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Stabilization of aqueous α-Al2O3 suspensions with block copolymers 嵌段共聚物对α-Al2O3悬浮液的稳定作用
Acta Polymerica Pub Date : 2003-03-11 DOI: 10.1002/actp.1997.010481105
J. Orth, W. H. Meyer, C. Bellmann, G. Wegner
{"title":"Stabilization of aqueous α-Al2O3 suspensions with block copolymers","authors":"J. Orth,&nbsp;W. H. Meyer,&nbsp;C. Bellmann,&nbsp;G. Wegner","doi":"10.1002/actp.1997.010481105","DOIUrl":"https://doi.org/10.1002/actp.1997.010481105","url":null,"abstract":"<p>Water-soluble diblock copolymers (DBCPs) with a polyelectrolyte block are accessible by sequential anionic polymerization of <i>tert</i>-butylmethacrylate (TBMA) and ethylene oxide (EO), followed by polymer analogous conversion of the PTBMA into poly(methyacrylic acid) (PMAA) blocks. These materials are highly efficient dispersants for oxide ceramic powders in aqueous media. A series of block copolymer samples with <i>M</i><sub>n</sub> ranging from 1300 to 38 900, and (EO:MAA) block length ratios from 0.5 to 11.7 were prepared with polydispersities close to 1.2. The influence of overall molecular weight and block length ratio, pH and ionic strength on the stability of aqueous α-Al<sub>2</sub>O<sub>3</sub> suspensions was investigated by sedimentation and adsorption experiments, surface plasmon resonance (SPR) and electrokinetic measurements. The copolymers are capable of stabilizing alumina suspensions by a combination of specific adsorption of one block on the particle surface and a shielding effect provided by the nonadsorbing block. In addition, the adsorption of the negatively charged PMAA block on the oppositely charged alumina surface reverses the electrophoretic potential of the oxide particles, a process which is strongly pH dependent. With respect to the powder dispersing efficiency, an optimum was found when the DBCP consisted of a short PMAA anchoring and an approximately tenfold longer PEO stabilizer block with an overall molecular weight of about 5000. Alumina suspensions with the DBCP added were highly dispersed and rather stable against salt addition in a much wider pH window than block-copolymer-free suspensions.</p>","PeriodicalId":7162,"journal":{"name":"Acta Polymerica","volume":"48 11","pages":"490-501"},"PeriodicalIF":0.0,"publicationDate":"2003-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/actp.1997.010481105","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91827184","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 31
Chirality induction in cyclopolymerization 环聚合中的手性诱导
Acta Polymerica Pub Date : 2003-03-11 DOI: 10.1002/actp.1997.010481101
K. Yokota, T. Kakuchi, T. Uesaka, M. Obata
{"title":"Chirality induction in cyclopolymerization","authors":"K. Yokota,&nbsp;T. Kakuchi,&nbsp;T. Uesaka,&nbsp;M. Obata","doi":"10.1002/actp.1997.010481101","DOIUrl":"https://doi.org/10.1002/actp.1997.010481101","url":null,"abstract":"<p>An overview of the synthesis of optically active polymers due to main-chain chirality based on the configurational arrangement in cyclopolymerization and cyclocopolymerization is presented. The template having chiral twist transmitted its chirality to the main chain in the intramolecular cyclization of divinyl monomers to form the enantiomeric racemo cyclic units. The asymmetric cyclocopolymerization produced the polymers which were optically active even after cleaving the template. The synthesis of optically active polymers from achiral monomers using a slight amount of chiral initiator was achieved by the enantioselective cyclopolymerization. The cyclopolymerization capable of controlling stereochemistry of the cyclic constitutional units was one of useful means for asymmetric polymerization.</p>","PeriodicalId":7162,"journal":{"name":"Acta Polymerica","volume":"48 11","pages":"459-470"},"PeriodicalIF":0.0,"publicationDate":"2003-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/actp.1997.010481101","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91827190","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 7
Polydimethylsiloxane-cyclodextrin networks synthesized into a porous polystyrene gel – an investigation by energy filtering transmission electron microscopy 聚二甲基硅氧烷-环糊精网络合成多孔聚苯乙烯凝胶的能量过滤透射电镜研究
Acta Polymerica Pub Date : 2003-03-11 DOI: 10.1002/actp.1997.010480403
A. Du Chesne, K. Wenke, G. Lieser, G. Wenz
