摘要:

AbstractThe differential scanning calorimetry studies have shown that high‐molecular linear poly(diethylsiloxane) can exist in two high‐temperature polymorphs which melt at 280 and 290 K. The heats of fusion of the high‐temperature polymorphs are 17 and 21 J/g, respectively. Each of the high‐temperature forms arises from the corresponding low‐temperature form the corresponding low‐temperature form when the polymer is heated: the first at 214 K (transition heat is 28 J/g) and the second at 206 K (transition heat is 26 J/g). The mesophase formed from the molten high‐temperature crystalline phases melts in a rather broad temperature range of 290 to 327 K, and the heat of this transition is 2.7 J/g. Crystallization of poly(diethylsiloxane) from the mesomorphic and the supercooled amorphous state is different. In the first case, apparently, the whole mesophase is converted to the crystalline phase and the samples have a crystallinity near 1. In the second case the crystallinity is only ca. 0.3. The temperature range in which the mesophase melts depends on the molecular weight of the polymer, presence of crosslinks and the conditions under which it has been formed, e.g.

ISSN:0360-6376    

DOI:10.1002/pol.1984.170221201

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe copolymerizations of acrylamide (AM) withN‐(1,1‐dimethyl‐3‐oxybutyl)acrylamide (DAAM) and withN,N‐dimethylacrylamide (DMAM) have been studied. The values ofr1,r2have been determined to be 0.75 for the AM‐DAAM pair and 0.86 for the AM‐DMAM pair. The molecular weights of the copolymers were found to decrease with an increase in the feed composition of DAAM or DMAM. The microstructure was predicted for a wide range of feed compositions through a knowledge of reactivity ratios. These model structures are utilized for assessment of structure/dilute solution relationships reported in a subsequent paper i

ISSN:0360-6376    

DOI:10.1002/pol.1984.170221202

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractDilute solution properties of copolymers of acrylamide (AM) withN‐(1,1‐dimethyl‐3‐oxybutyl)acrylamide (DAAM) and withN,N‐dimethylacrylamide (DMAM) have been studied as a function of composition, temperature, time, and added electrolytes sodium chloride and calcium chloride. Unlike the AM‐DMAM copolymers, the AM‐DAAM copolymers show solution viscosity increases in the presence of added NaCl and CaCl2and decreases with increasing temperature which are related to copolymer composition. The unusual viscosity behavior of the DAAM‐AM copolymers is suspected to be due to chain extension resulting from intramolecular hydrogen bonding and other cooperative associations along the macromol

ISSN:0360-6376    

DOI:10.1002/pol.1984.170221203

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractTwo calculation methods for estimating reactivity ratios, one method based on the differential Alfrey‐Mayo equation and one based on the integrated form of this model, are compared with respect to precision and bias. Both methods are characterized by the use of information about the monomer feed composition only and are assumed to be valid up to high conversion. As only monomer feed composition has to be analyzed, several sampling designs are feasible. Two extreme designs can be distinguished. One consists of repetitive sampling of the initial and final monomer feed mixture, whereas the other consists of sequential sampling during the course of the reaction. The influence of both designs of the calculatedr‐values is investigated by means of simulation. In the present paper the second calculation method, based on the integrated form, is solved by a nonlinear least squares method considering errors in both variables. This method required additional information about the errorstructure of the data. As this information is mostly of approximate nature, the influence of misspecification of this error structure on the calculatedr‐values is also exa

ISSN:0360-6376    

DOI:10.1002/pol.1984.170221204

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractSome properties of the membranes obtained by preirradiation grafting of acrylic acid onto poly(tetrafluoroethylene‐perfluorovinyl ether) copolymer (PFA) films have been investigated. The dimensional change caused by grafting and swelling behavior, water uptake, electrical conductivity, and mechanical properties of the grafted films were found to increase as the grafting proceeds. The influence of the preparation conditions (such as preirradiation dose, monomer concentration, grafting temperature, and film thickness) on those properties was studied. These properties were found to be dependent mainly on the degree of grafting regardless of grafting conditions, except at higher monomer concentration (>40 wt %). The electric conductivity and mechanical properties for the membranes obtained at higher AAc concentrations were lower than those obtained at lower ones. Analysis by x‐ray microscopy of the grafted films revealed that the grafting begins at the part close to the film surface and proceeds into the central part with progressive diffusion of monomer to give finally homogeneous distribution of the electrolytes in the whole bulk of the polymer. The membranes show good electrochemical and mechanical properties which make them acceptable for practical use as cation‐exchange memb

