ATNRC and SET‐NRC synthesis of PtBA‐g‐PEO well‐defined amphiphilic graft copolymers

A series of new well‐defined amphiphilic graft copolymers containing hydrophobic poly(tert‐butyl acrylate) backbone and hydrophilic poly(ethylene oxide) side chains were reported. Reversible addition‐fragmentation chain transfer homopolymerization of tert‐butyl 2‐((2‐bromopropanoyloxy)methyl)acrylate was first performed to afford a well‐defined backbone with a narrow molecular weight distribution (M_w/M_n = 1.07). The target poly(tert‐butyl acrylate)‐g‐poly(ethylene oxide) (PtBA‐g‐PEO) graft copolymers with low polydispersities (M_w/M_n = 1.18–1.26) were then synthesized by atom transfer nitroxide radical coupling or single electron transfer‐nitroxide radical coupling reaction using CuBr(Cu)/PMDETA as catalytic system. Fluorescence probe technique was employed to determine the critical micelle concentrations (cmc) of the obtained amphiphilic graft copolymers in aqueous media. Furthermore, PAA‐g‐PEO graft copolymers were obtained by selective acidic hydrolysis of hydrophobic PtBA backbone while PEO side chains kept inert. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Glass transition temperature of allyl methacrylate‐n‐butyl acrylate gradient copolymers in dependence on chemical composition and molecular weight

Glass transition temperatures (T_gs) of P(AMA‐co‐BA) copolymers and the corresponding homopolymers, where AMA is allyl methacrylate and BA is n‐butyl acrylate, obtained by means of atom transfer radical polymerization were measured using differential scanning calorimetry. Because of the (pseudoliving) nature of this polymerization technique an increase in molecular weight (MW) is produced as the reaction progresses, which gives rise to an increase in T_gs. This increment can be adequately described by the Fox–Flory's equation in both homopolymers. However, in the spontaneous gradient copolymers of P(AMA‐co‐BA), the expected increase in T_g with the augment of the monomer conversion is compensated by the enrichment of BA as the polymerization reaction progresses. These opposite effects with respect to the T_g values almost balance each other, and therefore no significant influence on the MW or on conversion is found. This fact establishes that T_gs can be used to describe the profile of these gradient copolymers, and can be theoretically determined because of its dependence on the molar fraction in the copolymer. From this dependence on chemical composition along with the experimental behavior, a prediction of the T_g variation with the MW was performed. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1845–1855, 2007     

Synthesis of starlike PtBA‐g‐PEO amphiphilic graft copolymer via highly efficient Cu‐catalyzed SET‐NRC reaction at ambient temperature

Two new amphiphilic star graft copolymers bearing hydrophobic poly(tert‐butyl acrylate) backbone and hydrophilic poly(ethylene oxide) (PEO) side chains with different molecular weights were synthesized by sequential reversible addition fragmentation chain transfer (RAFT) polymerization and single electron transfer‐nitroxide radical coupling (SET‐NRC) reaction under mild conditions. RAFT homopolymerization of tert‐butyl 2‐((2‐bromopropanoyloxy)methyl)acrylate was mediated by a four‐armed chain transfer agent in a controlled way to afford a well‐defined starlike backbone with a narrow molecular weight distribution (M_w/M_n = 1.26). The target poly(tert‐butyl acrylate)‐g‐PEO (PtBA‐g‐PEO) star graft copolymers were synthesized by SET‐NRC reaction between Br‐containing PtBA‐based starlike backbone and PEO end functionalized with 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) group using copper/N,N,N′,N′,N″‐pentamethyldiethylenetriamine as catalytic system at ambient temperature via grafting‐onto strategy. The critical micelle concentration values of the obtained amphiphilic star graft copolymers in aqueous media and brine were determined by fluorescence probe technique using pyrene as probe. Diverse micellar morphologies were formed by varying the content of hydrophilic PEO segment as well as the initial concentration of stock solution. In addition, poly(acrylic acid)‐g‐PEO double hydrophilic star graft copolymers were obtained by selective acidic hydrolysis of hydrophobic PtBA starlike backbone without affecting PEO side chains. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Combination of nitroxide‐mediated polymerization and SET‐LRP for the synthesis of high molar mass branched and star‐branched poly(n‐butyl acrylate) characterized by size exclusion chromatography and rheology

