Copolymer solutions chloroform

In Fig. 49 the dependences of D, on copolymers composition are adduced, about which the following should be said. All values D, were determined for copolymers solution in chloroform, but copolymers synthesis was realized in other solvents APESF — in dimethylsulfonoxide and the two remaining copolymers — in methylene chloride. Since the interactions polymer-solvent fix the macromolecular coil stracture in synthesis process [46], then it is necessary either D, determination for the indicated solvents or recalculation of the value Dj. in chlo-... 

MHz F-NMR spectra of the copolymers in chloroform solution were recorded at room temperature. p-Difluorobenzene was used as the internal standard and its chemical shift in chloroform solution relative to CFCI3 was found to be +120.2 ppm. [Following the proposed convention , the chemical shift of CFCI3 is taken to be zero and resonances upfield from it are assigned positive values. These are represented by the symbol 6f in subsequent discussion]. 

Styrenated fatty acids and alkyd resins spectrophoto-metric analysis using a modified Kappelmeier procedure, with ultraviolet determination of polymerized styrene Styrene and fumerate in esters and resins 0.1-2% styrene in polystyrene at 250-260 m/i direct determination polystyrene in a copolymer in chloroform solution at 269 mu partial separation, nitration, and determination as neutralized p-nitrobenzoic acid, of bound styrene in raw and cured polymers, using a three-wavelength ultraviolet measurement to check for unexpected interfer-... 

Spectroscopic Measurements. and NMR spectra were obtained on either a Bruker AC-250 or an AM-360 spectrometer operating in the FT mode. Si NMR spectra were recorded on an IBM Bruker WP-270-SY spectrometer. Five percent w/v solutions of copolymer in chloroform-c/ were used to obtain NMR spectra. NMR spectra were run with broad band proton decoupling. A heteronuclear gated... 

Most of the compounds in this class have been prepared from preexisting crown ether units. By far, the most common approach is to use a benzo-substituted crown and an electrophilic condensation polymerization. A patent issued to Takekoshi, Scotia and Webb (General Electric) in 1974 which covered the formation of glyoxal and chloral type copolymers with dibenzo-18-crown-6. The latter were prepared by stirring the crown with an equivalent of chloral in chloroform solution. Boron trifluoride was catalyst in this reaction. The polymer which resulted was obtained in about 95% yield. The reaction is illustrated in Eq. (6.22). 

Tablc 16-2. Absorption and emission data lor copolymers and OPV5s in chloroform solution. 

Proton and carbon-13 nuclear magnetic resonance (NMR) spectra were recorded on a IBM Instruments 270 MHz NMR Spectrometer on 6-8 weight percent solutions in deuterated chloroform. Ultraviolet spectra were recorded on an IBM Ultraviolet Spectropluitometer Model 9420 using chloroform solutions containing 2 x 10-5 g/ml of the copolymers. 

SCHEME 2.20 Tuning the band gap and the emission wavelength in PPV block copolymers 184-187 (in chloroform solution). 

Other thiophene-thiophene-5,5-dioxide copolymers were reported by Berlin et al. [544], who synthesized copolymers 443 and 444 with an alternating electron acceptor thiophene-5,5-dioxide unit and donor ethylenedioxythiophene (EDOT) units (Chart 2.107). The polymers absorbed at 535 nm (Eg = 2.3 eV) in chloroform solution and in films (which is consistent with their electrochemistry Eox 0.40-0.50 V, Emd -1.75-1.8 V AE 2.2-2.25 V) and emitted at 650 nm (<1> M (film) 1%). Such a high band gap (which exceeds that in PEDOT... 

Some solvent effects on the UV absorption have already been reported 35,36). Harrah et.al. reported that the UV absorption in hexamethyldisiloxane solution is not very different from that in THF(35). They also reported that toluene solution gives a somewhat different UV absorption than hexane. Recently, polysilane copolymers were reported to become more expanded in chloroform than in THF(52). There is no discription of the UV absorption properties of polysilanes in polar solvents. 

Acetylated m-cresol novolac copolymers were prepared by acetylation of m-cresol novolac with acetic anhydride in the presence of sodium hydroxide. The following acetylation procedure is typical. 3.2g of sodium hydroxide (50 mmol) was added to 4.8g of cresol novolac (40mmol) in 10 ml. of water. The reaction mixture was stirred for 10 mins, until all polymer went into solution. The required amount of acetic anhydride was then added, the reaction mixture was stirred for 10 more mins, and poured in 150 ml. of iced water. The polymer was filtered and purified by reprecipitation from a chloroform/benzene (5 2 v/v) solution by the addition of hexane. The acetylation content was determined by H and 13C NMR. 

Fig. 6 AFM topographic images (a-d, i, j) and cross sections (e, f, k, I) of a miktoarm PS-P2VP star copolymer adsorbed on mica from chloroform (a-c, e), from THF (d, f) and from acidic water (HC1, pH = 2) in salt free (i, k) and in the presence of 1 mM Na3P04 (j, I). Schematic representation of the solution conformations and conformations in adsorbed state of the PS-P2VP in chloroform (g), THF (h), in water at pH = 2 before (n) and after adsorption (m) respectively (PS arms in red, P2VP ones in blue). Reprinted with permission from [116]. Copyright (2003) American Chemical Society...

Table 2 contains the characteristics of the amic ester-aryl ether copolymers including coblock type, composition, and intrinsic viscosity. Three series of copolymers were prepared in which the aryl ether phenylquinoxaline [44], aryl ether benzoxazole [47], or aryl ether ether ketone oligomers [57-59] were co-re-acted with various compositions of ODA and PMDA diethyl ester diacyl chloride samples (2a-k). The aryl ether compositions varied from approximately 20 to 50 wt% (denoted 2a-d) so as to vary the structure of the microphase-separated morphology of the copolymer. The composition of aryl ether coblock in the copolymers, as determined by NMR, was similar to that calculated from the charge of the aryl ether coblock (Table 2). The viscosity measurements, also shown in Table 2, were high and comparable to that of a high molecular weight poly(amic ethyl ester) homopolymer. In some cases, a chloroform solvent rinse was required to remove aryl ether homopolymer contamination. It should also be pointed out that both the powder and solution forms of the poly(amic ethyl ester) copolymers are stable and do not undergo transamidization reactions or viscosity loss with time, unlike their poly(amic acid) analogs.

The off-line measurements of the linear block copolymer "arm" samples were not difficult. However, in most cases, chloroform solutions demonstrated noticeably more LALLS baseline instability than those prepared in THF and toluene intensity readings changed as much as 10% within several minutes regardless of the amount of solution prefiltration. 

Similar to micellar assemblies in water, reverse micelles have also been utilized to bring about nonspecific binding interactions in organic solvents. Akiyoshi et al. (2002) have synthesized an amphiphilic block copolymer containing PEO and an amylase chain as receptor for methyl orange (MO Chart 2.2). Amylases are insoluble and methoxy-PEO (MPEO) is soluble in chloroform. Hence, an MPEO-amylase block copolymer forms reverse micelles in chloroform. Akiyoshi et al. established the capability of the buried receptors to extract the complementary analyte by studying the ultraviolet visible (UV-vis) spectra. A solution of polymer was shaken... 

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