(2-hydroxypropyl methacrylate) diblock copolymers (DHX). Solid concentration (SC) and the average degree of polymerization - Xnˉ- of PHPMA block (X) were varied to investigate their impact on the size and the morphology of latex nanoparticles termed here SCDHX. Light scattering and transmission electron microscopy analysis revealed that SCDHX form exclusively spherical nano-objects. However, the size of nano-objects, ranging from 20 nm to 240 nm, increases according to PHPMA block length.

scholarly journals Synthesis of Poly(3-vinylpyridine)-Block-Polystyrene Diblock Copolymers via Surfactant-Free RAFT Emulsion Polymerization

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3145 ◽  
Author(s):  
Katharina Nieswandt ◽  
Prokopios Georgopanos ◽  
Clarissa Abetz ◽  
Volkan Filiz ◽  
Volker Abetz
Keyword(s):  
Emulsion Polymerization ◽  
Self Assembly ◽  
Diblock Copolymers ◽  
Chain Transfer ◽  
Raft Polymerization ◽  
Free Water ◽  
Monomer Conversion ◽  
Molecular Weights ◽  
Reversible Addition

In this work, we present a novel synthetic route to diblock copolymers based on styrene and 3-vinylpyridine monomers. Surfactant-free water-based reversible addition–fragmentation chain transfer (RAFT) emulsion polymerization of styrene in the presence of the macroRAFT agent poly(3-vinylpyridine) (P3VP) is used to synthesize diblock copolymers with molecular weights of around 60 kDa. The proposed mechanism for the poly(3-vinylpyridine)-block-poly(styrene) (P3VP-b-PS) synthesis is the polymerization-induced self-assembly (PISA) which involves the in situ formation of well-defined micellar nanoscale objects consisting of a PS core and a stabilizing P3VP macroRAFT agent corona. The presented approach shows a well-controlled RAFT polymerization, allowing for the synthesis of diblock copolymers with high monomer conversion. The obtained diblock copolymers display microphase-separated structures according to their composition.

Evaluation of intercalation and interaction in in-situ polymerized PLA-HNT bionanocomposites

2020 ◽  
pp. 096739112092779
Author(s):  
P Manju ◽  
P Santhana Gopala Krishnan ◽  
SK Nayak
Keyword(s):  
Electron Microscopy ◽  
Halloysite Nanotubes ◽  
Poly Lactic Acid ◽  
Resonance Spectroscopy ◽  
Hydroxyl Groups ◽  
Scanning Calorimetry ◽  
Transmission Electron Microscopy Analysis ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis

We report the in-situ synthesis of poly(lactic acid)–halloysite nanotubes (PLA-HNT) bionanocomposites, with a perspective to improve the interaction between PLA and HNT. Three PLA-HNT bionanocomposites with different HNT weight percentages were synthesized by polycondensation, followed by azeotropic distillation technique. Fourier transform infrared spectroscopy studies indicated the existence of hydrogen bonding between terminal hydroxyl groups of PLA and Si–O–Si groups present in the outer surface of HNT. Wide-angle X-ray diffraction, 29Si- and 27Al-nuclear magnetic resonance spectroscopy analysis confirmed the intercalation of PLA into HNT. Scanning electron microscopy analysis confirmed that there was no significant agglomeration and PLA matrix was found to be embedded with HNT. Transmission electron microscopy analysis also gave ample proof to substantiate the intercalation of PLA chains into HNT. Studies on zeta potential of PLA-HNT bionanocomposites, as compared with PLA, also confirmed the interactions between PLA and HNT. Single melting peak in differential scanning calorimetry analysis indicated the existence of one form of crystalline structure.

scholarly journals Uniform electroactive fibre-like micelle nanowires for organic electronics