Branched and star‐branched polymers were successfully synthesized by the combination of two successive controlled radical polymerization methods. A series of linear and star poly(n‐butyl acrylate)‐co‐poly(2‐(2‐bromoisobutyryloxy) ethyl acrylate) statistical copolymers, P(nBA‐co‐BIEA)_x, were first synthesized by nitroxide‐mediated polymerization (NMP at T > 100 °C). The subsequent polymerization of n‐butyl acrylate by single electron transfer‐living radical polymerization (SET‐LRP at T = 25 °C), initiated from the brominated sites of the P(nBA‐co‐BIEA)_x copolymer, produced branched or star‐branched poly(n‐butyl acrylate) (PnBA). Both types of polymerizations (NMP and SET‐LRP) exhibited features of a controlled polymerization with linear evolutions of logarithmic conversion versus time and number‐average molar masses versus conversion for final M_n superior to 80,000 g mol^?1. The branched and star‐branched architectures with high molar mass and low number of branches were fully characterized by size exclusion chromatography. The Mark–Houwink Sakurada relationship and the analysis of the contraction factor (g′ = ([η]_branched/[η]_linear)_M) confirmed the elaboration of complex PnBA. The zero‐shear viscosities of the linear, star‐shaped, branched, and star‐branched polymers were compared. The modeling of the rheological properties confirmed the synthesis of the branched architectures. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Star‐like PAA‐g‐PPO well‐defined amphiphilic graft copolymer synthesized by ATNRC and SET‐NRC reaction

A series of well‐defined amphiphilic star graft copolymers consisting of hydrophilic poly(acrylic acid) backbone and hydrophobic poly(propylene oxide) side chains were synthesized by the sequential reversible addition‐fragmentation chain transfer (RAFT) polymerization and atom transfer nitroxide radical coupling (ATNRC) or single electron transfer‐nitroxide radical coupling (SET‐NRC) reaction followed by the selective hydrolysis of poly(tert‐butyl acrylate) backbone. A Br‐containing acrylate monomer, tert‐butyl 2‐((2‐bromopropanoyloxy)methyl)acrylate, was first homopolymerized via RAFT polymerization using a new star‐like chain‐transfer agent with four arms in a controlled way to give a well‐defined star‐like backbone with a narrow molecular weight distribution (M_w/M_n = 1.23). The grafting‐onto strategy was used to synthesize the well‐defined PtBA‐g‐PPO star graft copolymers with narrow molecular weight distributions (M_w/M_n = 1.14–1.25) via ATNRC or SET‐NRC reaction between the Br‐containing PtBA‐based star‐like backbone and poly(propylene oxide) with 2,2,6,6‐tetramethylpiperidine‐1‐oxyl end group using CuBr/PMDETA or Cu/PMDETA as catalytic system. PAA‐g‐PPO amphiphilic star graft copolymers were obtained by the selective acidic hydrolysis of star‐like PtBA‐based backbone in acidic environment without affecting the side chains. The critical micelle concentrations in aqueous media and brine were determined by the fluorescence probe technique. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2084–2097, 2010     

The Naked‐Eye Detection of NH3–HCl by Polyaniline‐Infiltrated TiO2 Inverse Opal Photonic Crystals

A reversible color change of a polyaniline‐infiltrated TiO₂ inverse opal photonic crystal (PC) film can be obtained when the PC is switched from an acidic to alkali vapor environment. In a saturated NH₃ environment, the stopband of the as‐prepared PCs changes from 556 to 688 nm; such large shift of 132 nm could be observed, corresponding to a clear color change from green to red. After placing in HCl vapor, the stopband undergoes a blue‐shift and the color turns back to green. The result is ascribed to PANI being doped or dedoped by acid or base and the effective refractive index of the PC film varying accordingly. The naked‐eye detection of NH₃ and HCl vapors can be realized by the reversible color change of the PC film, which is of importance for chemical and biological sensors.     

