@article{afshari_gupta_jung_kotek_tonelli_vasanthan_2008, title={Properties of films and fibers obtained from Lewis acid-base complexed nylon 6,6}, volume={49}, ISSN={["0032-3861"]}, DOI={10.1016/j.polymer.2008.01.038}, abstractNote={A nylon 6,6 complex with GaCl 3 in nitromethane (4–5 wt% nylon 6,6) was prepared at 50–70 °C over 24 h for the purpose of disrupting the interchain hydrogen bonding between nylon 6,6 chains, resulting in amorphous nylon 6,6, and increasing the draw ratio for improving the performance of nylon 6,6 fibers. After drawing, complexed films and fibers were soaked in water to remove GaCl 3 and regenerate pure nylon 6,6 films and fibers. FTIR, SEM, DSC, TGA, and mechanical properties were used for characterization of the regenerated nylon 6,6 films and fibers. The amorphous complexed nylon 6,6 can be stretched to high draw ratios at low strain rates, due to the absence of hydrogen bonding and crystallinity in these complexed samples. Draw ratios of 7–13 can be achieved for complexed fibers, under low strain rate stretching. This study indicates that nylon 6,6 fibers made from the GaCl 3 complexed state, using a high molecular weight polymer, can reach initial moduli up to 13 GPa, compared to initial moduli of 6 GPa for commercial nylon 6,6 fibers. Lewis acid–base complexation of polyamides provides a way to temporarily suppress hydrogen bonding, potentially increasing orientation while drawing, and following regeneration of hydrogen bonding in the drawn state, to impart higher performance to their fibers.}, number={5}, journal={POLYMER}, author={Afshari, M. and Gupta, A. and Jung, D. and Kotek, R. and Tonelli, A. E. and Vasanthan, N.}, year={2008}, month={Mar}, pages={1297–1304} }
 @misc{kotek_jung_tonelli_vasanthan_2005, title={Novel methods for obtaining high modulus aliphatic polyamide fibers}, volume={C45}, ISSN={["1532-1797"]}, DOI={10.1081/MC-200067716}, abstractNote={Super high modulus polyethylene fibers can be created by converting high molecular weight flexible PE chains into highly oriented and extended chain conformations. However, unlike polyethylene, aliphatic polyamides have very high cohesive energy and therefore cannot be easily drawn and highly oriented. This review addresses this fundamental problem by analyzing various novel approaches that can be used to suppress hydrogen bonding in these types of polyamides. Plasticization of such polymers with ammonia, iodine, salts, and Lewis acids, as well as dry spinning, wet spinning, and gel spinning, are discussed. Specialized techniques that involve vibrational zone drawing and annealing as well as laser heating zone drawing and annealing are also reviewed. Some of these methods definitely lead to remarkable improvements in initial modulus and other mechanical properties. The development of recombinant spider silk proteins as well progress in spinning these materials is also reported. The advantages and disadvantages of all of these processes are then summarized.}, number={3}, journal={JOURNAL OF MACROMOLECULAR SCIENCE-POLYMER REVIEWS}, author={Kotek, R and Jung, D and Tonelli, AE and Vasanthan, N}, year={2005}, pages={201–230} }
 @article{vasanthan_kotek_jung_shin_tonelli_salem_2004, title={Lewis acid-base complexation of polyamide 66 to control hydrogen bonding, extensibility and crystallinity}, volume={45}, DOI={10.1016/j.polmer.2004.03.074}, number={12}, journal={Polymer}, author={Vasanthan, N. and Kotek, R. and Jung, D. W. and Shin, D. and Tonelli, A. E. and Salem, D. R.}, year={2004}, pages={4077–4085} }
 @article{kotek_afshari_gupta_kish_jung_2004, title={Polypropylene alloy filaments dyeable with disperse dyes}, volume={120}, DOI={10.1111/j.1478-4408.2004.tb00202.x}, abstractNote={Polypropylene fibres which can be conventionally dyeable using disperse dyes have been prepared by alloying with nylon 6 and a polypropylene grafted maleic anhydride compatibiliser during extrusion. The dyeing performance of fibres containing various amounts of these components has been assessed.}, number={1}, journal={Coloration Technology}, author={Kotek, R. and Afshari, M. and Gupta, B. S. and Kish, M. H. and Jung, D.}, year={2004}, pages={26–29} }
