Suppressed Surface Reorganization in a High-Density Poly(methyl methacrylate) Brush

Zuo, Biao; Xu, Quanyin; Jin, Tiancheng; Xing, Huimin; Shi, Jing; Hao, Zhiwei; Zhang, Li; Tanaka, Keiji; Wang, Xinping

doi:10.1021/acs.langmuir.9b02581

Cited by 14 publications

(10 citation statements)

References 76 publications

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“…A picosecond SFG system was used for experiments in this study (EKSPLA, Lithuania, model PL2231-20-RS232). SFG vibrational spectroscopy was extensively used to probe the surfaces and interfaces of the materials due to its intrinsic surface sensitivity. − SFG theories, setups, and instrumentation will thus not be stated in detail. Briefly, two input beams, a visible beam with a fixed wavelength at 532 nm and a frequency-tunable infrared (IR) beam, were overlapped spatially and temporally on the surfaces of the samples.…”

Section: Methodsmentioning

confidence: 99%

“…Sum frequency generation (SFG) vibrational spectroscopy has been demonstrated to be a suitable tool to understand the change of molecular structures of surfaces and interfaces. − SFG enables precisely measuring the molecular structure/behavior of surfaces/interfaces by its surface/interface-sensitive nature. − SFG has been extensively applied to study the surface and interfacial molecular structures of polymers, including various polymer adhesives. − ,− In this study, the atmospheric moisture effect on the surfaces of isocyanate-based primers was probed by SFG, and the molecular behaviors of such surfaces were correlated to the macroscopic properties to investigate the relationship. Different conditions in the experiments were set up in a variation of humidity levels and exposure time to understand the influences of their effects on the primer surfaces.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of the Atmospheric Moisture Effect on the Molecular Behavior of an Isocyanate-Based Primer Surface

et al. 2021

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A primer coating is engineered to facilitate compatibility between products like adhesives, sealants, and potting compounds and targeted substrates. Prolonged exposure of isocyanate-based primer surfaces to the environment is known to negatively affect the interfacial adhesion between itself and the products subsequently applied on top of it. However, the molecular behavior behind this observed phenomenon remained to be further investigated. In this study, sum frequency generation (SFG) vibrational spectroscopy, a nonlinear optical spectroscopic technique, was applied to study the surface of an isocyanate-based primer exposed to different environments at the molecular level. Atmospheric moisture was considered to be a potential factor in impairing the adhesion performance of the primer, and thus, time-and humidity-dependent experiments were executed to monitor the molecular behavior at the primer surface using SFG. In addition, 180°peel testing experiments were conducted to measure the adhesion properties of primers after being exposed to the corresponding conditions to correlate to SFG results and establish a chemical structure−macroscopic performance relationship. This study on the changes at the primer surface in different environments with varied humidity levels as a function of time aims to provide an in-depth understanding of the moisture effect on isocyanatebased primers. These learnings may also be helpful toward exploring a broader range of coatings and surface layers and improving customer product use guidelines.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Investigation of the Atmospheric Moisture Effect on the Molecular Behavior of an Isocyanate-Based Primer Surface

et al. 2021

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“…However, these techniques lack general monolayer surface and interfacial selectivity and sensitivity. Over the past three decades, sum frequency generation (SFG) vibrational spectroscopy has proven to be a powerful technique to directly and nondestructively study polymer surfaces/interfaces due to its inherently surface/interfacial specific selectivity and sensitivity, and its capability to provide molecular level structural information in situ. − SFG has been used extensively to characterize molecular structures at buried polymer/solid or polymer/liquid interfaces. ,, In this study, we push the boundaries of SFG to systematically analyze chemical reactions at the buried polymer/polymer interface of nylon and maleic-anhydride grafted polyethylene.…”

Section: Introductionmentioning

confidence: 99%

Observing a Chemical Reaction at a Buried Solid/Solid Interface in Situ

Andre

Chen

et al. 2020

Anal. Chem.

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Chemical reactions are the most important phenomena in chemistry. However, chemical reactions at buried solid/solid interfaces are very difficult to study in situ. In this research, the chemical reaction between two solid polymer materials, a nylon film and a maleic anhydride (MAH) grafted poly(ethylene-octene) (MAHgEO) sample, was directly analyzed at the buried nylon/MAHgEO interface at the molecular level in real time and in situ, using surface and interface sensitive sum-frequency generation (SFG) vibrational spectroscopy. Disappearance of nylon signals indicated a chemical reaction between amine and hydrolyzed amide groups of nylon and MAH groups on the MAHgEO at the buried interface. The appearance of SFG signals from reaction products was also observed at the buried nylon/MAHgEO interface. The mechanism of the observed interfacial reaction was further analyzed. Temperature-dependent SFG experiments were performed to measure the activation energy of the interfacial reaction, enabling a comparison with that reported for the bulk materials. The interfacial chemical reaction between nylon and MAHgEO greatly improved the adhesion of these dissimilar materials. The detailed analysis of a chemical reaction between two polymers at the polymer/polymer buried interface underscores the utility of SFG as a powerful analytical tool to build understanding of buried interfaces and to accelerate the design of interfacial structures with desired properties.

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“…Deionized water was used as a solvent in all solutions. The detailed theory of SFG has been reported in other articles. − The sum frequency (SF) signal in a second-order nonlinear optical process was generated by a visible light of 532 nm (incident angle 60 o ) and an infrared light with a tunable wavelength (incident angle 55 o ). In this study, SFG spectra with an ssp polarization combination were collected from the air/solution interface, where s and p represent the light polarized in the plane and normal to the plane of the interface, respectively.…”

Section: Experimental Partmentioning

confidence: 99%

Surface Activity and Structure of Temperature-Responsive Polymer Surfactants Based on PNIPAm at the Air/Solution Interface

et al. 2021

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Thermally sensitive polymers have attracted tremendous interest in the design of stimulus-responsive surfactants. In this article, poly(propylene oxide)-bpoly(N-isopropylacrylamide) (PPO-b-PNIPAm) with different block lengths of PNIPAm was synthesized through atom transfer radical polymerization (ATRP). Different from commercial Pluronic surfactants, four distinct sections appeared in the decrease of surface tension with concentration. First, with increasing concentration, the amount of adsorbed polymers increased and the surface tension decreased sharply until a plateau was reached, which was caused by the rearrangement of methyl groups. The increasing adsorbed amount of PPO-b-PNIPAm resulted in the rearrangement of isopropyl groups, which changed from a lying down or horizontal conformation to a standing up or vertical conformation. This behavior led to the decrease in surface tension in part III until the critical micelle concentration (CMC) was reached. The surface tension of PPO-b-PNIPAm was thermally responsive. Except for the hysteresis observed in the first cycle, the surface tension was reversible during the heating-andcooling cycles. At low concentrations, the low surface tension at higher temperatures was mainly caused by the increasing adsorption amount and ordered arrangement of methyl groups, while the standing up conformation of isopropyl groups at higher concentrations resulted in the low surface tension observed at high temperatures.

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Suppressed Surface Reorganization in a High-Density Poly(methyl methacrylate) Brush

Cited by 14 publications

References 76 publications

Investigation of the Atmospheric Moisture Effect on the Molecular Behavior of an Isocyanate-Based Primer Surface

Investigation of the Atmospheric Moisture Effect on the Molecular Behavior of an Isocyanate-Based Primer Surface

Observing a Chemical Reaction at a Buried Solid/Solid Interface in Situ

Surface Activity and Structure of Temperature-Responsive Polymer Surfactants Based on PNIPAm at the Air/Solution Interface

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