Functional Polyolefins: Poly(ethylene)‐graft‐Poly(tert‐butyl acrylate) via Atom Transfer Radical Polymerization From a Polybrominated Alkane

Poly(cis‐cyclooctene) is synthesized via ring‐opening metathesis polymerization in the presence of a chain‐transfer agent and quantitatively hydrobrominated. Subsequent graft polymerization of tert‐butyl acrylate (tBA) via Cu‐catalyzed atom transfer radical polymerization (ATRP) from the non‐activated secondary alkyl bromide moieties finally results in PE‐g‐PtBA copolymer brushes. By varying the reaction conditions, a series of well‐defined graft copolymers with different graft densities and graft lengths are prepared. The maximum extent of grafting in terms of bromoalkyl groups involved is approximately 80 mol%. DSC measurements on the obtained graft copolymers reveal a decrease in T_m with increasing grafting density.     

An efficient way to tune grafting density of well‐defined copolymers via an unusual Br‐containing acrylate monomer

A series of well‐defined amphiphilic graft copolymers, containing hydrophilic poly(acrylic acid) backbone and hydrophobic poly(butyl acrylate) side chains, were synthesized by sequential reversible addition fragmentation chain transfer (RAFT) polymerization and atom transfer radical polymerization (ATRP) without any postpolymerization functionality modification followed by selective acidic hydrolysis of poly(tert‐butyl acrylate) backbone. tert‐Butyl 2‐((2‐bromopropanoyloxy)methyl)‐acrylate was first homopolymerized or copolymerized with tert‐butyl acrylate by RAFT in a controlled way to give ATRP‐initiation‐group‐containing homopolymers and copolymers with narrow molecular weight distributions (M_w/M_n < 1.20) and their reactivity ratios were determined by Fineman‐Ross and Kelen‐Tudos methods, respectively. The density of ATRP initiation group can be regulated by the feed ratio of the comonomers. Next, ATRP of butyl acrylate was directly initiated by these macroinitiators to synthesize well‐defined poly(tert‐butyl acrylate)‐g‐poly(butyl acrylate) graft copolymers with controlled grafting densities via the grafting‐from strategy. PtBA‐based backbone was selectively hydrolyzed in acidic environment without affecting PBA side chains to provide poly(acrylic acid)‐g‐poly(butyl acrylate) amphiphilic graft copolymers. Fluorescence probe technique was used to determine the critical micelle concentrations in aqueous media and micellar morphologies are found to be spheres visualized by TEM. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2622–2630, 2010     

Nanostructured latexes made by a sequential multistage emulsion polymerization

A series of linear and lightly crosslinked nanostructured latices was prepared by a sequential multistage semicontinuous emulsion polymerization process alternating styrene (S) and n‐butyl acrylate (BA) monomer feeds five times, that is ten stages, and vice versa, along with several control latices. Transmission electron micrographs of the RuO₄‐stained cross sections of nanostructured and copolymer latex particles and films showed that their particle morphologies were not very different from each other, but the nanostructured latex particles were transformed into a nanocomposite film containing both polystyrene (PS) and poly(n‐butyl acrylate) (PBA) nanodomains interconnected by their diffuse polymer mixtures (i.e. interlayers). The thermal mechanical behaviors of the nanostructured latex films showed broad but single T_gs slightly higher than those of their counterpart copolymer films. These single T_gs indicated that their major component phases were the diffuse interlayers and that they behaved like pseudopolymer alloys. The minimum film formation temperatures of nanostructured latices capped with PBA and PS, respectively, were 15 °C lower than and equal to those of their counterpart copolymer latices, but their T_gs were about 10 °C higher. Consequently, nanostructured latices enabled us to combine good film formation with high strengths for adhesives and coatings applications. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2826–2836, 2006     

Convenient synthesis of thermo‐responsive PtBA‐g‐PPEGMEMA well‐defined amphiphilic graft copolymer without polymeric functional group transformation

