Elastomers are an important class of polymers for many applications. Often, additives are added to the polymer matrix of elastomers to promote vulcanization or enhance physical or chemical properties. In this study, vapor phase infiltration (VPI) is investigated for transforming unvulcanized cis -polyisoprene (from natural rubber) into an organic/inorganic hybrid material. Specifically, we examine single-cycle infiltration with diethylzinc (DEZ) and water to form infiltrated zinc oxide species. Interestingly, low-temperature pre-heating of the cis -polyisoprene acutely affects the processes of infiltration, including diffusivity, maximum solubility, and chemical reactivity. We attribute these effects to a combination of film relaxation and oxidation. Independent of thermal pre-treatments, all infiltration processes exhibited consistent zinc oxide loading irrespective of purge time between the DEZ and water doses, indicating the presence of a strongly bound intermediate state between the DEZ precursor and the cis -polyisoprene polymer. Increasing infiltration process temperature accelerates diffusion and lowers the maximum solubility, in accordance with Fick's law and gas phase sorption equilibrium. Resulting organic–inorganic hybrid films show enhanced resistance to dissolution in toluene, a good solvent for the pure polymer.
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Effect of vapor phase ethylenediamine crosslinking of matrimid on alcohol vapor sorption and diffusion
This work examines the sorption, diffusion, and polymer relaxation behavior for water and C1‐C7 alcohol vapors at 30 °C in ethylenediamine vapor‐phase crosslinked Matrimid. Ethylenediamine is sufficiently volatile that crosslinking can occur by exposing the polymeric film to saturated vapor, in contrast to more conventional means of dissolving the crosslinker in a solvent and immersing the polymeric film in the solution. The vapor‐phase exposure method avoids the use of additional solvent and undesired solvent‐induced swelling. Sorption isotherms demonstrate that water and C1‐C5 alcohols do not appreciably differ for unmodified and crosslinked Matrimid; however, an approximate 90% reduction in sorption was determined for hexanol and heptanol. A minor impact on diffusion coefficients for water, methanol, and ethanol was observed, while those of propanol and butanol were reduced over an order of magnitude. Relaxation kinetics were similarly unchanged for water and C1‐C3 alcohols, while being significantly reduced for butanol and higher alcohols. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci.
- NSF-PAR ID:
- 10035213
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Journal of Applied Polymer Science
- Volume:
- 134
- Issue:
- 27
- ISSN:
- 0021-8995
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Behavior of nanoconfined water in porous materials has important implications for the development of advanced water purification and storage. In the current study, the kinetics of water sorption from the vapor phase into a metal organic nanotube ((C 4 N 2 H 6 )[(UO 2 )(C 4 O 4 NH 5 )(C 4 O 4 NH 6 )]·2H 2 O (UMON)) are investigated with varying relative humidity. The UMON compound contains nanoconfined water molecules arranged in an ice-like array along the length of its one-dimensional pore and exhibits complete specificity to liquid water. Total hydration of the material is observed upon exposure to relative humidity of 60% or higher. Water uptake curves are modeled as diffusion and irreversible condensation in the pore, which leads to a modeled diffusion coefficient of (1.2 ± 0.6) × 10 −12 cm 2 s −1 for water in UMON nanochannels. This value is much lower than observed for other porous material and is most similar to water diffusivity in low-density amorphous ice. In addition, on exposure to various solvent vapors, the UMON material maintained specificity for water in the gas phase.more » « less
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