Solution properties and chain flexibility of poly(p-tert-butylstyrene)

The dilute solution properties of anionically synthesized poly(p-tert-butylstyrene) (PtBS) were studied in tetrahydrofuran, cyclohexane 1,4-dioxane, 1-nitropropane and 2-octanol. Cyclohexane and tetrahydrofuran are good solvents for PtBS, 1,4-dioxane is of intermediate solvent power, and 1-nitropropane and 2-octanol are theta solvents. The unperturbed dimension results show PtBS to be a more extended chain than polystyrene. These observations are interpreted in light of rotational isomeric state (RIS) models for polystyrene and poly(p-chlorostyrene) and experimental data available for polystyrene and its substituted derivatives.     

Synthesis and chain flexibility of poly(cyclohexylethyl methacrylate)

The synthesis and characterization of fractions of poly(cyclohexylethyl methacrylate) (PCHEM) are reported. A combination of low-angle laser light scattering and intrinsic viscosity experiments was employed to estimate the characteristic ratio (C_∞) of this polymer. The value of 10.7 obtained for PCHEM is similar to the value of 11.3 found previously for poly(phenylethyl methacrylate) but is smaller than values measured for poly(cyclohexyl methacrylate) and poly(cyclohexylmethyl methacrylate) (C_∞ = 11.6 and 11.9, respectively). Received: 28 October 1996/Revised: 16 December 1996/Accepted: 19 December 1996     

Solution properties of poly(thiocarbonates)

Poly(thiocarbonates) with alkyl side chains have been prepared, and the solution properties of these polymers were studied in different solvents. Comparison with other poly(thiocarbonate) analogues and poly(carbonates) shows that the conformational parameter (K_θ) and rigidity factor increase as the volume of the side chain increases. The effect of the side-chain structure on the solution properties is analyzed.     

Mechanical and dielectric properties of bulky side chain poly(methacrylates). Analysis of the low frequency phenomena. 1: Poly(5-indanyl methacrylate)

This paper composes the dynamic mechanical and dielectric relaxation properties for Poly (5-indanyl methacrylate) (P51M), a polymer with a bulky side chain. Measurements were carried out from about ?100°C to near 250°C. A secondary loss peak was observed in dielectric measurements at room temperature (20°C at 0.1 Hz.), whereas nothing was resolved in the mechanical spectrum. A prominent α relaxation associated with the glass transition was also observed near 107°C at 0.1 Hz. in the dielectric and the mechanical spectra. Dipolar dielectric loss overlapped with conductivity at high temperatures and low frequencies. A new method to split the conductive, interfacial, and dipolar contributions to the spectrum is proposed.     

Poly(arylene ether nitrile) copolymers containing pendant phenyl: Synthesis and properties

A series of poly(arylene ether nitrile) copolymers (PENAPs) were synthesized with bisphenol A (BP-A), bisphenol AP (BP-AP) and 2,6-Dichlorobenzonitrile (DCBN) via a nucleophilic substitution polycondensation reaction. FTIR and ¹H-NMR were used to confirm the structure of PENAPs. Glass transition temperature (T_g) of PENAPs determined by differential scanning calorimetry (DSC) ranged from 154.2 to 200.8°C. The 5% weight lost temperature (T_5%) of PENAPs were 418.9–447.7°C. The tensile and DMA test indicated that PENAPs possessed excellent mechanical properties with tensile strength more than 92.8 MPa and storage modulus more than 1.0 GPa at about 150°C. The melt flowability was measured by rheology properties testing ranging from 80 to 1639 GPa at 290°C and under shear frequency 100 Hz, which indicated the copolymers had good flowability and thermal stability. Additionally, PENAPs could be dissolved in many solutions, which meant PENAPs had good solubility and can be processed by solution method.     

