Effects of Pairwise, Self-Associating Functional Side Groups on Polymer Solubility, Solution Viscosity, and Mist Control

Abstract

The extent of MPA incorporation was determined upon analysis of 1 H NMR spectra by integration of backbone and side-group peaks, with the following complication. For PB functionalization with MPA, we expect two peaks between 2.85 and 2.55 ppm corresponding to HO 2 CCH 2 CH 2 S-protons and HO 2 CCH 2 CH 2 S-, with one or more additional peaks (depending on whether cyclic structures are formed or not) around 2.55 ppm, corresponding to HO 2 CCH 2 CH 2 SCH 2 -protons. Experimental results consistentlyshowed two large, partially overlapping peaks between 2.825 and 2.575 ppm, and a much smaller, broad overlapping shoulder below 2.575 ppm, extending in some cases down to 2.4 ppm (for instance, for 510kPB4.7A polymer that shoulder peak was about 1/3 of the size of the first two). These observations indicate that the signal for HO 2 CCH 2 CH 2 SCH 2 -is broad, with significant overlap with the middle peak, and that for simplicity the 2.85-2.4 ppm range should be integrated as a whole, accounting for 6 protons for each functionalized monomer. The complication is that the integration of the small shoulder region between 2.55 and 2.4 ppm was found to be completely unreliable (due both to its small size at the very low extents of functionalization investigated, and apparently to the presence of the very large neighboring PB backbone peak): in many cases, the softwarecomputed integral was a physically nonsensical negative number. As a result, extents of MPA functionalization were approximated instead in all cases by integrating between 2.825 and 2.575 ppm and estimating that that integral accounted for 5 protons for each functionalized monomer. A.1.2 Extensional Viscosity ResultsFigure A.1 below reports apparent extensional viscosity for the solutions whose capillary breakup behavior is shown in Figure 13.A-1 A.2 Numerical Approach for Chain Statistics of Self-Associating Chains atInfinite Dilution in θ-Solvent A.2.1 Model DescriptionOur objective is to determine the size of a linear chain of N monomers, f of which are modified to act as stickers capable of forming pair-wise only, physical associations. The stickers are assumed to be equidistantly spaced l monomers apart along the chain, and the energy of association is εkT. We will assume Gaussian chain statistics for any segment of the chain whose configuration is unrestrained by reversible crosslinks.To calculate the size of the chain in the very dilute regime (all associations are intramolecular), we define a semi-Markov process X(t), t > 0 such that each state i is fully specified by identifying which pairs of stickers form bonds. (Note here that a given state has an infinite number of chain configurations.) The chain goes from one state to the next by either breaking or forming a bond, as illustrated in Figure A. Assume the polymer chain enters state i at time t. Clearly, the state it enters next is determined by which bond is broken or formed first; and the time spent in the present state is the time it took for that bond-breaking or bond-forming event to take place.B...

Thiol‐Ene Radical Addition of L‐Cysteine Derivatives to Low Molecular Weight Polybutadiene

“…[36] Determination of the Functionalisation Degree A preliminary experiment with 1:1 molar ratio RSH/vinyl (theoretically achievable DF: 90.9%, DF v : 100%), performed under the experimental conditions pointed out in Table 1, showed that the functionalisation occurred: the purified reaction product, a white powder, dissolved quantitatively in a 1% KOH solution, while a mix of NCys and pristine PBL did not (in this latter case, the formation of a white milk-like emulsion was observed). An analogous improved solubility was noticed in 1984 for TGA-functionalised PBL by Priola et al; [27] Ameri David et al [61] have recently described in detail, the effects of self-associating functional side groups on the polymer solubility in 3-mercaptopropanoic acidfunctionalised PBLs.…”

Effect of Supramolecular Interchain Sticking on the Low‐Frequency Relaxation of Transient Polymer Networks

“…Supramolecular polymer networks consist of 3D assemblies of transiently interlinked polymer chains with side groups that undergo mutual noncovalent association. These networks display soft viscoelastic mechanics, depending on the strength of noncovalent chain interlinkage: whereas chain association by weak hydrogen bonding or by hydrophobic interaction typically leads to viscoelastic liquids, strong metal complexation often entails rubbery elastic, solidlike mechanics . In general, there are three effects observed in rheological studies on supramolecular polymer networks as a function of increasing strength and extent of supramolecular polymer interlinkage: (i) the longest relaxation time, τ 0 , increases, (ii) the elastic part of the complex shear modulus, G ′, increases on timescales longer than that, and (iii) the frequency‐dependent power‐law scaling of G ′ on these long timescales gets shallower.…”

Megasupramolecules for safer, cleaner fuel by end association of long telechelic polymers

“…This is in contrast to the collapsed, inextensible supramolecules formed by long chains with associative groups distributed along their backbone (Fig. 1A, left) (11,12). To mimic ultralong polymers, association must occur at chain ends and be predominantly pairwise.…”