Creating an efficient and cost-effective approach that can provide advanced microporous membranes with high waterproofness and good breathability has proved to be tremendously challenging. This work responds to these challenges by designing, fabricating and evaluating an electrospun polyacrylonitrile (PAN) fibrous membrane which was modified with waterborne fluorinated polyurethane (WFPU) to achieve high waterproof and breathable performances. By employing the WFPU modification, the pristine PAN fibrous membranes possessed remarkable superhydrophobicity with an advancing water contact angle of 159 as well as adjustable pore structure. Significantly, the waterproofness was confirmed to depend on the maximum pore size and surface wettability, in good agreement with the Young-Laplace equation, and a geometric coefficient A was introduced as a geometric factor to evaluate the torturous pore structure in electrospun fibrous membranes. Furthermore, the resultant membranes could present a high waterproofness up to 83.4 kPa, large water vapor transmission rate over 9.2 kg per m 2 per day, good air permeability over 5.9 L m À2 s À1 , suggesting them as promising candidates for a variety of potential applications such as protective clothing. † Electronic supplementary information (ESI) available: Details synthesis and structure conrmation of WFPU, FE-SEM, stress-strain curves of PAN and WFPU@PAN-8 membranes, pore size distribution and maximum pore size of WFPU@PAN-8 membranes, and Movies S1 and S2. See

No abstract

Different from traditional crosslinked polymer diverting agents, a polymeric and non-crosslinked acid self-thickening agent (ZPAM) based on hydrophobically associating water-soluble polymer of acrylamide (AM), [2-(methacryloyloxy)ethyl]trimethylammonium chloride (DMC) and N,N 0 -dimethyl octadecyl allyl ammonium chloride (DOAC) was synthesized. The apparent viscosity variation of ZPAM acid solutions in acid rock reaction and rheological properties of ZPAM spent acid solutions were studied. Results showed that ZPAM acid solutions demonstrated good uninterruptedly thickening ability from low apparent viscosity to high apparent viscosity during the acid rock reaction. Meanwhile, ZPAM spent acid solutions showed good shear resistance, viscoelasticity and high temperature resistance. The thickening mechanism of ZPAM acid solutions during the acid rock reaction was explained by apparent viscosity change, rheological properties of simulative ZPAM acid solutions, and ZPAM aqueous solutions with different concentrations of CaCl 2 . The results showed increasing calcium chloride concentration enhanced the hydrophobic association strength of the thickener solution, resulting in increasing solution viscosity, in other words, the self-thickening agent showed excellent salt resistance and acid resistance. In addition, the change of association strength of ZPAM acid solutions during the acid rock reaction was further confirmed via environmental scanning electron micrographs and UV spectrum.