The polymerization of MMA, at ambient temperature, mediated by dansyl chloride is investigated using controlled radical polymerization methods. The solution ATRP results in reasonably controlled polymerization with PDI < 1.3. The SET-LRP polymerization is less controlled while SET-RAFT polymerization is controlled producing poly(methyl methacrylate) (PMMA) with the PDI < 1.3. In all the cases, the polymerization rate followed first order kinetics with respect to monomer conversion and the molecular weight of the polymer increased linearly with conversion. The R group in the CTAs do not appear to play a key role in controlling the propagation rate. SET-RAFT method appears to be a simpler tool to produce methacrylate polymers, under ambient conditions, in comparison with ATRP and SET-LRP. Fluorescent diblock copolymers, P(MMA-b-PhMA), were synthesized. These were highly fluorescent with two distinguishable emission signatures from the dansyl group and the phenanthren-1-yl methacrylate block. The fluorescence emission spectra reveal interesting features such as large red shift when compared to the small molecule. © 2012 Wiley Periodicals, Inc.

R. Dhamodharan

Department Of Chemistry

Ambient conditions

CONTROLLED POLYMERIZATION

CONTROLLED RADICAL POLYMERIZATION

DANSYL CHLORIDE

First order kinetics

FLUORESCENCE EMISSION SPECTRA

Fluorescent polymers

METHACRYLATE POLYMERS

Monomer conversions

POLYMERIZATION OF MMA

POLYMERIZATION RATES

PROPAGATION RATE

Red shift

REVERSIBLE ADDITION FRAGMENTATION CHAIN TRANSFER

SET-LRP

SINGLE ELECTRON TRANSFER

Small molecules

SOLUTION ATRP

Acrylic monomers

Block copolymers

Chlorine compounds

Emission spectroscopy

Esters

Fluorescence

Free radical polymerization

LIVING POLYMERIZATION

Polymers

Temperature

ATOM TRANSFER RADICAL POLYMERIZATION

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

Journal of Polymer Science, Part A: Polymer Chemistry

Controlled radical polymerization of cyclohexyl methacrylate (CHMA), at ambient temperature, using various chain transfer agents (CTAs) is successfully demonstrated via single electron transfer-radical addition fragmentation chain transfer (SET-RAFT). Well-controlled polymerization with narrow molecular weight distribution (Mw/Mn) &lt; 1.25 was achieved. The polymerization rate followed first-order kinetics with respect to monomer conversion, and the molecular weight of the polymer increased linearly up to high conversion. A novel, fluorescein-based initiator, a novel fluorescent CTA and two other CTAs comprising of butane thiol trithiocarbonate with cyano (CTA 1) and carboxylic acid (CTA 3) as the end group were synthesized and characterized. The polymerization is observed to be uncontrolled under SET and less controlled under atom transfer radical polymerization (ATRP) condition. CTA 2 and 3 produces better control in propagation compared with CTA 1, which may be attributed to the presence of R group that undergoes ready fragmentation to radicals, at ambient temperature. The poly(cyclohexyl methacrylate) [P(CHMA)] prepared through ATRP have higher fluorescence intensity compared with those from SET-RAFT, which may be attributed to the quenching of fluorescence by the trithiocarbonate and the long hydrocarbon chain. It is observed that block copolymers P(CHMA-b-t-BMA) produced from P(CHMA) macroinitiators synthesized via SET-RAFT result in lower polydispersity index in comparison with those synthesized via ATRP. © 2010 Wiley Periodicals, Inc.

Controlled polymerization of methacrylates at ambient temperature using trithiocarbonate chain transfer agents via SET-RAFT-cyclohexyl methacrylate: A model study

Controlled polymerization of styrene was carried out using ambient temperature single electron transfer initiation and propagation through the radical addition fragmentation chain transfer (SET-RAFT) method. SET-RAFT method was expected to have much wider applicability, especially for monomers that polymerize very rapidly by free/living radical polymerization. The typical RAFT polymerization required thermal/photochemical initiation and one of the end groups was required to be a fragment from the initiator. Under the SET-RAFT conditions, the ambient temperature initiation and the use of functional initiators would overcome some of the limitations of RAFT. SET-RAFT condition is expected to be very effective for monomers with a slower rate of initiation compared to the rate of propagation and those with a very high rate of propagation that require control.

Macromolecules

Ambient temperature polymerization of styrene by single electron transfer initiation, followed by reversible addition fragmentation chain transfer control

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

Journal of Polymer Science Part A: Polymer Chemistry

SET-LRP of methyl acrylate to complete conversion with zero termination

Covalent polymeric modification of graphene nanosheets via surface-initiated single-electron-transfer living radical polymerization

Synthesis of fluorescent, dansyl end-functionalized PMMA and poly(methyl methacrylate-b-phenanthren-1-yl-methacrylate) diblock copolymers, at ambient temperature

Journal	Journal of Polymer Science, Part A: Polymer Chemistry
ISSN	0887624X
Open Access	No