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Homo‐ and copolymers of 4‐fluorostyrene (FSt) and styrene (St) were synthesized with different feed ratios using free radical bulk polymerization with azobisisobutyronitrile (AIBN) as initiator. It yielded series of (co)polymers with various amounts of included FSt, P(St‐co‐FSt) (5–50 mol%) and PFSt. The effect of the initiator concentration on the molecular weights of the homopolymers, that is, PSt and PFSt was investigated. Copolymer compositions were determined by nuclear magnetic resonance spectroscopy. The relative reactivity ratios of both comonomers were determined by applying the conventional linearization methods of Jaacks (J), Finemann–Ross (F–R), inverted Finemann–Ross (IF–R), and Kelen‐Tüdos (K–T). The reactivity ratios values of St and FSt obtained from J plot are 1.06 and 0.84, F–R plot are 1.18 and 1.06, IF–R 1.01 and 0.86, and K–T plot 1.04 and 0.88, respectively. Thermal properties of prepared (co)polymers, that is, glass transition temperature (Tg) and thermal stability, were determined from differential scanning calorimetry and thermogravimetrical measurements. The lack of significant influence of FSt comonomer content on Tg of (co)polymers was observed. Additionally, the thermal degradation kinetics of obtained PSt and PFSt was studied by thermogravimetric analysis. Kinetic parameters such as the thermal decomposition activation energy (E) and frequency factor (A) were estimated by Ozawa model [E(O) and A(O), respectively] and Kissinger model [E(K) and A(K), respectively]. The activation energy and the frequency factor of PFSt (253 kJ/mol) were higher than PSt (236 kJ/mol). The resulting activation energies estimated using the two methods were quite close. POLYM. ENG. SCI., 54:1170–1181, 2014. © 2013 Society of Plastics Engineers

Two series of new aromatic polyimides were synthesized from 2,5-bis(4-aminophenyl)-1,3,4-oxadiazole and 2,5-diamino-pyridine and various diamidedianhydrides and dietherdianhydride via high-temperature polycondensation in N-methyl-2-pyrrolidinone. The structures of polymers were characterized by means of FTIR, (1)H NMR spectroscopy, and elemental analysis; the results showed an agreement with the proposed structure. The polymers exhibited high glass-transition temperatures (T(g) = 199-290 degrees C) and high thermal stability with decomposition temperatures (T(d)) in the range of 437-510 degrees C. The optical properties, that is, absorption and photoluminescence (PL) of synthesized polymers, were investigated in solution and in solid state as a blend with inert poly(methyl methacrylate) (PMMA). The polymers in solution emitted violet-blue light in the range of 417-453 nm depending on the polymer structure. The polymers containing pyridine rings in the backbone emitted light at a longer wavelength than polymers with oxadiazole units. The effect of solvent polarity on polymer emission was found. Additionally, the photoluminescence properties of the polymers before and after protonation with HCl were tested.

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Chemical modification based on incorporation of flame retardants (FR) into the polymer backbone was used in order to reduce polystyrene flammability. 3‐(trifluoromethyl)styrene (StCF3) and 3,5‐bis(trifluoromethyl)styrene (St(CF3)2) were applied as reactive FR. Copolymers were synthesized with different feed ratios and it gave series of copolymers with various amounts of StCF3 and St(CF3)2 (5–50% mol/mol of St). Glass transition temperature (Tg) and thermal stability of obtained (co)polymers were determined from differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively. Kinetic parameters such as the thermal decomposition activation energy (E) and frequency factor (A) were estimated by Ozawa and Kissinger models. Pyrolysis combustion flow calorimeter (PCFC) was applied as a tool for assessing the flammability of the synthesized (co)polymers. Relative reactivity ratios were determined by applying the conventional linearization Jaacks method (rSt = 1.34, rStCF3 = 0.54), (rSt = 0.47, rSt(CF3)2 = 0.13). The results suggest that incorporation of fluorinated styrenes into PSt enchance flame retardance. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42839.

Aromatic diamine 4,4¢-[oxybis(4,1-phenylenethio)]dianiline and various dianhydrides with isopropylidene, hexafluoroisopropylidene, fluorenylidene diphenyl, ether, thioether and/or amide linkages were applied in a polycondensation reaction to obtain new processable polyimides and poly(amideimide)s (PIs). PIs were synthesized by the conventional two-step procedure of ring-opening polyaddition and subsequent thermal cyclic dehydration. The structures of the polymers were characterized with Fourier-transform infrared spectroscopy and elemental analysis. The thermal behaviors of the PIs were characterized with differential scanning calorimetry, thermogravimetric analysis and dynamic mechanical thermal analysis. The glass transition temperature (T g ) of the PIs were in the range of 175-298 1C and depended on the dianhydride used. The 5% weight loss temperatures were in the range of 423-515 1C, which shows the high thermal resistance characteristics of the PI. The optical absorption properties in the UV-visible range of the obtained polymers were studied in solution and in the solid state. The average refractive indices (n) of the PI films measured at the low absorption range were in the range of 1.96-1.50. The permeation properties of the PIs were studied for He, O 2 , N 2 and CO 2 at 6 atm, with a constant pressure/variable volume setup. The hexafluoroisopropylidene-based PI showed the largest permeability for all gases.

A series of aromatic poly(amideimide)s containing 9,9-diphenylfluorene moieties and the amide units in the main chain have been synthesized by solution polycondensation reaction of newly prepared diamidedianhydride with several aromatic diamines: 1, 3-phenylenediamine, 3,3'-dimethoxy-biphenyl-4,4'-diamine, 4,4'-oxydianiline, 4,4'-(1,3-phenylenedioxy)dianiline, 4,4'-(9-fluorenylidene)dianiline and 1,5-diaminonaphthalene. Molecular structures of the polymers obtained have been characterized using 13 C NMR, 1 H NMR and FTIR spectroscopies. The polymers prepared are readily soluble in aprotic polar solvents, and form optically transparent films by solution casting. The resultant poly(amideimide)s have been analyzed by differential scanning calorimetry (DSC), thermogravimetry (TG) and wide-angle X-ray diffraction measurements. They exhibited high levels of thermal stability, with decomposition temperatures in the range 452-494• C, and high glass transition temperatures (181-278• C). The optical behavior of these polymers has been investigated in NMP solution as well as in the films. The photoluminescence (PL) spectra of the free-standing films prepared from the poly(amideimide)s exhibited maximum emission bands around 506-525 nm in the green region.

A series of new aromatic poly(amideimide)s is synthesized via one-step high- temperature polycondensation from prepared diamidedianhydrides and various diamines: 4,4'-(hexafluoro-isopropylidene)dianiline, 4,4'-(9-fluorenylidene)dianiline, 2,7-diaminofluorene and 2,4-diamino-6-phenyl-1,3,5-triazine. Molecular and structural characterization of the resulting polymers is carried out using Fourier transform infrared and nuclear magnetic resonance spectroscopies. The resulting polymers exhibit a good level of thermal stability. The temperature of 10% weight loss is in the range of 420—525 °C (in N2) associated with relatively high glass transition temperatures (249—299 °C). The polymers' residual weight loss at 800 °C is higher than 40%. The optical and photoluminescence characteristics of synthesized poly(amideimide)s were investigated in solution and in blend with poly(methylmethacrylate) (PMMA). The photoluminescence spectra of the polymers in N-methyl-2-pyrrolidinone solution exhibit maximum emission wavelength in the range of 405—495 nm depending upon the polymer structure.