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All sourcesNASA NTRSDOE OSTI
NASA NTRS1998

Determining the Molecular Growth Mechanisms of Tetragonal Lysozyme Crystals

Studies of the growth of tetragonal lysozyme crystals employing atomic force microscopy (AFM) have shown the advantages of this technique in investigating the growth mechanisms of protein crystals [1]. The resolution of these studies was in the micron range, which revealed surface features such as the occurrence of dislocations and 2D nucleation islands, similar to those found in inorganic systems. They clearly showed that the crystals grew by these surface growth mechanisms. However, the studies also revealed some surprising features, such as bimolecular growth step heights and pronounced growth anisotropies on the (110) face, which could not be explained. In previous studies we employed Periodic Bond Chain (PBC) theory to tetragonal lysozyme crystal growth and found that the crystals were constructed by strongly bonded molecular chains forming helices about the 43 axes [2,3]. The helices were connected to each other with weaker bonds. The growth process was shown to proceed by the formation of these 43 helices, resulting in bimolecular growth steps on the (110) face. It was also shown to explain many other observations on tetragonal lysozyme crystal growth. Although PBC analysis is not a new technique [4], it has not been widely used as the mechanisms predicted from it could not be experimentally verified. In this study the growth process of these crystals was investigated, particularly for the (110) face, employing some newly developed high resolution AFM techniques. These techniques allowed individual lysozyme molecules on the crystal faces to be resolved and predictions from PBC analyses to be tested. The analyses had shown that of the two possible packing arrangements on (110) faces, only one would actually occur. Employing the first of the newly developed techniques, these faces were scanned by high resolution AFM. The resulting images were then compared with the theoretically constructed images for the two possible packing arrangements on the (110) face. The theoretical images were constructed by convolution of the crystal surface shape obtained from crystallographic data with the AFM tip shape. The comparison confirmed the prediction that the molecular packing arrangement of these faces corresponded to that for complete 43 helices. The second AFM technique that was developed was used to follow the growth process by measuring the dimensions of individual growth units on the (110) face. Linescans across a growth step, performed near the saturation limit of the crystals, allowed the growth unit dimensions to be measured. These measurements showed that growth on the (110) face proceeded by the formation of new 43 helices from the addition of at least tetramer units in the [110] direction. In the [001] direction growth proceeded by the addition of various aggregate units corresponding to the 4(sub 3) helices.

Li, Huayu↗
NASA NTRS1997

Crystallization of Chicken Egg-White Lysozyme from Ammonium Sulfate

Chicken egg-white lysozyme was crystallized from ammonium sulfate over the pH range 4.0-7.8, with protein concentrations from 100 to 150 mg/ml. Crystals were obtained by vapor-diffusion or batch-crystallization methods. The protein crystallized in two morphologies with an apparent morphology dependence on temperature and protein concentration. In general, tetragonal crystals could be grown by lowering the protein concentration or temperature. Increasing the temperature or protein concentration resulted in the growth of orthorhombic crystals. Representative crystals of each morphology were selected for X-ray analysis. The tetragonal crystals belonged to the P4(sub 3)2(sub 1)2 space group with crystals grown at ph 4.4 having unit-cell dimensions of a = b = 78.7 1, c=38.6 A and diffracting to beyond 2.0 A. The orthorhombic crystals, grown at pH 4.8, were of space group P2(sub 1)2(sub 1)2 and had unit-cell dimensions of a = 30.51, b = 56.51 and c = 73.62 A.

Forsythe, Elizabeth L.↗
NASA NTRS1998

Comparative Analysis of Thaumatin Crystals Grown on Earth and in Microgravity

The protein thaumatin was studied as a model macromolecule for crystallization in microgravity environment experiments conducted on two U.S. Space Shuttle missions (second United States Microgravity Laboratory (USML-2) and Life and Microgravity Spacelab (LMS)). In this investigation we evaluated and compared the quality of space- and Earth-grown thaumatin crystals using x-ray diffraction analysis and characterized them according to crystal size, diffraction resolution limit, and mosaicity. Two different approaches for growing thaumatin crystals in the microgravity environment, dialysis and liquid-liquid diffusion, were employed as a joint experiment by our two investigative teams. Thaumatin crystals grown under a microgravity environment were generally larger in volume with fewer total crystals. They diffracted to significantly higher resolution and with improved diffraction properties as judged by relative Wilson plots. The mosaicity for space-grown crystals was significantly less than for those grown on Earth. Increasing concentrations of protein in the crystallization chambers under microgravity lead to larger crystals. The data presented here lend further support to the idea that protein crystals of improved quality can be obtained in a microgravity environment.

