Tailoring the morphology of branched poly(N-isopropylacrylamide) via self-condensing atom-transfer radical copolymerization and its unique self-assembly behavior in alcohol

Abstract

Highly branched poly(N-isopropylacrylamide) (PNIPAM) was first synthesized by self-condensing atom transfer radical copolymerization (SCATRCP) catalyzed by CuBr/tris[2-(dimethylamino)ethyl] amine (Me 6 TREN) complex in isopropanol at room temperature. This method showed good control over chain morphology and lower critical solution temperature (LCST) type phase transition behavior of PNIPAM by varying reaction time and monomer/inimer feed ratios. On the basis of GPC, FTIR, 1 HNMR and DSC results, four stages were discerned during the polymerization procedure, at which chain architectures experienced ''linear -comblike -slightly branched -highly branched'' transformations. Additionally, the synthesized highly branched PNIPAM chains were found to be able to self-assemble into hollow spheres in alcohols such as methanol and ethanol, which arise from the presence of large amounts of hydrophobic branched points inside polymer chains.

Analysis using size exclusion chromatography of poly( N -isopropyl acrylamide) using methanol as an eluent

“…HB-PNIPAM has been prepared previously for a number applications [11] , [13] , [14] and we considered that methanol as an eluent would provide a general system for the analysis of these and other complex amphiphilic polymers. On the other hand, in our experience the alternative eluents, DMF, THF + tetrabutylammonium bromide or aqueous systems are often useful for only a narrow range of compositions.…”

“…Analysis of samples is restricted by the requirement that the mobile phase must be compatible with both the analyte and the stationary phase. Common mobile phases in SEC are tetrahydrofuran (THF) [2] , [3] , [4] , [5] , [6] , dimethyl formamide (DMF) [5] , [7] , [8] , [9] , [10] , [11] , [12] , [13] , [14] , Chloroform [4] and water [9] and common calibration standards used include polystyrene [2] , [3] , [4] , [5] , [7] , polyethylene oxide [8] or polymethyl methacrylate [5] , [6] , [10] , although many variations and alternatives have been reported [15] . However SEC measurements in eluent blends including alcohols have only been reported rarely [16] , [17] and there appears to be only one recent report on the use of methanol or ethanol as the sole component of the eluent, in an ultra high pressure SEC system [1] .…”

Effect of aggregation behavior and phenolic hydroxyl group content on the performance of lignosulfonate doped PEDOT as a hole extraction layer in polymer solar cells

“…[6][7][8] The various structures are central to a range of advanced application nanotechnologies. [9][10][11] In previous work, variations of controllable self-assemblies could be realized with numerous synthetic polymers with known structures such as poly(styrene sulfonic acid) (PSS) 12 and poly(Nisopropylacrylamide) (PNI), 13 however, it is relatively challenging to obtain a unique self-assembly with an amorphous polymer. Recently, we were surprised to nd that lignosulfonate RSC Advances PAPER (LS) and alkyl chain-coupled lignosulfonate-based polymer (ALS) from our previous manuscript 14 could form a unique block-like self-assembly in selective solvents without the help of a foreign interface.…”

Quadrangular Prism: A Unique Self‐Assembly from Amphiphilic Hyperbranched PMA‐b‐PAA

“…The vesicle size could be controlled from 0.1 to 100 μm. Hyperbranched poly( N ‐isopropylacrylamide) (PNIPAM) also formed hollow spheres in alcohols due to the largely existing hydrophobic‐branched points . As recently demonstrated, amphiphilic HBPs could form nano‐ or microfibers through the solution self‐assembly or Langmuir–Blodgett (LB) technique.…”