Transparent Intrinsic Barrier Polymer via Dynamic Pressure Engineering

Abstract

Polymers with desirable barrier performances are urgently demanded for various applications, especially in dealing with COVID19. Current art mostly focuses on copolymerization, crystallization, melt blending, and surface modification, ultimately leading to compromised transparency, mechanical performances, and potential medical safety. In this work, we report a dynamic pressure driven approach for the first time can translate conventional nonbarrier polyethylene terephthalate (PET) into intrinsic barrier (ib-PET) material while maintaining its outstanding transparence by a single step. The oxygen permeability and water vapor transmission rate are 88% and 43% lower than those for conventional technique-processed nonbarrier PET, respectively, resulting from slower chain dynamics and reduction in the free volume. This work can construct a prospective avenue toward rational design for pristine materials with outstanding barrier properties and provide in-depth insight into the perception of dynamic pressure engineering, as well as provide a novel concept for tailoring and design of advanced polymers from the energy point of view.

Toward Excellent Barrier Performance for Semicrystalline Polyethylene Terephthalate via Controlling Crystallinity and Rigid Amorphous Fraction

“…The rational selection of T off plays a crucial role in oxygen barrier performances. The OPC decreases and then increases, along with the increment of T off , and the gas barrier performance can be optimized when T off is fixed at 1.20 s. It should be noted that the OPC of PET-1.20 is much lower than that of transparent intrinsic barrier PET reported in our previous work, 30 which decreases from 9.86 × 10 −15 for amorphous transparent intrinsic barrier PET to 5.94 × 10 −15 cm 3 •cm/cm 2 • s•Pa for PET-1.20. It confirmed that the OPC of PET can be depressed further by MDPE, showing more excellent intrinsic barrier performance, in contrast to amorphous PET.…”

“…To calculate the OPC of the amorphous region of various specimens, the relationship between the density and OPC of amorphous PET is displayed in Figure 4f, according to our previous work. 30 There is a good linear relationship between the OPC of amorphous PET and its density. Based on the result in Figure 4b,f, the OPC of the amorphous region of semicrystalline PET can be calculated, as illustrated in Figure 4g.…”

“…The OPC of PET-1.20 is comparable to 25.9% of the reference sample, which corresponds to a high BIF of 3.85, manifesting the significant promotion of the gas barrier performance of PET. To reveal the superiority of MDPE, we comprehensively compared the OPC of PET-1.20 with that of competitors reported in the previous literature involving stress field, 30 copolymerization, 31,32 the addition of fillers, 33,34 antiplasticization, 35 and crystallization, 25,36 as illuminated in Figure 2d. It shows that the novel PET-1.20 possesses a pronouncedly low oxygen permeability coefficient (OPC) compared with the references prepared by diversified approaches that have been widely reported in recent decades, which means that MDPE is a more feasible approach to fabricating excellent barrier polymer materials.…”

“…Our previous work has confirmed that chain dynamics and packing density of molecular chains could be effectively modulated by cyclic pulsating pressure, ultimately, resulting in the remarkable enhancement of barrier performance. 30 It is reasonable to speculate that MDPE can realize the regulation of the nature of the amorphous phase, except for the crystalline region, which is of paramount importance in influencing the small molecule transmission behavior. Therefore, the influence of the T off on the change in the nature of the amorphous region will be discussed in detail in the next section.…”

“…25 Recently, we reported that the oxygen permeability behavior of PET was pronouncedly suppressed by dynamic pressure engineering (DPE), via modulating chain dynamics and chain packing density. 30 However, the gas barrier performances of transparent intrinsic barrier material prepared by DPE are still inferior to achieving high-value applications, which need to be further enhanced. Based on the relationship between microstructure and properties, to further boost the gas barrier capacity of polymers, it is urgently necessary to develop a feasible approach to modulating crystalline and amorphous regions of bulk materials, simultaneously.…”