Ng, Joseph D.↗
NASA NTRS1999

Crystallization of Chicken Egg White Lysozyme from Assorted Sulfate Salts

Chicken egg white lysozyme has been found to crystallize from ammonium, sodium, potassium, rubidium, magnesium, and manganese sulfates at acidic and basic pH, with protein concentrations from 60 to 190 mg/ml. Crystals have also been grown at 4 C in the absence of any other added salts using isoionic lysozyme which was titrated to pH 4.6 with dilute sulfuric acid. Four different crystal forms have been obtained, depending upon the temperature, protein concentration, and precipitating salt employed. Crystals grown at 15 C were generally tetragonal, with space group P4(sub 3)2(sub 1)2. Crystallization at 20 C typically resulted in the formation of orthorhombic crystals, space group P2(sub 1)2(sub 1)2(sub 1). The tetragonal reversible reaction orthorhombic transition appeared to be a function of both the temperature and protein concentration, occurring between 15 and 20 C and between 100 and 125 mg/ml protein concentration. Crystallization from 1.2 M magnesium sulfate at pH 7.8 gave a trigonal crystal, space group P3(sub 1)2(sub 1), a = b = 87.4, c = 73.7, gamma = 120 deg, which diffracted to 2.8 A. Crystallization from ammonium sulfate at pH 4.6, generally at lower temperatures, was also found to result in a monoclinic form. space group C2, a = 65.6, b = 95.0, c = 41.2, beta = 119.2 deg. A crystal of approximately 0.2 x 0.2 x 0.5 mm grown from bulk solution diffracted to approximately 3.5 A.

Forsythe, Elizabeth L.↗
NASA NTRS2000

Molecular View of Protein Crystal Growth: Molecular Interactions, Surface Reconstruction and Growth Mechanism

Studies of the growth and molecular packing of tetragonal lysozyme crystals suggest that there is an underlying molecular growth mechanism, in addition to the classical one involving screw dislocation/2D) nucleation growth. These crystals are constructed by strongly bonded molecular chains forming helices about the 43 axes. The helices are connected to each other by weaker bonds. Crystal growth proceeds by the formation of these 4(sub 3) helices, which would explain some unexpected observations by earlier investigators, such as bimolecular growth steps on the (110) face. Another consequence of these molecular considerations is that only one of two possible packing arrangements could occur on the crystal faces and that their growth unit was at least a tetramer corresponding to the 4(sub 3) helix. Two new high resolution atomic force microscopy (AFM) techniques were developed to directly confirm these predictions on tetragonal lysozyme crystals. Most earlier investigations of protein crystal growth with AFM were in the low resolution mode which is adequate to investigate the classical growth mechanisms, but cannot resolve molecular features and mechanisms. Employing the first of the newly developed techniques, high resolution AFM images of the (110) face were compared with the theoretically constructed images for the two possible packing arrangements on this face. The prediction that the molecular packing arrangement of these faces corresponded to that for complete 4(sub 3) helices was confirmed in this manner. This investigation also showed the occurrence of surface reconstruction on protein crystals. The molecules on the surface of the (110) face were found to pack closer along the 4(sub 3) axes than those in the interior. The second new AFM technique was used to follow the growth process by measuring the dimensions of individual growth units on the (110) face. Linescans across a growth step, performed near the saturation limit of the crystals, allowed the growth unit dimensions to be measured as they were being incorporated into the crystal. These measurements showed that growth on the (110) face proceeded by the formation of new 4(sub 3) helices from the addition of many growth units of at least tetramer size. This is the first time that a time-resolved AFM technique has been used to observe individual molecular events during crystal growth.

Nadarajah, Arunan↗
NASA NTRS1997

Validity Using Pump-Probe Pulses to Determine the Optical Response of Niobate Crystals