A series of well‐defined amphiphilic graft copolymers bearing hydrophobic poly(tert‐butyl acrylate) backbone and hydrophilic poly[poly(ethylene glycol) methyl ether methacrylate)] (PPEGMEMA) side chains were synthesized by sequential reversible addition fragmentation chain transfer (RAFT) polymerization and single‐electron‐transfer living radical polymerization (SET‐LRP) without any polymeric functional group transformation. A new Br‐containing acrylate monomer, tert‐butyl 2‐((2‐bromoisobutanoyloxy)methyl)acrylate (tBBIBMA), was first prepared, which can be homopolymerized by RAFT to give a well‐defined PtBBIBMA homopolymer with a narrow molecular weight distribution (M_w/M_n = 1.15). This homopolymer with pendant Br initiation group in every repeating unit initiated SET‐LRP of PEGMEMA at 45 °C using CuBr/dHbpy as catalytic system to afford well‐defined PtBBIBMA‐g‐PPEGMEMA graft copolymers via the grafting‐from strategy. The self‐assembly behavior of the obtained graft copolymers in aqueous media was investigated by fluorescence spectroscopy and TEM. These copolymers were found to be stimuli‐responsive to both temperature and ions. Finally, poly(acrylic acid)‐g‐PPEGMEMA double hydrophilic graft copolymers were obtained by selective acidic hydrolysis of hydrophobic PtBA backbone while PPEGMEMA side chains kept inert. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis,photophysics, structure‐tunable photoluminescence,and electrochemical properties of soluble poly(p‐phenylenevinylene)‐based polymers with adjacent 1,3,4‐oxadiazoles in the backbone

Three new poly(p‐phenylenevinylene)‐based polymers containing two 1,3,4‐oxadiazole moieties in the main chain per repeat unit were synthesized by Heck coupling. A single, double, or triple bond was introduced between the oxadiazoles to provide a means for modifying the polymer properties. The polymers were readily soluble in common organic solvents and showed T_g values lower than 50 °C. The color of the emissive light in both the solid state and the solution could be tuned by a change in the nature of the bond between the oxadiazole rings. The polymers emitted ultraviolet‐green light in solution with a photoluminescence (PL) emission maximum at 345–483 nm and blue‐green light at 458–542 nm in thin films. The PL quantum yields in solution were 0.36–0.43. The electrochemical properties are affected by the nature of the bond between the oxadiazoles as well. In polymers with a single bond between the oxadiazoles, a lower ionization potential was observed than in polymers with a double or triple bond. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3079–3090, 2005     

Preparation and properties of oxadiazole‐containing polyacetylenes as electron transport materials

A series of functional polyacetylenes (PAs) bearing diphenyl oxadiazole pendant groups ( P1 – P4 ) were prepared, and the resultant polymers are completely soluble in common organic solvents. Their structures and properties were characterized and evaluated by DSC, TGA, UV, PL, CV, and EL analyses. The results show that all the resulting polymers possesses low LUMO energy level and high thermal stability, and the resultant functional polyacetylenes without spacer group between the polyacetylene conjugated main chain and oxadiazole pendant groups ( P1 – P3 ) show lower LUMO energy level (～?3.87 eV) and higher thermal properties (T_g) than that ( P4 ) with a flexible spacer. The resultant polymer ( P2 ) was applied as an ETM in bilayer electroluminescent devices and effectively enhances external quantum efficiency and the brightness of device, and decreases turn‐on voltages of devices. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1406–1414, 2010     

Synthesis of poly(n‐butyl acrylate) homopolymer and poly(styrene‐b‐n‐butyl acrylate‐b‐styrene) triblock copolymer via AGET emulsion ATRP using a cationic surfactant

Cationic emulsions of triblock copolymer particles comprising a poly(n‐butyl acrylate) (PⁿBA) central block and polystyrene (PS) outer blocks were synthesized by activator generated by electron transfer (AGET) atom transfer radical polymerization (ATRP). Difunctional ATRP initiator, ethylene bis(2‐bromoisobutyrate) (EBBiB), was used as initiator to synthesize the ABA type poly(styrene‐b‐n‐butyl acrylate‐b‐styrene) (PS‐PⁿBA‐PS) triblock copolymer. The effects of ligand and cationic surfactant on polymerizations were also discussed. Gel permeation chromatography (GPC) was used to characterize the molecular weight (M_n) and molecular weight distribution (MWD) of the resultant triblock copolymers. Particle size and particle size distribution of resulted latexes were characterized by dynamic light scattering (DLS). The resultant latexes showed good colloidal stability with average particle size around 100–300 nm in diameter. Glass transition temperature (T_g) of copolymers was studied by differential scanning calorimetry (DSC). © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 611–620     