 @article{hunt_jung_shamsheer_uyar_tonelli_2004, title={Polystyrenes in channels}, volume={45}, ISSN={["1873-2291"]}, DOI={10.1016/j.polymer.2003.03.002}, abstractNote={Abstract Polystyrenes (PS) with various stereosequences have been modeled in narrow cylindrical channels corresponding to those found in polymer–inclusion compounds (ICs), such as those formed with host cyclodextrins (CDs), where the polymers reside as guests. Isotactic (i) PS is found to fit in channels with narrower diameters (D) than syndiotactic (s) PS, when both adopt conformations permitted by the Yoon, Sundararajan, Flory RIS conformational model of PSs, while atactic (a) PS can be included in channels with D intermediate to those for i- and s-PS. In ICs formed with host γ-CD and guest a-PS homopolymer and guest poly(ϵ-caprolactone) (PCL)-b-a-PS diblock copolymer it was observed that the a-PS homopolymer and the a-PS copolymer blocks were and were not included, respectively. Thus, it appears that a-PS is barely able to be threaded by γ-CD, whose internal diameter is ∼8 A. Because the channel conformers found for i- and s-PS have smaller and larger diameters, respectively, than those found for a-PS, we would expect i-PS to be complexed by γ-CD, while s-PS might not. As a consequence IC formation with γ-CD may provide a means to physically separate the stereoregular forms of polystyrene. In addition, only the mrm and rmr PS stereoisomers show channel conformations with significant probabilities, so we suggest that in situ polymerization of styrene monomer in the narrow channels of its IC formed with γ-CD might produce a new stereoregular form of PS with regularly alternating m and r diads.}, number={4}, journal={POLYMER}, author={Hunt, MA and Jung, DW and Shamsheer, M and Uyar, T and Tonelli, AE}, year={2004}, month={Feb}, pages={1345–1347} }
 @article{kotek_jung_kim_smith_guzman_schmidt_2004, title={Surface hydrolysis of filaments based on poly(trimethylene terephthalate) spun at high spinning speeds}, volume={92}, ISSN={["0021-8995"]}, DOI={10.1002/app.20132}, abstractNote={The surface alkaline hydrolysis of fibers made from poly(trimethylene terephthalate) (PTT) was studied after extruding the polymer at high spinning speeds from 2000 to 6000 m/min and heat setting in the range of temperatures from 100 to 180°C. Fiber weight loss increased with an increasing heat-setting temperature but it was also dependent on the spinning speed. Some of the partially hydrolyzed fibers had a well-developed, hydrophilic surface, and pore size in the range of 0.69 to 1.20 μm. The optimum reaction and morphological conditions for increasing porosity in PTT fibers depends on spinning speed and heat-setting temperature. A temperature of 180°C is the upper limit for heat-setting PTT filaments but seems to be the most effective for making porous fibers. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1724–1730, 2004}, number={3}, journal={JOURNAL OF APPLIED POLYMER SCIENCE}, author={Kotek, R and Jung, DW and Kim, JH and Smith, B and Guzman, P and Schmidt, B}, year={2004}, month={May}, pages={1724–1730} }
 @article{jung_koo_dai_whangbo_2001, title={Electronic structure study of scanning tunneling microscopy images of the rutile TiO2(110) surface and their implications on the surface relaxation}, volume={473}, ISSN={["1879-2758"]}, DOI={10.1016/S0039-6028(00)00970-5}, abstractNote={In scanning tunneling microscopy (STM) images recorded for rutile TiO2(1 1 0) surfaces with oxygen vacancies, the non-defect-site five-coordinate Ti atoms and the vacancy sites of the bridging oxygen atom rows appear bright while the six-coordinate Ti atoms and the bridging oxygen atoms appear dark. To find what kinds of surface relaxation can cause such STM images, we carried out partial density plot calculations for the unrelaxed structure and a number of model relaxed structures of the rutile TiO2(1 1 0) surface with oxygen vacancies using the extended Hückel tight binding method. We also performed density functional theory calculations to estimate the Ti atom displacements for the three types of Ti atoms present on TiO2(1 1 0) surfaces with oxygen vacancies.}, number={3}, journal={SURFACE SCIENCE}, author={Jung, D and Koo, HJ and Dai, D and Whangbo, MH}, year={2001}, month={Feb}, pages={193–202} }