Organized Molecular Interface-Induced Noncrystallizable Polymer Ultrathin Nanosheets with Ordered Chain Alignment

Abstract

The orientation and state of organization of polymer chains play significant roles in determining the final properties and functions of these materials. Unlike most semicrystalline polymers, which have an inherent driving force toward crystallization, the means to control chain packing in noncrystallizable polymers is still restricted and remains a challenge. We report herein a 2D soft template-directed fabrication for ultrathin polyacrylamide nanosheets with a thickness as low as 3.5 nm and large dimensions (>20 μm). More importantly, the polymer chains in the nanosheets produced are well aligned with a clear interchain spacing. The formation of polymer nanosheets with ordered chain alignment was performed in a special solution containing a periodic sandwich structure of lamellar bilayer membranes and water layers that are hundreds of nanometers thick. It functions as a 2D orientation template to align the monomers in an orderly manner along the in-plane direction of the bimolecular membrane via hydrogen bonding.

Disentangling and Lamellar Thickening of Linear Polymers during Crystallization: Simulation of Bimodal and Unimodal Molecular Weight Distribution Systems

“…The role of entanglements and possible mechanisms of disentanglement during polymer crystallization has been debated in the literature, − but experimental investigation on entanglement properties is difficult. , No quantitative relations between the degree of entanglement and crystallization processes have been made. In order to quantify the degree of disentanglement, we define it as , where ⟨ Z ⟩( t ) is the entanglement concentration of the system at time t of the isothermal period and t 0 is the incubation time, that is, the time when crystallization starts.…”

“…These observations also hold for crystallization process at other temperatures, except that no evident incubation period is detected. crystallization has been debated in literature, [44][45][46][47] but experimental investigation on entanglement properties is difficult. 39,45 No quantitative relations between the degree of entanglement and crystallization processes have been made.…”

Gelation of Lyotropic Liquid-Crystal Phases—The Interplay between Liquid Crystalline Order and Physical Gel Formation

“…A soft templating mechanism has already been reported to fabricate ultrathin polyacrylamide nanosheets, where lamellar bilayer membranes served as a two-dimensional (2D) template . In contrast to the previously described physical gels formed by low-molecular-weight gelators, the monomers are linked via chemical bonds in this case.…”

Studying Polymer Surfaces and Interfaces with Sum Frequency Generation Vibrational Spectroscopy

“…This SFG study provided direct evidence that the PLA surface crystallization mediates the degradation and, subsequently, the drug release behavior . In addition to this SFG study on surface crystallization of PLA in water, SFG has recently been used to confirm the ordered chain alignment of interface induced monocrystalline polymer nanosheets …”

“…137 In addition to this SFG study on surface crystallization of PLA in water, SFG has recently been used to confirm the ordered chain alignment of interface induced monocrystalline polymer nanosheets. 139 Other Liquid Environments. Besides the studies on polymer/water interfaces, SFG has been used to study molecular structures of interfaces between polymers and a variety of other liquids.…”