Nonsolvents Cause Swelling at the Interface with Poly(methyl methacrylate) Films

Abstract

Density profiles of a perdeuterated poly(methyl methacrylate) (dPMMA) film spin-coated on a substrate in water, hexane, and methanol, which are "nonsolvents" for dPMMA, were examined along the direction normal to the interface by specular neutron reflectivity (NR). The interfaces of dPMMA with the liquids were diffuse in comparison with the pristine interface with air; the interfacial width with water was thicker than that with hexane. Interestingly, in water, the dPMMA film was composed of a swollen layer and the interior region, which also contained water, in addition to the diffused layer. The interface of dPMMA with hexane was sharper than that with water. Although there were slight indications of a swollen layer for the dPMMA in hexane, the solvent molecules did not penetrate significantly into the film. On the other hand, in methanol, the whole region of the dPMMA film was strikingly swollen. To conserve mass, the swelling of the film by the nonsolvents is accompanied by an increase in the film thickness. The change in the film thickness estimated by NR was in excellent accord with the results of direct observations using atomic force microscopy (AFM). The modulus of dPMMA in the vicinity of the interfaces with liquids was also examined on the basis of force-distance curves measured by AFM. The modulus decreased closer to the outermost region of the film. The extent to which the modulus decreased in the interfacial region was consistent with the amount of liquid sorbed into the film.

Water-enhanced Adhesion at Interface in Immiscible Bilayer Film of Polystyrene and Poly(methyl methacrylate)

“…On the other hand, in the WF method, a floating PS film on a water surface was skimmed off by the PMMAcoated silicon wafer from the water side. Here, the PMMA film was once dipped in water and swollen by uptaking water molecules [6] . The floating PS film was provided by peeling off a spin-cast PS film from a Si wafer on a water surface.…”

Precise control of surface physicochemical properties for electrospun fiber mats by surface-initiated radical polymerization

“…Similarly, diameters of 1.1 and 1.2 mm were observed in the cases of PHEMA and PFA-C 8 . Tanaka et al 34 have investigated the interfaces between deuterated PMMA (dPMMA) film and poor or nonsolvents by neutron reflectivity and AFM. Although water is a typical nonsolvent for dPMMA, the liquid/solid interfaces were diffuse in comparison with the interface between air and dPMMA.…”

“…The solvent or monomer molecules might penetrate further into the polymer chains at a surface with a large roughness factor than at a smooth surface; the monomers may then polymerize from the inside. 34 The fibers inside the PMMA-co-PBIEM may have been swelled by the solvent or monomer. The fiber was swelled in a concentric circle, whereas the swelling area of the spin-coated film expanded in a perpendicular direction.…”

Surface modification of stereoregular and stereocomplex poly(methyl methacrylate) films with biologically identified peptides

“…9,10 In other words, the films' outermost surface of waterinsoluble polymers such as poly(methyl methacrylate) (PMMA) tends to swell with water molecules, thus forming 'soft' interfaces. Neutron reflectivity measurements have recently suggested that the thickness of the water-swollen layers of atactic (at) (in fact, syndiotactic (st)-rich) PMMA films was more than 8 nm from the outermost surface.…”

“…Neutron reflectivity measurements have recently suggested that the thickness of the water-swollen layers of atactic (at) (in fact, syndiotactic (st)-rich) PMMA films was more than 8 nm from the outermost surface. 9 It has also been suggested that the water-swollen layers of isotactic (it)-PMMA might be thicker than that of atactic-PMMA. 10 Therefore, considering the functional modification of PMMA surfaces using short peptides (for example, the length of 10-mer peptides with an extended chain conformation is expected to be less than 4 nm), the peptides on the PMMA film surfaces might be embedded inside the water-swollen layers, and would not function as surface modifiers (Figure 1, top).…”