Effect of Low Surface Energy Chain Ends on the Glass Transition Temperature of Polymer Thin Films

Xie, Fajun; Zhang, H.F.; Lee, Fuk Kay; Du, Binyang; Tsui, Ophelia Kwan Chui; Yokoe, Yasuyuki; Tanaka, Keiji; Takahara, Atsushi; Kajiyama, Tisato; He, Tianbai

doi:10.1021/ma011689a

Cited by 65 publications

(52 citation statements)

References 18 publications

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“…12 Also, T g s for a,x-PS(R f ) 2 was lower than that for PS. 24 As a result, the difference between the T adh value of Figure 8. Time evolution of G L for a,x-PS(R f ) 2 layers at 365 K. The data for the corresponding PS systems are also shown.…”

Section: -22mentioning

confidence: 94%

“…Our strategy for improving the interfacial adhesion for PS layers is similar, but the extra component is added to the chain ends. We have previously studied the effect of chain ends on surface mobility in PS films 23,24 and found that the surface mobility is much enhanced for PS with hydrophobic end groups 24 because the ends are preferentially segregated to the surface. 12 On the basis of this notion, we tried to improve the interfacial adhesion.…”

Section: -22mentioning

confidence: 99%

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Relation between the adhesion strength and interfacial width for symmetric polystyrene bilayers

Akabori

Baba

Koguchi

et al. 2006

J Polym Sci B Polym Phys

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Polystyrene (PS) bilayers were prepared and were adhered at a temperature between the surface and bulk glass-transition temperatures for a given time. Then, the interfacial adhesion strength (G L ) was examined with a conventional lapshear measurement. G L first increased with increasing adhesion time and then reached a constant value. This result implied that the segments moved across the interface, to a certain depth, even at a temperature below the bulk glass-transition temperature. To confirm this, the interfacial evolution for the PS/deuterated PS bilayers was examined with dynamic secondary-ion mass spectrometry. The G L value was linearly proportional to the thickness of the interfacial adhesion layer. Finally, we propose a strategy for regulating the adhesion strength based on the chain-end chemistry.

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Section: -22mentioning

confidence: 94%

Section: -22mentioning

confidence: 99%

Relation between the adhesion strength and interfacial width for symmetric polystyrene bilayers

Akabori

Baba

Koguchi

et al. 2006

J Polym Sci B Polym Phys

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“…The sample names, component structures, uses, and bulk compositions are listed in Table 1, where the compositions are listed in terms of mass fractions of the P104 component (χ P104 ). Each concentration of polymer thin films was fabricated by spin-casting (model EC 101 spin-coater, Headway Research Inc., Garland, TX) the corresponding solution onto three to six glass coverslips at 1500 rpm for 60 s. The spin-cast samples were immediately vacuum-dried in a vacuum oven (model 5830 vacuum oven, National Appliance Co., Portland, OR) at room temperature under reduced pressure (107 Pa or 0.8 Torr) for at least 24 h. The spin-cast procedure was conducted according to the guidelines of Frank et al 11 and Xie et al 12 The blend film thicknesses were 600–900 nm: some were measured by a profilometer (alpha-step 200, Tencor Instruments, Milpitas, CA) employing a 9.81 × 10 −5 N (10 mg) stylus force; the others were estimated by scanning electron microscopy (SEM) images. The pure P104 films were the thinnest (≈500 nm).…”

Section: Methodsmentioning

confidence: 99%

Phase Separation at the Surface of Poly(ethylene oxide)-Containing Biodegradable Poly(l-lactic acid) Blends

Mahoney

Fahey

et al. 2009

Langmuir

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The surface chemistry and in-depth distribution of the composition of a poly(ethylene oxide) (PEO)-containing biodegradable poly(l-lactic acid) (PLLA) blend matrix system have been investigated using X-ray photoelectron spectroscopy (XPS). This study reports detailed quantitative compositional information using a novel numerical method for determining depth profiles. The PEO system studied is an amphiphilic Pluronic P104 surfactant, PEO–b-poly(propylene oxide) (PPO)–b-PEO. The extent of phase separation is analyzed by determining the surface enrichment of the PEO component via measurement of chemical composition at the polymer–air interface. For this blend system, the combination of the PPO component in the Pluronic surfactants drives the formation of a surface excess of Pluronic in the blends with PLLA. The surface excess profile shows a rapid increase in Pluronic surface composition versus bulk Pluronic mass fractions of 1–5%, but the profile levels off above bulk Pluronic mass fractions of 5%.

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“…These solutions were spin cast at 3000 rpm for 30 s onto the aluminum substrate. The spin-cast procedure was carried out under the guidelines of Frank et al and Xie et al13, 14 The films were then dried further in a vacuum oven (National Appliance Company Model 5830 vacuum oven, Portland, OR at room temperature under reduced pressure (107 Pa) for 72 hrs. Samples used for depth profiling were prepared as described except cast onto a silicon substrate.…”

Section: Methodsmentioning

confidence: 99%

Quantitative ToF-SIMS studies of protein drug release from biodegradable polymer drug delivery membranes

Burns

Gardella

2008

Applied Surface Science

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Biodegradable polymers are of interest in developing strategies to control protein drug delivery. The protein that was used in this study is Keratinocyte Growth Factor (KGF) which is a protein involved in the re-epithelialization process. The protein is stabilized in the biodegradable polymer matrix during formulation and over the course of polymer degradation with the use of an ionic surfactant Aerosol-OT (AOT) which will encapsulate the protein in an aqueous environment. The release kinetics of the protein from the surface of these materials requires precise timing which is a crucial factor in the efficacy of this drug delivery system. Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) was used in the same capacity to identify the molecular ion peak of the surfactant and polymer and use this to determine surface concentration. In the polymer matrix, the surfactant molecular ion peak was observed in the positive and negative mode at m/z 467 and 421, respectively. These peaks were determined to be [AOT + Na+] and [AOT−Na+]-. These methods are used to identify the surfactant and protein from the polymer matrix and are used to measure the rate of surface accumulation. The second step was to compare this accumulation rate with the release rate of the protein into an aqueous solution during the degradation of the biodegradable film. This rate is compared to that from fluorescence spectroscopy measurements using the protein autofluorescence from that released into aqueous solution.

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Effect of Low Surface Energy Chain Ends on the Glass Transition Temperature of Polymer Thin Films

Cited by 65 publications

References 18 publications

Relation between the adhesion strength and interfacial width for symmetric polystyrene bilayers

Relation between the adhesion strength and interfacial width for symmetric polystyrene bilayers

Phase Separation at the Surface of Poly(ethylene oxide)-Containing Biodegradable Poly(l-lactic acid) Blends

Quantitative ToF-SIMS studies of protein drug release from biodegradable polymer drug delivery membranes

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