Solution properties of poly(propylene sulphide)

Poly(propylene sulphide) (PPS) initiated by cadmium bis(phenyl allyl thiolate) was fractionated from benzene-methanol, and the fractions were examined by viscosity, osmotic pressure and light scattering determinations. Gel permeation chromatography with Styragel columns was found unsatisfactory in tetrahydrofuran (THF) and toluene at room temperature. Polymer stored in the dark at room temperature underwent a very slow degradation which broadened the distribution in the fractions. The following quantitative relationships were found at 25°C:

Extrapolations to derive the unperturbed coil dimensions indicate a possible, but doubtful, solvent effect. The value derived from the θ-mixture gives $\text{A = 696 × 10}{}^{\mathrm{?11}}\text{cm mol}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{g}{}^{\mathrm{<mtext>?</mtext><mtext>1</mtext><mtext>2</mtext>}}$ and a steric factor σ = 1.49, consistent with a high ‘chain flexibility’ expected from the relatively long C-S-C linkages.     

Solution properties of poly(diallyldimethylammonium chloride) (PDDA)

Size exclusion chromatography (SEC) with dual detection, i.e. employing a refractive index (RI), concentration sensitive, detector together with a multiangle light scattering (MALS) detector which is sensitive to molecular size, has been applied to study the solution properties of poly(diallyldimethylammonium chloride) (PDDA) in water containing different electrolytes, namely: NaCl, NaBr and LiCl, at 25 °C. The analysis of a single highly polydisperse sample is enough for obtaining calibration curves for molecular weight and radius of gyration and the scaling law coefficients. The effect of the ionic strength on the conformational properties of the polymer can also be analyzed and unperturbed dimensions can be obtained by extrapolation of the values measured in a good solvent. The values of the characteristic ratio of the unperturbed dimensions thus obtained were: 17, 11 and 17, respectively, for NaCl, NaBr and LiCl solutions. Viscosity and conductivity measurements support the results obtained by SEC. Moreover, the experimental results are in good agreement with the theoretical calculations performed by combining molecular dynamics and Monte Carlo sampling procedures.     

Novel aprotic polar polymers 3. Synthesis and properties of poly(phenyl vinyl sulfoxide)

Summary Poly(phenyl vinyl sulfoxide) 1 was prepared by anionic polymerization and its properties as a polymer homolog of dimethyl sulfoxide (DMSO) were examined. Polysulfoxide 1 was found to have good miscibility with poly(vinyl acetate) as well as poly(2-methyl-2-oxazoline) and poly(N-vinylpyrrolidone) by comparing glass transition temperature(s) (T_gs) of the mixture of these polymers with T_gs of the original polymers by differential scanning calorimetry. Received: 4 March 1998/Accepted: 23 March 1998     

Solution properties and unperturbed dimensions of poly (vinylpyrrolidone)

The dilute solution properties of nine poly(vinylpyrrolidone) fractions in methanol covering the molecular weight range 6.76 × 10⁴ to 1.02 × 10⁷ were studied. Constants a and K_m of the Mark-Houwink-Sakurada (M.H.S.) equation were found to be 0.60 and 2.64 × 10^?4 respectively using light scattering and intrinsic viscosity data and were compared with the literature values. The second virial coefficient, A₂ decreases gradually as the molecular weight increases while the root-mean-square radius of gyration, ² increases. The dependence of A₂ on molecular weight is in agreement with other flexible polymers dissolved in moderate to good solvents. The unperturbed chain dimension, (r/M) was calculated using the Stockmayer-Fixman (S—F) equation and a value of 4.9 × 10^?17 cm was obtained. The S—F plot slightly bends in the region of high molecular weight which is according to expectation.     

Nucleophilic substitution reaction of ethanolamine onto poly(phenyl acrylate) and substituted poly(phenyl acrylate)s

The nucleophilic substitution reaction of differently substituted phenoxy groups with ethanolamine in various poly(phenyl acrylate)s was investigated in dioxane at 60, 80, and 100°C. The conversion, as determined from IR- and ¹H-NMR spectroscopy and elemental analysis, depends on the temperature and the kind of substituents at the phenyl ring.     

