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Linear aliphatic copolyesters consisting of the biobased diols ethylene glycol, 1,3-propane diol, and 1,4-butane diol, the biobased dicarboxylic acids succinic acid, adipic acid, and sebacic acid, and a 9,10-dihydro-9-oxa-10-phospha-phenanthren-10-oxide (DOPO)-containing diol or dicarboxylic acid are presented. Structural characteristics of the new copolyesters are studied by 1H and 13C NMR spectroscopy. The influence of chemical composition on the property profile is examined evaluating glass transition temperature Tg, melting behavior, thermal degradation and combustion, mechanical and burning behavior. Incorporation of DOPO monomers suppresses crystallization and yields materials with reduced toughness except in case of sebacates. Tg rises with the content of DOPO monomer. Correlations between the number of methylene groups in the repeating unit and the thermogravimetric analysis degradation maximum, as well as the heat release capacity from pyrolysis combustion flow calorimeter reflect the systematic influence of chemical structure. Copolycondensation with DOPO monomers enhances the limiting oxygen index providing materials with improved overall value. [ABSTRACT FROM AUTHOR]

Poly(methyl methacrylate)/silica (PMMA/SiO x) nanocomposites were synthesized via sol-gel method and studied by various techniques. The dispersion of the silica particles (10-100 nm) in the matrix was probed by transmission electron microscopy (TEM), while solid-state NMR and Raman spectroscopy detected the formation of an inorganic network with high degree of crosslinking. To elucidate the impact of the filler on the molecular dynamics of the PMMA, different methods were used; namely differential scanning calorimetry, thermally stimulated depolarization current and broadband dielectric relaxation spectroscopy. All three methods observed a significant impact of the nanoparticles on the segmental dynamics of the matrix, which was expressed as an increase of the glass transition temperature ( Tg) in terms of calorimetry and as a shift of the α (segmental) relaxation to lower frequencies in terms of dielectric spectroscopy. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

Abstract: Glass transition temperature dependence on the branching degree can be empirically estimated by excluding additional effects on this parameter as molecular weight distribution, end group interactions or crystallization. In this communication aliphatic–aromatic polyesters with a well defined degree of branching between 0% (linear) and 50% (hyperbranched) are investigated by differential scanning calorimetry. The hydrogen bonding effect of the OH-terminal groups was successfully extracted from the pure branching effect by protection of the end-functionalities. Fractionation of samples with variation of the branching degree and end-functionalities led to series of narrowly distributed molar masses. The dependence of the molecular weight on the glass transition temperature for different branching degrees was calculated and compared for polar and non-polar end groups. [Copyright &y& Elsevier]

Phosphorus polyesters provide sustainable flame retardancy to conventional polyesters like PET (poly(ethylene terephthalate)) and PBT (poly(butylene terephthalate)). Their use as a flame retardant additive results in the formation of a classical polymer blend. The morphology of such blends should determine the resulting fire behavior and has therefore to be examined in detail. This study investigates the state of miscibility in blends of standard polyesters (mainly PBT) with phosphorus (co)polyesters mainly using the behavior of the glass transition (Tg). The Tg values were determined by modulated DSC measurements and compared to the ones calculated assuming complete miscibility according to the Fox–Flory concept. The homopolyesters are completely immiscible with each other. Miscibility can be improved by transesterification reactions in the melt as well as by copolyester consisting of segments of PBT or PET and the phosphorus polymer. [ABSTRACT FROM PUBLISHER]

Several new random and block copoly(imide siloxane)s have been prepared by the solution polycondensation of commercially available 4,4'-oxydianiline (ODA) and amino-propyl terminated polydimethylsiloxane (APPS) with 4,4'-(hexafluoro-isopropylidene)diphthalic anhydride (6FDA). The siloxane loading was kept to 10, 20, 30, 40 and 50 wt% in the copolymers. The random copolymers were prepared by a one pot solution imidization technique, and two pot solution imidization technique was adopted for the synthesis of the block copolymers. The diamine ODA and the dianhydride 6FDA composed the hard block segment, while APPS and 6FDA composed the soft block segment. The hard block length was kept constant while the soft block lengths were varied by varying the siloxane loading. Accordingly, block copoly(imide siloxane)s were prepared on increasing the soft block lengths (DP) from 3 to 6, 10, 18 and 36 for fixed hard block length of 22. The resulting polymers have been well characterized by IR, NMR and GPC techniques. Thermal and mechanical properties of the random and block copolymers were compared with the already reported homopolyimide without siloxane moiety. [ABSTRACT FROM AUTHOR]

