Synthesis of carboxylated derivatives of poly(isobutylene-co-isoprene) by azide–alkyne “click” chemistry

The final publication is available at Springer via https://dx.doi.org/10.1038/s41428-018-0130-yThe synthesis of carboxylated derivatives of poly(isobutylene-co-isoprene) (isobutylene–isoprene rubber, IIR) with substitution levels ranging from 1 to 4 mol% and different spacer lengths was accomplished through azide–alkyne Huisgen cycloaddition. Azido-functionalized IIR was first prepared by reacting brominated IIR with sodium azide to full conversion in a 90:10 tetrahydrofuran/N,N-dimethylacetamide mixture. The click reaction of azido-functionalized IIR with acetylenic acids, which was carried out using the copper(I) bromide/N,N,N′,N″,N″-pentamethyldiethylenetriamine catalyst system in tetrahydrofuran, yielded carboxylated IIRs. The products were characterized by 1H NMR and FT-IR spectroscopy, and their molecular weight was determined by size exclusion chromatography analysis. The conversion to carboxylated groups reached up to 100% as determined by NMR spectroscopy but was highly dependent on the type of solvent and the amounts of catalysts and reactants used in the procedures.ARLANXEO Canada Inc.Natural Sciences and Engineering Research Council (NSERC) of Canad

SET-LRP of acrylates catalyzed by a 1 penny copper coin

crosscheck: This document is CrossCheck deposited related_data: Supplementary Information identifier: R. Aksakal (ORCID) identifier: R. Aksakal (ResearcherID) identifier: C. R. Becer (ORCID) identifier: C. R. Becer (ResearcherID) copyright_licence: The Royal Society of Chemistry has an exclusive publication licence for this journal copyright_licence: This article is freely available. This article is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported Licence (CC BY-NC 3.0) history: Received 25 July 2016; Accepted 25 August 2016; Accepted Manuscript published 26 August 2016; Advance Article published 6 September 2016; Version of Record published 1 November 201

Self-healing polymers prepared via living radical polymerisation

Diels-Alder chemistry has been used to synthesise polymerisation initiators and a dimethacrylic crosslinker that leads to efficient cleavage and reformation; self healing. The initiators were prepared using 1-(2-hydroxyethyl)-1H-pyrrole-2,5-dione (3) as an intermediate, and reacting this with furfuryl alcohol to afford 2-bromo-2-methyl-propionic acid 2-[1-(2-bromo-2-methyl-propionyloxymethyl)-3,5-dioxo-10-oxa-4-aza-tricyclo[5.2.1.02,6]dec-8-en-4-yl]-ethyl ester (7) and 9-anthracenemethanol to yield initiator (8). The former exhibited polymers with excellent cleavage properties (M-n 12 000 g mol(-1) to 6500 g mol(-1)) with reformation at efficiency of 50% (M-n 8900 g mol(-1)). The initiator from the anthracene derivative initially indicated that retro-Diels-Alder was not occurring with no change in the NMR or GPC data. An excess of a rhodamine-based dienophile was added to capture any cleaved anthracene-terminated polymer, with results indicating that the polymer is cleaving and reforming upon the cooling cycle. Similar results were observed with arm first stars, made using a Diels-Alder based dimethacrylate cross-linker. Little cleavage was observed initially, however, addition of the tag gave a significant reduction in M-w (7080 g mol(-1) to 5300 g mol(-1)) and M-w/M-n (1.78 to 1.26)

The effect of linker length on ConA and DC-SIGN binding of S-glucosyl functionalized poly(2-oxazoline)s

This study is supported by Turkish Army Forces and Engineering and Physical Sciences Research Council (EP/P009018/1)

Pessimism Reduction in Crosstalk Noise Aware STA

Abstract — High performance circuits are facing increasingly severe signal integrity problems due to crosstalk noise and crosstalk noise awareness has become an integral part of static timing analysis (STA). Existing crosstalk noise aware STA methods compute noise induced delay uncertainty on a net by net basis and in a pessimistic way, without considering the overlap bounds of the victim and aggressor timing windows and realistic delay impact on early and late signal arrival times. Since crosstalk induced delay on indivudial nets contribute cumulatively on data and clock paths, even small amounts of pessimism in computation can add up to produce several unrealistic timing violations. Unlike glitch noise analysis where noise often attenuates during propagation, quality of delay noise analysis is severely affected by any pessimism in noise estimation and can unnecessarily cost valuable silicon and design resources for fixing unreal violations. In this paper, we propose two temporal techniques to reduce pessimism in crosstalk noise aware STA. The first method, “effective delay noise”, is a net based method where the exact overlap points of victim and aggressor timing windows are considered to obtain the part of delay noise that actually impacts early and late signal arrival times. The second method, “path based delay noise”, is a path based method where the reduced arrival uncertainty of the nets of a given path are utilized for pessimism reduction. We also propose a novel “uncertainty propagation ” technique as part of the second method, which results in an iteration free crosstalk noise aware STA of the path with significantly reduced pessimism. The two techniques are combined in a proposed methodology that is compatible with existing industrial static timing analyzers with very little computational overhead compared to the traditional noise aware STA and a significant improvement in eliminating unreal violations. The proposed techniques resulted in 77% reduction of worst case negative slack and 57 % reduction in the number of failing paths in the setup analysis of a 90nm industrial design. I

Noise propagation and failure criteria for vlsi designs

Noise analysis has become a critical concern in advanced chip designs. Traditional methods suffer from two common issues. First, noise that is propagated through the driver of a net is combined with noise injected by capacitively coupled aggressor nets using linear summation. Since this ignores the non-linear behavior of the driver gate the noise that develops on a net can be significantly underestimated. We therefore propose a new linear model that accurately combines propagated and injected noise on a net and which maintains the efficiency of linear simulation. After the propagated and injected noise are correctly combined on a victim net, it is necessary to determine if the noise can result in a functional failure. This is the second issue that we discuss in this paper. Traditionally, noise failure criteria have been based on unity gain points of the DC or AC transfer curves. However, we will show that for digital designs, these approaches can result in a pessimistic analysis in some cases, while in other cases, they allow circuit operation that is extremely close to regions that are unstable and do not allow sufficient margin for error in the analysis. In this paper, we compare the effectiveness of the discussed noise failure criteria and also present a propagation based method, which is intended to overcome these drawbacks. The proposed methods were implemented in a noise analysis tool and we demonstrate results on industrial circuits