End‐linked amphiphilic polymer conetworks: Synthesis by sequential atom transfer radical polymerization and swelling characterization

Conetworks based on end‐linked homopolymers and amphiphilic gradient copolymers were synthesized by the atom transfer radical polymerization (ATRP) of 2‐(dimethylamino)ethyl methacrylate (DMAEMA, hydrophilic monomer), methyl methacrylate (MMA, hydrophobic monomer), and ethylene glycol dimethacrylate (EGDMA, hydrophobic cross‐linker). Sequential, rather than step‐wise polymerizations, were performed to enhance the livingness of the polymerization, particularly for the end‐linking step, and to ultimately obtain conetworks based on gradient rather than pure block copolymers. Amphiphilic conetworks based on end‐linked MMA‐DMAEMA‐MMA gradient copolymers of different compositions were successfully synthesized as confirmed by the narrow molecular weight distributions of the linear precursors, the rigidity of the amphiphilic conetwork products and the low sol‐fraction extracted from the conetworks. Similarly successful was the ATRP synthesis of an end‐linked conetwork based on a DMAEMA‐MMA statistical copolymer and of a randomly cross‐linked conetwork that resulted from the simultaneous terpolymerization of DMAEMA, MMA and EGDMA. An amphiphilic conetwork based on an end‐linked DMAEMA‐MMA‐DMAEMA gradient copolymer presented a less rigid, mucous‐like, texture. The degrees of swelling (DS) in tetrahydrofuran of all the conetworks were higher than those measured in pure water, whereas the aqueous DS values increased by lowering the pH and increasing the DMAEMA content of the conetworks. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1878–1886, 2010     

Thermoresponsive terpolymers based on methacrylate monomers: Effect of architecture and composition

A series of amphiphilic thermoresponsive copolymers was synthesized by group transfer polymerization. Seven copolymers were prepared based on the nonionic hydrophobic n‐butyl methacrylate (BuMA), the ionizable hydrophilic and thermoresponsive 2‐(dimethylamino)ethyl methacrylate (DMAEMA) and the nonionic hydrophilic poly(ethylene glycol)methyl methacrylate (PEGMA). In particular, one diblock copolymer and six tricomponent copolymers of different architectures and compositions, one random and five triblock copolymers, were synthesized. The polymers and their precursors were characterized in terms of their molecular weight and composition using gel permeation chromatography and proton nuclear magnetic resonance spectroscopy, respectively. Aqueous solutions of the polymers were studied by turbidimetry, hydrogen ion titration, and light scattering to determine their cloud points, pK_as, and hydrodynamic diameters and investigate the effect of the polymers' composition and architecture. The thermoresponsive behavior of the copolymers was also studied. By increasing the temperature, all polymer solutions became more viscous, but only one polymer, the one with the highest content of the hydrophobic BuMA, formed a stable physical gel. Interestingly, the thermoresponsive behavior of these triblock copolymers was affected not only by the terpolymers' composition but also by the terpolymers' architecture. These findings can facilitate the design and engineering of injectable copolymers for tissue engineering that could enable the in situ formation of physical gels at body temperature. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 775–783, 2010     

Thermoresponsive gels based on ABA triblock copolymers: Does the asymmetry matter?

The aim of this study was to investigate the effect of the asymmetry of the triblock copolymers on their thermoresponsive self‐assembly behavior. To this end, nine ABA‐type triblock copolymers with n‐butyl methacrylate and 2‐(dimethylamino)ethyl methacrylate (DMAEMA) consisting of the A and the B blocks, respectively, were synthesized. Polymers of three different DMAEMA contents (50, 60, and 70 wt %) were synthesized while varying the length ratio of the two hydrophobic A blocks. Specifically, one symmetric ABA triblock copolymer and two asymmetric ABA′ triblock copolymers with the length of the second A block to be twice or four times bigger than the length of the first A block (AB2A and AB4A triblock copolymer) were synthesized for each DMAEMA composition. Three statistical copolymers were also synthesized for comparison. The thermoresponsive behavior of the copolymers was studied and it was found that the cloud point and rheological properties of the polymers were strongly affected by the architecture (statistical vs. block) and less strongly by the DMAEMA composition and the asymmetry of the polymers. Nevertheless, interestingly the asymmetry of the ABA triblock copolymers did influence the thermoresponsive behavior with the more symmetric polymers presenting a sol–gel transition at lower temperatures. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2850–2859.     