Wepresent the synthesis and characterization of two different kindsof triblock copolymers prepared via RAFT polymerization by only twosynthetic steps applying a sequential monomer addition approach. Bothtriblock copolymers consist of a hydrophilic, a hydrophobic and ananchor block which is located in the middle or at the end of the polymerchains. In both triblock copolymer systems the hydrophobic blocksconsist of randomly polymerized tert-butylstyrene(tBS) and n-hexyl acrylate (nHA) monomers in a ratioof approximately 2:1, respectively, whereas the hydrophilic blockswere accomplished by polymerization of N,N-dimethylacrylamide (DMA). As a result of the employedsynthetic approach, every anchor block contains several N-acryloxysuccinimide (NAS) units besides tBS and nHA units in thecase of the triblock copolymer with the central anchor block and DMAunits in the case of the triblock copolymer with the terminal anchorblock. The structures as well as the compositions of all synthesizedpolymers were verified by means of 1H, 13C NMR,and FT-IR analysis. Molar masses and molecular weight distributionswere determined by GPC measurements. The thermogravimetric measurementsshowed a sufficient thermal stability for all prepared polymers upto 210 °C, while DSC investigations revealed that the glass transitiontemperatures of the hydrophobic blocks of both triblock copolymersare in the targeted range between 50 and 65 °C. The unique designof these triblock copolymer systems combined with the special propertiesof their blocks (polarity, Tg) predestinatethese systems for an application as a durable dual-action texile finishrendered by virtue of a thermoresponsive block copolymer brush covalentlyattached on the texile fabric surface. The synthesis and the characterizationof these triblock copolymer systems are emphasized in this paper. [ABSTRACT FROM AUTHOR]

We characterized the glass transition temperature T g of thin polyimide films by temperature-dependent spectroscopic ellipsometry and compared the results to DSC measurements of the bulk polymer. The effect of the curing temperature on T g and the thermal expansion α(T) was analyzed. An improved ellipsometric data evaluation was used to get most precise and reliable T g data. T g increased with increasing curing temperature, while the bulk T g was considerably lower than the thin film T g . Both observations are attributed to the temperature sensitive release of the imidization by-product 2-hydroxyethyl methacrylate (HEMA) and crosslinker components as well as decomposition products from the material. Variation in the curing temperatures of 230–380 °C led to an increase in the T g of 34 °C. [ABSTRACT FROM AUTHOR]

Abstract: Monomers with phosphorus-containing substituents were incorporated into aromatic–aliphatic polyesters to develop polymeric halogen-free flame retardants as additives for poly(butylene terephthalate) (PBT). They were built into the polyester backbone of PBT substituting 1,4-butane diol as monomer by phosphorus-containing aromatic–aliphatic diols. Starting from 10-(2,5-bis(2-hydroxyethoxy)phenyl)-9,10-dihydro-9-oxa-10-phospha-phenanthrene-10-oxide (DOPO-HQ-GE), the chemical structure of the phosphorus monomers was systematically varied resulting in new polymers with diphenyl phosphine oxide substituents and bridged phosphine oxide units. The polymers were prepared by transesterification polycondensation in the melt in lab-scale as well as in a 2.4 l-autoclave. The properties of the polyesters were determined and compared to the DOPO-based polyester with respect to the achieved molar mass and polydispersity, solid state structure, glass transition temperature, thermal stability and combustion behavior. It was found that the different phosphorus substituents lead to different glass transition temperatures. The polymers containing bridged phosphorus structural units showed higher glass transition temperatures T g and resulted in higher char yields after thermal decomposition. Both phosphine oxide structures showed only one-step decomposition with a shoulder at the end of the step. In contrast, two separate steps were observed in the polyesters with DOPO-substituents. The results indicated that the phosphorus polyesters under discussion are suitable to adjust the flame retarding mechanism. [Copyright &y& Elsevier]

Abstract: Five new block copoly(imide siloxane)s have been prepared by reacting two different diamines, 4,4″-bis(p-aminophenoxy)-3,3″-trifluoromethyl terphenyl (APTTFT) and amino-propyl terminated polydimethylsiloxane (APPS), separately with 4,4′-(4,4′-isopropylidenediphenoxy)bis(phthalic anhydride); BPADA. The reactions were conducted by a two pot solution imidization technique. The diamine APTTFT and the dianhydride BPADA composed the hard block segment while APPS and BPADA composed the soft block segment. The soft and hard blocks of different block lengths were generated by different stoichiometric imbalance in two different flasks and the final polymers were obtained by reacting both the blocks together. Different block copoly(imide siloxane)s were prepared on increasing the hard block lengths (DP) from 7 to 12, 18, 23 and 28 and the soft block lengths (DP) from 4 to 6, 8, 10 and 12, respectively. The resulting polymers have been well characterized by NMR, DSC and DMA techniques. The properties of the block copolymers were compared with the analogous random copolymers and homopolyimide prepared without APPS. [Copyright &y& Elsevier]