ISSN:0360-6376    

DOI:10.1002/pol.1984.170221205

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractTo regulate the pH value of an aqueous solution containing polyelectrolyte by photoirradiation, an azoaromatic poly(carboxylic acid), acrylic acid(AA)‐p‐phenylazoacrylanilide (PAAn) copolymer was synthesized and the photoresponse of the polymer solution was investigated. AA‐PAAn copolymer, which takes a compact form in the ordinary state owing to the presence of azoaromatic side chains, is transformed into an extended form when azoaromatic moieties are isomerized by photoirradiation. Thus, the pH value of the solution can be reversible regulated by irradiation and interruption of light through a change in polymer conformation. The range of the pH change was about 0.15. These phenomena can be explained on the basis of polarity change induced by the photoisomerization of azoaromatic side c

ISSN:0360-6376    

DOI:10.1002/pol.1984.170221206

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractInterpolymer complex formation has been studied between methacrylic acid‐methacrylamide copolymer and acrylic acid–acrylamide copolymer. The respective co‐monomer units of the two copolymers enter into complex formation through H‐bonding and ion dipole interactions. The unreacted units in the copolymer complex also interact with homopolymers such as PEO and PVP to form ternary complex. Formation of complexes and replacement reactions could be shown through several experimental techniques, e.g., viscometry, conductometry, and potent

ISSN:0360-6376    

DOI:10.1002/pol.1984.170221207

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractTen polyfumaramides based on fumaric acid and aromatic diamines and six polystilbenediamides based on 4,4′‐stilbenedicarboxylic acid and aromatic diamines were synthesized and characterized by solubility, viscosity, density, infrared and UV‐visible spectroscopy, and thermal analyses. Variation in properties with structure is discussed

ISSN:0360-6376    

DOI:10.1002/pol.1984.170221208

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe objective of this project was to utilize the alternating copolymerizability of electrondonor monomers with electron‐acceptor monomers to selectively introduce nucleic acid bases into copolymers in a controlled sequence distribution. To this end, maleimide monomers containing the adenine, thymine, cytosine, and 6‐chloropurine moieties were converted to their hompolymers. The homopolymer of 1‐(vinyloxyethoxy)thymine was also prepared. Alternating copolymers of the adenine maleimide monomer and the corresponding 6‐chloropurine maleimide monomer with 1‐(vinyloxyethoxy)thymine were prepared. The latter copolymer was converted to the alternating adenine–thymine copolymer by reaction with ammonia. Characterization of the polymers and copolymers via spectroscopic methods and physical measurements confirm their proposed structures. Monomer syntheses and characterization, as well as studies designed to establish the extent and nature of adenine–thymine interactions in the copolymers, are reported in accomp

ISSN:0360-6376    

DOI:10.1002/pol.1984.170221209

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractA study was conducted of the complementary base pair interactions between various pairs of electron‐donor monomers, electron‐acceptor monomers, homopolymers and alternating copolymers selected from the following group: (1) 9‐(2‐vinyloxyethyl)adenine; (2) 1‐(2‐vinyloxyethyl)thymine; (3) 1‐(2‐vinyloxyethyl)cytosine; (4) 9‐(2‐maleimidoethyl)adenine; (5) 6‐chloro‐9‐(2‐maleimidoethyl)purine; (6) 1‐(2‐maleimidoethyl)thymine; (7) 1‐(2‐maleimidoethyl)cytosine; (8) homopolymer of (4); (9) homopolymer of (6); (10) alternating copolymer of (2) and maleic anhydride; (11) alternating copolymer of (2) and (5); and (12) alternating copolymer of (2) and (4). By1H‐NMR, in CDCL3, the base pair interactions between (1) and (2) were shown to be hydrogen bonding, the extent of which was shown by a calculated binding constant,K= 61.81 L/mol. The nature of this interaction was conformed by IR. Neither monomer pairs (1)/(2) nor (4)/(6) exhibited hydrogen bonding in DMSO‐d6. However, hydrogen bonding interaction was observed for DMSO‐d6solutions of homopolymers (8) and (9) and for alternating copolymer (12). On the basis of an upfield chemical shift of the 2‐ and 8‐aromatic protons of ademine of (1) in D2O, a partial overlap stacking interaction is proposed. No charge‐transfer interactions could be obse

ISSN:0360-6376    

DOI:10.1002/pol.1984.170221210

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY