Microstructure and swelling behavior of ion-exchange resin

The microstructure and swelling kinetics of ion-exchange resins having sulfonic acid groups were investigated by small-angle neutron scattering (SANS) and swelling experiments as functions of the crosslinking density (CD), pH, and the salt concentration (C_salt). The swelling kinetics was analyzed on the basis of the Tanaka-Fillmore swelling equation for the cooperative diffusion of polymer gels. The swelling behavior was very sensitive to CD, but not to pH and C_salt. The SANS intensity functions, I(q), were independent of CD and well described with a power law function, I(q) ∼ q^−D, where q and D are the magnitude of the scattering vector and the mass-fractal dimension, respectively. D was estimated to be ∼2, indicating that the resin consisted of a rather coarsely interconnected domains irrespective of CD at swelling equilibrium. It was found that CD is the most important parameter determining the swelling power of ion-exchange resin. However, no remarkable variations were found in the microstructure in the order of tens to hundreds of angstrom. © 1996 John Wiley & Sons, Inc.     

Calcium induced volume transition in polyelectrolyte gels

The osmotic properties and the small angle neutron scattering (SANS) behaviour of fully neutralized sodium polyacrylate gels are investigated in the presence of calcium ions. Analysis of the SANS response displays three characteristic length scales, two of which are of thermodynamic origin, while the third, associated with the frozen-in structural inhomogeneities, is static. The SANS results are consistent with direct osmotic observations which indicate that the thermodynamic properties cannot be adequately described by a single correlation length. The concentration dependence of the osmotic pressure displays a power law behaviour with an exponent that decreases with increasing calcium concentration.     

Dynamic light scattering and small-angle neutron scattering studies on organogels formed with a gelator

Small-angle neutron scattering (SANS) and light scattering studies were carried out on an organogel consisting of a gelator, coded P-1, and dimethyl sulfoxide (DMSO). The gelator was made of an oligosiloxane stem and about eight branches of an amino acid derivative combined with a long alkyl chain. The amino acid part, N-n-pentanoyl-L -isoleucylaminooctadecane, was responsible for intermolecular association via hydrogen bonding between amide groups. After the complete dissolution of P-1 in DMSO at 85 °C, the solution was cooled, and the variations of the scattered light intensity were monitored as a function of the temperature. The scattered intensity increased drastically at about 40 °C when the P-1 concentration (C) was 3.5 g/L, and this indicated gel formation. The SANS results showed that the scattering intensity function was a monotonically decreasing function, regardless of C. A master relationship of the scattering intensity was obtained with respect to C. These scattering studies disclosed the following facts. First, gelation could be monitored as an abrupt increase in the intensity. Second, the gel was composed of randomly oriented bundlelike clusters. Third, the structure factor could be reduced by the gelator concentration, and this indicated the presence of a self-similar structure across the gelation threshold. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1841–1848, 2004     

Comparative Study of Scattering and Osmotic Properties of Synthetic and Biopolymer Gels

Summary: The effect of monovalent/divalent cation exchange on the structure and osmotic properties of chemically cross-linked polyacrylate and DNA gels swollen in near physiological salt solutions has been investigated. Both systems exhibit a reversible volume phase transition in the presence of calcium ions. The small-angle neutron scattering spectra of these gels display qualitatively similar features. At low values of q surface scattering is observed, while in the intermediate q range the signal is characteristic of scattering from rod-like elements. At high values of q the scattering intensity is governed by the local (short-range) geometry of the polymer chains. The competition between monovalent and divalent cations has been studied by anomalous small-angle X-ray scattering (ASAXS). The ASAXS results reveal that the local concentration of the divalent counter-ions in the vicinity of the polymer chains significantly exceeds that of the monovalent counter-ions.     

Gelation mechanism and microstructure of organogels formed with various types of gelators

The small‐angle neutron scattering (SANS) and dynamic light scattering (DLS) investigation were carried out for organogels in toluene, formed by organogelators, to elucidate the relationship between the chemical structure and the gelation mechanism as well as the physical properties of the gels. Three different organogelators, that is cyclo(L ‐β‐3,7‐dimethyloctylasparaginyl‐L ‐phenylalanyl) (CPA), trans‐(1R,2R)‐bis(undecylcarbonylamino)cyclohexane (TCH), and N^ε‐lauroyl‐N^α‐stearylaminocarbonyl‐L ‐lysine ethyl ester (LEE), were chosen for comparison. The SANS intensity functions of toluene solutions of these gelators could be reduced with the concentration and were described with a scattering function for thin rods. This indicates that the gels consist of noncorrelated, rod‐like elements aggregated to each other. The characteristic features of the gelation properties, such as the critical gelation concentration, C_gel, the gelation temperature, T_gel, the gel structure, and the gelation mechanism, were different from each other. CPA had the lowest C_gel and became a gel gradually as the temperature decreased, while TCH and LEE had higher C_gels and underwent a sharp sol–gel transition. We conclude that the gelation mechanisms between the CPA and TCH solutions are different. The “CPA type” gelators form a gel by a linear extension of hydrogen‐bonded plane, while the “TCH type” gelators form a twisted wire, because of its strong helicity and crystallizability. In addition, in the latter type, a next generation of fibrils easily stacks on top of the previous ones to form larger fibrils. These models well explain the DLS results and the mechanical properties. That is, the fibrillar stems in CPA gels are rather mobile and fragile, while those in TCH and LEE are frozen and brittle. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 3567–3574, 2005     

Calcium-induced volume transition in polyacrylate hydrogels swollen in physiological salt solutions

Osmotic and small-angle neutron-scattering measurements are performed to study the volume transition that occurs in sodium polyacrylate gels swollen in sodium chloride solutions when calcium ions are introduced. In the presence of calcium ions, the osmotic pressure depends sensitively on the sodium chloride concentration, indicating that calcium preferentially replaces condensed sodium ions. This substitution modifies the effective attractive interaction between polymer chains. Analysis of the osmotic data in terms of the Flory–Huggins theory reveals a sharp increase in the third-order ternary thermodynamic interaction parameter upon introduction of calcium ions. The neutron-scattering response at low scattering vectors q displays power-law behavior with a slope of approximately −3.6, consistent with scattering from surfaces of large objects. These results are in agreement with the development of dense polymer-rich regions dispersed in a soft polymer matrix. At larger q, a region with slope −1 is observed, characteristic of rigid linear structures.

Small-angle neutron-scattering spectra of polyacrylate hydrogels swollen by 40 mM sodium chloride solutions containing different amounts of CaCl₂ (+: 0.5 mM , ○: 0.85 mM , ×: 1.7 mM ). The dashed curve shows the least squares fit of the 0.85 mM CaCl₂ data to Equation ( 5 ) in which the first term is replaced by Equation ( 8 ), and the second term is approximated by a simple power law.     

Similarities between polyelectrolyte gels and biopolymer solutions

Small angle neutron scattering (SANS) measurements and osmotic swelling pressure measurements are reported for polyelectrolyte gels and solutions under nearly physiological conditions. A synthetic polymer (sodium-polyacrylate) and three biopolymers (DNA, hyaluronic acid, and polyaspartic acid) are studied. The neutron scattering response of these anionic polyelectrolytes is closely similar, indicating that at larger length scales the organization of the polymer molecules is not significantly affected by the fine details of the molecular architecture (e.g., size and chemical structure of the monomer unit, type of polymer backbone). The results suggest that specific interactions between the polyelectrolyte chains and the surrounding monovalent cations are negligible. It is found that the osmotic compression modulus of these biopolymer solutions determined from the analysis of the SANS response decreases with increasing chain persistence length. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3679–3686, 2006     

The solution phase characterization of poly(ferrocenyldimethylsilane)s by small‐angle neutron scattering

