Photopolymerization kinetics of multifunctional monomers

https://web.itu.edu.tr/okayo/pdf/00review.pdf

Macroporous copolymer networks

The sorption behavior of four hydrophobic organic contaminants (HOCs) (i.e., phenanthrene, naphthalene, lindane, and 1-naphthol) by three types of polymers namely polyethylene (PE), polystyrene (PS), and polyphenyleneoxide (PPO) was examined in this work. The organic carbon content-normalized sorption coefficients (K(oc)) of phenanthrene, lindane, and naphthalene by PEs of same composition but distinct physical makeup of domains increased with their crystallinity reduction (from 58.7 to 25.5%), suggesting that mobility and abundance of rubbery domains in polymers regulated HOC sorption. Cross-linking in styrene-divinylbenzene copolymer (PS2) created substantial surface area and porosity, thus, K(oc) values of phenanthrene, lindane, naphthalene, and 1-naphthol by PS2 were as high as 274.8, 212.3, 27.4, and 1.5 times of those by the linear polystyrene (PS1). The K(oc) values of lindane, naphthalene, and 1-naphthol by polar PPO were approximately 1-3 orders of magnitude higher than those by PS1, and PPO had comparable sorption for phenanthrene but higher sorption for naphthalene and 1-naphthol than PS2. This can be a result that a portion of O-containing moieties in PPO were masked in the interior part, while leaving the hydrophobic domains exposed outside, therefore demonstrating the great influence of the spatial arrangement of domains in polymers on HOC sorption.

Sorption of four hydrophobic organic compounds by three chemically distinct polymers: role of chemical and physical composition.

Reaction behaviour and kinetic constants for photopolymerizations of multi(meth)acrylate monomers

In polymer science and technology, linear, branched and crosslinked structures are usually distinguished. For crosslinked polymers, insolubility and lack of fusibility are considered as characteristic properties. However, insoluble polymers are not necessarily covalently crosslinked because insolubility and infusibility may be also caused by extremely high molecular masses,strong intermolecular interaction via secondary valency forces or by the lack of suitable solvents. For a long time, insolubility was the major obstacle for characterization of crosslinked polymers because it excluded analytical methods applicable to linear and branched macromolecules. In particular, the most important structural characteristic of crosslinked polymers, the crosslink density, could mostly be determined by indirect methods only [1],or was expressed relatively by the fraction of crosslinking monomers used in the synthesis.

Microgels-Intramolecularly Crossünked Macromolecules with a Globular Structure

The structure of low conversion polymers of ethylene dimethacrylate

The porosity of styrene-divinylbenzene copolymers prepared by suspension copolymerisation of the monomers carried out in the presence of inert diluent changes due to solvent pretreatment is investigated. The changes seem to reflect the inhomogeneity of copolymer gel. Various portions of it are transferred from the rubber-like into the glassy state at different stages of either swelling solvent exchange or the drying process. A microsyneresis, i.e. a local collapse of loosely crosslinked gel portions not followed by a shrinkage of the whole system, leads to the porosity changes.

Inhomogeneity of gel and microsyneresis in porous styrene-divinylbenzene copolymers

Porous structure of two series of styrene (S)-divinylbenzene (DVB) copolymers has been studied. The copolymers were prepared by suspension copolymerization of the monomers (50 wt.-% of DVB) in the presence of heptane-toluene mixtures as inert diluents. The fraction of diluents in the polymerization system or heptane: toluene ratio was changed.



Both the pore volume and specific surface area increase as does dilution or the fraction of heptane in diluents, but the measured values change depending on sample pretreatment.



A mechanism of structure built up is discussed and the porosity changes explained in terms of a microsyneresis of inhomogeneous S-DVB copolymer gel.



Die porose Struktur zweier Serien von Styrol-Divinylbenzol-Copolymeren (S-DVB) wurde untersucht. Die Copolymeren wurden durch Suspensionscopolymerisation der Monomeren (50 Gew.-% DVB) in Anwesenheit von Heptan-Toluol-Mischungen als inertem Verdunner hergestellt. Hierbei wurde entweder der Anteil des Verdunners im Polymerisationssystem oder das Verhaltnis Heptan-Toluol verandert.



Sowohl das Porenvolumen als auch die spezifische Oberflache nehmen mit steigender Verdunnung oder steigendem Anteil an Heptan im Verdunner zu. Allerdings sind die gemessenen Werte von der Probenvorbehandlung abhangig.



Der Mechanismus des Strukturaufbaus wird diskutiert. Die Porositatsanderungen werden durch die Mikrosynerese des inhomogenen Copolymergels erklart.

Porous structure of highly crosslinked styrene‐divinylbenzene copolymers

The porosity measured for two series of diluent-modified styrene (S) — divinylbenzene (DVB) copolymers (10 and 20 wt.-% of DVB) was found to depend on sample pre-treatment. A correlation between the volume fraction of the polymer in the swollen gel and the volume fraction of octane used as diluent has been established assuming the isotropic swelling of the sample pretreated with water before porosity determination.

Porosity variation and swelling of styrene-divinylbenzene copolymers

The porosity of suspension copolymers of methacrylic acid (MA) and divinylbenzene (DVB) has been studied. The copolymers were prepared both directly from monomer blends and with toluene or n-octane as inert diluents. The pore volume and radii of pores were larger for copolymers containing 5.0% of DVB than those for copolymers containing 9.1% of DVB. The volume and radii of pores increased with increasing diluent content, but the effect of n-octane was more pronounced than that of toluene. Based on considerations of monomer reactivities and copolymer-diluent and copolymer-unreacted monomer interactions, the following model of structure of MA and DVB copolymers has been proposed: The copolymers are composed of microgels interconnected into a rigid skeletonlike structure, surrounded by lightly crosslinked and unentangled poly(methacrylic acid) chains.

Henryk Galina

Papers

The structure of low conversion polymers of ethylene dimethacrylate

Inhomogeneity of gel and microsyneresis in porous styrene-divinylbenzene copolymers

Porous structure of highly crosslinked styrene‐divinylbenzene copolymers

Porosity variation and swelling of styrene-divinylbenzene copolymers

Studies of porous polymer gels. II. Structure and porosity of moderately crosslinked poly(methacrylic acid) gels