{"title":"Polydimethylsiloxane-cyclodextrin networks synthesized into a porous polystyrene gel – an investigation by energy filtering transmission electron microscopy","authors":"A. Du Chesne,&nbsp;K. Wenke,&nbsp;G. Lieser,&nbsp;G. Wenz","doi":"10.1002/actp.1997.010480403","DOIUrl":"10.1002/actp.1997.010480403","url":null,"abstract":"<p>Crosslinked poly(styrene)-poly(dimethylsiloxane)-cyclodextrin systems are a new class of multicomponent polymer networks. They are prepared by swelling a polystyrene gel (PS) with the components of the poly(dimethylsiloxane)-cyclodextrin network (PDMS(CDX)) and subsequent crosslinking. Electron spectroscopic imaging and elemental mapping are appropriate methods for the investigation of these polymer systems, which contain heteroatoms in one of their components. It is shown that PDMS(CDX) is uniformly distributed within PS. Interpenetration with PS is responsible for the stable anchoring of PDMS(CDX) and prevents phase separation.</p>","PeriodicalId":7162,"journal":{"name":"Acta Polymerica","volume":"48 4","pages":"142-148"},"PeriodicalIF":0.0,"publicationDate":"2003-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/actp.1997.010480403","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87899060","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 6
Viscosity of fractions from end-linked polystyrene star macromolecules 端链聚苯乙烯星型大分子馏分的粘度
Acta Polymerica Pub Date : 2003-03-11 DOI: 10.1002/actp.1997.010481207
M. Weissmüller, W. Burchard
{"title":"Viscosity of fractions from end-linked polystyrene star macromolecules","authors":"M. Weissmüller,&nbsp;W. Burchard","doi":"10.1002/actp.1997.010481207","DOIUrl":"10.1002/actp.1997.010481207","url":null,"abstract":"<p>A number of OH-terminated three-arm star molecules were prepared by anionic polymerization with a specially functionalized initiator. The stars were crosslinked over the OH groups with varying amounts of toluene-2,4-diisocyanate. The samples were fractionated by size exclusion chromatography (SEC) on-line with a low angle laser light scattering (LALLS) and a viscosity (VISC) detector. The Kuhn—Mark—Houwink—Sakurada (KMHS) relationships from the various samples resulted in a common relationship. Shrinking parameters <i>g</i>′<sub>j</sub>≡[η]<sub><i>j,b</i></sub>/[η]<sub><i>j</i>,lin</sub> were determined for each slice and could satisfactorily be interpreted on the basis of the Zimm—Stockmayer theory in connection with a suggestion by Kurata et al. The Kurata suggestion was checked with data from star molecules. The examination revealed that randomly branched and star-branched macromolecules exhibit significantly different hydrodynamic behavior. The ratio of the Fox—Flory coefficients Φ<sub>b</sub>/Φ<sub>lin</sub> in the relationship [η] = Φ(<i>R</i>/<i>M</i>) increases in both cases with branching. This is a consequence of the enhanced segment density and the resulting increase in the hydrodynamic interaction.</p>","PeriodicalId":7162,"journal":{"name":"Acta Polymerica","volume":"48 12","pages":"571-578"},"PeriodicalIF":0.0,"publicationDate":"2003-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/actp.1997.010481207","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75197701","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 14
Comparison of polydipentylsilylenes and -siloxanes containing chiral groups 含手性基团的聚二戊基硅氧烷和-硅氧烷的比较
Acta Polymerica Pub Date : 2003-03-11 DOI: 10.1002/actp.1997.010481004
L. A. Schwegler, A. Molenberg, M. Möller
{"title":"Comparison of polydipentylsilylenes and -siloxanes containing chiral groups","authors":"L. A. Schwegler,&nbsp;A. Molenberg,&nbsp;M. Möller","doi":"10.1002/actp.1997.010481004","DOIUrl":"10.1002/actp.1997.010481004","url":null,"abstract":"<p>Polydipentylsilylene and -siloxane copolymers, containing bis[(<i>S</i>)-(+)-2-methylbutyl]silane units have been synthesized. Thermal analysis demonstrated for both types of copolymers that crystallization was hindered on incorporation of the 2-methylbutyl groups. Optical rotation measurements in various solvents yielded a much stronger optical activity of the polysilylene copolymers, compared to the polysiloxanes. This effect has been explained by the formation of a chiral supramolecular structure in the case of the polysilylenes. The measurements have indicated that the solvent quality can be employed to enhance the formation of this structure at relatively low 2-methylbutyl contents.</p>","PeriodicalId":7162,"journal":{"name":"Acta Polymerica","volume":"48 10","pages":"438-445"},"PeriodicalIF":0.0,"publicationDate":"2003-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/actp.1997.010481004","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75813256","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 5
