Conformational relaxation of single polymer chains confined in a two-dimensional plane studied by scanning near-field optical microscopy

Abstract

The conformational rearrangement of poly(methyl methacrylate) (PMMA) chains confined in a two-dimensional monolayer to a three-dimensional random coil was studied by the shape and segment density analysis of an individual PMMA chain, and was directly observed by scanning near-field optical microscopy. A perylene-labeled PMMA chain was dispersed in the unlabeled PMMA monolayer, after which it was placed on a thick film of unlabeled PMMA and annealed above the glass transition temperature. Although the polymer chain of the monolayer penetrated into the bulk substrate with thermal activation, the radius of gyration in the lateral direction was maintained throughout the annealing process. The diffusion rate in the depth direction was much faster than that of the translational diffusion of the entire polymer chains, suggesting that an unstable twodimensional conformation of the polymer chain relaxed into a three-dimensional one. This indicates that the polymer chains confined in a monolayer interlaced with the surrounding chains and expanded mainly toward the depth direction in the relaxation process, while maintaining the dimensions of the averaged radius of gyration in the lateral direction.

Molecular weight tuning optimizes poly(2-methoxyethyl acrylate) dispersion to enhance the aging resistance and anti-fouling behavior of denture base resin

“…It has been reported that PMMA polymer chains at the water interface have high chain mobility although the PMMA bulk is glassy ( T g = ∼100 °C). 25 We hypothesize that the PMEA additive increased the surface chain mobility of the resin surface. The rubbery states of PMEA could contribute to loosening the tight packing of glassy PMMA chains and swelling, thus increasing the chain mobility of surface polymers.…”

“…This differs from the conventional method for polymer films in which PMEA and PMMA polymers are dissolved in an organic co-solvent and cast on substrates, followed by evaporation and annealing. 25 It has been previously demonstrated that PMEA migrates to the surface of a PMMA film after annealing at high temperatures above the glass transition temperature ( T g ) of the polymers. However, our resin with PMEA-1 did not show any surface segregation (Fig.…”

“…Because of its oily/rubbery state, the use of PMEA in high contents has been limited to low-mechanical-load applications. In addition, it has been previously demonstrated that PMEA migrates to the surface of PMMA films after annealing, 25 which is not ideal for dental resins that require the polishing of the resin surface in the standard fabrication process.…”

Molecular dynamics simulations of bottlebrush macromolecules in two dimensional polymeric melts under flow conditions

“…Two dimensional polymeric systems play an important role in our understanding of precursor film spreading, 1 surface lubrication, 2 dynamics of adsorbed polymer chains, [3][4][5][6] and DNA fractionation dynamics. [7][8][9] Extensive experimental, 3,4,6,[10][11][12][13][14][15][16][17][18][19][20] computational and theoretical [21][22][23][24][25][26][27] studies were devoted to static and dynamic properties of polymers at surfaces and interfaces. These studies showed that confinement of macromolecules to surfaces and interfaces can strongly modify not only their conformations, but also their motion and relaxation (see for review ref.…”