A series of monodisperse (M_w/M_n < 1.1) poly(ferrocenyldimethylsilane)s was prepared with number‐averaged degrees of polymerization, 〈z〉_n, of 9, 33, 206, and 506 ( 2 – 5 , respectively), as determined by gel permeation chromatography (GPC). The polymers were studied by small‐angle neutron scattering (SANS) in solution with the aim of obtaining the radius of gyration, R_g, the weight‐averaged molecular weight, M_w, and the polydispersity index, M_w/M_n. Data were collected over the range 0.008 < Q/Å^?1 < 0.5 and for a series of concentrations (weight fraction, w = 0.0063, 0.0125, 0.025, and 0.05). The scattered intensity, I(Q), was fitted to a model based on a Schultz–Zimm distribution of isolated chains with excluded volume. A comparison of the molecular weight and size data determined by GPC and SANS indicated an acceptable agreement between the values for R_g, M_w and M_w/M_n. The results of this study demonstrate the potential utility of SANS to fully characterize metallopolymers, and other polymer systems where traditional methods cannot be applied. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4011–4020     

Phase behavior of blends of PCBM with amorphous polymers with different aromaticity

The phase behavior of [6,6]‐phenyl C₆₁‐butyric acid methyl ester (PCBM) blends with amorphous polymers with different degrees of aromaticity has been investigated by differential scanning calorimetry (DSC) and small‐angle neutron scattering (SANS). The polymers investigated are the homologous series of polystyrene (PS), poly(2‐vinyl‐naphthalene) (P2VN), and poly(9‐vinyl‐phenanthrene) (P9VPh). The DSC results show that the miscibility of PCBM in these polymers increases nonlinearly from 16.5 wt % in PS, 57.0 wt % in P2VN, and 74.9 wt % in P9VPh. The SANS results show that at all concentrations of PCBM, the blends are composed of two mixed phases. Analysis shows that the phase dimensions remain largely independent of PCBM content, but there is a strong dependence of the PCBM concentration difference in the two phases with increasing PCBM content. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 994–1001     

Interactions among spherical poly(acrylic acid) brushes: Observation by rheology and small angle X‐ray scattering

Interactions among annealed spherical polyelectrolyte brushes (SPB) in concentrated aqueous dispersion under the effect of concentration, pH, and salt concentration are investigated by means of rheology, and small angle X‐ray scattering (SAXS). SPB consist of a solid polystyrene (PS) core and linear poly(acrylic acid) (PAA) chains densely grafted onto the core by one end. Rheological investigation demonstrates that the viscosity, the storage modulus G′ and the loss modulus G″ of SPB dispersion increase significantly upon increasing the SPB concentration and pH value which reflects the enhanced interactions among SPB. At high pH, a further increase in pH from 8 to 13 has almost no impact on the rheological properties and SAXS curves, while a “Uniform Shell Model” can fit the SAXS data very well probably due to the uniform filling of polyelectrolyte chains among SPB. When increasing the salt concentration from 10^?5 to 10^?3 M, the so‐called “polyelectrolyte peak” appears at middle to high q range in SAXS curves which means the overlapped polyelectrolyte chains are associated under the bridging effect of counterions, which disappears at higher salt concentration due to the screening effect of further added salts. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 405–413     

Influences of nonsolvent and temperature on critical viscoelastic behaviors of ternary polyacrylonitrile solutions around the sol-gel threshold

Viscoelastic experiments were performed to study the influence of nonsolvent and temperature on critical viscoelastic behaviors of ternary polyacrylonitrile (PAN) solutions around the sol-gel threshold. The dynamic critical parameters around the sol-gel threshold were determined using dynamic rheometer. The sol-gel transition takes place at a critical gel temperature at which the scaling law of G′(ω) ∼ G″(ω) ∝ ωⁿ holds, allowing an accurate determination of the critical gel temperature by means of the frequency independence of the loss tangent. Although the gel points of PAN solutions increase with increasing H₂O content, the results show that the scaling exponent n at the gel point is found to be universal for all ternary PAN solutions, which is independent of temperature and H₂O content, indicating the similarity of the fractal structure in the critical PAN gels. The gelation of ternary PAN solutions induced by adding a nonsolvent and by decreasing the temperature is demonstrated to be a thermoreversible process, which implies that the PAN gels are physical gels. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 2637–2643, 2008     

