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Papers by Eric Verploegen

We used small-angle X-ray scattering (SAXS) to quantitatively characterize the morphological char... more We used small-angle X-ray scattering (SAXS) to quantitatively characterize the morphological characteristics of pristine and mechanically manipulated multiwall carbon nanotube (MWCNT) films. We determined that CNT diameters measured near the edges of a film were smaller compared to those measured in the interior. Uniaxially compressed MWCNT films exhibited a buckling deformation that was observable both in scanning electron microscopy (SEM) and SAXS. CNT films were also converted into cellular foams of CNTs through capillarity-induced densification. By examining spatially- and time-resolved SAXS data for the cellular foams, we identified low angle features in the scattering curves that correspond to the average spacing between CNTs, demonstrating that SAXS is a useful method for monitoring the packing density of CNTs in a film. For all of the morphologies that were examined (aligned, disordered, compressed, and densified), SAXS data showed good correspondence with SEM images.

This paper describes new experiments designed to characterize the micromechanical response of str... more This paper describes new experiments designed to characterize the micromechanical response of structural materials. As a way to calibrate microscale constitutive models and to understand grain scale elastic-plastic deformation, our group worked closely with CHESS personnel to develop a high energy x-ray method for measuring lattice Strain Pole Figures (SPFs) in situ in the A2 experimental station at CHESS. Results from experiments and crystal-based finite element simulations on copper are presented in the paper.

2018 IEEE Global Humanitarian Technology Conference (GHTC)

cycle film) depositions. Figure S2. Compilation of thicknesses evolution of e-LBL and l-LBL films... more cycle film) depositions. Figure S2. Compilation of thicknesses evolution of e-LBL and l-LBL films as a function of number of deposited layers and with different deposition intervals. A) Comparison of thicknesses from SEM for (PDDA/MTM/PDDA/PAA)n films with the specified deposition intervals prepared on microscope glass slides. The (PDDA/MTM)n regression is based on the values obtained by Tang et al..[1] B) Comparison of (PDDA/MTM/PDDA/PAA)n with and without MTM following 5 min depositions.

International Journal of Heat and Mass Transfer

By systematically controlling the covalent attachment of side chain liquid crystals to a block co... more By systematically controlling the covalent attachment of side chain liquid crystals to a block copolymer backbone, the morphology of both the liquid crystalline (LC) mesophase and the phase segregated BCP microstructures can be precisely manipulated. A wide range of morphologies can be achieved from a single block copolymer backbone during a one step LC attachment reaction. The anchoring of the

Synchrotron Radiation News, 2010

... DOI: 10.1080/08940886.2010.501491 Eric Verploegen a c ... colleagues for their contribution t... more ... DOI: 10.1080/08940886.2010.501491 Eric Verploegen a c ... colleagues for their contribution to this work: Rajib Mondal, Christopher J. Bettinger, Seihout Sok, Stefan Mannsfeld, Zhenan Bao, Nichole C. Cates, Roman Gysel, Zach Beiley, Michael D. McGehee, Alex Hexemer ...

A series of well defined smectic side chain liquid crystalline (LC) block copolymers with a low T... more A series of well defined smectic side chain liquid crystalline (LC) block copolymers with a low Tg siloxane center block has been synthesized via anionic polymerization. The presence of a smectic liquid crystalline phase and the block copolymer mesophase are observed across various temperature ranges via Small Angle X-ray Scattering (SAXS) and Grazing Incidence Small Angle X-ray Scattering (GISAXS). The

