The specific refractive index increments of a random methylmethacrylate/ benzylacrylate/styrene-terpolymer and of the three corresponding homopolymers was measured in several solvents and at six different wavelengths. With the known terpolymer composition and the specific refractive index increments of the homopolymers the specific refractive index increment of the terpolymer is calculated by means of an equation formerly derived. Calculated and experimental values are compared. 相似文献
Refractive index increments of 11 poly(di-n-alkylitaconate) polymers were determined systematically in seven organic solvents, expected to be suitable for light scattering and other solution property measurements. Of 13 solvents tried, poly(dimethylitaconate) was soluble only in 6, however higher members of the polymer series exhibit better solubility. The measured dn/dc values in butanone and ethyl-and amylacetate are practically independent of an increase of the number of carbon atoms in the ester substituents of the monomer, however a decrease of the values for solvents with higher refractive indices can be observed. For statistical poly(styrene-co-di-n-alkylitaconate) samples the additive character of dn/dc in butanone and toluene was observed and verified from copolymer compositions determined by UV and elemental analysis. 相似文献
The gamma radiation stability, optical properties, and mechanical properties of 1H, 1H, 3H-hexafluorobutyl and 1H, 1H-heptafluorobutyl methacrylate homopolymers and copolymers were determined and compared to poly(methyl methacrylate), PMMA. The aim of this study was to identify polymers for fiber cladding materials that exhibit improved optical radiation resistance and physical properties. Using 60Co source, the samples absorbed 10 Mrads of gamma radiation at 0.04 Mrads/hr in an air environment. UV/Vis transmission spectra were obtained before irradiation, just after 10 Mrads, and regularly thereafter, to track recovery in transmittance. The glass transition temperatures, decomposition temperatures, refractive indices and flexural moduli were also obtained. Poly(heptafluorobutyl methacrylate) exhibited the greatest resistance to radiation induced discoloration and the lowest refractive index of the compositions tested. As the composition of the copolymers increased in hexafluorobutyl methacrylate concentration, both the radiation induced discoloration and the refractive index increased. 相似文献
The objective of this research was to examine the capabilities of QSPR (Quantitative Structure Property Relationship) modeling to predict specific biological responses (fibrinogen adsorption, cell attachment and cell proliferation index) on thin films of different polymethacrylates. Using 33 commercially available monomers it is theoretically possible to construct a library of over 40,000 distinct polymer compositions. A subset of these polymers were synthesized and solvent cast surfaces were prepared in 96 well plates for the measurement of fibrinogen adsorption. NIH 3T3 cell attachment and proliferation indices were measured on spin coated thin films of these polymers. Based on the experimental results of these polymers, separate models were built for homo-, co-, and terpolymers in the library with good correlation between experiment and predicted values. The ability to predict biological responses by simple QSPR models for large numbers of polymers has important implications in designing biomaterials for specific biological or medical applications. 相似文献
Specific refractive index increments of three agarose samples in dimethyl sulfoxide and in water were measured at 436, 546 and 633 nm, and at several temperatures. The wavelength and temperature dependences of the increments were determined, simultaneously correlated using the surface regression method, and presented in a form suitable for tabulation. The influence of differences in the structure of agaroses from various algal sources on the specific refractive index increment is discussed. 相似文献
Summary: We propose in this paper a new plastic rod‐lens with low chromatic aberration. Since a plastic rod‐lens has a parabolic refractive index distribution, it usually also shows a distribution of Abbe number. This Abbe number distribution is thought to cause the chromatic aberration of the plastic rod‐lens array. We have studied novel materials for a new plastic rod‐lens with low chromatic aberration and have provided new transparent polymer blends consisting of two polymers with different refractive indices and with almost equal Abbe numbers by using a fabrication process based on photopolymerization of methacrylate monomer(s) in the presence of other methacrylic polymers. The process can give new transparent polymer blends which cannot be formed using conventional techniques for polymer blend formation. In this work, tricyclo[5,2,1,02,6]deca‐8‐yl methacrylate is used as a high refractive index monomer and tert‐butyl methacrylate is used as a low refractive index one. By using polymer blends including these monomer units, we have created a plastic rod‐lens with lower chromatic aberration.
