Radivoje Vuković

Compatibility of poly(p-fluorostyrene-co-o-fluorostyrene) with poly(2,6-dimethyl-1,4-phenylene oxide) and polystyrene

Abstract The compatibility of blends prepared from random copolymers of p-fluorostyrene and o-fluorostyrene with poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) and blends of the copolymers with polystyrene (PS) has been examined using differential scanning calorimetry. It was found that compatibility in these systems depends on copolymer composition: copolymers containing from 10 to 38% of p-fluorostyrene are miscible with PPO in all proportions. The thermally induced phase separation in these systems was also studied and the existence of lower critical solution temperatures (LCST) was established for all compatible blends. The copolymers were found to be incompatible with PS regardless of composition.

Phase behavior in copolymer blends of polystyrene and poly(o-chlorostyrene-co-p-chlorostyrene)

The miscibility of random copolymers of o‐chlorostyrene and p‐chlorostyrene [P(oClS‐pClS)] with polystyrene (PS) has been studied by differential scanning calorimetry (DSC). A miscibility ‘‘window’’ was found, extending in copolymer composition from about 68 to 98 mole % o‐chlorostyrene at a temperature of 150 °C. The maximum in the miscibility window occurred at approximately 170 °C and a composition of 83 mole % o‐chlorostyrene. This result differs only slightly from theoretical predictions based on interaction parameters previously calculated from miscibility behavior in blends of poly(2,6‐dimethyl‐1,4‐phenylene oxide) with P(oClS‐pClS), poly(styrene‐co‐o‐chlorostyrene) and poly(styrene‐co‐p‐chlorostyrene). The implication of this result for the numerical values of the six interaction parameters required to describe these blends is discussed.

Phase Behavior and Miscibility in Binary Blends Containing Polymers and Copolymers of Styrene, of 2,6-Dimethyl-1,4-Phenylene Oxide, and of Their Derivatives

This article presents a comprehensive and systematic survey of miscibility in binary mixtures of polymers and copolymers based on styrene, on 2,6-dimethyl-1,4-phenylene oxide, and on their derivatives. Certain other systems based on methacrylate, acrylonitrile, and maleic anhydride-containing polymers are also included to complete the analysis. Experimental and theoretical studies of miscibility and phase behavior of homopolymer/homopolymer, homopolymer/copolymer, and copolymer/copolymer blends are analyzed. A mean field model is employed to correlate and predict miscibility in new systems. This model is also used to account for the different phenomena governing miscibility/immiscibility behavior, with special reference to the influence of the chemical structure of the polymers. Tables containing experimental data and related details are included for 127 polymer/polymer systems; these tables also contain summaries of the binary phase behavior. Calculated segmental interaction parameters, together with the...

FREE RADICAL-INITIATED COPOLYMERIZATION OF 2,6-DICHLOROSTYRENE WITH MALEIMIDE, N-METHYLMALEIMIDE, AND N-PHENYLMALEIMIDE

The free-radical-initiated copolymerization of 2,6-dichloro-styrene (2,6-DClSt), with maleimide (MI), N-methylmaleimide (NMeMI) and N-phenylmaleimide (NPhMI) was carried out in butanone or in toluene at 65°C with different monomer-to-monomer ratios in the feed. The copolymer composition was evaluated by chlorine content in polymers. The reactivity ratios determined by Kelen-Tüdös method indicate the random arrangement of monomers in copolymer chains. In all studied systems, azeotropic points were observed at ratios of: 0.5 (2,6-DClSt) to 0.5 (MI) and 0.4 (2,6-DClSt) to 0.6 (NMeMI and NPhMI). Molecular weights of copolymer, which contain equimolar ratio of 2,6-DClSt-co-MI, NMeMI, and NPhMI are: Mw· 10−3 = 46.1; 90.4; 81.4. Mn 10−3 = 27.1; 46.0; 37.0. The copolymers are thermostable, film forming materials, which decompose by one-step mechanism between 400°C, and 500°C. The Tgs are linearly distributed between Tgs of homopolymers and in all cases, single well defined Tgs are obtained.

Miscibility in blends of sulfonylated poly(2,6-dimethyl-1,4-phenylene oxide) (SPPO) with homopolymers of halogen-substituted styrene derivatives

Abstract Miscibility and phase behaviour in blends of poly(p-fluorostyrene) (PpFSt), poly(o-fluorostyrene) (PoFSt), poly(p-chlorostyrene) (PpClSt), poly(o-chlorostyrene) (PoClSt), poly(p-bromostyrene) (PpBrSt) and poly(o-bromostyrene) (PoBrSt) with partially sulfonylated poly(2,6-dimethyl-1,4-phenylene oxide) (SPPO) copolymers [i.e. systems of the type ( A ) n 1 ( C 1− y D y ) n 2 have been studied by d.s.c. as a function of temperature and degree of sulfonylation. For all the para-substituted styrene polymers/SPPO blends studied, limited miscibility regimes are found. A miscibility regime is also found for PoFSt/SPPO blends. However, PoClSt and PoBrSt are not miscible with any SPPO. Using the mean-field approach, we have calculated all the pertinent segmental interaction parameters for these blends. In several systems, certain blends have been found to exhibit lower critical solution temperature behaviour.