Chemistry of Materials, 2015

We observed a thermotropic phase transition in poly[3,4-dihexyl thiophene-2,2′:5,6′-benzo[1,2-b:4... more We observed a thermotropic phase transition in poly[3,4-dihexyl thiophene-2,2′:5,6′-benzo[1,2-b:4,5-b′]dithiophene] (PDHBDT) thin films accompanied by a transition from a random orientation to an ordered lamellar phase via a nearly hexagonal lattice upon annealing. We demonstrate the effect of temperature-dependent molecular packing on charge carrier mobility (μ) in organic field-effect transistors (OFETs) and photovoltaic characteristics, such as exciton diffusion length (LD) and power conversion efficiency (PCE), in organic solar cells (OSCs) using PDHBDT. The μ was continuously improved with increasing annealing temperature and PDHBDT films annealed at 270 °C resulted in a maximum μ up to 0.46 cm2/(V s) (μavg = 0.22 cm2/(V s)), which is attributed to the well-ordered lamellar structure with a closer π–π stacking distance of 3.5 A as shown by grazing incidence-angle X-ray diffraction (GIXD). On the other hand, PDHBDT films with a random molecular orientation are more effective in photovoltaic devices th...

MRS Proceedings, 2005

ABSTRACTThe synthesis of a polystyrene-b-polyvinylmethylsiloxane-b-polystyrene diblock and triblo... more ABSTRACTThe synthesis of a polystyrene-b-polyvinylmethylsiloxane-b-polystyrene diblock and triblock copolymer functionalized with liquid crystals exhibiting a smectic C* phase on the PVMS central block is described. The synthetic route is based on the anionic polymerization of styrene and trimethyltrivinylsiloxane monomers and the functionalization of resulting triblock copolymers. The resulting polymer can self assemble into a thermoplastic elastomer where the high Tg styrene blocks serve as physical crosslinks for a low Tg siloxane block. The presence of a smectic liquid crystalline phase and the block copolymer mesophase are observed across various temperature ranges depending on the length of the spacer connecting the liquid crystalline moiety to the polymer backbone. The influence of mechanical deformation upon the morphologies of the liquid crystalline and block copolymer mesophases was investigated. The interactions between the smectic LC and the block copolymer morphologies ...

The Journal of Physical Chemistry C, 2009

The Journal of Physical Chemistry C, 2007

Films of multiwall carbon nanotubes (MWCNTs) grown by thermal chemical vapor deposition were stud... more Films of multiwall carbon nanotubes (MWCNTs) grown by thermal chemical vapor deposition were studied using small-angle X-ray scattering (SAXS). We assessed the extent of alignment of carbon nanotubes (CNTs) by examining relative SAXS intensities as a function of azimuthal angle. We also identified features in the SAXS patterns that correspond well to CNT diameters measured through high-resolution transmission electron microscopy. For the case of thick films, corresponding to CNTs with lengths on the order of a millimeter, we were able to study the morphology of the films as a function of distance from the catalyst substrate. We examined two different films in which the morphologies of CNTs range from vertically aligned to entangled and tortuous. We determined that the alignment of CNTs as well as their average diameter can vary significantly throughout the film, demonstrating the utility of SAXS for quantitative structural analysis of CNT films, indicating the potential to reveal new information about the CNT growth process, and relating variations in morphology to evolution of the catalyst and reaction conditions.

Journal of Physical Chemistry C, 2007

We used small-angle X-ray scattering (SAXS) to quantitatively characterize the morphological char... more We used small-angle X-ray scattering (SAXS) to quantitatively characterize the morphological characteristics of pristine and mechanically manipulated multiwall carbon nanotube (MWCNT) films. We determined that CNT diameters measured near the edges of a film were smaller compared to those measured in the interior. Uniaxially compressed MWCNT films exhibited a buckling deformation that was observable both in scanning electron microscopy (SEM) and SAXS. CNT films were also converted into cellular foams of CNTs through capillarity-induced densification. By examining spatially-and time-resolved SAXS data for the cellular foams, we identified low angle features in the scattering curves that correspond to the average spacing between CNTs, demonstrating that SAXS is a useful method for monitoring the packing density of CNTs in a film. For all of the morphologies that were examined (aligned, disordered, compressed, and densified), SAXS data showed good correspondence with SEM images.

Soft Matter, 2008

... Eric Verploegena, Tejia Zhangb, Nicholas Murloa and Paula T. Hammond*c. a Department of Mater... more ... Eric Verploegena, Tejia Zhangb, Nicholas Murloa and Paula T. Hammond*c. a Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA. ...

Review of Scientific Instruments, 2009

We used small-angle X-ray scattering (SAXS) to quantitatively characterize the morphological char... more We used small-angle X-ray scattering (SAXS) to quantitatively characterize the morphological characteristics of pristine and mechanically manipulated multiwall carbon nanotube (MWCNT) films. We determined that CNT diameters measured near the edges of a film were smaller compared to those measured in the interior. Uniaxially compressed MWCNT films exhibited a buckling deformation that was observable both in scanning electron microscopy (SEM) and SAXS. CNT films were also converted into cellular foams of CNTs through capillarity-induced densification. By examining spatially- and time-resolved SAXS data for the cellular foams, we identified low angle features in the scattering curves that correspond to the average spacing between CNTs, demonstrating that SAXS is a useful method for monitoring the packing density of CNTs in a film. For all of the morphologies that were examined (aligned, disordered, compressed, and densified), SAXS data showed good correspondence with SEM images.

This paper describes new experiments designed to characterize the micromechanical response of str... more This paper describes new experiments designed to characterize the micromechanical response of structural materials. As a way to calibrate microscale constitutive models and to understand grain scale elastic-plastic deformation, our group worked closely with CHESS personnel to develop a high energy x-ray method for measuring lattice Strain Pole Figures (SPFs) in situ in the A2 experimental station at CHESS. Results from experiments and crystal-based finite element simulations on copper are presented in the paper.

2018 IEEE Global Humanitarian Technology Conference (GHTC)

cycle film) depositions. Figure S2. Compilation of thicknesses evolution of e-LBL and l-LBL films... more cycle film) depositions. Figure S2. Compilation of thicknesses evolution of e-LBL and l-LBL films as a function of number of deposited layers and with different deposition intervals. A) Comparison of thicknesses from SEM for (PDDA/MTM/PDDA/PAA)n films with the specified deposition intervals prepared on microscope glass slides. The (PDDA/MTM)n regression is based on the values obtained by Tang et al..[1] B) Comparison of (PDDA/MTM/PDDA/PAA)n with and without MTM following 5 min depositions.

International Journal of Heat and Mass Transfer

By systematically controlling the covalent attachment of side chain liquid crystals to a block co... more By systematically controlling the covalent attachment of side chain liquid crystals to a block copolymer backbone, the morphology of both the liquid crystalline (LC) mesophase and the phase segregated BCP microstructures can be precisely manipulated. A wide range of morphologies can be achieved from a single block copolymer backbone during a one step LC attachment reaction. The anchoring of the

Synchrotron Radiation News, 2010

... DOI: 10.1080/08940886.2010.501491 Eric Verploegen a c ... colleagues for their contribution t... more ... DOI: 10.1080/08940886.2010.501491 Eric Verploegen a c ... colleagues for their contribution to this work: Rajib Mondal, Christopher J. Bettinger, Seihout Sok, Stefan Mannsfeld, Zhenan Bao, Nichole C. Cates, Roman Gysel, Zach Beiley, Michael D. McGehee, Alex Hexemer ...

A series of well defined smectic side chain liquid crystalline (LC) block copolymers with a low T... more A series of well defined smectic side chain liquid crystalline (LC) block copolymers with a low Tg siloxane center block has been synthesized via anionic polymerization. The presence of a smectic liquid crystalline phase and the block copolymer mesophase are observed across various temperature ranges via Small Angle X-ray Scattering (SAXS) and Grazing Incidence Small Angle X-ray Scattering (GISAXS). The

Chemistry of Materials, 2015

We observed a thermotropic phase transition in poly[3,4-dihexyl thiophene-2,2′:5,6′-benzo[1,2-b:4... more We observed a thermotropic phase transition in poly[3,4-dihexyl thiophene-2,2′:5,6′-benzo[1,2-b:4,5-b′]dithiophene] (PDHBDT) thin films accompanied by a transition from a random orientation to an ordered lamellar phase via a nearly hexagonal lattice upon annealing. We demonstrate the effect of temperature-dependent molecular packing on charge carrier mobility (μ) in organic field-effect transistors (OFETs) and photovoltaic characteristics, such as exciton diffusion length (LD) and power conversion efficiency (PCE), in organic solar cells (OSCs) using PDHBDT. The μ was continuously improved with increasing annealing temperature and PDHBDT films annealed at 270 °C resulted in a maximum μ up to 0.46 cm2/(V s) (μavg = 0.22 cm2/(V s)), which is attributed to the well-ordered lamellar structure with a closer π–π stacking distance of 3.5 A as shown by grazing incidence-angle X-ray diffraction (GIXD). On the other hand, PDHBDT films with a random molecular orientation are more effective in photovoltaic devices th...

MRS Proceedings, 2005

ABSTRACTThe synthesis of a polystyrene-b-polyvinylmethylsiloxane-b-polystyrene diblock and triblo... more ABSTRACTThe synthesis of a polystyrene-b-polyvinylmethylsiloxane-b-polystyrene diblock and triblock copolymer functionalized with liquid crystals exhibiting a smectic C* phase on the PVMS central block is described. The synthetic route is based on the anionic polymerization of styrene and trimethyltrivinylsiloxane monomers and the functionalization of resulting triblock copolymers. The resulting polymer can self assemble into a thermoplastic elastomer where the high Tg styrene blocks serve as physical crosslinks for a low Tg siloxane block. The presence of a smectic liquid crystalline phase and the block copolymer mesophase are observed across various temperature ranges depending on the length of the spacer connecting the liquid crystalline moiety to the polymer backbone. The influence of mechanical deformation upon the morphologies of the liquid crystalline and block copolymer mesophases was investigated. The interactions between the smectic LC and the block copolymer morphologies ...

The Journal of Physical Chemistry C, 2009

The Journal of Physical Chemistry C, 2007

Films of multiwall carbon nanotubes (MWCNTs) grown by thermal chemical vapor deposition were stud... more Films of multiwall carbon nanotubes (MWCNTs) grown by thermal chemical vapor deposition were studied using small-angle X-ray scattering (SAXS). We assessed the extent of alignment of carbon nanotubes (CNTs) by examining relative SAXS intensities as a function of azimuthal angle. We also identified features in the SAXS patterns that correspond well to CNT diameters measured through high-resolution transmission electron microscopy. For the case of thick films, corresponding to CNTs with lengths on the order of a millimeter, we were able to study the morphology of the films as a function of distance from the catalyst substrate. We examined two different films in which the morphologies of CNTs range from vertically aligned to entangled and tortuous. We determined that the alignment of CNTs as well as their average diameter can vary significantly throughout the film, demonstrating the utility of SAXS for quantitative structural analysis of CNT films, indicating the potential to reveal new information about the CNT growth process, and relating variations in morphology to evolution of the catalyst and reaction conditions.

Journal of Physical Chemistry C, 2007

We used small-angle X-ray scattering (SAXS) to quantitatively characterize the morphological char... more We used small-angle X-ray scattering (SAXS) to quantitatively characterize the morphological characteristics of pristine and mechanically manipulated multiwall carbon nanotube (MWCNT) films. We determined that CNT diameters measured near the edges of a film were smaller compared to those measured in the interior. Uniaxially compressed MWCNT films exhibited a buckling deformation that was observable both in scanning electron microscopy (SEM) and SAXS. CNT films were also converted into cellular foams of CNTs through capillarity-induced densification. By examining spatially-and time-resolved SAXS data for the cellular foams, we identified low angle features in the scattering curves that correspond to the average spacing between CNTs, demonstrating that SAXS is a useful method for monitoring the packing density of CNTs in a film. For all of the morphologies that were examined (aligned, disordered, compressed, and densified), SAXS data showed good correspondence with SEM images.

Soft Matter, 2008

... Eric Verploegena, Tejia Zhangb, Nicholas Murloa and Paula T. Hammond*c. a Department of Mater... more ... Eric Verploegena, Tejia Zhangb, Nicholas Murloa and Paula T. Hammond*c. a Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA. ...

Review of Scientific Instruments, 2009