Exploitation of acetalization process of poly(vinyl alcohol) for the formation of crosslinked poly(vinyl formal) foams

Abstract

In the present work, poly(vinyl formal) (PVF) foams were prepared using water as the pore‐forming agent and formaldehyde as the crosslinking agent. The acetalization process of poly(vinyl alcohol) was exploited in depth in order to obtain a precise guidance on the preparation of PVF foams with adjustable properties. With the increasing of formaldehyde, the crosslinking degree was gradually increased and the prepared PVF foams changed to be amorphous. Morphology observation showed that the porous structure of PVF foams was successfully created using water as the blowing agent and it was strongly affected by the crosslinking agent and polymer concentration, leading to an easily tuned pore size from hundreds of microns to few microns. The prepared foams were proved to have small apparent density below 0.27 g/cm−3 and excellent mechanical strength, with the largest specific compressive strength of 11.54 MPa·cm3·g−1. Based on the results, it is believed that this study can provide a scientific basis for the design and optimization of PVF foams with controllable structure and properties.

Highly stable and air-resistant photonic upconversion organogels with self-healing and temperature responsiveness

“…Prior to this, Nobuo Kimizuka et al reported the upconversion of an organic gel in which the dye pair gathers inside the fibers, which play a good role in shielding oxygen. 41 However, this system is far inferior to the PVA-C8 gel system in terms of transparency, quantum yield, and mechanical properties. In order to demonstrate its admirable mechanical properties, we knotted the gel and stretched it to about five times its original length without it being broken (Fig.…”

“…14 The three-dimensional polymer crosslinked network contains a large number of unique structural characteristics of solvent molecules, 34 and thus not only can it possess the performance merits of both classic fluorescent polymer solution and solid materials, but also present outstanding new properties such as inherent soft and humid characteristics, air stability, and stimulus responsiveness with multifunctional synergistic change characteristics. [35][36][37][38][39][40][41] This is also one of the significant development directions in the field of advanced light-emitting polymer materials. These materials include a continuous polymer network and a liquid organic phase in which the upconversion chromophores are dissolved.…”

Graphene‐Based Composite Foams with Tunable Porosity for Ultra‐Sensitive Low‐Pressure Applications

“…Further, the molar ratio between PVA and formaldehyde significantly alters foams' morphology. [ 23 ] PVA foams with 30 vol% loadings were chosen, and (PVA/GS‐30) and (PVA/GS‐30a) were prepared at two different molar ratios of OH: HCHO. They exhibit a difference in their morphology, porosity, and density.…”

A New Blending Method for the Preparation of Macroporous Open‐cell Polyvinyl Formaldehyde Foams with High Water‐Absorption Capacity

“…[6][7] Usually, PVA with a high degree of polymerization has strong intra-and intermolecular hydrogen bonds and can be used for the preparation of PVF foams. [8][9][10][11] In addition, to having the general properties of foam plastics, PVF foams have low toxicity with the advantage of being biodegradable and can be used in medicine, cleaning, washing, filtration, environmental protection, etc.. [12][13] The excellent performance of PVF foams is mainly due to internal pore structure.…”

“…Nevertheless, the properties of PVA are also influenced by its degree of polymerization [6–7] . Usually, PVA with a high degree of polymerization has strong intra‐ and intermolecular hydrogen bonds and can be used for the preparation of PVF foams [8–11] . In addition, to having the general properties of foam plastics, PVF foams have low toxicity with the advantage of being biodegradable and can be used in medicine, cleaning, washing, filtration, environmental protection, etc.…”