Synthesis of gradient copolymers with simultaneously tailor‐made chain composition distribution and glass transition temperature by semibatch ATRP: From modeling to application

Recent studies have demonstrated that gradient copolymers exhibit unique thermal properties. Although these properties can be determined by copolymer composition, other factors such as chain and sequence lengths and their distributions can also influence them. Accordingly, the synthesis of gradient copolymers requires simultaneously tailor‐made chain structure and thermal properties. In this work, we carried out a systematic study on the preparation of poly(methyl methacrylate‐grad‐2‐hydroxyethyl methacrylate) [poly(MMA‐grad‐HEMA)] with synchronously tailor‐made chain composition distribution and glass transition temperature (T_g) through semibatch atom transfer radical polymerization. First, a comprehensive model for simultaneously predicting gradient copolymer microstructure and T_g was presented using the concept of pseudo‐kinetic rate coefficients and Johnston equation. The model was validated by comparing simulation results with the classical reference data. Furthermore, the model was used to guide the experimental synthesis of the poly(MMA‐grad‐HEMA) gradient copolymers potentially as excellent damping material. The thermal properties of these gradient copolymer samples were evaluated. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis and characterization of polycholesteryl methacrylate–polyhydroxyethyl methyacrylate block copolymers

We report the synthesis and characterization of a series of novel diblock copolymers, poly(cholesteryl methacrylate‐b‐2‐hydroxyethyl methacrylate) (PCMA‐b‐PHEMA). Monomers, cholesteryl methacrylate (CMA) and 2‐(trimethylsiloxy)ethyl methacrylate (HEMA‐TMS), were prepared from methyacryloyl chloride and 2‐hydroxyethyl methacrylate, respectively. Homopolymers of CMA, PCMA, with well‐defined molecular weights and polydispersity indices (PDI), were prepared by reversible addition fragmentation and chain transfer (RAFT) method. Precursor diblock copolymers, PCMA‐b‐P(HEMA‐TMS), were synthesized using PCMA as macromolecular chain transfer agent and monomer, HEMA‐TMS. Product diblock copolymers, PCMA‐b‐PHEMA, were prepared by deprotecting trimethylsilyl units in the precursor diblock copolymers using acid catalysts. Detailed molecular characterization of the precursor diblock copolymers, PCMA‐b‐P(HEMA‐TMS), and the product diblock copolymers, PCMA‐b‐PHEMA, confirmed the composition and structure of these polymers. This versatile synthetic strategy can be used to prepare new amphiphilic block copolymers with cholesterol in one block and hydrogen‐bonding moieties in the second block. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6801–6809, 2008     

Near‐monodisperse α‐hydroxy and α,ω‐dihydroxy amine‐based polymers: Synthesis and characterization

α‐Hydroxy and α,ω‐dihydroxy polymers of 2‐(dimethylamino)ethyl methacrylate (DMAEMA) of various molecular weights were synthesized by group transfer polymerization (GTP) in tetrahydrofuran (THF), using 1‐methoxy‐1‐(trimethylsiloxy)‐2‐methyl propene (MTS) as the initiator and tetrabutylammonium bibenzoate (TBABB) as the catalyst. The hydroxyl groups were introduced by adding one 2‐(trimethylsiloxy) ethyl methacrylate (TMSEMA) unit at one or at both ends of the polymer chain. The ends were converted to 2‐hydroxyethyl methacrylate (HEMA) units after the polymerization by acid‐catalyzed hydrolysis. Gel permeation chromatography (GPC) in THF and proton nuclear magnetic resonance (¹H‐NMR) spectroscopy in CDCl₃ were used to determine the molecular weight and composition of the polymers. These mono‐ and difunctional methacrylate polymers can be covalently linked at the hydroxy termini to form star polymers and model networks, respectively. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1597–1607, 1999     