Antimicrobial loading into and release from poly(ethylene glycol)/poly(acrylic acid) semi‐interpenetrating hydrogels

Electrostatic interactions within a semi‐interpenetrating network (semi‐IPN) gel can control the postsynthesis loading, long‐term retention, and subsequent release of small‐molecule cationic antibiotics. Here, electrostatic charge is introduced into an otherwise neutral gel [poly(ethylene glycol) (PEG)] by physically entrapping high‐molecular‐weight poly(acrylic acid) (PAA). The network structure is characterized by small‐angle neutron scattering. PEG/PAA semi‐IPN gels absorb over 40 times more antibiotic than PAA‐free PEG gels. Subsequent soaking in physiological buffer (pH 7.4; 0.15 M NaCl) releases the loaded antibiotics for periods as long as 30 days. The loaded gels elute antibiotics with diffusivities of 4.46 × 10^?8 cm²/s (amikacin) and 2.08 × 10^?8 cm²/s (colistin), which are two orders of magnitude less than those in pure PEG gels where diffusion is controlled purely by gel tortuosity. The release and hindered diffusion can be understood based on the partial shielding of the charged groups within the loaded gel, and they have a significant effect on the antimicrobial properties of these gels. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 64–72     

Synthesis and thermoresponsive properties of OEGylated polypeptide with a LCST at body temperature in water and with a UCST in alcohol or ethanol/water solvent mixture

Thermoresponsive polypeptides bearing oligo(ethylene glycol) (OEG) pendants (i.e., P1‐OEG_x and P2‐OEG_x, x = 3, 7) were synthesized by copper‐mediated 1,3‐dipolar cycloaddition with high grafting efficiency (≥97%) between side‐chain “clickable” polypeptides, namely poly(γ‐4‐(propargoxycarbonyl)benzyl‐l ‐glutamate) (P1) or poly(γ‐4‐(4‐propargoxyphenoxycarbonyl)benzyl‐l ‐glutamate) (P2) and azido functionalized OEG (N₃‐OEG_x). P1 and P2 with similar degree of polymerization (DP = 35 or 37) were prepared from triethylamine initiated ring‐opening polymerization of respective N‐carboxyanhydrides. P1‐OEG_x (x = 3, 7) and P2‐OEG₇ showed reversible UCST‐type phase transitions in various alcoholic solvents (e.g., ethanol, propanol, n‐butanol, and n‐pentanol). P2‐OEG₃ also showed reversible UCST‐type phase transitions in ethanol/water solvent mixtures at the weight percentage of ethanol no less than 50 wt %. P1‐OEG₇ and P2‐OEG₇ showed reversible LCST‐type phase transitions in aqueous solutions. Variable‐temperature UV–vis spectroscopy revealed that the LCST‐type phase transition temperature (T_pt) of P2‐OEG₇ with benzoic acid phenyl ester linkages was at around body temperature and it was barely changed with the variation of polymer concentration, yet it showed noticeable dependence on the nature of salt (i.e., NaCl, NaBr, NaI, or KCl) and salt concentration in the range of 0–300 mM. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 163–173     

Association,emulsifying, and solubilization properties of amphiphilic hyperbranched poly(acrylic acid) with short polystyrene stickers