Miscibility and phase behaviour in poly(2,6-dimethyl-1,4-phenylene oxide) and poly(fluorostyrene-co-bromostyrene) blends

Abstract Copolymers of ortho(para) fluorostyrene and ortho(para) bromostyrene with a range of copolymer compositions were prepared by free radical polymerization in toluene solution using azobis(isobutyronitrile). The miscibility and phase behaviour of these copolymers in blends with poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) have been studied by differential scanning calorimetry. Of the four possible copolymer systems, miscibility was observed only for PPO/poly( o -fluorostyrene-co- p -bromostyrene) blends in which the copolymer contains between 11 and 73 mol% p -bromostyrene. High temperature phase separation in the miscible blends is a function of copolymer composition and of the thermal history. The results can be explained on the basis of the mean field theory of phase behaviour for homopolymer-copolymer systems.

SYNTHESIS AND POLYMERIZATION OF N-ACRYL-DICYCLOHEXYLUREA AND N-METHACRYL-DICYCLOHEXYLUREA AND COPOLYMERIZATION WITH α-METHYLSTYRENE

The title compounds have been prepared by the addition of acrylic acid and methacrylic acid to dicyclohexylcarbodiimide (DCC). N-Acryl-N,N′-dicyclohexylurea (Acryl-DCU) homo-polymerizes and copolymerizes with α-methylstyrene (αMeSt), while Methacryl-DCU does not polymerize under the standard free-radical-initiated polymerization. Copolymers of Acryl-DCU with αMeSt prepared under different monomer-to-monomer ratios in the feed have random composition with an azeotropic point at ratio of 0.75 (Acryl-DCU) to 0.25 (αMeSt). Reactivity ratios determined by the Kelen-Tüdös method are r1 (Acryl-DCU) = 0.72 and r2 (αMeSt) = 0.07. Poly(Acryl-DCU) and copolymers with αMeSt decompose under the TGA conditions by a two step mechanism. In the first step between 180 and 250°C, cyclohexylisocyanate separates by degradation of dicyclohexylurea in the side chain, while the thermally stable residue represents the poly(cyclohexylacrylamide) and copolymers with αMeSt.

Free-radical-initiated polymerization of N(p-phenoxy-phenyl)maleimide and copolymerization with styrene, α-methylstyrene and β-methylstyrene

Abstract Synthesis and free-radical-initiated homopolymerization of phenoxy-phenylmaleimide (PhOPhMI) and copolymerization with styrene (St), (α-methylstyrene (αMeSt) and β–methylstyrene (β-MeSt) are described. It was found that alternating copolymers are formed under different monomer-to-monomer ratios in the feed and that the mechanism based on the participation of CT-complex best explains the formation of alternating copolymers. Equilibrium constants of CT-complexes are: K PhOPhMI/St = 0.20 Lmol−1; KPhOPhMI/αMeSt = 0.05 Lmol−1; KPhOPhMI/βMeSt = 0.02 Lmol−1. Homopolymer and co-polymers are film-forming materials, stable up to 350°C under TGA conditions. Tg s and higher transition temperatures are within the thermally stable region.

Separation of Cyclohexylisocyanate from the Crosslinked Copolymers of N-Acryl-dicyclohexylurea with Ethylene Glycol Dimethacrylate or Divinyl Benzene

Copolymerization of N-acryl-N,N′-dicyclohexylurea with ethylene glycol dimethacrylate or divinyl benzene in the presence of dibenzoyl peroxide as initiator gave corresponding crosslinked copolymers. Both copolymers thermally decompose by two-step mechanism. The first step separates cyclohexylisocyanate, thus forming the thermostable residue, which contains molecular imprints of cyclohexylisocyanates.

Preparation of Nanoporous Crosslinked Poly(Methacryl‐N‐cyclohexylamide‐co‐ethylene Glycol Dimethacrylate) by Thermal Degradation of Poly(Methacryl‐N,N′‐dicyclohexylurea‐co‐ethylene Glycol Dimethacrylate)

Abstract Copolymers of methacryl‐dicyclohexylurea (MA‐DCU) with ethylene glycol dimethacrylate (EDMA) at monomer‐to‐monomer ratios in the feed: 0.3/0.7, 0.5/0.5, 0.7/0.3, 0.8/0.2 were prepared in butanone in the presence of 2% of dibenzoyl peroxide at 70°C for 48 hr. Copolymers, regardless of the ratio of comonomers in the feed, decompose thermally at 200–250°C under the separation of cyclohexylisocyanate (C6H11NCO). Residues after the removal of C6H11NCO are thermally stable nanoporous crosslinked copolymers of methacryl‐cyclohexylamide (MA‐CHA) with EDMA, which decompose by a one‐step mechanism between 300°C and 480°C.