Papers by Keyword: ATRP

Abstract: A series of styrene–acrylonitrile (SAN) copolymer nanoparticles were prepared by grafting styrene–acrylonitrile from both aggregated silica and colloidally dispersed silica nanoparticles using atom-transfer radical polymerisation (ATRP). Cross-linking and macroscopic gelation were minimised by using a miniemulsion system. The thermal and mechanical behavior of composites were made from PSAN aggregated silica nanoparticles or colloidally dispersed silica has been examined by Differential scanning calorimetry (DSC) and Dynamic mechanical thermal analysis (DMTA). The filler particles increased the rubbery modulus above the T_g of PSAN considerably and led to a temperature-independent plateau of the modulus between 130 and 240 °C similar to that normally observed for crosslinked amorphous polymers. Covalent attachment of PSAN to the silica nanoparticles, by grafting the polymer from the surface of the silica using atom-transfer radical polymerization (ATRP), gave rise to hybrid materials with a comparable elastic plateau. While neat PSAN started to flow and deform irreversibly above 120 °C, the new silica nanoparticle–polymer hybrid materials proved stable up to 240 °C, which was more than 120 °C above the T_g of the polymer. Aggregated silica nanoparticles displayed more affect compared to colloidally dispersed silica.

Abstract: Thermo-responsive random copolymer poly (2-(2-methoxyethoxy) ethoxyethyl methacrylate-co-poly (ethylene glycol) methyl ether methacrylate), abbreviated as P(MEO₂MA-co-OEGMA₃₀₀) was synthesized by 2-(2-methoxyethoxy) ethoxyethyl methacrylate (MEO₂MA) and poly (ethylene glycol) methyl ether methacrylate (OEGMA₃₀₀) with a molar ratio of 1:1 via atom transfer radical polymerization (ATRP). The structure of P(MEO₂MA-co-OEGMA₃₀₀) was confirmed by ¹H NMR and GPC. The transition behaviors of P(MEO₂MA-co-OEGMA₃₀₀) in aqueous solution were investigated by UV-Vis and DLS. While the transition behaviors of P(MEO₂MA-co-OEGMA₃₀₀) thin films were probed by white light interferometry. Compared to the P(MEO₂MA-co-OEGMA₃₀₀) in solution, it shows a much broader transition region, which is a promising candidate for the slow release of drug in the field of medicine.

Abstract: Thermo-responsive textile is a widely studied smart material, which finds wide application in self-adjustment, water-storage and medicine control releasing etc. Cotton is one of the mostly researched textiles due to its low cost and easy-preparation. However, it is difficult to graft thermal responsive polymers on cotton because the hydroxyl groups on the surface are not reactive enough. In this study, a dye mediate, 2-Chloro-4,6-diamino-1,3,5-triazine (CDATA) was used to introduce amino groups onto cotton fibers. NIPAAm was then grafted onto cotton by atom transfer radical polymerization (ATRP), which was measured by infrared and contact angle measurements. The obtained cotton-PNIPAAm exhibited an efficient thermal responsive performance, which was indicated by transitions between hydrophilicity and hydrophobicity reversibly according to the temperature changes.

Abstract: Using of petro-polymers such as polymethylmethacrylate, polypropylene and polyethylene in the world has been undergoing a critical problem due to significantly decreasing of petroleoum stock as monomer sources. Therefore reducing of the petro-polymer usage should be performed by using natural resources such as modified starches.This study reported addition of an acyl bromide compound to substitute hydroxyl groups on the starch obtains a macro initiator for graft-copolymerizing polymethylmethacrylate (PMMA) onto the functionalized starch as starch-g-PMMA through atomic transfer radical polymerization (ATRP) method. The starch activation through the substitution of the hydroxyl functional group creates ability of the starch to transfer a radical atom onto a petro-monomer such an alkylmethacrylate which furthermore polymerize into starch-g-PMMA at mild condition. This paper reported study of the starch activation describing about screening catalysts and acyl bromide compounds, optimizing process variables such as amount ratio of a selected acyl bromide compound to starch and temperature. The functionalized starchs were analysed by 13-CNMR, FTIR, titration and their morphology was observed by FE-SEM.