Amphiphilic hyperbranched copolymer chains made of large hyperbranched poly(acrylic acid) cores grafted with short polystyrene stickers (HB‐PAA_n‐g‐PS_{n + 1}) with different n values (n = 1, 10, 47) were well prepared and confirmed by size exclusion chromatography, Fourier transform infrared spectroscopy and ¹H nuclear magnetic resonance. The study on the interchain association behavior of these amphiphilic chains indicates that larger HB‐(PAA)_n‐g‐(PS)_{n + 1} copolymer chains have a less tendency to undergo interchain association. Moreover, the simple vial‐inversion and rheological experiments show that the apparent critical gel concentration (C_g) decreases with n, but no sol–gel transition was observed for triblock PS‐PAA‐PS even when the concentration is up to 200 g L^?1. Further transmission electron microscopy study of the latex particles prepared with HB‐(PAA)_n‐g‐(PS)_{n + 1} as surfactant reveals that the latex particles are spherical and narrowly dispersed; while the measured latex particle number (N_p) indicates the surfactant efficiency of HB‐(PAA)₄₇‐g‐(PS)₄₈ is poorer than that of triblock PS‐PAA‐PS (n = 1). Finally, pyrene solubilization measurement shows the solubilization efficiency of HB‐(PAA)_n‐g‐(PS)_{n + 1} copolymers decreases with n, consistent with the previous observed interchain association result. The present study demonstrates that both the chain topology and the styrene weight fraction dominates the final solution properties of amphiphilic HB‐(PAA)_n‐g‐(PS)_{n + 1} chains in aqueous solution. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 128–138     

Structure of gum arabic in aqueous solution

Gum arabic, a natural polysaccharide derived from exudates of Acacia senegal and Acacia seyal trees, is a commonly used food hydrocolloid. The complex chemical structure of the gum has been widely studied revealing a multifraction material consisting mainly of a highly branched polysaccharide and a protein–polysaccharide complex (GAGP) as a minor component. This work investigates its mesoscopic structure in aqueous solution by small‐angle X‐ray and neutron scattering combined with cryotransmission electrons microscopy. Scattering measurements reveal an intricate shape composed of many spheroidal aggregates assigned to the polysaccharide with a small amount of larger coils. A scattering peak is observed at moderate to high concentrations, the spacing of which exhibits a c^?1/3 power law relation to polymer concentration (c). Upon addition of salt, this peak disappears, indicating its electrostatic nature. The large coils contribute a q^?2 power law at the low scattering vector (q) range. However, at low concentration in which the interaggregate peak is not observed, a q^?1 power law at the low q range indicates the possible existence of a fraction with a locally extended conformation. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3265–3271, 2006     

SANS investigations of oxide gel formation in inverse micelle and lamellar surfactant systems

The mechanisms of oxide gel formation in inverse micelle and lamellar surfactant systems have been investigated by Small Angle Neutron Scattering (SANS). In the first of these processes colloidal particles and gels are formed by the controlled hydrolysis and condensation of metal alkoxides in a reversed microemulsion system (water in oil), where the water is confined in the microemulsion core. With this route the rate of formation and structure of the oxide gel can be controlled by appropriate choice of the surfactant molecule (e.g. chain length) and the volume fraction of the micelles dispersed in the continuous organic phase. Investigations have been made with the system cyclohexane/water/C₈E _x , where C₈E _x is the non-ionic surfactant octylphenyl polyoxyethylene. The influence of the size and structure of the microemulsion has been studied by contrast variation (using deuterated solvents) before and during the reaction to form zirconia gels, and the mechanism of gelation is analysed in terms of percolation of fractal cluster aggregates. The structure of gels formed in surfactant/water lamellar phase systems, using surfactants with greater chain length, has also been investigated by SANS. The application of contrast variation to study such anisotropic bilayer systems, in which oriented gel films can be formed, is illustrated.     

Self‐assembly of thermo‐ and pH‐responsive poly(acrylic acid)‐b‐poly(N‐isopropylacrylamide) micelles for drug delivery

Self‐assembled thermo‐ and pH‐responsive poly(acrylic acid)‐b‐poly(N‐isopropylacrylamide) (PAA‐b‐PNIPAM) micelles for entrapment and release of doxorubicin (DOX) was described. Block copolymer PAA‐b‐PNIPAM associated into core‐shell micelles in aqueous solution with collapsed PNIPAM block or protonated PAA block as the core on changing temperature or pH. Complexation of DOX with PAA‐b‐PNIPAM triggered by the electrostatic interaction and release of DOX from the complexes due to the changing of pH or temperature were studied. Complex micelles incorporated with DOX exhibited pH‐responsive and thermoresponsive drug release profile. The release of DOX from micelles was suppressed at pH 7.2 and accelerated at pH 4.0 due to the protonation of carboxyl groups. Furthermore, the cumulative release of DOX from complex micelles was enhanced around LCST ascribed to the structure deformation of the micelles. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5028–5035, 2008     