Hydrogels based on physiologically clotted fibrin–gelatin composites

Fibrin–gelatin composite (PFG) films were prepared and crosslinked with glutaraldehyde as reported by us previously. These composites were graft‐copolymerized with poly(2‐hydroxyethyl methacrylate) (PHEMA) and poly(2‐hydroxypropyl methacrylate) (PHPMA) with a potassium persulfate and sodium metabisulfite redox initiation system. The graft copolymers (PFG‐HEMA and PFG‐HPMA) were characterized for their percentage of grafting, percentage of equilibrium water content, and percentages of free water and bound water. The chemical composition and thermal, mechanical, morphological, and surface characteristics were also evaluated. The optimum conditions for obtaining a maximum percentage of grafting were standardized. PFG and its graft copolymers exhibited higher equilibrium water contents ranging from 60 to 77% when compared with those of HEMA and HPMA homopolymers. DSC studies revealed increased freezing water contents and decreased bound‐water contents for the graft copolymers when compared with those of PFG alone. These properties improved the efficacy of hydrogels. PFG demonstrated better mechanical properties as compared with its graft copolymers. This may be attributed to the alkaline reaction conditions wherein protein hydrolysis of PFG would have occurred thereby reducing the overall strength of the graft copolymers. IR and scanning electron microscopic studies confirmed the grafting of PHEMA and PHPMA onto PFG. Contact‐angle studies revealed increased polarity for graft copolymers, which is a symbol for increased hydrophilicity. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2241–2252, 2004     

Preparation of amphiphilic statistical copolymers of 2‐hydroxyethyl methacrylate with 2‐diethylaminoethyl methacrylate,precursors of water‐soluble copolymers

Statistical copolymers of 2‐hydroxyethyl methacrylate (HEMA) and 2‐diethylaminoethyl methacrylate (DEA) were synthesized at 50 °C by free‐radical copolymerization in bulk and in a 3 mol L^?1 N,N′‐dimethylformamide solution with 2,2′‐azobisisobutyronitrile as an initiator. The solvent effect on the apparent monomer reactivity ratios was attributed to the different aggregation states of HEMA monomer in the different solvents. The copolymers obtained were water‐insoluble at a neutral pH but soluble in an acidic medium when the molar fraction of the DEA content was higher than 0.5. The quaternization of DEA residues increased the hydrophilic character of the copolymers, and they became water‐soluble at a neutral pH when the HEMA content was lower than 0.25. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2427–2434, 2002     

Model‐based design and synthesis of gradient MMA/tBMA copolymers by computer‐programmed semibatch atom transfer radical copolymerization

Methyl methacrylate (MMA)/tert‐butyl methacrylate (tBMA) gradient copolymers having linear and hyperbolic composition profiles were synthesized. These special copolymer products were achieved via a model‐based computer‐controlled semibatch atom transfer radical copolymerization (ATRcoP) process. A simple ATRcoP model was developed based on the terminal model. The equilibrium constants in the ATRP of MMA and tBMA were estimated by the data correlation. The model was verified by batch experiments and was found to give good correlation for the polymerization rate, molecular weight, and copolymer composition data. The model coupled with a reactor model was then applied to the semibatch ATRcoP and was used to calculate comonomer feeding rates for the targeted gradient composition profiles. It was found that the experimental monomer conversion, molecular weight, and cumulative copolymer composition were in good agreement with their targeted theoretical values. The gradient copolymers had low polydispersities close to 1.1. This work demonstrated the feasibility of the model‐based semibatch ATRcoP in fine‐tuning gradient copolymer composition profiles. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 69–79, 2009     

pH‐ and temperature‐sensitive statistical copolymers poly[2‐(dimethylamino)ethyl methacrylate‐stat‐2‐vinylpyridine] with Functional succinimidyl‐ester chain ends synthesized by nitroxide‐mediated polymerization

