The arborescent polystyrene (APS) is used as a precursor to form ordered honeycomb-like microstructured template through self-assembly of water molecules at the air-solution interface via breath-figure mechanism. The APS is synthesized by successive cycles of functionalization (bromination) of polystyrene and grafting reactions via ambient temperature ATRP using the graft-from-graft approach. The resulting polymer film self-assembles to a micrometer-sized honeycomb-like arrangement. The morphology is investigated using AFM and SEM. © 2009 American Chemical Society.

R. Dhamodharan

Department Of Chemistry

Kothandapani Ganesh Sanjeevi Babu

AIR-SOLUTION INTERFACE

Ambient temperatures

functionalization

GRAFT-FROM

GRAFTING REACTIONS

Water molecule

ATOM TRANSFER RADICAL POLYMERIZATION

Grafting (chemical)

Honeycomb structures

Phase shifters

Polymer films

Polystyrenes

Temperature

Phase interfaces

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Macromolecules

The preparation of porous films (average size variation from 1 to 32 μm) of a 1:1 blend of chitosan with poly(EG-ran-PG) by the controlled evaporation of water from a 2 wt % aqueous acetic acid solution is reported. Interestingly, the blend exhibited porosity that could be tailored from 1 to 32 μm with the temperature of preparation of the blend film. The powder X-ray diffraction, Fourier transform infrared, and differential scanning calorimetry analyses of the films suggested the formation of partially miscible blends. Temperature-induced phase separation of the blend appears to be the mechanism of pore formation. The tensile strength, cytotoxicity, and biocompatibility of the blend films for the growth of mesenchymal stem cells were assessed vis-a-vis chitosan. The 1:1 blend film was observed to lack cytotoxicity and was also viable for the growth of mesenchymal stem cells. The tensile properties of the 1:1 blend were superior to those of the chitosan film. The simple preparation of porous, nontoxic, and biocompatible films could find use as a scaffold in the growth of tissue, and especially bone tissue, in wound dressing, and in filtration if a better control over pore size is achieved. © 2018 American Chemical Society.

Fulltext

ACS Omega

Biocompatible Porous Scaffolds of Chitosan/Poly(EG- ran-PG) Blends with Tailored Pore Size and Nontoxic to Mesenchymal Stem Cells: Preparation by Controlled Evaporation from Aqueous Acetic Acid Solution

New, eco-friendly nanocomposite materials have been synthesized from natural rubber (NR) and magnetite nanoparticles for the first time. The poor oil resistance of natural rubber is exploited for the removal of oil spills. Towards this purpose, mildly epoxidized natural rubber (ENR)-magnetite nanoparticle (MN) nanocomposites are prepared and the absorption of petrol (gasoline) is studied. The extent of epoxidation is controlled in such a manner that the NR does not lose its elasticity while retaining to a significant degree its oil absorbing property. Epoxidation also serves as a means for binding sufficient quantity of MNs so that the composite can be recovered using a magnetic field. ENR with 5 mol% of epoxidation served as the best absorbent among all the absorbents studied as it was stable in petrol even after many days of immersion. It is observed that the ENR-MN nanocomposite absorbs 7 g of petrol per gram without any mass loss. The material was reused for several cycles without much loss in the capacity. The petrol uptake of ENR-MN is greater than that of butyl rubber which is the most commercially used rubber for oil spill removal. Porous rubber was also synthesized for the first time as oil uptake is facilitated not only by the hydrophobicity but also by the capillary absorption. Porous ENR absorbed a relatively larger amount of oil and exhibited the highest stability in oil. All the sorbents have quite high absorption capacities to be applied practically with a very low water uptake and a few of the absorbents could be satisfactorily reused. The model studies promise their potential use in the environmental field. © 2013 The Royal Society of Chemistry.

Journal of Materials Chemistry A

Epoxidized natural rubber-magnetite nanocomposites for oil spill recovery

A new synthetic methodology is developed for preparing graft copolymers via RAFT polymerization method by the "R group approach" onto styrenic polymers. In this approach, latent sites of the styrenic polymer was brominated first and then converted into macro-RAFT agents with pyrazole and thio dodecyl as the Z groups. This was used to synthesize graft copolymer such as polystyrene-graft-polymethyl methacrylate (PS-g-PMMA), polystyrene-graft- poly(isobornyl acrylate), polystyrene-graft-poly[2-(acetoacetoxy)ethyl methacrylate] (PS-g-PAEMA), and poly(para-methoxystyrene)-graft-polystyrene (P(p-MS)-g-PS). The polymers are characterized by gel permeation chromatography, 1H NMR, IR, and atomic force microscopy (AFM). The morphology of PS-g-PMMA in THF was investigated using AFM and island-like features were noticed. The AFM studies of the PS-g-PAEMA graft copolymers revealed the formation of globules and ribbon-like morphological features. The PS-g-PAEMA graft copolymers form complex with Fe(III) in dimethylformamide and the AFM studies suggest the formation of globular superstructures. Copyright © 2012 Wiley Periodicals, Inc.