Viscoelasticity of nanobubble‐inflated ultrathin polymer films: Justification by the coupling model

The nanobubble inflation method is the only experimental technique that can measure the viscoelastic creep compliance of unsupported ultrathin films of polymers over the glass–rubber transition zone as well as the dependence of the glass transition temperature (T_g) on film thickness. Sizeable reduction of T_g was observed in polystyrene (PS) and bisphenol A polycarbonate by the shift of the creep compliance to shorter times. The dependence of T_g on film thickness is consistent with the published data of free‐standing PS ultrathin films. However, accompanying the shift of the compliance to shorter times, a decrease in the rubbery plateau compliance is observed. The decrease becomes more dramatic in thinner films and at lower temperatures. This anomalous viscoelastic behavior was also observed in poly(vinyl acetate) and poly (n‐butyl methacrylate), but with large variation in the change of either the T_g or the plateau compliance. By now, well established in bulk polymers is the presence of three different viscoelastic mechanisms in the glass–rubber transition zone, namely, the Rouse modes, the sub‐Rouse modes, and the segmental α‐relaxation. Based on the thermorheological complexity of the three mechanisms, the viscoelastic anomaly observed in ultrathin polymer films and its dependence on chemical structure are explained in the framework of the Coupling Model. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013     

Effects of hyperbranched prepolymers prepared from butyl acrylate and butyl methacrylate on the electro‐optical properties of polymer dispersed liquid crystal

Two hyperbranched prepolymers were synthesized via the reversible addition‐fragmentation chain transfer copolymerization of butyl acrylate or butyl methacrylate with divinyl benzene, respectively. These prepolymers were used in the photopolymerization‐induced phase separation process of preparing polymer dispersed liquid crystal (PDLC) films with no risk of gelation. The morphologies of PDLC samples were investigated. Of particular interest was that the driving voltage (V₉₀) of PDLC with high glass transition temperature (T_g) matrix was as low as 5 V, whereas the V₉₀ of PDLC with low T_g matrix was still high. An explanation for this phenomenon is the hypothesis that different interaction modes function at the interface of liquid crystal and polymer. Meanwhile, the hysteresis of the two systems was minor, which correlated with the hyperbranched structure of polymer. The on‐state transmittance (T_ON) of PDLC films enhanced because of the well matching between the refractive index of polymer and that of liquid crystal. Copyright © 2011 John Wiley & Sons, Ltd.     

Biomass‐derived furanic polycarbonates: Mild synthesis and control of the glass transition temperature

Bis(hydroxymethyl)furan (BHMF) is a promising biomass‐derived polymer platform, but it is incompatible with traditional methods used for synthesizing polycarbonates (PCs) owing to its thermal instability. In this study, BHMF‐based furanic (FR) PCs were prepared successfully at a relatively low temperature through the mediation of carbonyldiimidazole. The low T_g of aliphatic FR‐PCs was controlled elaborately, exploiting the reactivity of furan in the Diels–Alder reactions and the molecular rigidity of the resulting oxabicycles. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 1796–1800     

