摘要:

AbstractPhotopolymerization reaction in din‐propyl ester of dicyanop‐phenylene diacrylic acid crystal is shown to be mediated by exciton–phonon coupling. Raman phonon spectra suggest that at the initial stage of reaction progress, the reactant and the product form a solid solution. In the later stage, the reactant segregates out and forms its own lattice. The polymer lattice is shown to maintain a good degree of order. Infrared and Raman spectra confirm that the polymerization occurs by cyclobutane ring formation. © 1994 John Wiley&Son

ISSN:0887-624X    

DOI:10.1002/pola.1994.080320501

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractThe conditions for preparing poly‐N,N‐diethylacrylamide by group transfer polymerization (GTP) were investigated. While electrophiles did not catalyze the reaction, various nucleophilic substances could be used for that purpose. By using an appropriate initiator, either an ester or a carboxylic acid end group could be formed. The highest yields in the first case were obtained using tetrabutylammonium acetate and dimethylketene methyl trimethylsilyl acetal as catalyst and initiator, respectively, while the use of the corresponding bistrimethylsilyl compound as initiator gave polymers, albeit at lower yields, which carried the acidic end group. The1H‐NMR,13C‐NMR, and IR spectra of the polymers were taken and used together with information obtained with soft‐ionization mass spectrometric methods (MALDI‐MS, ESI‐MS, and FD‐MS) to elucidate molecule structure, apparent molecular weight distribution, polydispersity, and possible mechanisms of the termination reaction. The poly‐N,N‐diethylacrylamide prepared, showed an inverse temperature dependency in its water‐solubility, with a lower critical solution temperature between 29.8°C and 30°C. © 1

ISSN:0887-624X    

DOI:10.1002/pola.1994.080320502

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractOligomers of glycerol and succinic acid have been prepared by three different methods and characterised by solution13C‐NMR spectroscopy at 125.8 MHz. The first series of five oligomers was prepared by reacting glycerol with succinic anhydride; only one acid function of each succinic acid residue formed an ester by this means. They were readily distinguished as the shifts of their glycerol residues were dispersed over 16 ppm, and their shifts provided a guide to the assignment of shifts in the more elaborate oligomers. The second set of oligomers was prepared by treating glycerol with a small quantity of succinic acid, ester links being promoted by means of the reagent dicyclohexylcarbodiimide (DCCDI). When we used 2 mol of DCCDI/mol of acid in the presence of an excess of glycerol, no free acid functions remained, and a new set of oligomers was obtained. Furthermore, within this set the proportion of ring molecules was enhanced by repeating the reaction under much more dilute conditions. In this way the shifts of two ring oligomers were recognized in the spectrum. A different set of oligomers again was obtained when the esterification was performed with 1 mol of DCCDI/mol of succininic acid. After the first generation of oligomers had been identified in the mixtures produced by these three experiments, the reactions continued to produce larger oligomers with new fine structure features in the spectra. Glycerol trisuccinate was prepared in a pure form and heated in a vacuum to eliminate succinic acid groups and allow the formation of oligomers with two and three branch points. The structures successively produced by this reaction were readily recognized. In all we were able to recognize the formation of component structures in at least 17 different oligomers. The shifts of the carbons of the glycerol residues are sensitive to the substitution pattern at that residue, to whether the succinic acid residue to which they are linked has reacted a second time, and in some cases the methine shift is sensitive to how the succinic acid residue attached to a neighboring methylene carbon has reacted. © 1994 John Wiley&Sons, I

ISSN:0887-624X    

DOI:10.1002/pola.1994.080320503

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractChemical modification of poly(epichlorohydrin) (PECH) with nadimide derivatives using 1,8‐diazabicyclo (5.4.0)−7 undecene to catalyze the substitution of the chlorine atom by acid compounds (DBU method) was accomplished. The linear polyethers obtained showed a degree of substitution from 5–80%, depending on time and temperature reaction. TheTgof modified polymers and Ea, calculated in the cure reactions, increases with substitution degree. Residual enthalpies were observed in all cases, which suggests that the curing reaction is incomplete. TGA measurements showed that the degradation has a greater dependence on the modification degree than on the introduced pendant group. © 1994 John Wiley&Son