Clear evidence of the sensitivity of the solvatochromic effect to side chain functionalization in 3-hexyl-substituted polythiophenes 3-己基取代的多噻吩的侧链功能化对溶剂致变色效应的敏感性的明确证据
Acta Polymerica Pub Date : 2003-03-11 DOI: 10.1002/actp.1997.010480703
C. Della-Casa, P. Costa-Bizzarri, M. Lanzi, F. Bertinelli
{"title":"Clear evidence of the sensitivity of the solvatochromic effect to side chain functionalization in 3-hexyl-substituted polythiophenes","authors":"C. Della-Casa,&nbsp;P. Costa-Bizzarri,&nbsp;M. Lanzi,&nbsp;F. Bertinelli","doi":"10.1002/actp.1997.010480703","DOIUrl":"10.1002/actp.1997.010480703","url":null,"abstract":"<p>The solvatochromic properties of 3-hexyl-substituted polythiophenes functionalized with an ester, ether or hydroxy group at the end of the alkyl side chain are reported. An extraordinarily large shift, Δ<sub>max</sub> = 99 nm, and a dramatic change of the UV/ vis spectral profile are found when the carboxylate is replaced with the hydroxy group by functionalization exchange. The solvatochromic behavior of each polymer is believed to be strictly related to the type of functional group owing to different physical interactions (solvation) between groups different in polarity and solvent molecules. A unique and common chromophoric unit for the final conformation of the 3-hexyl-substituted polythiophenes, induced by the solvatochromic effect, is also suggested.</p>","PeriodicalId":7162,"journal":{"name":"Acta Polymerica","volume":"48 7","pages":"251-255"},"PeriodicalIF":0.0,"publicationDate":"2003-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/actp.1997.010480703","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82957363","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 10
Polyesters with 1,4,7-trioxanonyl segments in their main chain. Novel ion-conducting matrices 主链上有1,4,7-三恶壬基段的聚酯。新型离子导电基质
Acta Polymerica Pub Date : 2003-03-11 DOI: 10.1002/actp.1997.010480804
J. J. A. Mertens, L. W. Jenneskens, B. B. Wentzel, M. Wübbenhorst, J. Van Turnhout, R. H. M. Van de Leur
{"title":"Polyesters with 1,4,7-trioxanonyl segments in their main chain. Novel ion-conducting matrices","authors":"J. J. A. Mertens,&nbsp;L. W. Jenneskens,&nbsp;B. B. Wentzel,&nbsp;M. Wübbenhorst,&nbsp;J. Van Turnhout,&nbsp;R. H. M. Van de Leur","doi":"10.1002/actp.1997.010480804","DOIUrl":"10.1002/actp.1997.010480804","url":null,"abstract":"<p>The amorphous polyester <b>1a</b> prepared by melt condensation of 1,5-<i>bis</i>-(9-hydroxy-1,4,7-trioxanonyl)naphthalene (<b>2a</b>) and adipoylchloride (<b>3a</b>), which contains <i>bis</i>-1,4,7-trioxanonyl (triethyleneglycol) segments in its main chain, represents a matrix for ion-conducting materials. Despite the fact that only triethyleneglycol segments are present, which are shorter than the minimum required for full solvation of Li<sup>+</sup> cations, ion-conductivities of σ = 3.3 times; 10<sup>—5</sup> S cm<sup>—1</sup> at 368 K are found for Li<sup>+</sup>/<b>1a</b> 0.25 (cations <i>per</i> polymer repeat unit). Hence, more than one <i>bis</i>-1,4,7-trioxanonyl segment (either intra- or interchain) has to be involved in Li<sup>+</sup> complexation. The σ value compares favorably with previous data for more complex polymer matrices.</p>","PeriodicalId":7162,"journal":{"name":"Acta Polymerica","volume":"48 8","pages":"314-318"},"PeriodicalIF":0.0,"publicationDate":"2003-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/actp.1997.010480804","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81050070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Novel fluorinated block copolymers for the construction of ultra-low energy surfaces and as dispersion stabilizers in solvents with low cohesion energy 新型氟化嵌段共聚物，用于超低能表面的构建和低凝聚能溶剂的分散稳定剂
Acta Polymerica Pub Date : 2003-03-11 DOI: 10.1002/actp.1997.010480705
M. Antonietti, S. Förster, M. A. Micha, S. Oestreich