Molecular structures of comonomers in the study. 相似文献
We designed and synthesized quaternary copolymers of methyl methacrylate (MMA), 2,2,2-trifluoroethyl methacrylate (TFEMA), benzyl methacrylate (BzMA), and 3,3,5-trimethylcyclohexyl methacrylate (TMCHMA) and we investigated their birefringence, thermal properties, and other optical properties. When the copolymer composition was MMA/TFEMA/BzMA/TMCHMA = 50:38:8:4, 40:30:7:23, or 30:21:7:42 (wt%), a zero–zero-birefringence polymer that exhibited neither orientational nor photoelastic birefringence was obtained. We demonstrated that such zero–zero-birefringence polymers with a variety of compositions could be successfully prepared in the quaternary system by using the same compensation method as applied in ternary random copolymerization. We also demonstrated that the glass-transition temperature (Tg) and refractive index (nD) of these copolymers could be controlled with high accuracy while retaining their zero–zero-birefringence property. We can therefore predict the type of birefringence, the Tg, and the nD of a particular copolymer before polymerization. Zero–zero-birefringence polymers with the most appropriate characteristics can then be synthesized selectively by quaternary copolymerization. 相似文献
The results of a study of irradiated and unirradiated samples of polymers prepared by plasma polymerization in an inductively coupled radiofrequency (rf) reactor using infrared, elemental, thermogravimetric, and ESR analyses and density and refractive index measurements are presented. The plasma-formed polymers studied include polypropylene, poly(ethylbenzene), poly(methyl methacrylate), poly(tetrafluoroethylene), poly(chlorotrifluoroethylene), and poly(trimethylchlorosilane). 相似文献
Blends of poly(ethylene ortho-phthalate) (PEOP), and poly(vinyl acetate) (PVAc), appear to be compatible at all compositions, from visual examination at room temperature and differential scanning calorimetry tests. Both low- (PEOP-1) and high-molecular weight (PEOP-2) alloys with PVAc show a single composition-dependent glass transition temperature (Tg). Some blends show Tg values that are below the Tg for either of the pure polymers. Couchman's equation, with a slight modification, can be used to model Tg behavior. All PEOP-2 blends with PVAc, phase separate at high temperatures, whereas PEOP-1–PVAc blends remain miscible under the same conditions. The composition dependence of the blends refractive index shows a deviation from simple additivity rules, and a similar trend is observed in density measurements. When comparing Flory's characteristic parameters for the polymers, compatibility is predicted for PVAc–PEOP blends. In contrast, blends of PEOP and poly(methyl methacrylate) (PMMA), which has a similar chemical structure to that of PVAc are predicted to be incompatible, in agreement with experimental evidence. It is suggested that compatibility is produced because of possible specific interactions between the aromatic group of PEOP and the ester carbonyl on PVAc, which is not sterically hindered as is the corresponding moiety on PMMA. 相似文献
The first large-scale fractionation method for polyacrylamides is reported. This has been optimized to prepare a series of narrowly distributed polymer standards with molecular weights between 10,000 and 1,000,000. These were subsequently hydrolyzed to between 5 and 35% sodium acrylate content through a saponification reaction. It has been found that the classical light-scattering theory, derived for nonionic scattering bodies, can be applied to polyelectrolytes provided the specific refractive index increment (?n/?c) is evaluated at constant electrochemical potential (μ). This is obtained by dialyzing the polymer solution against the dialysate (0.2MNa2SO4 for polyacrylamide-co-sodium acrylate) for a predetermined equilibrium period, specific to the pore size of the membrane used. From such measurements at various copolymer compositions (F), the following empirical relationship is established: where a was found to be ?0.076. The validity of the specific refractive index increment at constant chemical potential is established through light-scattering measurements of the weight-average chain length of the hydrolyzed polyacrylamides. These were then compared with the chain lengths of the parent nonionic polymers from which they were derived. Excellent agreement is observed, implying the polyelectrolyte characterization method developed, and specifically the (?n/?c)μ's, are accurate and reliable. 相似文献
Summary A R 401 Waters Assoc. differential refractometer has been modified to obtain the variation of refractive index increments, dn/dc, of polymer solutions at 633 nm. The introduced modifications were in the sample injection system and in the light source. The performance of the modified refractometer both with aqueous and organic solutions is analyzed. In order to localize a conformational transition in lysozyme, the dependence of dn/dc on temperature for lysozyme solutions in phosphate buffer is studied. Similarly, (dn/dc)k values for the ternary n-alkane/butanone/poly(dimethyl siloxane) systems over the whole composition range of the binary solvent mixtures are evaluated. 相似文献
Copolymers of 2,4-dichlorophenyl methacrylate and butyl methacrylate were synthesized with different monomer concentrations using toluene as a solvent and 2,2′-azobisisobutyronitrile (AIBN) as an initiator at 70°C. The copolymers were characterized by IR-spectroscopy. Copolymer compositions were determined by UV-spectroscopy. The reactivity ratios for monomer pairs were determined by Fineman-Ross method. Gel permeation chromatography was employed for determining the average molecular weights and the polydispersity index. The intrinsic viscosities of polymers were also discussed. Thermogravimetric analyses of polymers were carried out in nitrogen atmosphere. The homo- and copolymers were tested for their effect on the growth of various microorganisms. 相似文献
Measurements of the second virial coefficient as function of the copolymer composition show, that the parameter χAB, which characterizes the energy of interaction of heterocontacts, is negative for random p-iodostyrene/styrene copolymers. This means there exist weak attractive intramolecular interaction forces between the two different monomer units. Fractionation of the copolymers yields STOCKMAYER-FIXMAN-plots, which confirm this result. Measurements of the specific refractive index increments as function of the wave length show, that for these copolymers, in the region from red to ultraviolet light, the specific refractive index increment is additive. 相似文献
The specific refractive index increments of amylose, amylose acetate, amylopectin and glycogen in various aqueous and non-aqueous solvents have been determined. These were measured by the direct determination of deviation method. 相似文献
Hydrogels (crosslinked polymers with a defined water content) based on 3-O-acryloyl-1,2;5,6-di-O-isopropylidene-α-D(-)-glucofuranose and 2-hydroxyethyl methacrylate were prepared by radical copolymerization and acid hydrolysis of the isopropylidene protecting groups. The obtained hydrogel samples were examined for linear expansion to hydration, weight-percent hydration, refractive index, extractables, percent transmission of visible light and oxygen permeability as typical properties for contact lens materials. 相似文献