ISSN:0887-624X    

DOI:10.1002/pola.1994.080320504

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractThe reaction of the alternating ethylene–carbon monoxide copolymer with Lawesson's reagent resulted in the conversion of 75% of the carbonyl groups to thiophene units. A few thioketone groups were also present in the derived polymer. A polymer with furan units in the backbone was formed upon treatment of the alternating propylene–carbon monoxide copolymer with P2O5. Depending on the reaction conditions, up to 90% of the carbonyl groups were converted. Finally, 1,4‐polyalcohols were prepared from the alternating propylene‐carbon monoxide copolymer by reduction. Hydrogenation using Raney nickel as catalyst resulted in the reduction of 60% of the carbonyl groups, whereas reaction with LiAlH4at room temperature caused the reduction of 85% of the carbonyl groups. The glass transition temperature was found to increase monotonically with increasing concentration of hydroxyl groups in the polymer backbone. © 1994 John Wiley&S

ISSN:0887-624X    

DOI:10.1002/pola.1994.080320505

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractPhenylacetylenes having one or two trimethylsilyl groups at their benzene ring were synthesized, and polymerized by [Rh(cyclooctadiene) (PPh3)2]PF6, [Rh(norbornadiene)Cl]2, or WCl6to afford high molecular‐weight polymers in high yields. These poly(phenylacetylene)s were soluble in many kinds of solvents and were fabricated to tough membranes by the solvent casting method. The oxygen permselectivities of these membranes were very good. The oxygen permeability coefficients (Po2) and oxygen separation factors (α =Po2/PN2) of poly[2,4‐(o,p)‐bis(trimethylsilyl)phenylacetylene] [poly (o‐1‐p‐1)] and poly[(4(p)‐trimethylsilyl)phenylacetylene] [poly(p‐1)] membranes were 4.73 × 10−8cc(STP) cm/cm2s cmHg and 2.65, and 1.52 × 10−8cc(STP) cm/cm2s cmHg and 3.39, respectively. In the case of poly(o‐1‐p‐1),Po2was comparable to that of polydimethylsiloxane (PDMS) and α was higher than that of PDMS. However, thePo2value reduced to 48% of its initial value in about 1 year. In the case of poly(p‐1), thePo2value did not change in about 1 year. Ethanol permeated preferentially through these membranes (αEtOH>1) in pervaporation of aqueous ethanol solution, whereas poly(phenylacetylene) [poly(PhA)] showed water permselectivity (αEtOH<1). These favorable effects of trimethylsilyl groups on the oxygen and ethanol permselectivities were discussed on the basis of comparison with those of poly(PhA), other poly(substituted phenyl‐acetylene)s, and trimethylsilyl‐group containing poly

ISSN:0887-624X    

DOI:10.1002/pola.1994.080320506

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractWater‐soluble graft copolymers with phospholipid polar group were synthesized by the macromonomer method and their properties in water were investigated by surface tension and fluorescence spectroscopic measurements. At first, 2‐methacryloyloxyethyl phosphorylcholine (MPC) was polymerized in the presence of 3‐mercapt propionic acid as a chain transfer agent and carboxyl group‐terminated oligo (MPC) was obtained. The oligo (MPC) reacted with glycidyl methacrylate to convert the carboxyl group to a polymerizable methacryloyl group. The MPC macromonomer obtained was copolymerized with hydrophobicn‐butyl methacrylate (BMA) and a graft copolymer was obtained. The graft copolymer, poly(MPC‐graft‐BMA), was water‐soluble when the MPC unit mole fraction was above 0.40. The surface tension of the aqueous solution of poly(MPC‐graft‐BMA) did not depend on the polymer concentration below 0.1 wt %. This tendency was the same as that which appeared in aqueous poly(MPC) solution. The fluorescence intensity of hydrophobic probes observed in an aqueous solution of the poly (MPC‐graft‐BMA) was also the same level as that observed in the case of poly(MPC). These results clearly indicated that the poly(MPC‐graft‐BMA) took a domain structure like micelle in water, i.e., the hydrophobic poly(BMA) backbone was in the core part and the hydrophilic poly(MPC) chain formed the shell part of the micelle.