Statistical copolymerizations of 2‐(dimethylamino)ethyl methacrylate (DMAEMA) with 2‐vinylpyridine (2VP) with 80 to 99 mol % DMAEMA in the feed utilizing a succinimidyl ester‐terminated alkoxyamine unimolecular initiator (NHS‐BlocBuilder) at 80 °C in bulk were performed. The effectiveness of 2VP as a controlling comonomer is demonstrated by linear increases in number‐average molecular weight versus conversion, relatively low PDI (1.5–1.6 with up to 98% DMAEMA) and successful chain extensions with 2VP. Additional free nitroxide does not significantly improve control for the DMAEMA/2VP copolymerizations. The succinimidyl ester on the initiator permits coupling to amine‐terminated poly(propylene glycol) (PPG), yielding an effective macroinitiator for synthesizing a doubly thermo‐responsive block copolymer of PPG‐block‐P(DMAEMA/2VP). A detailed study of the thermo‐ and pH‐sensitivities of the statistical and block copolymers is also presented. The cloud point temperature of the statistical copolymers is fine tuned from 14 to 75 °C by varying polymer composition and pH. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012.     

Synthesis and characterization of functional gradient copolymers of allyl methacrylate and butyl acrylate

Functional spontaneous gradient copolymers of allyl methacrylate (A) and butyl acrylate (B) were synthesized via atom transfer radical polymerization. The copolymerization reactions were carried out in toluene solutions at 100 °C with methyl 2‐bromopropionate as the initiator and copper bromide with N,N,N′,N″,N″‐pentamethyldiethylenetriamine as the catalyst system. Different aspects of the statistical reaction copolymerizations, such as the kinetic behavior, crosslinking density, and gel fraction, were studied. The gel data were compared with Flory's gelation theory, and the sol fractions of the synthesized copolymers were characterized by size exclusion chromatography and nuclear magnetic resonance spectroscopy. The copolymer composition, demonstrating the gradient character of the copolymers, and the microstructure were analyzed. The experimental data agreed well with data calculated with the Mayo–Lewis terminal model and Bernoullian statistics, with monomer reactivity ratios of 2.58 ± 0.37 and 0.51 ± 0.05 for A and B, respectively, an isotacticity parameter for A of 0.24, and a coisotacticity parameter of 0.33. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5304–5315, 2006     

Cationic methacrylate copolymers containing primary and tertiary amino side groups: Controlled synthesis via RAFT polymerization,DNA condensation,and in vitro gene transfection

A versatile family of cationic methacrylate copolymers containing varying amounts of primary and tertiary amino side groups were synthesized and investigated for in vitro gene transfection. Two different types of methacrylate copolymers, poly(2‐(dimethylamino)ethyl methacrylate)/aminoethyl methacrylate [P(DMAEMA/AEMA)] and poly(2‐(dimethylamino)ethyl methacrylate)/aminohexyl methacrylate [P(DMAEMA/AHMA)], were obtained by reversible addition‐fragmentation chain transfer (RAFT) copolymerization of dimethylaminoethyl methacrylate (DMAEMA) with N‐(tert‐butoxycarbonyl)aminoethyl methacrylate (Boc‐AEMA) or N‐(tert‐butoxycarbonyl)aminohexyl methacrylate (Boc‐AHMA) followed by acid deprotection. Gel permeation chromatography (GPC) measurements revealed that Boc‐protected methacrylate copolymers had M_n in the range of 16.1–23.0 kDa and low polydispersities of 1.12–1.26. The copolymer compositions were well controlled by monomer feed ratios. Dynamic light scattering and agarose gel electrophoresis measurements demonstrated that these PDMAEMA copolymers had better DNA condensation than PDMAEMA homopolymer. The polyplexes of these copolymers revealed low cytotoxicity at an N/P ratio of 3/1. The in vitro transfection in COS‐7 cells in serum free medium demonstrated significantly enhanced (up to 24‐fold) transfection efficiencies of PDMAEMA copolymer polyplexes as compared with PDMAEMA control. In the presence of 10% serum, P(DMAEMA/AEMA) and P(DMAEMA/AHMA) displayed a high transfection activity comparable with or better than 25 kDa PEI. These results suggest that cationic methacrylate copolymers are highly promising for development of safe and efficient nonviral gene transfer agents. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2869–2877, 2010     