Solution properties and unperturbed dimensions of poly(vinylidene fluoride)

A commercial sample of poly(vinylidene fluoride) (PVF₂) was fractionated and characterized. The following relationships were found: (η) = 1.93 × 10^?4M^0.677 (in dimethylacetamide at 25°C); (η) = 2.13 × 10^?4M^0.62 (in acetophenone at 85°C); (η) = 6.86 × 10^?4M^0.50 (in benzophenone at 190°C), leading to a value of the steric factor: σ = (〈r²〉₀/〈r²〉_0f) = 1.66 ± 0.05, which is in agreement with the crystalline properties of the polymer. The concept of M(η) as a universal parameter for g.p.c. calibration was valid for PVF₂ in dimethylacetamide.     

Aging of poly(lactide)/poly(ethylene glycol) blends. Part 1. Poly(lactide) with low stereoregularity

Poly(lactide) (PLA) is rapidly gaining interest as a biodegradable thermoplastic for general usage in degradable disposables. To improve mechanical properties, a PLA with low stereoregularity was blended with polyethylene glycol (PEG). Blends with up to 30 wt% PEG were miscible at ambient temperature. Blending with PEG significantly decreased the T_g, decreased the modulus and increased the fracture strain of PLA. However, the PLA/PEG 70/30 blend became increasingly rigid over time at ambient conditions. The mechanism of aging primarily under ambient conditions of temperature and humidity was studied. Changes in mechanical properties, thermal transitions and solid state morphology were examined over time. Aging was caused by slow crystallization of PEG. Crystallization of PEG depleted the amorphous phase of PEG and gradually increased the T_g. As T_g approached the aging temperature, reduced molecular diffusivity slowed the crystallization rate dramatically. Aging essentially ceased when T_g of the amorphous phase reached the aging temperature. The increase in matrix T_g and the reinforcing effect of the crystals produced a change in mechanical properties from elastomer-like to thermoplastic-like.     

Multiple transitions in poly(allylbenzene): 1. Thermophysical properties

Polyallylbenzene is a semicrystalline material the thermal behaviour and physical properties of which reveal several transitions. Thermal and differential calorimetric analysis have shown the influence of the history of the material about the glass transition and melting. Several techniques such as thermomechanical analysis, dilatometry and inverse gas chromatography give additional information for the unidimensional and volume behaviour of the polymer versus temperature.     

Solubility parameters of poly(di-n-alkyl cyclohexyl-) and poly(di-n-alkyl phenyl itaconates)

Solubility parameters of poly(dicyclohexyl-), poly(diphenyl itaconate) and of the first three members of the poly(dialkyl cyclohexyl-) and poly(dialkyl phenylitaconate) homologous series were determined from limiting viscosity numbers in various solvents and solvent mixtures, differing in structure, polarity and composition. The values obtained are within limits of 19.0 and 16.7 (J^1/2. cm^-3/2). Phenyl groups in the substituents lead to slightly higher values than cyclohexyl rings and the introduction of alkyl groups in both series results in a progressive decrease of the solubility parameter. The experimental values are slightly lower than those obtained by calculation from molar attraction constants.     

New Miscible Poly(ether imide)/Poly(phenyl sulfone) Blends

Summary: Blends of PEI and PPSU were prepared directly during the plasticization step of an injection molding process throughout the full composition range. The molded blends were transparent and showed a single glass transition and no dispersed phase by SEM. These characteristics did not allow the presence of a single miscibilized phase to be inferred unambiguously due to the very similar T_gs and refractive indices of the two components of the blends. Miscibility was inferred after close observation of the position, height and area of the enthalpy relaxation peak of the 50/50 blend. The modulus of elasticity and yield stress changed linearly with composition, leading to polymer materials with intermediate characteristics. The linearity was attributed to the lack of decrease in free volume induced by mixing and to the similar orientation of the components before and after mixing. The PPSU presence only slightly reduced the known tendency towards brittle fracture of PEI under notched impact conditions, but the presence of a single amorphous phase led to an expected ductile behavior of the blends close to that predicted by the single rule of mixtures.

Break stress (?) and break strain (○) of PEI/PPSU blends as a function of composition.     

Poly(amidine)s and poly(guanidine)s — synthesis and some properties

Synopsis Several poly(amidine) and poly(guanidine) copolymers and their hydrochloride salts were synthesized by introducing the functional groups into suitable polymers. The properties of the resulting copolymers were investigated by base and acid titration.