Catalogo Articoli (Spogli Riviste)

OPAC HELP

Titolo:
Off-lattice approach to simulate radical chain polymerizations of tetrafunctional monomers
Autore:
Hutchison, JB; Anseth, KS;
Indirizzi:
Univ Colorado, Howard Hughes Med Inst, ECCH 111, Boulder, CO 80309 USA Univ Colorado Boulder CO USA 80309 Inst, ECCH 111, Boulder, CO 80309 USA Univ Colorado, Dept Chem Engn, ECCH 111, Boulder, CO 80309 USA Univ Colorado Boulder CO USA 80309 Engn, ECCH 111, Boulder, CO 80309 USA
Titolo Testata:
MACROMOLECULAR THEORY AND SIMULATIONS
fascicolo: 6, volume: 10, anno: 2001,
pagine: 600 - 607
SICI:
1022-1344(20010803)10:6<600:OATSRC>2.0.ZU;2-A
Fonte:
ISI
Lingua:
ENG
Soggetto:
KINETIC GELATION; PERCOLATION THEORY; REACTION BEHAVIOR; NETWORK FORMATION; PHOTOPOLYMERIZATION; INHOMOGENEITY; PREDICTIONS; CYCLIZATION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
24
Recensione:
Indirizzi per estratti:
Indirizzo: Anseth, KS Univ Colorado, Howard Hughes Med Inst, ECCH 111, Campus Box 424, Boulder, CO 80309 USA Univ Colorado Campus Box 424 Boulder CO USA 80309 CO 80309 USA
Citazione:
J.B. Hutchison e K.S. Anseth, "Off-lattice approach to simulate radical chain polymerizations of tetrafunctional monomers", MACROMOL TH, 10(6), 2001, pp. 600-607

Abstract

Radical homopolymerization of multifunctional monomers leads to highly crosslinked networks that demonstrate structural heterogeneity. Spatially non-uniform diffusion limitations result in complex reaction behavior such as unequal functional group reactivity, radical trapping, and microgel formation. The heterogeneity that arises in these systems on the molecular and nanoscopic scales is very difficult to characterize experimentally. A unique off-lattice simulation approach is described to provide insight into structural evolution during multifunctional monomer polymerizations. This simulation approach combines simple Monte Carlo principles to incorporate specie mobility with the basic reaction framework of traditional kinetic gelation models. Simulation volumes containing up to 100000 Lennard-Jones spheres, prepresenting tetrafunctional monomer units, were randomly configured with the Metropolis Method. Rules for initiation, propagation, and termination were developed and implemented, as well as local and periodic particle relaxation schemes. The simulation captures more realistic particle dynamics and mobility than traditional, lattice-based kinetic gelation models. In this work, a detailed description of the simulation method and selected results are presented. Agreement of simulated and experimental trends related to radical trapping frequency as a function of mobility is shown. Visual images of microgel evolution and simulated information about functional group reacitvity within microgels are set forth. Information within microgels is organized into concentric shells extendingfrom the center of the microgel (top schematic). Of the monomer reacted into the network, the fractions that are single (filled symbols) or doubly (open symbols) reacted are plotted versus distance from the center of reactedends. The size of the reaction volume differs for the two series of data (circle; r(ixn) = 1.1 sigma (LI), square; r(ixn) = 0.9 sigma (LJ)). The system with the larger reaction volume has a higher fraction of doubly reacted monomer units located near the center of reactivity. The system with the smaller reaction volume has a more even distribution of doubly reacted units. The former system forms divinyl loops since a propagating radical can react with the pendant double bond from the same monomer. The latter system hasa higher propensity to form longer singly reacted chains with less cyclization.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 28/03/20 alle ore 23:26:46