Intrinsically Microporous Polyimides Derived from 2,2'-Dibromo-4,4',5,5'-bipohenyltetracarboxylic Dianhydride for Gas Separation Membranes.

This work aims to expand the structure-property relationships of bromo-containing polyimides and the influence of bromine atoms on the gas separation properties of such materials. A series of intrinsically microporous polyimides were synthesized from 2,2'-dibromo-4,4',5,5'-bipohenyltetracarboxylic dianhydride (Br-BPDA) and five bulky diamines, (7,7'-(mesitylmethylene)bis(8-methyldibenzo[b,e][1,4]dioxin-2-amine) (MMBMA), 7,7'-(Mesitylmethylene)bis(1,8-dimethyldibenzo[b,e][1,4] dioxin-2-amine) (MMBDA), 4,10-dimethyl-6H,12H-5,11-methanodibenzo[b,f][1,5]diazocine-2,8-diamine (TBDA1), 4,10-dimethyl-6H,12H-5,11-methanodibenzo[b,f][1,5]diazocine-3,9-diamine (TBDA2), and (9R,10R)-9,10-dihydro-9,10-[1,2]benzenoanthracene-2,6-diamine (DAT). The Br-BPDA-derived polyimides exhibited excellent solubility, high thermal stability, and good mechanical properties, with their tensile strength and modulus being 59.2-109.3 MPa and 1.8-2.2 GPa, respectively. The fractional free volumes (FFVs) and surface areas (SBET) of the Br-BPDA-derived polyimides were in the range of 0.169-0.216 and 211-342 m2 g-1, following the order of MMBDA > MMBMA > TBDA2 > DAT > TBDA1, wherein the Br-BPDA-MMBDA exhibited the highest SBET and FFV and thus highest CO2 permeability of 724.5 Barrer. Moreover, Br-BPDA-DAT displayed the best gas separation performance, with CO2, H2, O2, N2, and CH4 permeabilities of 349.8, 384.4, 69.8, 16.3, and 19.7 Barrer, and H2/N2 selectivity of 21.4. This can be ascribed to the ultra-micropores (<0.7 nm) caused by the high rigidity of Br-BPDA-DAT. In addition, all the bromo-containing polymers of intrinsic microporosity membranes exhibited excellent resistance to physical ageing.

Effect of intraoperative pressure ulcer preventive nursing on inflammatory markers in patients with high-risk pressure ulcers: A protocol of systematic review and meta-analysis.

BACKGROUND: This study will be designed to appraise the effects of intraoperative pressure ulcer preventive nursing (IPUPN) on inflammatory markers (IMs) in patients with high-risk pressure ulcers (HRPU) based on high quality randomized controlled trials (RCTs). METHODS: In this study, we will perform a rigorous literature search from the following electronic databases: Cochrane Library, MEDLINE, Embase, Cumulative Index to Nursing and Allied Health Literature, Allied and Complementary Medicine Database, and Chinese Biomedical Literature Database. All electronic databases will be retrieved from their initial time to March 1, 2020 without limitations of language and publication status. We will only consider high quality RCTs that explored the effects of IPUPN on IMs in patients with HRPU. Two investigators will identify relevant trials, extract data, and appraise risk of bias in each eligible trial. Data will be pooled by either a fixed-effects model or a random-effects model according to the results of heterogeneity identification. The primary outcomes include IMs, and incidence of new pressure ulcers. The secondary outcomes are time to ulcer development, quality of life, length of hospital stay, and adverse events. Statistical analysis will be undertaken using RevMan 5.3 software. RESULTS: This study will summarize high quality clinical evidence of RCTs to evaluate the effects of IPUPN on IMs in patients with HRPU. CONCLUSION: The expected findings may provide helpful evidence to determine whether IPUPN is an effective intervention on IMs in patients with HRPU. INPLASY REGISTRATION NUMBER: INPLASY202040029.

Semi-Interpenetrating Polymer Networks Based on Cyanate Ester and Highly Soluble Thermoplastic Polyimide.

Thermoplastic polyimide (TPI) was synthesized via a traditional one-step method using 2,3,3',4'-biphenyltetracarboxylic dianhydride (3,4'-BPDA), 4,4'-oxydianiline (4,4'-ODA), and 2,2'-bis(trifluoromethyl)benzidine (TFMB) as the monomers. A series of semi-interpenetrating polymer networks (semi-IPNs) were produced by dissolving TPI in bisphenol A dicyanate (BADCy), followed by curing at elevated temperatures. The curing reactions of BADCy were accelerated by TPI in the blends, reflected by lower curing temperatures and shorter gelation time determined by differential scanning calorimetry (DSC) and rheological measurements. As evidenced by scanning electron microscopy (SEM) images, phase separation occurred and continuous TPI phases were formed in semi-IPNs with a TPI content of 15% and 20%. The properties of semi-IPNs were systematically investigated according to their glass transition temperatures (Tg), thermo-oxidative stability, and dielectric and mechanical properties. The results revealed that these semi-IPNs possessed improved mechanical and dielectric properties compared with pure polycyanurate. Notably, the impact strength of semi-IPNs was 47%-320% greater than that of polycyanurate. Meanwhile, semi-IPNs maintained comparable or even slightly higher thermal resistance in comparison with polycyanurate. The favorable processability and material properties make TPI/BADCy blends promising matrix resins for high-performance composites and adhesives.

Bio-Based Poly(Ether Imide)s from Isohexide-Derived Isomeric Dianhydrides.

In this work, four isohexide-derived isomeric dianhydrides were synthesized through a four-step procedure using isohexide and chloro-N-phenylphthalimides as the starting materials. The one-step solution polymerization of these dianhydrides with petroleum- or bio-based diamines enabled the synthesis of poly(ether imide)s (PEIs), which had viscosities of 0.41 to 2.40 dL∙g-1. The isohexide-derived PEIs were characterized based upon their solubility and their thermal, mechanical, and optical properties. The results showed that most of the isohexide-derived PEIs possessed comparable glass transition temperatures (Tg), tensile strengths, and moduli to petroleum-based PEIs. However, the thermo-oxidative stability of the PEIs was found to be lower than that of the common petroleum-based PEIs. Moreover, the PEIs displayed good optical activity, which originated from their unique chiral isohexide moieties. The isomeric effects of dianhydride monomers on the properties of the resulting PEIs were comparatively studied. The results suggested that the corresponding 4,4'-linked PEIs possessed lower Tg, higher mechanical properties, and higher specific rotations compared to 3,3'-linked polymers. Meanwhile, the polyimides with isomannide residue displayed higher Tg and more specific rotations than the corresponding polymers with isosorbide residue. These results contributed to more restricted rotations of phthalimide segments in 3,3'-linked or isomannide containing polyimides.