Poly synthesis conditions

The mechanical properties, degradation, and surface characteristics of poly(diol citrates) could be controlled by choosing different diols and by controUing synthesis conditions such as cross-linking temperature and time, vacuum, and initial monomer molar ratio. 

This paper concerns the cationic isomerization polymerization of 3-methyl-1-butene and 4-methyl-1-pentene. Specifically, the microarchitecture (composition) of poly(3-methyl-l-butene) and poly(4-methyl-1-pentene) has been investigated, and the effect of synthesis conditions on polymer composition, polymer molecular weight and polymerization rate of 4-methyl-1-pentene has been studied. 

The second objective of our work was to investigate the relation between synthesis conditions and the composition of poly(4-methyl-l -pentene). Having developed a satisfactory method for determining the composition of the polymer, a study was undertaken of the effect of monomer concentration, coinitiator concentration, conversion, temperature, coinitiator type, and solvent polarity on the composition of the polymer. 

The results of the study of the effect of synthesis conditions on the composition of poly(4-methyl-l-pentene) have shown that even under conditions most favorable for the successful competition of isomerization with propagation, i.e., —120° C, using EtAlCl2, in ethyl chloride, the polymer contains only 50% of the desired 1,4-structure. It appears that in the series (n— l)-methyl-l-alkenes as n increases the likelihood of obtaining completely isomerized products via cationic isomerization polymerization is decreased. This is supported qualitatively by results obtained in the cationic polymerization of 4-methyl-l-hexene, an (n—2)-methyl-1-alkene (17). 

The 300 MHz H NMR and 20 MHz 13C NMR spectra of poly(4-methyl-l-pentene) have been found to be more complex than the corresponding spectra of poly(3-methyl-l-butene) due to the presence of an additional isomer structure in the polymer. Investigation of the 20 MHz 13C NMR spectrum of the polymer has indicated that placement of units in different triad sequences is die cause of multiple methyl proton resonances which have been observed in the H NMR spectra of poly(3-methyl-l-butene) and poly(4-methyl-l-pentene). The use of a computer program for simulating and plotting spectra has enabled measurements of polymer composition to be made of poly(4-methyl-l-pentene) s prepared under a variety of synthesis conditions. 

The comonomer distribution can be alternated by controlling the synthesis conditions, such as the copolymerization at different reaction temperatures at which the thermally sensitive chain backbone has different conformations (extended coil or collapsed globule). In this way, hydrophilic comonomers can be incorporated into the thermally sensitive chain backbone in a more random or more segmented (protein-like) fashion. On the other hand, short segments made of hydrophobic comonomers can be inserted into a hydrophilic chain backbone by micelle polymerization. One of the most convenient ways to control and alternate the degree of amphiphilicity of a copolymer chain, i.e., the solubility difference of different comonomers in a selective solvent, is to use a thermally sensitive polymer as the chain backbone, such as poly(N-isopropylacrylamidc) (PNIPAM) and Poly(N,N-diethylacrylamide) (PDEA). In this way, the incorporation of a hydrophilic or hydrophobic comonomer into a thermally sensitive chain backbone allows us to adjust the degree of amphiphilicity by a temperature variation. 

Table 14. Some parameters of cyclolinear poly(alkylcarbosiloxanes) with regard to synthesis conditions...

Orakdogen N, Okay O (2006) Reentrant conformation transition in poly(N, N-dimethylacryla-mide) hydrogels in water-organic solvent mixtures. Polymer 47 561-568 Panayiotou M, Freitag R (2005) Influence of the synthesis conditions and ionic additives on the swelling behaviour of thermo-responsive polyalkylacrylamide hydrogels. Polymer 46 6777-6785... 

H. Feil, Y.H. Bae, J. Feijen and S.W. Kim, Molecular separation by thermosensitive hydrogel membranes, J. Membr. Sci., 1991, 64, 283 N. Kyaman, D. Kazan, A. Eearslan, O. Okay and B.M. Baysal, Structure and protein separation efficiency of poly(Y-isopropylacrylamide) gels Effect of synthesis conditions, J. Appl. Polym. Sci., 1998, 67, 805. 