Dispersion polymerization of MMA in supercritical CO2 stabilized by random copolymers of 1H,1H–perfluorooctyl methacrylate and 2‐(dimethylaminoethyl methacrylate)

A series of random copolymers, composed of 1H,1H‐perfluorooctyl methacrylate (FOMA) and 2‐dimethylaminoethyl methacrylate (DMAEMA) were prepared as stabilizers for the dispersion polymerization of methyl methacrylate in supercritical CO₂ (scCO₂). Free‐flowing, spherical poly(methyl methacrylate) (PMMA) particles were produced in high yield by the effective stabilization of poly(FOMA‐co‐DMAEMA) containing 34–67 w/w % (15–41 m/m %) FOMA structural units. Less stabilized but micron‐sized discrete particles could be obtained even with 25 w/w % (10 m/m %) FOMA stabilizer. The result showed that the composition of copolymeric stabilizers had a dramatic effect on the size and morphology of PMMA. The particle size was controllable with the surfactant concentration. The effect of the monomer concentration and the initial pressure on the polymerization was also investigated. The dry polymer powder obtained from dispersion polymerization could be redispersed to form stable aqueous latexes in an acidic buffered solution (pH = 2.1) by an electrostatic stabilization mechanism due to the ionization of DMAEMA units in the stabilizer. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1365–1375, 2008     

Copolymers of methyl methacrylate and fluoroalkyl methacrylates: Effects of fluoroalkyl groups on the thermal and optical properties of the copolymers

Fluoroalkyl methacrylates, 2,2,2‐trifluoroethyl methacrylate ( 1 ), hexafluoroisopropyl methacrylate ( 2 ), 1,1,1,3,3,3‐hexafluoro‐2‐methyl‐2‐propyl methacrylate ( 3 ), and perfluoro t‐butyl methacrylate ( 4 ) were synthesized. Homopolymers and copolymers of these fluoroalkyl methacrylates with methyl methacrylate (MMA) were prepared and characterized. With the exception of the copolymers of MMA and 2,2,2‐trifluoroethyl methacrylate ( 1 ), the glass transition temperatures (T_gs) of the copolymers were found to deviate positively from the Gordon‐Taylor equation. The positive deviation from the Gordon‐Taylor equation could be accounted for by the dipole–dipole intrachain interaction between the methyl ester group and the fluoroalkyl ester group of the monomer units. These T_g values of the copolymers were found to fit with the Schneider equation. The fitting parameters in the Schneider equation were calculated, and R² values, the coefficients of determination, were almost 1.0. The refractive indices of the copolymers, measured at 532, 633, and 839 nm wavelengths, were lower than that of PMMA and showed a linear relationship with monomer composition in the copolymers. 2 and MMA have a tendency to polymerize in an alternating uniform monomer composition, resulting in less light scattering. This result suggests that the copolymer prepared with an equal molar ratio of 2 and MMA may have useful properties with applications in optical devices. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4748–4755, 2008     

Thermosensitive gradient copolymers by living cationic polymerization: Semibatch precision synthesis and stepwise dehydration‐induced micellization and physical gelation

