Photoinitiated polymerization of methacrylic monomers in a polybutadiene matrix (PB): Kinetic, mechanistic, and structural aspects

Abstract

The kinetics and mechanism of the photoinitiated polymerization of tetrafunctional and difunctional methacrylic monomers [1,6‐hexanediol dimethacylate (HDDMA) and 2‐ethylhexyl methacrylate (EHMA)] in a polybutadiene matrix (PB) have been studied. The maximum double‐bond conversion, the maximum polymerization rate, the intrinsic reactivity, and the kinetic constants for propagation and termination have been calculated. Unlike the behavior followed by the SBS‐HDDMA and PS‐HDDMA systems, where a reaction‐diffusion mechanism occurs from the start of the polymerization at low monomer concentrations (<30–40%), in the PB‐HDDMA system the reaction diffusion controls the termination process only after approximately 10% conversion is reached, as for the bulk polymerization of polyfunctional methacrylic monomers. Before reaching 10% conversion the behavior observed can be better explained by a combination of segmental diffusion‐controlled (autoaccelerated) and reaction‐diffusion mechanisms. This is probably a consequence of the lower force of attraction between the monomer and the matrix and between the growing macroradical and the matrix than those corresponding to the other systems mentioned. For the PB‐EHMA system, the termination mechanism is principally diffusion‐controlled from the beginning of the polymerization for monomer concentrations below 30–40%, and for higher monomer concentrations, a standard termination mechanism takes place (kt ≈ 106) at low double‐bond conversions, which is diffusion‐controlled for high conversions (>40%). For PB‐HDDMA and PB‐EHMA systems, crosslinked polymerized products are obtained as a result of the participation of the double bonds of the matrix in the polymerization process. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2444–2453, 2001

Resorbable elastomeric networks prepared by photocrosslinking of high-molecular-weight poly(trimethylene carbonate) with photoinitiators and poly(trimethylene carbonate) macromers as crosslinking aids

“…Earlier studies on the photopolymerization of multifunctional methacrylates mixed into different polymer matrices have shown that semi-interpenetrating networks are formed [38,39]. Growing methacrylate chains can be terminated by combination with other growing methacrylate chains or with formed polymer macroradicals.…”

Methacrylate-based polymer blends containing oligomeric 1,2-polybutadienes

“…Kinetic curves obtained for other dimethacrylate/LBH systems behave similarly. The DSC traces registered for the neat HDDM have a bimodal shape typical for the polymerization of a multifunctional monomer of low viscosity [14]. The R p = f(p) curve shows a slight inflection point at about 4-5 % of double bond conversion, which corresponds to Final double bond conversion p f as a function of LBH3 content and polymerization temperature for HDDM/LBH and EGDM/ LBH systems the beginning of autoacceleration.…”

“…A group of polymers used as components of IPNs or semi-IPNs are polybutadienes with predominant 1,4-structure [8][9][10][11][12][13][14][15][16][17]. One of the most common investigations is preparation of IPNs [8][9][10][11]13] or semi-IPNs [12] with methacrylic polymers.…”

“…In a typical procedure hydroxylterminated butadiene was reacted with isocyanate, and the resulting polymer was swollen with a methacrylate, dimethacrylate, or mixture of methacrylates of various functionality which was then polymerized to form IPN. Some articles describe polymerization of methacrylates in solid 1,4-polybutadiene matrix [14] or grafting of a methacrylate on the polybutadiene during miniemulsion polymerization [15]. High-shock or high-impact polystyrene was obtained by polymerization of styrene in the presence of 1,4-polybutadiene [16] or by mixing of polystyrene with 1,4-polybutadiene [17].…”

Kinetic modeling of the peroxide cross-linking of polymer/monomer blends: From a theoretical model framework to its application for a complex polymer/monomer dispersion system

“…Sen et al [9] applied the analogy based model for the silane grafting and moisture cross-linking of PE and poly(ethylene-co-propylene) (PEP). Mateo et al [10] adopted a modified alternative for the photo-initiated polymerization of methacrylic monomers in PB matrix, describing kinetic, mechanistic and structural aspects of apparent polymerization while Ghosh et al [11] studied the modification of low density PE by grafting of acrylic monomers. A general shortcoming of this type of kinetic models is the inability to distinguish among several possible cross-linking reaction sites such as hydrogen atoms bonded to aliphatic carbon atom and double bonds, which are subjected to hydrogen abstraction and addition reactions, respectively.…”