Journal of Polymer Science, Part A: Polymer Chemistry

Synthesis of graft copolymers onto styrenic polymer backbone via "grafting from" raft process

Well defined graft copolymers are prepared by "grafting from" atom transfer radical polymerization (ATRP) at room temperature (30°C). The experiments were aimed at grafting methacrylates and styrene at latent initiating sites of polystyrene. For this purpose, the benzylic hydrogen in polystyrene was subjected to allylic bromination with Af-bromosuccinimide and azobisisobutrylnitirle to generate tertiary bromide ATRP initiating sites (Br-C-PS). The use of Br-C-PS with lesser mol % of bromide initiating groups results in better control and successful graft copolymerization. This was used to synthesize a series of new graft copolymers such as PS-g-PBnMA, PS-g-PBMA, PS-g-GMA, and PS-g-(PMMA-b-PtBA) catalyzed by CuBr/PMDETA system, in bulk, at room temperature. The polymers are characterized by GPC, NMR, FTIR, TEM, and TGA. Graft copolymerization followed by block polymerization enabled the synthesis of highly branched polymer brush, in which the grafting density can be adjusted by appropriate choice of bromide concentration in the polystyrene. © 2007 Wiley Periodicals, Inc.

Grafting of methacrylates and styrene on to polystyrene backbone via a "grafting from" ATRP process at ambient temperature

The ability to do very rapid bulk atom transfer radical polymerization (ATRP) of benzyl methacrylate using a CuX/PMDETA complex at room temperature was demonstrated in this study. The experimental conditions required to synthesize low- and high-molecular-weight poly(benzyl methacrylate) with low polydispersity are reported here. The controlled/living nature of the polymerization was demonstrated through kinetic studies, and chain-extension studies. © 2004 Wiley Periodicals, Inc.

Very Rapid Copper-Mediated Atom Transfer Radical Polymerization of Benzyl Methacrylate at Ambient Temperature

A detailed investigation of the atom transfer radical polymerization of methyl methacrylate (MMA) with the ethyl 2-bromoisobutyrate (2-EiBBr)/CuBr/N,N′,N′,N″-pentamethyldiethylenetriamine (PMDETA) catalyst system in anisole was performed at 30 °C. The number-average molecular weight of the PMMA was observed to increase gradually and linearly while the polydispersity index (PDI) remained narrow throughout the reaction time. The summary of these studies showed that PMMA with molecular weight up to 105 g/mol could be synthesized in a controlled fashion at room temperature. The new route developed was utilized to demonstrate the facile synthesis of ABC and CBABC multiblock copolymers of styrene, tert-butyl acrylate (tBA), and MMA. For this, the starting blocks of AB and BAB were synthesized by coupling different ATRP methods reported. The end-block consisting of PMMA was synthesized by the ATRP of MMA using the CuCl/PMDETA catalyst system (halogen exchange) with anisole as the solvent at room temperature. Gel permeation chromatography (GPC) was used to determine the Mn, Mw, and PDI of the polymers synthesized. The PDI of all the block copolymers is found to be low (1.1-1.4). 1H NMR spectroscopy was used to determine the chemical composition of the block copolymers. Additional evidence for the blocky nature was also gained from FT-IR and thermal analysis.

Facile synthesis of ABC and CBABC multiblock copolymers of styrene, tert-butyl acrylate, and methyl methacrylate via room temperature ATRP of MMA

Langmuir

Patterning on Nonplanar Substrates: Flexible Honeycomb Films from a Range of Self-assembling Star Copolymers

Progress in Polymer Science

Erratum to: “Controlled/living radical polymerization: Features, developments and perspectives” [Prog. Polym. Sci. 32 (2007) 93–146]

Arborescent polystyrene via ambient temperature ATRP: Toward ordered honeycomb microstructured templates

Journal	Macromolecules
ISSN	00249297
Open Access	No