Thermosensitive forced gradient copolymers with various sequence distributions were synthesized by living cationic polymerization in the presence of an added base. The synthesis was conducted using a semibatch reaction method, which is unfavorable for ionic polymerization, especially when a simple apparatus is employed. Polymerization of 2‐ethoxyethyl vinyl ether (EOVE) was initiated using a conventional syringe technique. Immediately after initiation, 2‐methoxyethyl vinyl ether (MOVE) was continuously added using a syringe pump at regulated feed rates, which allowed control of the sequence distribution. The resulting gradient copolymers of EOVE and MOVE underwent thermally induced association in water, forming micelles with a hydrophobic core derived from EOVE‐rich segments. Interestingly, the size of the micelles obtained from gradient copolymers decreased monotonously with increasing solution temperature, while the micelles of the corresponding block copolymers were unchanged in size. This self‐association behavior can be controlled by designing the gradient pattern of the instantaneous composition. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6151–6164, 2008     

Controlled polymerizations of 2‐(dialkylamino)ethyl methacrylates and their block copolymers in protic solvents at ambient temperature via ATRP

Very well‐controlled polymerizations of 2‐(dimethylamino)ethyl methacrylate (DMAEMA) and 2‐(diethylamino)ethyl methacrylate (DEAEMA) in aqueous and methanolic solutions via atom transfer radical polymerization (ATRP) at ambient temperature were demonstrated. Poly(DMAEMA) and poly(DEAEMA) of low polydispersity index (PDI) of ～1.07 were obtained using the p‐toluenesulfonyl chloride/CuCl/1,1,4,7,10,10‐hexamethyl‐triethylenetetramine (p‐TsCl/CuCl/HMTETA) system. Excellent control of polymerization was achieved even in pure methanol. This is in contrast with the very poor control of DMAEMA ATRP in methanol reported previously using a different intiator/catalyst/ligand system. The initiator p‐TsCl underwent hydrolysis reaction in aqueous methanolic solutions with a second‐order rate constant of 6.1 × 10^?4 dm³ mol^?1 s^?1 at 25 °C. Both poly(DMAEMA) and poly(DEAEMA) retained almost full chlorine‐functionization at the chain ends. Well‐defined block copolymers of DEAEMA and DMAEMA were successfully obtained by starting with either macroinitiators of DEAEMA or DMAEMA. Other well‐defined diblock copolymers could be prepared using these macroinitiators. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5161–5169, 2004     

Hydrophobic coatings from photochemically prepared hydrophilic polymethacrylates via electrospraying

Linear poly(hydroxyethyl methacrylate‐co‐methyl methacrylate) P(HEMA‐co‐MMA) and poly(dimehylaminoethyl methacrylate‐co‐methyl methacrylate) P(DMAEMA‐co‐MMA) and their corresponding hyperbranched copolymers were synthesized by conventional photoinitiated free radical polymerization and self‐condensing vinyl polymerization (SCVP) using Type I and Type II photoinitiators, respectively. Then, the polymers were processed by electrospraying in N, N‐dimethylformamide. The surface of the resulting electrospray coatings was examined by SEM, XPS, and WCA then compared with those prepared by drop casting. Regardless of the structural nature of the polymers, electrospraying allows the preparation of rough surface that shows more hydrophobic behavior. Electrospray coatings with linear and hyperbranched copolymers exhibited WCA as ～150° and ～130°, respectively, indicating that branching reduces the WCA. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 1338–1344     

Synthesis of sequence‐controlled copolymers from extremely polar and apolar monomers by living radical polymerization and their phase‐separated structures