A variety of niobate crystals have found their places in nonlinear optical applications as well as in laser devices. In recent years much attention has been paid to study the ultrafast optical response in a variety of photorefractive crystals such as KTa(1-x)Nb(x)O3 and KNbO3 crystals, glasses, semiconductors and polymers for applications in optical switching, information processing, optical computing, and all-optical device systems. Third-order optical nonlinearity is the most important property for realization of all-optical switching. Therefore experiments have been performed on the third order susceptibility using a variety of techniques such as the third-order harmonic generation, EFISH and degenerate four-wave mixing(DFWM). The latter has been conducted with a variety of pump wavelengths and with nanosecond, picosecond and femtosecond pulses. Niobate crystals, such as potassium niobate KNbO3, potassium tantalate niobate KTN family (KTa(1-x)Nb(x)O3), strontium barium niobate SBN (Sr(x)Ba(1-x)Nb2O6) and potassium-sodium niobate SBN (KNSBN) are attractive due to their photorefractive properties for application in optical storage and processing. The pulsed probe experiments performed on theses materials have suggested two types of time responses. These responses have been associated with an coherent response due to Chi(sup 3), and a long lived component due to excited state population. Recent study of DFWM on KNbO3 and KTN family reveals that the long lived component of those crystals depends on the crystal orientation. A slowly decaying signal is observable when the grating vector K(sub g) is not perpendicular to the C-axis of those photorefractive crystals', otherwise the optical response signal would be only a narrow coherent peak with FWHM equal to the cross-correlation width of the write beam pulses. Based on this understanding, we study the photodynamical process of a variety of niobate crystals using DFWM in a Kg perpindicular to C geometry with a ps-YAG: Nd laser operating at 532nm. However, the discrepancies in numerical estimations of Chi(sup 3) in these materials and other nonlinear optical media have resulted in a number of discussions. In order to better understand the photodynamical process of niobate crystals after an short pulse excitation we analyze the factors governing the coherent signal and present the DFWM spectra of niobate crystals.

Liu, Huimin↗
NASA NTRS2001

First Protein Crystallization Experiments on The International Space Station: Sweet Success in Space With Thaumatin

We determined the room temperature 1.2 A structure of thaumatin using a crystal grown in the first protein crystallization experiment conducted aboard the International Space Station (ISS). The crystals were grown in the Enhanced Gaseous Nitrogen Dewar (EGN) developed by Alexander McPherson and co-workers. EGN transports frozen solutions contained in tygon tubing in a liquid nitrogen Dewar to ISS where the tubes then thaw. Batch, free interface diffusion (FID), or vapor diffusion crystallization occurs after thawing. EGN was flown to the ISS on STS-106 on September 8, 2000. This was a "risk mitigation" flight that tested EGN performance and the process of conducting experiments on ISS. We focused on how to map a hanging drop crystallization recipe to the EGN FID method. Thaumatin was chosen as the test system. Three series of crystallization recipes were set-up. Each series tested different volume ratios of protein-rich solution to precipitant-rich solution. The series differed from each other by fixing either the protein concentration or the amount of protein in the solutions. Upon return of the samples to Earth on October 24 by STS-92, bubbles that spanned the diameter of the tubing were observed in all tubes. Such bubbles interrupt liquid-liquid diffusion and force vapor diffusion equilibration to occur instead. Nonetheless, crystals grew in 9 of 30 tubes. Many large crystals were grown, the largest being 2.0 x 1.1 x 1.0 cubic mm. The largest crystal was used to collect data at room temperature on beamline 7-1 of the Stanford Synchrotron Radiation Source to a maximum resolution of 1.2 A. The structure was refined anisotropically using SHELX with a data to parameter ratio of 4.5 to give an R(sub factor) of 15.8% (R(sub free) = 18.2%) for ail reflections without generated hydrogens. This refinement is proceeding. Comparisons of this 1.2 A microgravity structure to previous reports of the thaumatin structure at 1.75 A and to ground control crystals will be presented.

Kundrot, Craig E.↗
NASA NTRS2003

Protein Crystal Growth With the Aid of Microfluidics

Protein crystallography is one of three well-known methods to obtain the structure of proteins. A major rate limiting step in protein crystallography is protein crystal nucleation and growth, which is still largely a process conducted by trial-and-error methods. Many attempts have been made to improve protein crystal growth by performing growth in microgravity. Although the use of microgravity appears to improve crystal quality in some attempts, this method has been inefficient because several reasons: we lack a fundamental understanding of macromolecular crystal growth in general and of the influence of microgravity in particular, we have to start with crystal growth conditions in microgravity based on conditions on the ground and finally the hardware does not allow for experimental iteration without reloading samples on the ground. To partially accommodate the disadvantages of the current hardware, we have used microfluidic technology (Lab-on-a-Chip devices) to design the concept of a more efficient crystallization device, suitable for use on the International Space Station and in high-throughput applications on the ground. The concept and properties of microfluidics, the application design process, and the advances in protein crystal growth hardware will be discussed in this presentation. Some examples of proteins crystallized in the new hardware will be discussed, including the differences between conventional crystallization versus crystallization in microfluidics.