Hyperbranched copolyfluorene from a 2,4,7‐trifunctional fluorene monomer

A new hyperbranched ( P1 ) and linear copolyfluorene ( P2 ) were prepared from 2,4,7‐trifunctional (branching) and 2,7‐bifunctional fluorene monomer, respectively, by the Wittig reaction, followed with end‐capping by aromatic oxadiazole groups, to study the effect of hyperbranch structure. The weight‐average molecular weights (M_w) of P1 and P2 , determined by gel permeation chromatography using polystyrene as standard, were 33,000 and 25,700, respectively. The polymers were readily soluble in common organic solvents and exhibited good thermal stability (T_d > 400 °C). Optical properties, both in solution and film state, were investigated using absorption and photoluminescence (PL) spectra. In film state, the absorption and PL spectra peaked at 401–425 nm and 480–495 nm, respectively. The P1 showed energy funnel effect and enhanced fluorescence efficiency owing to hyperbranched structure and terminal oxadiazole groups. The HOMO and LUMO levels of P1 ( P2) , estimated from cyclic voltammograms, are ?5.34 (?5.25) eV and ?2.94 (?2.94) eV, respectively. Two‐layer polymer light‐emitting diodes devices (ITO/PEDOT/ P1 /Ca/Al) exhibited maximal luminance and luminous efficiency of 3630 cd/m² and 0.78 cd/A, respectively, which are superior to its linear counterpart P2 (598 cd/m², 0.11 cd/A). © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5541–5551, 2007     

Selective Metal‐vapor Deposition on Organic Surfaces

Selective metal‐vapor deposition signifies that metal‐vapor atoms are deposited on a hard organic surface, but not on a soft (low glass transition temperature, low T_g) surface. In this paper, we introduce the origin, extension, and applications of selective metal‐vapor deposition. An amorphous photochromic diarylethene film shows light‐controlled selective metal‐vapor deposition, which is caused by a large T_g change based on photoisomerization, but various organic surfaces, including organic crystal and polymers, can be utilized for achieving selective metal‐vapor deposition. Various applications of selective metal‐vapor deposition, including cathode patterning of organic light‐emitting devices, micro‐thin‐film fuses, multifunctional diffraction gratings, in‐plane electrical bistability for memory devices, and metal‐vapor integration, have been demonstrated.     

Well‐defined amphiphilic graft copolymer consisting of hydrophilic poly(acrylic acid) backbone and hydrophobic poly(vinyl acetate) side chains

A series of well‐defined amphiphilic graft copolymers containing hydrophilic poly(acrylic acid) (PAA) backbone and hydrophobic poly(vinyl acetate) (PVAc) side chains were synthesized via sequential reversible addition‐fragmentation chain transfer (RAFT) polymerization followed by selective hydrolysis of poly(tert‐butyl acrylate) backbone. A new Br‐containing acrylate monomer, tert‐butyl 2‐((2‐bromopropanoyloxy)methyl) acrylate, was first prepared, which can be polymerized via RAFT in a controlled way to obtain a well‐defined homopolymer with narrow molecular weight distribution (M_w/M_n = 1.08). This homopolymer was transformed into xanthate‐functionalized macromolecular chain transfer agent by reacting with o‐ethyl xanthic acid potassium salt. Grafting‐from strategy was employed to synthesize PtBA‐g‐PVAc well‐defined graft copolymers with narrow molecular weight distributions (M_w/M_n < 1.40) via RAFT of vinyl acetate using macromolecular chain transfer agent. The final PAA‐g‐PVAc amphiphilic graft copolymers were obtained by selective acidic hydrolysis of PtBA backbone in acidic environment without affecting the side chains. The critical micelle concentrations in aqueous media were determined by fluorescence probe technique. The micelle morphologies were found to be spheres. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6032–6043, 2009     

Temperature‐induced phase transition of poly(N‐n‐propylacrylamide‐co‐butyl methacrylate‐co‐N,N‐diethylaminoethyl methacrylate)

Terpolymers composed of N‐n‐propylacrylamide (NPAAm), butyl methacrylate (BMA), and N,N‐diethylaminoethyl methacrylate (DEAEMA) were prepared in an attempt to investigate the temperature‐induced phase transition and its mechanism. Poly(NPAAm) showed the lower critical solution temperature (LCST) around 24°C in water. With the incorporation of DEAEMA with NPAAm, the LCST change was characterized by an initial increase. However, the LCST was shifted to the lower temperature at the later stage. This might be explained in terms of hydrophilic/hydrophobic contribution of DEAEMA to the LCST. The swelling behavior of copolymer gel in the various solvents and spin‐lattice relaxation time (T₁) study by NMR strongly suggested the hydrophilic/hydrophobic contribution of DEAEMA to the LCST depending on the local environment. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 1407–1411, 1999