ISSN:0887-624X    

DOI:10.1002/pola.1994.080320507

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractPolyisoprene (PIP) was found to react with trifluoroacetic acid (TFA) to give an adduct. Saponification of the ester gave a new alternating copolymer of ethylene and α‐methyl vinyl alcohol. TFA did not react with polybutadiene (PBD) under these conditions, thus providing a way to produce amphiphilic block copolymers from PBD‐b‐PIP. TFA addition to the PIP block took place cleanly at an ambient temperature with 2 equiv of the acid in toluene to give block copolymer of PBD and trifluoroacetated PIP. This polymer is very soluble in toluene regardless of molecular weight. Methanolysis with NaOMe cleaved the ester to give PDB‐b‐(ethylene‐alt‐α‐methyl vinyl alcohol) (PIPOH) in a MeOH/toluene mixture. Low molecular weight hydroxylated diblock copolymer is a viscous liquid when the ratio of PIP/PBD is 0.1 (\documentclass{article}\pagestyle{empty}\begin{document}$\overline {M_n }$\end{document}= 4100,D= 1.3), but a solid with the ratio 0.5 (\documentclass{article}\pagestyle{empty}\begin{document}$\overline {M_n }$\end{document}= 7170,D= 1.6). High molecular weight polymer (\documentclass{article}\pagestyle{empty}\begin{document}$\overline {M_n }$\end{document}= 114,000,D= 1.4) with PIP/PBD ratio 0.1 is a hazy rubbery material. Block copolymers of PIPOH and poly(methacrylic acid) was also obtained from copolymers of PIP and poly(t‐butyl methacrylate). The hydroxylated copolymers showed surface activity by monolayer formation on a Langmuir–Blodgett trough. The transfer of the monolayer on a silicon wafer gavez‐type deposition, with the average ellipsometer thickness of the layer being about 40 Å thick per monolayer for\documentclass{article}\pagestyle{empty}\begin{document}$\overline {M_n }$\end{document}= 4100 copolymer. ©

ISSN:0887-624X    

DOI:10.1002/pola.1994.080320508

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractIn the living cationic polymerization of isobutyl vinyl ether (IBVE) by the CH3CH (OiBu) OCOCH3(1)/EtAlCl2initiating system in the presence of the added base in hexane at +40°C, the stability of the initiating system1/EtAlCl2, which form initiating species CH3CH⊕(OiBu) derived from1, was investigated. In the presence of the Lewis base such as ethyl acetate or 1,4‐dioxane, the active species was stable for 300 min even at +40°C in the absence of IBVE, and the living polymers were quantitatively obtained by adding IBVE. However, the active species was partly consumed by side reactions during the standing time for 60 min in the presence of a less basic additive such as ethyl benzoate, and about 50% of the active species was deactivated in the presence of methyl chloroacetate. Consequently, in the case of a less basic additive such as methyl chloroacetate (which was effective for the fast living polymerization), it can be seen that the careful selection of polymerization conditions was required. The living polymerization rate was dependent on the second order of EtAlCl2concentration. EtAlCl2induced the cleavage of1into CH3CH⊕(OiBu) and EtAl⊖Cl2(OCOCH3), and the reactivity of CH3CH⊕(OiBu) and propagating carbocation may be controlled by EtAl⊖Cl2(OCOCH3) with the aid of other EtAlCl2. Et1.5AlCl1.5exists as a bimetallic complex of EtAlCl2and Et2AlCl, and it is expected that the polymers having a bimodal molecular weight distribution will be obtained due to two kinds of counteranions coming from EtAlCl2and Et2AlCl. However, in the cationic polymerization of IBVE by1/Et1.5AlCl1.5in the presence of ethyl acetate, the living polymer exhibiting a unimodal and very narrow molecular weight distribution was obtained. Thereby, it was suggested that the counteranions, EtAl⊖Cl2(OCOCH3) and Et2Al⊖Cl(OCOCH3), exchange rapidly with each other. © 1994 Jo

ISSN:0887-624X    

DOI:10.1002/pola.1994.080320509

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractA range of mixed ether‐esters of cellulose was prepared from partially substituted ethylcellulose and methylcellulose. The13C‐NMR analysis of ethylcellulose with a DS of 2.5 indicated that the hydroxyl groups at carbon six of anhydroglucose units were completely substituted. Acetylation of the ethylcellulose under different conditions yielded (acetyl) (ethyl) cellulose (AEC) samples with acetyl degree of substitution ranging from 0 to 0.5. Fully substituted (propionyl) (ethyl) cellulose (PEC) and (acetyl) (methyl) cellulose (AMC) were also prepared. Chiral nematic liquid crystals were formed in these mixed ester/ethers of cellulose in concentrated solutions of acidic solvents. The critical concentration for the phase separation of the cellulosic solutions depended on the nature of the substituent, the degree of substitution, and the solvent at a given temperature. Methylcellulose solutions in trifluoroacetic acid and dichloroacetic acid form chiral nematic liquid crystals with a left‐handed helicoidal structure. The acetylated methyl cellulose samples did not show the reversal of handedness with increasing acetyl content that was previously observed for the corresponding ethylcellulose samples. © 1994 John Wiley&Son

ISSN:0887-624X    

DOI:10.1002/pola.1994.080320510

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY