scholarly journals Surface Crystal Nucleation and Growth in Poly (ε-caprolactone): Atomic Force Microscopy Combined with Fast Scanning Chip Calorimetry

Polymers ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 2008
Author(s):  
Rui Zhang ◽  
Mengxue Du ◽  
Evgeny Zhuravlev ◽  
René Androsch ◽  
Christoph Schick
Keyword(s):  
Radial Symmetry ◽  
Crystal Nucleation ◽  
Melt Crystallization ◽  
Equilibrium Melting Temperature ◽  
Force Microscopy ◽  
Bulk Crystallization ◽  
Atomic Force ◽  
Chip Calorimetry ◽  
Surface Crystal ◽  
Fast Scanning Chip Calorimetry

By using an atomic force microscope (AFM) coupled to a fast scanning chip calorimeter (FSC), AFM-tip induced crystal nucleation/crystallization in poly (ε-caprolactone) (PCL) has been studied at low melt-supercooling, that is, at a temperature typically not assessable for melt-crystallization studies. Nanogram-sized PCL was placed on the active/heatable area of the FSC chip, melted, and then rapidly cooled to 330 K, which is 13 K below the equilibrium melting temperature. Subsequent isothermal crystallization at this temperature was initiated by a soft-tapping AFM-tip nucleation event. Crystallization starting at such surface nucleus led to formation of a single spherulite within the FSC sample, as concluded from the radial symmetry of the observed morphology. The observed growth rate in the sub-micron thin FSC sample, nucleated at its surface, was found being much higher than in the case of bulk crystallization, emphasizing a different growth mechanism. Moreover, distinct banding/ring-like structures are observed, with the band period being less than 1 µm. After crystallization, the sample was melted for gaining information about the achieved crystallinity and the temperature range of melting, both being similar compared to much slower bulk crystallization at the same temperature but for a much longer time.

Steady-State Crystal Nucleation Rate of Polyamide 66 by Combining Atomic Force Microscopy and Fast-Scanning Chip Calorimetry

2020 ◽  
Vol 53 (13) ◽  
pp. 5560-5571 ◽  
Author(s):  
Rui Zhang ◽  
Evgeny Zhuravlev ◽  
Jürn W. P. Schmelzer ◽  
René Androsch ◽  
Christoph Schick
Keyword(s):  
Atomic Force Microscopy ◽  
Steady State ◽  
Nucleation Rate ◽  
Crystal Nucleation ◽  
Polyamide 66 ◽  
Force Microscopy ◽  
Atomic Force ◽  
Chip Calorimetry ◽  
Fast Scanning Chip Calorimetry

scholarly journals Crystal growth of the core and rotated epitaxial shell of a heterometallic metal-organic framework revealed with atomic force microscopy

2021 ◽  
Author(s):  
Fajar Inggit Pambudi ◽  
Michael William Anderson ◽  
Martin Attfield
Keyword(s):  
Atomic Force Microscopy ◽  
Crystal Growth ◽  
Metal Organic Framework ◽  
Metal Organic Frameworks ◽  
Force Microscopy ◽  
The Core ◽  
Atomic Force ◽  
Metal Organic ◽  
Surface Crystal ◽  
Organic Framework

Atomic force microscopy has been used to determine the surface crystal growth of two isostructural metal-organic frameworks, [Zn2(ndc)2(dabco)] (ndc = 1,4-naphthalene dicarboxylate, dabco = 4-diazabicyclo[2.2.2]octane) (1) and [Cu2(ndc)2(dabco)] (2) from...

scholarly journals Fast-Scanning Chip-Calorimetry Measurement of Crystallization Kinetics of Poly(Glycolic Acid)

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 891
Author(s):  
Yongxuan Chen ◽  
Kefeng Xie ◽  
Yucheng He ◽  
Wenbing Hu
Keyword(s):  
Crystallization Kinetics ◽  
Temperature Region ◽  
Glycolic Acid ◽  
Crystal Nucleation ◽  
Side Group ◽  
Half Time ◽  
Temperature Range ◽  
Chip Calorimetry ◽  
Kinetics Of ◽  
Fast Scanning Chip Calorimetry