Volume transition and internal structures of small poly(N‐isopropylacrylamide) microgels

Monodispersed poly(N‐isopropylacrylamide) (PNIPAM) nanoparticles, with hydrodynamic radius less than 50 nm at room temperature, have been synthesized in the presence of a large amount of emulsifiers. These microgel particles undergo a swollen–collapsed volume transition in an aqueous solution when the temperature is raised to around 34 °C. The volume transition and structure changes of the microgel particles as a function of temperature are probed using laser light scattering and small angle neutron scattering (SANS) with the objective of determining the small particle internal structure and particle–particle interactions. Apart from random fluctuations in the crosslinker density below the transition temperature, we find that, within the resolution of the experiments, these particles have a uniform radial crosslinker density on either side of the transition temperature. This result is in contrast to previous reports on the heterogeneous structures of larger PNIPAM microgel particles, but in good agreement with recent reports based on computer simulations of smaller microgels. The particle interactions change across the transition temperature. At temperatures below the transition, the interactions are described by a repulsive interaction far larger than that expected for a hard sphere contact potential. Above the volume transition temperature, the potential is best described by a small, attractive interaction. Comparison of the osmotic second virial coefficient from static laser light scattering at low concentrations with similar values determined from SANS at 250‐time greater concentration suggests a strong concentration dependence of the interaction potential. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 849–860, 2005     

Critical fluctuations and static inhomogeneities in polymer gel volume phase transitions

Thermoresponsive polymer gels exhibit pronounced swelling and deswelling upon changes in temperature, accompanied by dynamic concentration fluctuations that have been interpreted as critical opalescence. These fluctuations span lengthscales similar to that of static structures in the gels, such as the gel polymer‐network meshsize (1–10 nm) and static polymer‐network crosslinking inhomogeneities (10–1000 nm). To systematically investigate this overlay, we use droplet‐based microfluidics and fabricate submillimeter‐sized gel particles with varying static heterogeneity, as revealed on a molecular scale by proton NMR. When these microgels are probed by small‐angle neutron scattering, the detection of dynamic fluctuations during the volume phase transitions is strongly perturbed by the co‐existing static inhomogeneity. Depending of the type of data analysis employed, the temperature‐dependent evolution of the correlation length associated to the dynamic fluctuations does or does not agree with predictions by the critical scaling theory. Only the most homogeneous sample of this study, prepared by controlled polymer crosslinking in droplet microfluidics, shows a diverging correlation length in agreement to the critical scaling theory independent of the specific approach of data analysis. These findings suggest that care must be taken about polymer‐network heterogeneity when gel volume phase transitions are evaluated as critical phenomena. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1112–1122     

Aqueous solution behavior of comb‐shaped poly(2‐ethyl‐2‐oxazoline)

A series of comb polymers consisting of a methacrylate backbone and poly(2‐ethyl‐2‐oxazoline) (PEtOx) side chains was synthesized by a combination of cationic ring‐opening polymerization and reversible addition–fragmentation chain transfer polymerization. Small‐angle neutron scattering (SANS) studies revealed a transition from an ellipsoidal to a cylindrical conformation in D₂O around a backbone degree of polymerization of 30. Comb‐shaped PEtOx has lowered T_g values but a similar elution behavior in liquid chromatography under critical conditions in comparison to its linear analog was observed. The lower critical solution temperature behavior of the polymers was investigated by turbidimetry, dynamic light scattering, transmission electron microscopy, and SANS revealing decreasing T_cp in aqueous solution with increasing molar mass, the presence of very few aggregated structures below T_cp, a contraction of the macromolecules at temperatures 5 °C above T_cp but no severe conformational change of the cylindrical structure. In addition, the phase diagram including cloud point and coexistence curve was developed showing an LCST of 75 °C of the binary mixture poly[oligo(2‐ethyl‐2‐oxazoline)methacrylate]/water. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013