Abstract: Well-defined triblock terpolymer polystyrene-block-poly (N,N-Dimethylaminoethyl methacrylate)-block-poly (methyl methacrylate) (PS-PDMAEMA-PMMA) is synthesized via sequential Atom transfer radical polymerization (ATRP) with designed molecular weights characterized by HNMR and GPC. Annealing in Chloroform which is a selective solvent for PS and PMMA induces the formation of micelles with patchy coronas, and subsequent dialysis against cyclohexane which is selective only for PS enables the stacking of the precursor micelles into core-compartmentalized self-assemblies. The micellizatinon and self-assembly behaviors are investigated via DLS and TEM.

Abstract: Mechanorphore-based Poly (glycidyl methacrylate) was synthesized by atom transfer radical polymerization (ATRP) of glycidyl methacrylate (GMA) in bulk by using spiropyran-based initiator, CuCl in combination with N,N,N’,N’’,N’’-pentamethyldiethylenetriamine (PMDETA) as catalyst. The resultant polymer was characterized by gel permeation chromatography (GPC) and ¹H NMR spectroscopy. The relative molecular mass of PGMA can be changed by polymerization time. The resultant polymers have controlled molecular weight and low polydispersity. The present synthetic strategy provides a convenient and efficient method to synthesize mechanophore-linked PGMA which can be ulteriorly crosslinked to form thermosetting polymer networks.

Abstract: ATRP is one of the most active fields in polymer science. The feature of ATRP is chain propagation by way of transfer of halide atom with or without the catalysis of transition mental compounds. The termination reaction between radicals is reduced by low concentration of free radicals under the control of the fast transfer. A variety of monomers including styrene, acrylates, methacrylates, and dienes can be used in this technique. ATRP is a simple and inexpensive process for controlled "living" radical polymerization leading to well-defined homopolymers and copolymers. In this paper, the mechanism, initiator, catalyst systems, polymerization mediums and conditions of ATRP are introduced, the prospect of ATRP is also discussed.

Abstract: In this study, a novel amphiphilic copolymer based on the flexible polydimethylsiloxane (PDMS) macroinitiator was successfully prepared by atom transfer radical polymerization (ATRP). First, the high molecular weight bis (hydroxyalkyl)-terminated PDMS was prepared by hydrosilation reaction between hydrogen-terminated PDMS and 2-allyloxyethanol in the presence of Karstedt’s catalyst. The macroinitiator Br-PDMS-Br was prepared by the reaction between different molecular weight bis (hydroxyalkyl)-terminated PDMS and 2-bromoisobutyry bromide. Then the amphiphilic ABA-type block copolymers of poly [dimethylsiloxane-b-(hydroxylethyl methacrylate)] were initiated by bromide end-capped PDMS with HEMA, under an appropriate catalyst/ligand system of CuCl/bpy. The polymerization proceeded with first-order kinetics. It showed that the reaction system was a controlled/‘living’ polymerization. The triblock copolymers were characterized by FTIR, ¹H-NMR, TGA and GPC techniques. GPC results showed the tribolck copolymer had narrow polydispersity of Mw/Mn (PDI<1.5). TGA results showed the good thermal stability of the triblock copolymer.

Abstract: In this paper, the macroinitiator (PVAc-Cl) was prepared from vinyl acetate telomerization reaction by using BPO as initiator and CCl₄ or CHCl₃ as chain transfer agent. Then the pH-responsive PVAc /poly (2-(dimethylamino) ethyl methacrylate) (PVAc/PDEAEMA) were synthesized via atom transfer radical polymerization (ATRP) and evidenced by FTIR spectroscopy. PVA/PDEAEMA were synthesized by alcoholysis PVAc/PDEAEMA and evidenced by FTIR spectroscopy.

Abstract: Cellulose is the most abundant, renewable, and biodegradable natural resource on the earth. Grafting copolymerization technique is one of the key methods to widen the application scope of cellulose. This paper concerned with the recent progress and application of living/controlled radical graft polymerization techniques such as NMP, ATRP, and RAFT in the grafting modification of cellulose. The advantages and disadvantage of them were also reviewed.