We report fast-scanning chip-calorimetry measurement of isothermal crystallization kinetics of poly(glycolic acid) (PGA) in a broad temperature range. We observed that PGA crystallization could be suppressed by cooling rates beyond -100 K s−1 and, after fast cooling, by heating rates beyond 50 K s-1. In addition, the parabolic curve of crystallization half-time versus crystallization temperature shows that PGA crystallizes the fastest at 130 °C with the minimum crystallization half-time of 4.28 s. We compared our results to those of poly(L-lactic acid) (PLLA) with nearby molecular weights previously reported by Androsch et al. We found that PGA crystallizes generally more quickly than PLLA. In comparison to PLLA, PGA has a much smaller hydrogen side group than the methyl side group in PLLA; therefore, crystal nucleation is favored by the higher molecular mobility of PGA in the low temperature region as well as by the denser molecular packing of PGA in the high temperature region, and the two factors together decide the higher crystallization rates of PGA in the whole temperature range.

Kinetics of Crystal Nucleation and Growth in Thin Films of Amorphous Te Alloys measured by Atomic Force Microscopy

2003 ◽  
Vol 803 ◽  
Author(s):  
J. Kalb ◽  
F. Spaepen ◽  
M. Wuttig
Keyword(s):  
Thin Films ◽  
Atomic Force Microscopy ◽  
Crystal Growth ◽  
Data Storage ◽  
Optical Data Storage ◽  
Crystal Nucleation ◽  
Ex Situ ◽  
Optical Data ◽  
Force Microscopy ◽  
Atomic Force

ABSTRACTBoth the crystal nucleation rate and the crystal growth velocity of sputtered amorphous Ag0.055In0.065Sb0.59Te0.29 and Ge4Sb1Te5 thin films used for optical data storage were determined as a function of temperature. Crystals were directly observed using ex-situ atomic force microscopy, and their change in size after each anneal was measured. Between 140°C and 185°C, these materials exhibited similar crystal growth characteristics, but differed in their crystal nucleation characteristics. These observations provide an explanation for the different re-crystallization mechanisms observed upon laser-induced crystallization of amorphous marks.

scholarly journals New Insights into Crystallization of Heterophasic Isotactic Polypropylene by Fast Scanning Chip Calorimetry

Polymers ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1683
Author(s):  
Daniela Mileva ◽  
Jingbo Wang ◽  
Markus Gahleitner ◽  
Katalee Jariyavidyanont ◽  
René Androsch
Keyword(s):  
Crystallization Kinetics ◽  
Isotactic Polypropylene ◽  
Crystallization Rate ◽  
Crystal Nucleation ◽  
Crystallization Time ◽  
Chip Calorimetry ◽  
The Matrix ◽  
Homogeneous Crystal ◽  
Kinetics Of ◽  
Fast Scanning Chip Calorimetry

The crystallization kinetics of metallocene-catalyzed heterophasic isotactic polypropylene composed of a matrix of isotactic polypropylene (iPP) and rubbery particles made of random ethylene–propylene copolymers (EPC), often denoted as heterophasic iPP copolymers, was analyzed as a function of the cooling rate and supercooling in nonisothermal and isothermal crystallization experiments, respectively. Fast scanning chip calorimetry (FSC) allowed assessing crystallization at processing-relevant conditions, and variation of the content (0–39 wt %) and composition (0–35 wt % propylene counits) of the EPC particles revealed qualitatively new insight about mechanisms of heterogeneous crystal nucleation. For neat iPP homopolymer, the characteristic bimodal temperature dependence of the crystallization rate due to predominance of heterogeneous and homogeneous crystal nucleation at high and low temperatures, respectively, is reconfirmed. At high temperatures, in heterophasic iPP, the here studied ethylene-(C2)-rich EPC particles accelerate crystallization of the iPP-matrix, with the acceleration or nucleation efficacy correlating with the EPC-particle content. The crystallization time reduces by more than half in presence of 39 wt % EPC particles. An additional nucleating effect of the EPC particles on iPP-matrix crystallization is detected after their crystallization, suggesting that liquid/rubbery particles are less effective than solid/semicrystalline particles in affecting crystallization of the surrounding iPP-matrix. At low temperature, homogeneous crystal nucleation in the iPP-matrix outpaces all heterogeneous nucleation effects, and the matrix-crystallization rate is independent of the sample composition. The obtained results lead to the conclusion that the crystallization kinetics of iPP can be affected significantly by the content and composition of EPC particles, even towards superfast crystallizing iPP grades.