A series of copolymers composed of two monomer units having a polar phosphorylcholine group and an apolar fluorocarbon group with a controlled monomer unit sequence were synthesized by a reversible addition‐fragmentation chain transfer (RAFT) living radical polymerization method. 2‐Methacryloyloxyethyl phosphorylcholine (MPC) and 2,2,2‐trifluoroethyl methacrylate (TFEMA) were selected as the monomers, because they have disparate polarity. Furthermore, to investigate the influence of the monomer unit sequence in a polymer chain on the phase‐separated structure in the bulk and surface structure, copolymers having a continuous change in the monomer unit composition along the polymer chain (gradient copolymer) were synthesized, as well as random and block copolymers. The analysis of instantaneous composition revealed a continuous change in the monomer unit composition in the gradient copolymer and the statistical monomer unit sequence in the random copolymer. Thermal analysis assumed that the gradient sequence of the monomer unit would make the phase‐separated structure in the bulk ambiguous, while the well‐defined and monodispersive block sequence would undergo the distinct phase‐separation due to the extreme difference in the polarity of the component monomer units. The preliminary surface characterization of the synthesized polymers indicated the monomer unit sequence in the polymer chain would much influence on the surface structure. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6073–6083, 2005     

“Smart” poly(2‐(dimethylamino)ethyl methacrylate‐ran‐9‐(4‐vinylbenzyl)‐9H‐carbazole) copolymers synthesized by nitroxide mediated radical polymerization

A series of poly(2‐(dimethylamino)ethyl methacrylate‐ran‐9‐(4‐vinylbenzyl)‐9H‐carbazole) (poly(DMAEMA‐ran‐VBK)) random copolymers, with VBK molar feed compositions f_VBK,0 = 0.02–0.09, were synthesized using 10 mol % [tert‐butyl[1‐(diethoxyphosphoryl)‐2,2‐dimethylpropyl]amino] nitroxide (SG1) relative to 2‐([tert‐butyl[1‐(diethoxyphosphoryl)‐2,2‐dimethylpropyl]amino]oxy)‐2‐methylpropionic acid (BlocBuilder) at 80 °C and 90 °C. Controlled polymerizations were observed, even with f_VBK,0 = 0.02, as reflected by a linear increase in number average molecular weight (M_n) versus conversion X ≤ 0.6 with final copolymers characterized by relatively narrow, monomodal molecular weight distributions (M_w/M_n ≈ 1.5). Poly(DMAEMA‐ran‐VBK) copolymers were deemed sufficiently pseudo‐“living” to reinitiate a second batch of N,N‐dimethylacrylamide (DMAA), with very few apparent dead chains, as indicated by the monomodal shift in the gel permeation chromatography chromatograms. Poly(DMAEMA‐ran‐VBK) random copolymers exhibited tuneable lower critical solution temperature (LCST), in aqueous solution, by modifying copolymer composition, solution pH and by the addition of the water‐soluble poly(DMAA) segment. ¹H NMR analysis determined that, in water, the VBK units of the poly(DMAEMA‐ran‐VBK) random copolymer were segregated to the interior of the copolymer aggregate regardless of solution temperature and that poly(DMAEMA‐ran‐VBK)‐b‐poly(DMAA) block copolymers formed micelles above the LCST. In addition, the final random copolymer and block copolymer exhibited temperature dependent fluorescence due to the VBK units. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Statistical copolymers of methyl methacrylate and 2‐methacryloyloxyethyl ferrocenecarboxylate: Monomer reactivity ratios,thermal and electrochemical properties

Statistical copolymers of methyl methacrylate (MMA) with 2‐methacryloyloxyethyl ferrocenecarboxylate (MAEFC) were prepared by free radical polymerization. The reactivity ratios were estimated using the Fineman‐Ross, inverted Fineman‐Ross, Kelen‐Tüdos, and extended Kelen‐Tüdos graphical methods. Structural parameters of the copolymers were obtained by calculating the dyad monomer sequence fractions and the mean sequence length. The glass‐transition temperature (T_g) values of the copolymers were measured and examined by means of several theoretical equations, allowing the prediction of these T_g values. The thermal degradation behavior of the copolymers was also studied and compared with the respective homopolymers. Cyclic voltammetry was employed to study the electrochemical properties of the copolymers. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011