vanderWoerd, Mark↗
NASA NTRS2003

Finding the Cold Needle in a Warm Haystack: Infrared Imaging Applied to Locating Cryo-cooled Crystals in Loops

Thermally imaging the cryocooling processes of crystals has been demonstrated showing the progression of a cold wave through a crystal from the face closest to the origin of the coldstream ending at the point furthest away. During these studies large volume crystals were clearly distinguished from the loop holding them. Large volume crystals, used for neutron studies, were chosen deliberately to enhance the imaging. The different infrared transmission and reflectance properties of the crystal in comparison to the cryo-protectant are thought to be the parameter that produces the contrast making the crystal visible. As an application of the technology to locating crystals, more small crystals of lysozyme and a bFGF/dna complex were cryo-protected and imaged in large loops. The crystals were clearly distinguished from the vitrified solution. In the case of the bFGF/dna complex the illumination had to be carefully manipulated to enable the crystal to be seen in the visible spectrum. These preliminary results will be presented along with advantages and disadvantages of the technique and a discussion of how it might be applied.

Snell, Edward↗
NASA NTRS2003

Perfectly Cold Crystals: What Happens When They Are X-rayed?

For many macromolecular crystals the cryo-preservation of these crystals during X-ray data collection is of crucial importance, particularly at synchrotron facilities where the crystals rapidly receive a high dose of radiation. A practical variable to ensure adequate preservation is the variation of the cryo-protectant present when the crystal is preserved. Our initial approach to study X-ray diffraction data quality as a function of cryo-protectant present when preserving a xylose isomerase crystal shows that the data quality can be tremendously improved by recipe adjustment. Guided by crystal mosaicity estimates, we optimized crystal growth conditions to obtain cryo-preserved xylose isomerase crystals that withstand a very high dose of X-rays, with only the smallest amount of radiation damage at ultra-high resolution (1.2Angstroms). The rate at which damage occurs allowed us to collect a series of complete data sets, which show how the data degradation proceeds over time. We are here presenting data for the xylose isomerase crystallization recipe improvement and our interpretation of the crystal degradation process during X-ray data collection.

vanderWoerd, Mark↗
NASA NTRS2004

Crystallization of a Li2O2SiO2 Glass under High Hydrostatic Pressures

The crystallization behavior of a Li2O.2SiO2 (LS2) glass subjected to a uniform hydrostatic pressure of 4.5 or 6 GPa was investigated between 550 and 800 C using XRD, IR, Raman, TEM, NMR, and DTA. The density of the glass subjected to 6 GPa was between 2.52 plus or minus 0.01 and 2.57 plus or minus 0.01 grams per cubic centimeters, depending upon the processing temperatures, and was higher than that of the stoichiometric LS2 crystals, 2.46 plus or minus 0.01 grams per cubic centimeter. Thus, crystallization in 6 GPa glass occurred in a condition of negative volume dilatation, deltaV = V(sub glass) - V(sub crystal), while that for the 4.5 GPa glass occurred in the condition deltaV greater than 0. For deltaV greater than 0, which also includes the control glass at ambient (one atmosphere) pressure, the glasses always crystallize Li2Si2O5 (orthorhombic, Ccc2) crystals, but for deltaV less than 0 (6 GPa), the glasses crystallize Li2SiO3 crystals with a slightly deformed structure. The crystal growth rate vs. temperature curve moved to higher temperature with increasing pressure, and was independent of the sign of deltaV. These results for the effect of hydrostatic pressure on the crystallization of LS2 glass were discussed from thermodynamic considerations.

Fuss, T.↗
NASA NTRS2004

The Nucleation and Growth of Protein Crystals

Obtaining crystals of suitable size and high quality continues to be a major bottleneck in macromolecular crystallography. Currently, structural genomics efforts are achieving on average about a 10% success rate in going from purified protein to a deposited crystal structure. Growth of crystals in microgravity was proposed as a means of overcoming size and quality problems, which subsequently led to a major NASA effort in microgravity crystal growth, with the agency also funding research into understanding the process. Studies of the macromolecule crystal nucleation and growth process were carried out in a number of labs in an effort to understand what affected the resultant crystal quality on Earth, and how microgravity improved the process. Based upon experimental evidence, as well as simple starting assumptions, we have proposed that crystal nucleation occurs by a series of discrete self assembly steps, which 'set' the underlying crystal symmetry. This talk will review the model developed, and its origins, in our laboratory for how crystals nucleate and grow, and will then present, along with preliminary data, how we propose to use this model to improve the success rate for obtaining crystals from a given protein.