{"title":"Novel fluorinated block copolymers for the construction of ultra-low energy surfaces and as dispersion stabilizers in solvents with low cohesion energy","authors":"M. Antonietti,&nbsp;S. Förster,&nbsp;M. A. Micha,&nbsp;S. Oestreich","doi":"10.1002/actp.1997.010480705","DOIUrl":"10.1002/actp.1997.010480705","url":null,"abstract":"<p>Block copolymers consisting of polystyrene and a block containing long fluorinated side chains are made by two very effective polymer analogous reactions from commercially available polystyrene-<i>b</i>-polybutadiene block copolymers. Since these polymers consist of two mutually immiscible blocks with hydrophobic and very hydrophobic character they form micelles in a wide range of media down to very hydrophobic solvents, e. g. toluene, tetrahydrofurane (THF), perfluorohexane, perfluoro(methylcyclohexane), hexafluorobenzene and 1,1,2-trichlorotrifluoroethane (Freon 113). First indications that our polymers are useful as effective steric stabilizers in such solvents are given by characterization of some polymer dispersions made in the solvents via precipitation polymerization.</p><p>In the solid state, mesophase formation typical for block copolymers is observed and characterized by quantitative small angle X-ray scattering (SAXS). The surface of such films is controlled by the fluorinated block and exhibits an ultra-low surface energy of the order of γ<sub>SV</sub> = 15 mN/m, below that of polytetrafluoroethylene (PTFE) or polydimethylsiloxanes (PDMS). Unlike PTFE, the blocky nature of the presented polymer enables thermoplastic processing and dissolution in standard solvents, which is of practical relevance. Gas-permeability measurements on membranes coated with these copolymers exhibit some interesting selectivities.</p>","PeriodicalId":7162,"journal":{"name":"Acta Polymerica","volume":"48 7","pages":"262-268"},"PeriodicalIF":0.0,"publicationDate":"2003-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/actp.1997.010480705","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88103885","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 16
Dielectric anomalies in the β-relaxation of glassy 1,4-polybutadiene 玻璃态1,4-聚丁二烯β-弛豫中的介电异常
Acta Polymerica Pub Date : 2003-03-11 DOI: 10.1002/actp.1997.010481104
C. Hansen, R. Richert
{"title":"Dielectric anomalies in the β-relaxation of glassy 1,4-polybutadiene","authors":"C. Hansen,&nbsp;R. Richert","doi":"10.1002/actp.1997.010481104","DOIUrl":"https://doi.org/10.1002/actp.1997.010481104","url":null,"abstract":"<p>We have measured the dielectric relaxation of the polymeric glass-former 1,4-polybutadiene in the glassy and supercooled liquid state. The loss spectra ϵ″ of the β-relaxation are measured between the lower detection limit at <i>T</i> = 125 K and <i>T</i> = 225 K &gt; <i>T</i><sub>β</sub>, with <i>T</i><sub>β</sub> ≈ 210 K being the α-β-merging temperature. The related storage data ϵ′(ω) indicates that the β-process is a signature of supressing the higher frequency polarization with increasing temperature, rather than giving rise to additional polarizability at frequencies below the average relaxation frequency of the β-process. This observation, as confirmed by data obtained for <i>o</i>-terphenyl and salol, contradicts the previous understandings of the mechanism underlying the Johari—Goldstein-type β-process in glasses. A tentative link between the β-process and high frequency vibrational modes is established.</p>","PeriodicalId":7162,"journal":{"name":"Acta Polymerica","volume":"48 11","pages":"484-489"},"PeriodicalIF":0.0,"publicationDate":"2003-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/actp.1997.010481104","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91827185","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 18
The study of chiral conjugated polymers 手性共轭聚合物的研究
Acta Polymerica Pub Date : 2003-03-11 DOI: 10.1002/actp.1997.010480402
L. Pu
{"title":"The study of chiral conjugated polymers","authors":"L. Pu","doi":"10.1002/actp.1997.010480402","DOIUrl":"10.1002/actp.1997.010480402","url":null,"abstract":"","PeriodicalId":7162,"journal":{"name":"Acta Polymerica","volume":"48 4","pages":"116-141"},"PeriodicalIF":0.0,"publicationDate":"2003-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/actp.1997.010480402","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72633173","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 112
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