Chain alignment can significantly influence the macroscopic properties of a polymeric material, but no general and versatile methodology has yet been reported to obtain highly ordered crystalline packing of polymer chains, with high stability. Here, we disclose a strategy that relies on 'ordered crosslinks' to produce polymeric materials that exhibit a crystalline arrangement. Divinyl crosslinkers (2,5-divinyl-terephthalate) were first embedded, as substitutional ligands, into the structure of a porous coordination polymer (PCP), [Cu(terephthalate)triethylenediamine0.5]n. A representative vinyl monomer, styrene, was subsequently polymerized inside the channels of the host PCP. The polystyrene chains that form within the PCP channels also crosslink with the divinyl species. This bridges together the polymer chains of adjacent channels and ensures that, on selective removal of the PCP, the polymer chains remain aligned. Indeed, the resulting material exhibits long-range order and is stable to thermal and solvent treatments, as demonstrated by X-ray powder diffraction and transmission electron microscopy.

Dipeptide crystals containing nanochannels of various sizes show remarkable and selective absorption of methane, carbon dioxide and hydrogen.

No abstract

Molecular crystals of dipeptides containing open channels can selectively absorb CO 2 over N 2 and CH 4 , as shown by experimental and simulated isotherms. The efficient CO 2 capture enabled separation from methane and allowed the direct observation by 2D MAS NMR of CO 2 sequestered in the peptide-based biozeolites.

A mathematical model for multicomponent botch distillation was derived, and a FORTRAN IV program was written for solution on a digital computer. The program has been used in the simulation of several commercial batch distillation columns.A calculation procedure for the numerical solution of botch distillation equations starting from total reflux steady state conditions was developed, and the step-by-step procedure is presented here. Also included is a discussion of the stability and relative computational effectiveness of various numerical integration techniques when applied to transient distillation calculations. The discussion applies equally well to both batch distillation and unsteady state continuous distillation.Most of the published work on transient distillation calculations has been primarily concerned with continuous distillation rather than with batch distillation, which is inherently an unsteady state process. The reason for this is twofold. First, there is wider industrial interest in continuous distillation, and second, unsteady state continuous distillation models are more easily derived and the related computational problems are less severe than those of batch distillation. For example, transients in continuous distillation are usually in the form of relatively small upsets from steady state operation, whereas in batch distillation individual components can completely disappear from the column, first from the reboiler and then from the entire column.Continuous distillation models have been solved with the use of linear perturbation methods on an analog computer (1 to 3 ) and by employing numerical integration techniques in the solution of nonlinear models on a digital G. P. Distefano is with Electronic Associates, Inc., Princeton, New Jersey.computer (4 to 6 ) . In general, most dynamic distillation models have been developed and solved for binary systems. There are, however, several publications pertaining to the solution of unsteady state multicomponent distillation models (7, 8).Primarily, batch distillation models have been methods of the so-called "short-cut" type, for example, minimum reflux ratio, minimum number of theoretical tra s, Although the authors presented both calculated and experimental results for comparison, the simplicity of the model and calculational procedure, and the slowness of the early digital device, made the study one of academic interest only.