Pusey, Marc↗
NASA NTRS2007

Use of dye to distinguish salt and protein crystals under microcrystallization conditions

An improved method of screening crystal growth conditions is provided wherein molecules are crystallized from solutions containing dyes. These dyes are selectively incorporated or associated with crystals of particular character thereby rendering crystals of particular character colored and improving detection of the dyed crystals. A preferred method involves use of dyes in protein solutions overlayed by oil. Use of oil allows the use of small volumes of solution and facilitates the screening of large numbers of crystallization conditions in arrays using automated devices that dispense appropriate solutions to generate crystallization trials, overlay crystallization trials with an oil, provide appropriate conditions conducive to crystallization and enhance detection of dyed (colored) or undyed (uncolored) crystals that result.

Cosenza, Larry↗
NASA NTRS2008

Effect of the Inhomogeneity of Ice Crystals on Retrieving Ice Cloud Optical Thickness and Effective Particle Size

Spherical or spheroidal air bubbles are generally trapped in the formation of rapidly growing ice crystals. In this study the single-scattering properties of inhomogeneous ice crystals containing air bubbles are investigated. Specifically, a computational model based on an improved geometric-optics method (IGOM) has been developed to simulate the scattering of light by randomly oriented hexagonal ice crystals containing spherical or spheroidal air bubbles. A combination of the ray-tracing technique and the Monte Carlo method is used. The effect of the air bubbles within ice crystals is to smooth the phase functions, diminish the 22deg and 46deg halo peaks, and substantially reduce the backscatter relative to bubble-free particles. These features vary with the number, sizes, locations and shapes of the air bubbles within ice crystals. Moreover, the asymmetry factors of inhomogeneous ice crystals decrease as the volume of air bubbles increases. Cloud reflectance lookup tables were generated at wavelengths 0.65 m and 2.13 m with different air-bubble conditions to examine the impact of the bubbles on retrieving ice cloud optical thickness and effective particle size. The reflectances simulated for inhomogeneous ice crystals are slightly larger than those computed for homogenous ice crystals at a wavelength of 0.65 microns. Thus, the retrieved cloud optical thicknesses are reduced by employing inhomogeneous ice cloud models. At a wavelength of 2.13 microns, including air bubbles in ice cloud models may also increase the reflectance. This effect implies that the retrieved effective particle sizes for inhomogeneous ice crystals are larger than those retrieved for homogeneous ice crystals, particularly, in the case of large air bubbles.

Xie, Yu↗
NASA NTRS2007

Extended-Range Ultrarefractive 1D Photonic Crystal Prisms

A proposal has been made to exploit the special wavelength-dispersive characteristics of devices of the type described in One-Dimensional Photonic Crystal Superprisms (NPO-30232) NASA Tech Briefs, Vol. 29, No. 4 (April 2005), page 10a. A photonic crystal is an optical component that has a periodic structure comprising two dielectric materials with high dielectric contrast (e.g., a semiconductor and air), with geometrical feature sizes comparable to or smaller than light wavelengths of interest. Experimental superprisms have been realized as photonic crystals having three-dimensional (3D) structures comprising regions of amorphous Si alternating with regions of SiO2, fabricated in a complex process that included sputtering. A photonic crystal of the type to be exploited according to the present proposal is said to be one-dimensional (1D) because its contrasting dielectric materials would be stacked in parallel planar layers; in other words, there would be spatial periodicity in one dimension only. The processes of designing and fabricating 1D photonic crystal superprisms would be simpler and, hence, would cost less than do those for 3D photonic crystal superprisms. As in 3D structures, 1D photonic crystals may be used in applications such as wavelength-division multiplexing. In the extended-range configuration, it is also suitable for spectrometry applications. As an engineered structure or artificially engineered material, a photonic crystal can exhibit optical properties not commonly found in natural substances. Prior research had revealed several classes of photonic crystal structures for which the propagation of electromagnetic radiation is forbidden in certain frequency ranges, denoted photonic bandgaps. It had also been found that in narrow frequency bands just outside the photonic bandgaps, the angular wavelength dispersion of electromagnetic waves propagating in photonic crystal superprisms is much stronger than is the angular wavelength dispersion obtained by use of conventional prisms and diffraction gratings and is highly nonlinear.