2017 ◽  
Vol 8 (1) ◽  
Author(s):  
Xiaoyu Li ◽  
Piotr J. Wolanin ◽  
Liam R. MacFarlane ◽  
Robert L. Harniman ◽  
Jieshu Qian ◽  
...  
Keyword(s):  
Block Copolymers ◽  
Charge Carrier ◽  
Self Assembly ◽  
Diblock Copolymers ◽  
Field Effect Transistors ◽  
Fibre Length ◽  
Charge Carrier Mobility ◽  
Degree Of Polymerization ◽  
Selective Solvents ◽  
The Individual

Abstract Micelles formed by the self-assembly of block copolymers in selective solvents have attracted widespread attention and have uses in a wide variety of fields, whereas applications based on their electronic properties are virtually unexplored. Herein we describe studies of solution-processable, low-dispersity, electroactive fibre-like micelles of controlled length from π-conjugated diblock copolymers containing a crystalline regioregular poly(3-hexylthiophene) core and a solubilizing, amorphous regiosymmetric poly(3-hexylthiophene) or polystyrene corona. Tunnelling atomic force microscopy measurements demonstrate that the individual fibres exhibit appreciable conductivity. The fibres were subsequently incorporated as the active layer in field-effect transistors. The resulting charge carrier mobility strongly depends on both the degree of polymerization of the core-forming block and the fibre length, and is independent of corona composition. The use of uniform, colloidally stable electroactive fibre-like micelles based on common π-conjugated block copolymers highlights their significant potential to provide fundamental insight into charge carrier processes in devices, and to enable future electronic applications.

scholarly journals Selenol-Based Nucleophilic Reaction for the Preparation of Reactive Oxygen Species-Responsive Amphiphilic Diblock Copolymers

Polymers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 827
Author(s):  
Xiaowei An ◽  
Weihong Lu ◽  
Jian Zhu ◽  
Xiangqiang Pan ◽  
Xiulin Zhu
Keyword(s):  
Reactive Oxygen Species ◽  
Molecular Weight ◽  
Self Assembly ◽  
Diblock Copolymers ◽  
Raft Polymerization ◽  
Reactive Oxygen ◽  
Oxygen Species ◽  
Amphiphilic Copolymers ◽  
Nucleophilic Reaction ◽  
Amphiphilic Diblock Copolymers

Selenide-containing amphiphilic copolymers have shown significant potential for application in drug release systems. Herein, we present a methodology for the design of a reactive oxygen species-responsive amphiphilic diblock selenide-labeled copolymer. This copolymer with controlled molecular weight and narrow molecular weight distribution was prepared by sequential organoselenium-mediated reversible addition fragmentation chain transfer (Se-RAFT) polymerization and selenol-based nucleophilic reaction. Nuclear magnetic resonance (NMR) and matrix-assisted laser desorption/ionization time-to-flight (MALDI-TOF) techniques were used to characterize its structure. Its corresponding nanomicelles successfully formed through self-assembly from the copolymer itself. Such nanomicelles could rapidly disassemble under oxidative conditions due to the fragmentation of the Se–C bond. Therefore, this type of nanomicelle based on selenide-labeled amphiphilic copolymers potentially provides a new platform for drug delivery.

scholarly journals In Situ Formation of Core–Shell Nanoparticles in Epoxy Resin via Reversible Addition–Fragmentation Chain Transfer Dispersion Polymerization

2021 ◽  
Author(s):  
Eun Ho Lee ◽  
Kyungho Kim ◽  
Gyeongdong Yeom ◽  
Bongkuk Seo ◽  
Wonjoo Lee ◽  
...  
Keyword(s):  
Epoxy Resin ◽  
Dispersion Polymerization ◽  
Chain Transfer ◽  
Shell Nanoparticles ◽  
Reversible Addition ◽  
Resin Mixture ◽  
In Situ Formation ◽  
Core Shell Nanoparticles ◽  
First Time

We report for the first time in situ reversible addition–fragmentation chain transfer (RAFT) dispersion polymerization in an epoxy resin mixture for toughening of epoxy. Good dispersion of latex particles in...

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