Figure 2.16 SEM and TEM images of PANI-NTs obtained from solutions that contained different polymeric acids (A) PSSA, (B) PAA and (C) poly (methyl vinyl ether-alt-maleic acid). The synthesis conditions were 0.1 M aniline, 2 wt% of the polyacid, which were reacted for 16 h at 3°C. (Reprinted with permission from Current Applied Physics, Polyaniline nanotubes doped with polymeric acids by L. Zhang, H. Peng, J. Sui et al., 8, 3, 312-315. Copyright (2008) Elsevier Ltd)...

Fig. 19 Thermally induced collapse of poly(A, Af-diethylacrylamide) hydrogel (curve 1) and cryogel samples (curve 2) upon increasing the temperature from room temperatiffe to 60 °C. The variation in the volume of the gel samples is shown as a function of the deswelling time. Synthesis conditions initial monomer concentration 5.66 wt% molar ratio of vinyl to divinyl monomers 200 1 gelation temperature +20 °C (curve 1) and — 10 C (curve 2). (From [172] with permission from Springer)...

Volkov, V. V., Fadeev, A. G., Khotimsky, V. S., Litvinova, E. G., Sehnskaya, Y. A., McmiUan, J. D., et al. (2004). Effects of synthesis conditions on the pervaporation properties of poly[l-(trimethylsilyl)-l-prop3me] useful for membrane bioreactors. Journal of Applied Polymer Science, 91, 2211—2211. 

Optimization of Synthesis Conditions of Poly(pyrrole) from Aqueous Solution. 

Figure 13 shows the correlation between synthesis conditions and yielded poly(phenylenes) using the oxidative coupling reaction. 

Figure 13 Conductivity of poly(phenylenes) as a function of number of aromatic units n and synthesis conditions [5].

Yu, C., Yun-Fei, L., Huan-Lin, T., Hui-Min, T. (2010). Study of carboxymethyl chitosan based polyampholyte superabsorbent polymer I optimization of synthesis conditions and pH sensitive property study of carboxymethyl chitosan-g-poly(acrylic acid-co-dimethyldi-allylammonium chloride) superabsorbent polymer. Carbohydrate Polymers, 81, 365-371. 

Poly(propylene oxide) was unique among stereospecific polymers developed up to that time. The monomer has an optical center which, under appropriate synthesis conditions, can be preserved In the polymer so that d or 1 forms could be Identified at each asymmetric carbon atom. Examination of the crystal structure of Isotactic poly(propylene oxide) (2) shows that it crystallizes in a helical form and that the crystals can accommodate only the helices of one optical form and are therefore optically active. 

N. Walsby, M. Paronen, J. Juhanoja and F. Sundholm, Radiation giafting of styrene onto poly(vinylidene fluoride) films in propanol The influence of solvent and synthesis conditions, J. Polym. Sci. A Polym. Chem. 38, 1512 (2000). 

Halophenols without 2,6-disubstitution do not polymerize under oxidative displacement conditions. Oxidative side reactions at the ortho position may consume the initiator or intermpt the propagation step of the chain process. To prepare poly(phenylene oxide)s from unsubstituted 4-halophenols, it is necessary to employ the more drastic conditions of the Ullmaim ether synthesis. A cuprous chloride—pyridine complex in 1,4-dimethoxybenzene at 200°C converts the sodium salt of 4-bromophenol to poly(phenylene oxide) (1) ... 

In another process for the synthesis of PPS, as well as other poly(arylene sulfide)s and poly(arylene oxide)s, a pentamethylcyclopentadienylmthenium(I) TT-complex is used to activate -dichlorobenzene toward displacement by a variety of nucleophilic comonomers (92). Important facets of this approach, which allow the polymerization to proceed under mild conditions, are the tremendous activation afforded by the TT-coordinated transition-metal group and the improved solubiUty of the resultant organometaUic derivative of PPS. Decomplexation of the organometaUic derivative polymers may, however, be compHcated by precipitation of the polymer after partial decomplexation. 

N-Alkylpyrroles may be obtained by the Knorr synthesis or by the reaction of the pyrrolyl metallates, ie, Na, K, and Tl, with alkyl haUdes such as iodomethane, eg, 1-methylpyrrole [96-54-8]. Alkylation of pyrroles at the other ring positions can be carried out under mild conditions with allyhc or hensylic hahdes or under more stringent conditions (100—150°C) with CH I. However, unless most of the other ring positions are blocked, poly alkylation and polymerisation tend to occur. N-Alkylation of pyrroles is favored by polar solvents and weakly coordinating cations (Na", K" ). More strongly coordinating cations (Li", Mg " ) lead to more C-alkylation. 

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