A study of the glass transition of polypropylene surfaces by sum-frequency vibrational spectroscopy and scanning force microscopy

Gracias, David H.; Zhang, D.; Lianos, L.; Ibach, Wolfram; Shen, Y. R.; Somorjai, Gábor A.

doi:10.1016/s0301-0104(99)00043-9

Cited by 75 publications

(61 citation statements)

References 18 publications

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“…4). SFG is a second-order nonlinear optical process, where electric-dipole in a bulk with inversion symmetry is forbidden, but it is allowed at interfaces because inversion symmetry is broken (Lambert et al 2005;Zhang et al 1997;Gracias et al 1999;Wei et al1999). Therefore, it is sensitive to the interfacial structure between two centrosymmetric media.…”

Section: Surface and Interface Propertiesmentioning

confidence: 99%

Solution behavior and surface properties of carboxymethylcellulose acetate butyrate

et al. 2009

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Solution behavior of carboxymethylcellulose acetate butyrate (CMCAB) in acetone and ethyl acetate has been investigated by small-angle X-ray scattering (SAXS) and capillary viscometry and correlated with the characteristics of CMCAB films. Viscosity and SAXS measurements showed that ethyl acetate is a better solvent than acetone for CMCAB. Thin films of CMCAB were deposited onto silicon wafers (Si/SiO 2 ) by spin coating. AFM images revealed that CMCAB spin coated films from solutions prepared in ethyl acetate were homogeneous and flat. However, films obtained from solutions in acetone were very rough. Contact angle measurements with polar and apolar test liquids characterized CMCAB surfaces as hydrophobic and allowed estimating the surface energy of CMCAB. Sum frequency generation vibrational spectroscopy was used to understand the role played by solvents and to gain insight about molecular orientation at Si/SiO 2 /CMCAB interface.

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Section: Surface and Interface Propertiesmentioning

confidence: 99%

Solution behavior and surface properties of carboxymethylcellulose acetate butyrate

et al. 2009

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“…5 The homebuilt walking-style AFM scanning head, controlled by RHK electronics, has been previously described and is enclosed within a 30-L glass bell jar. 6 The contact lens is supported on a polypropylene mold, immersed in saline solution, and covered by a stainless steel cover plate. The cover plate was machined to have an 8-mm inside curvature and a 4-mm outside orifice diameter.…”

Section: Atomic Force Microscopymentioning

confidence: 99%

Surface mechanical properties of pHEMA contact lenses: Viscoelastic and adhesive property changes on exposure to controlled humidity

Opdahl

Kim

Koffas

et al. 2003

J Biomedical Materials Res

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The surface mechanical properties of poly(hydroxyethyl)methacrylate (pHEMA)-based contact lenses were monitored as a function of humidity by atomic force microscopy (AFM). Surface viscoelastic and adhesion values were extracted from AFM force versus distance interaction curves and were found to be strongly dependent on the bulk water content of the lens and on the relative humidity. At low relative humidity, 40-50%, the dehydration rate from the surface is faster than the hydration rate from the bulk, leading to a rigid surface region that has mechanical properties similar to those measured on totally dehydrated lenses. At relative humidity values > 60%, the dehydration rate from the lens surface rapidly decreases, leading to higher surface water content and a softer surface region. The results indicate that, in an ocular environment, although the bulk of the pHEMA contact lens is hydrated, the surface region may be in a transition between a dehydrated glassy state and a hydrated rubbery state.

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“…[7][8][9] But while dielectric spectroscopy probes the (relatively low) frequency relaxation of electric-dipole vectors, numerous other a Department of Chemical Engineering and Biotechnology, University of Cambridge, techniques have been used to characterise the properties and glass-transition temperatures of glasses, including neutron scattering, 10 Brillouin light scattering (BLS), 11 dynamical mechanical analysis (DMA), 12 Raman scattering 13 and, more recently, terahertz time-domain spectroscopy (THz-TDS), 14 amongst many others. 15,16 In general, each of these methods were found to be sufficiently sensitive for detecting the a-and b-relaxation fingerprints, as well as the corresponding glass transitions (e.g. T ga and T gb ), which are loosely defined as the slowing of the corresponding dielectric relaxation processes beyond time scales that are readily detected by experiment (E100 s).…”

Section: Introductionmentioning

confidence: 99%

The significance of the amorphous potential energy landscape for dictating glassy dynamics and driving solid-state crystallisation

Ruggiero

Krynski

Kissi

et al. 2017

Phys. Chem. Chem. Phys.

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aThe fundamental origins surrounding the dynamics of disordered solids near their characteristic glass transitions continue to be fiercely debated, even though a vast number of materials can form amorphous solids, including small-molecule organic, inorganic, covalent, metallic, and even large biological systems.The glass-transition temperature, T g , can be readily detected by a diverse set of techniques, but given that these measurement modalities probe vastly different processes, there has been significant debate regarding the question of why T g can be detected across all of them. Here we show clear experimental and computational evidence in support of a theory that proposes that the shape and structure of the potentialenergy surface (PES) is the fundamental factor underlying the glass-transition processes, regardless of the frequency that experimental methods probe. Whilst this has been proposed previously, we demonstrate, using ab initio molecular-dynamics (AIMD) simulations, that it is of critical importance to carefully consider the complete PES -both the intra-molecular and inter-molecular features -in order to fully understand the entire range of atomic-dynamical processes in disordered solids. Finally, we show that it is possible to utilise this dependence to directly manipulate and harness amorphous dynamics in order to control the behaviour of such solids by using high-powered terahertz pulses to induce crystallisation and preferential crystal-polymorph growth in glasses. Combined, these findings provide compelling evidence that the PES landscape, and the corresponding energy barriers, are the ultimate controlling feature behind the atomic and molecular dynamics of disordered solids, regardless of the frequency at which they occur.

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A study of the glass transition of polypropylene surfaces by sum-frequency vibrational spectroscopy and scanning force microscopy

Cited by 75 publications

References 18 publications

Solution behavior and surface properties of carboxymethylcellulose acetate butyrate

Solution behavior and surface properties of carboxymethylcellulose acetate butyrate

Surface mechanical properties of pHEMA contact lenses: Viscoelastic and adhesive property changes on exposure to controlled humidity

The significance of the amorphous potential energy landscape for dictating glassy dynamics and driving solid-state crystallisation

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