Cryogenic atomic force microscopy

1991 ◽  
Vol 49 ◽  
pp. 54-55
Author(s):  
K. A. Fisher ◽  
M. G. L. Gustafsson ◽  
M. B. Shattuck ◽  
J. Clarke
Keyword(s):  
Room Temperature ◽  
Rapid Freezing ◽  
Cryogenic Temperatures ◽  
Soft Or ◽  
Electrically Conductive ◽  
Force Microscopy ◽  
Flexible Molecules ◽  
Advantages And Disadvantages ◽  
Atomic Force ◽  
Chemical Perturbation

The atomic force microscope (AFM) is capable of imaging electrically conductive and non-conductive surfaces at atomic resolution. When used to image biological samples, however, lateral resolution is often limited to nanometer levels, due primarily to AFM tip/sample interactions. Several approaches to immobilize and stabilize soft or flexible molecules for AFM have been examined, notably, tethering coating, and freezing. Although each approach has its advantages and disadvantages, rapid freezing techniques have the special advantage of avoiding chemical perturbation, and minimizing physical disruption of the sample. Scanning with an AFM at cryogenic temperatures has the potential to image frozen biomolecules at high resolution. We have constructed a force microscope capable of operating immersed in liquid n-pentane and have tested its performance at room temperature with carbon and metal-coated samples, and at 143° K with uncoated ferritin and purple membrane (PM).

AFM study of the dynamics of α-alumina surface faceting during high-temperature processing

1995 ◽  
Vol 53 ◽  
pp. 334-335 ◽  
Author(s):  
Michael W. Bench ◽  
Jason R. Heffelfinger ◽  
C. Barry Carter
Keyword(s):  
High Temperature ◽  
Thin Foil ◽  
Sem Analysis ◽  
Conductive Coatings ◽  
Force Microscopy ◽  
Minimal Sample ◽  
Atomic Force ◽  
Formation And Evolution ◽  
High Temperature Processing ◽  
Nominal Surface

To gain a better understanding of the surface faceting that occurs in α-alumina during high temperature processing, atomic force microscopy (AFM) studies have been performed to follow the formation and evolution of the facets. AFM was chosen because it allows for analysis of topographical details down to the atomic level with minimal sample preparation. This is in contrast to SEM analysis, which typically requires the application of conductive coatings that can alter the surface between subsequent heat treatments. Similar experiments have been performed in the TEM; however, due to thin foil and hole edge effects the results may not be representative of the behavior of bulk surfaces.The AFM studies were performed on a Digital Instruments Nanoscope III using microfabricated Si3N4 cantilevers. All images were recorded in air with a nominal applied force of 10-15 nN. The alumina samples were prepared from pre-polished single crystals with (0001), , and nominal surface orientations.

Scanning tunneling microscopy and atomic force microscopy: New tools for biology

1989 ◽  
Vol 47 ◽  
pp. 778-779
Author(s):  
CE Bracker ◽  
P. K. Hansma
Keyword(s):  
Physical Property ◽  
Scanning Probe ◽  
Scanning Tunneling ◽  
Small Scale ◽  
Tunneling Microscopy ◽  
Force Microscopy ◽  
New Family ◽  
Small Probe ◽  
Atomic Force ◽  
Transmission Electron

A new family of scanning probe microscopes has emerged that is opening new horizons for investigating the fine structure of matter. The earliest and best known of these instruments is the scanning tunneling microscope (STM). First published in 1982, the STM earned the 1986 Nobel Prize in Physics for two of its inventors, G. Binnig and H. Rohrer. They shared the prize with E. Ruska for his work that had led to the development of the transmission electron microscope half a century earlier. It seems appropriate that the award embodied this particular blend of the old and the new because it demonstrated to the world a long overdue respect for the enormous contributions electron microscopy has made to the understanding of matter, and at the same time it signalled the dawn of a new age in microscopy. What we are seeing is a revolution in microscopy and a redefinition of the concept of a microscope.Several kinds of scanning probe microscopes now exist, and the number is increasing. What they share in common is a small probe that is scanned over the surface of a specimen and measures a physical property on a very small scale, at or near the surface. Scanning probes can measure temperature, magnetic fields, tunneling currents, voltage, force, and ion currents, among others.

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