Ting, David Z.↗
NASA NTRS2004

Imaging of gamma-Irradiated Regions of a Crystal

A holographic technique has been devised for generating a visible display of the effect of exposure of a photorefractive crystal to gamma rays. The technique exploits the space charge that results from trapping of electrons in defects induced by gamma rays. The technique involves a three-stage process. In the first stage, one writes a holographic pattern in the crystal by use of the apparatus shown in Figure 1. A laser beam of 532-nm wavelength is collimated and split into signal and reference beams by use of a polarizing beam splitter. On its way to the crystal, the reference beam goes through a two-dimensional optical scanner that contains two pairs of lenses (L1y, L2y and L1x,L2x) and mirrors M1 and M2, which can be rotated by use of micrometer drives to make fine adjustments. The signal beam is sent through a spatial light modulator that imposes the holographic pattern, then through two imaging lenses L(sub img) on its way to the crystal. An aperture is placed at the common focus of lenses Limg to suppress high-order diffraction from the spatial light modulator. The hologram is formed by interference between the signal and reference beams. A camera lens focuses an image of the interior of the crystal onto a charge-coupled device (CCD). If the crystal is illuminated by only the reference beam once the hologram has been formed, then an image of the hologram is formed on the CCD: this phenomenon is exploited to make visible the pattern of gamma irradiation of the crystal, as described next. In the second stage of the process, the crystal is removed from the holographic apparatus and irradiated with rays at a dose of about 100 krad. In the third stage of the process, the crystal is remounted in the holographic apparatus in the same position as in the first stage and illuminated with only the reference beam to obtain the image of the hologram as modified by the effect of the rays. The orientations of M1 and M2 can be adjusted slightly, if necessary, to maximize the intensity of the image. Figure 2 shows such an image that was formed in a crystal of Fe:LiNbO3.

Dragoi, Danut↗
NASA NTRS2013

Can Fractional Crystallization of a Lunar Magma Ocean Produce the Lunar Crust?

New techniques enable the study of Apollo samples and lunar meteorites in unprecedented detail, and recent orbital spectral data reveal more about the lunar farside than ever before, raising new questions about the supposed simplicity of lunar geology. Nevertheless, crystallization of a global-scale magma ocean remains the best model to account for known lunar lithologies. Crystallization of a lunar magma ocean (LMO) is modeled to proceed by two end-member processes - fractional crystallization from (mostly) the bottom up, or initial equilibrium crystallization as the magma is vigorously convecting and crystals remain entrained, followed by crystal settling and a final period of fractional crystallization [1]. Physical models of magma viscosity and convection at this scale suggest that both processes are possible. We have been carrying out high-fidelity experimental simulations of LMO crystallization using two bulk compositions that can be regarded as end-members in the likely relevant range: Taylor Whole Moon (TWM) [2] and Lunar Primitive Upper Mantle (LPUM) [3]. TWM is enriched in refractory elements by 1.5 times relative to Earth, whereas LPUM is similar to the terrestrial primitive upper mantle, with adjustments made for the depletion of volatile alkalis observed on the Moon. Here we extend our earlier equilibrium-crystallization experiments [4] with runs simulating full fractional crystallization

Rapp, Jennifer F.↗
DOE OSTI2025

Increasing Branching and Functionalization Decreases Crystallinity and Crystallization Rate in Linear EVOH

Here, we report the crystallization behavior of a linear poly(ethylene-co-vinyl alcohol) (LEVOH) under isothermal crystallization as a function of both OH incorporation and undercooling, and compare the results to conventional branched EVOH. This LEVOH is synthesized by post-polymerization functionalization of polycyclooctene, and it exhibits a half-crystallization time and primary crystallization rate nearly an order of magnitude faster than branched EVOH at ~ 6 mol% OH incorporation. While the LEVOH obtains approximately twice the extent of crystallization compared to the branched equivalent, as OH incorporation increases, the crystallization kinetics and crystallinity of LEVOH decrease. The crystal structure of LEVOH is orthorhombic at low functionalization (≤ 11 mol% OH), a mixture of orthorhombic and hexagonal at moderate functionalization (17 - 21 mol%), and hexagonal at high functionalization (23 %). The LEVOH crystallizes into plates, with crystallite widths ~ 20 - 60 times the crystallite thickness. Ultimately, we show LEVOH crystallizes faster and to a greater extent than commercial branched EVOH, a potential advantage of post-polymerization functionalization as part of polymer-to-polymer upcycling.

36 MATERIALS SCIENCE↗