摘要:

AbstractThe base‐induced reaction ofp‐alkyl substituted phenols with formaldehyde yields oligomers which, in some cases, are cyclic [1,1,1,1]‐metacyclophames known as calixarenes. The present work attempts to provide insight into the mechanism of calixarene formation by studying various facets of the reaction, including the effect on the product distribution (i.e. cyclic tetramer, cyclic pentamer, cyclic hexamer, cyclic heptamer, and cyclic octamer) of (a) reactant ratios, temperature, solvent, and cation, (b) starting oligomer (i.e. monohydroxymethyl or dihydroxymethyl monomer phenol, dimer phenol, trimer phenol, or tetramer phenol), and (c)p‐alkyl group of the starting phenol. Product analyses were carried out by isolation and TLC methods in some cases and by HPLC methods in others. On the basis of the data that have been obtained it is postulated that (a) the calix[8]arenes are the product of kinetic control and are formed via a hemicalix[8]arene arising from intermolecular association between a pair of hydroxymethylated linear tetramers, (b) the calix[6]arenes are the product, in part, of template control and may be formed via a hemicalix[6]arene anion arising from intermolecular association between a pair of hemicalixarene anions from hydroxymethylated linear trimers, and (c) the calix[4]arenes are the product of thermodynamic control and can be formed via ring contraction of the calix[8]arenes and the calix[6

ISSN:0025-116X    

DOI:10.1002/macp.1987.021880501

出版商:Hüthig&Wepf Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractBase functionalization of saturated ethylene‐propylene rubbers (EPR) was performed either by means of the radical grafting of 2‐(dimethylamino)ethyl methacrylate onto EPR or by the reaction of a succinic anhydride grafted EPR withN,N‐dimethylethylenediamine. Differences in the structure of the grafted molecules and in their thermal stability are also reported. An investigation is made on the reactivity of EPR having tertiary amino pendant groups toward acid functionalized EPR leading to gel

ISSN:0025-116X    

DOI:10.1002/macp.1987.021880502

出版商:Hüthig&Wepf Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractThermal and mechanical properties of various functionalized ethylene‐propylene rubbers (EPR) were evaluated. The samples studied varied both in the type of functional groups and in the grafting degree. Grafted molecules included succinic anhydride, 2‐(dimethylamino)ethylsuccinimide and 2‐(dimethylamino)ethyl methacrylate. The insertion of these groups was found to influence deeply the elastic response of rubbers, leading to the formation of network whose properties were dependent upon the density of polar crosslinks introduced. On the other hand, the thermal properties were less influenced, i.e. the glass transition temperatureTgincreased only slightly with increasing content of functional g

ISSN:0025-116X    

DOI:10.1002/macp.1987.021880503

出版商:Hüthig&Wepf Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractAnalytical and kinetical aspects of the photooxidation in the solid state of two polyether‐block‐polyamides1cand1dare described. The block copolymers studied contain different polyether sequences at different percentages. In copolymer1das well as in copolymers1aand1b, previously studied, the photooxidation concerns mainly the ether groups. High maximal concentrations of hydroperoxy groups, CH(OOH)OCH2, are observed (0,12 mol.kg−1). These hydroperoxides are converted into hemi‐acetals, CH(OH)OCH2, saturated esters and formate through photolysis or thermolysis above 60°C. The hemi‐acetal groups are thermo‐unstable too and decompose into alcohol and aldehyde groups. The photooxidation of copolymer1cpresents different features. At long wavelengths, low stationary concentration of hydroperoxy groups are observed (0,02 mol.kg−1). Hydroperoxidation of the polyamide 6 sequences is revealed by the formation of imide groups. Hydroperoxidation of the poly(propylene glycol) sequences are surprisingly located on the ether methylene groups. Excitation of polyamide 6 sequences at short wavelength (254 nm) induces the formation

ISSN:0025-116X    

DOI:10.1002/macp.1987.021880504

出版商:Hüthig&Wepf Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractAnalytical and kinetic aspects of the photooxidation and photolysis in the solid state of various ethylene‐vinyl acetate (EVA) copolymers (0

ISSN:0025-116X    

DOI:10.1002/macp.1987.021880505

出版商:Hüthig&Wepf Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractPartially α‐brominated polystyrene was first prepared from commercial polystyrene andN‐bromosuccinimide by the Wohl‐Ziegler reaction. It was treated with silver perchlorate to initiate cationic graft copolymerization with tetrahydrofuran leading to polystyrene‐graft‐polytetrahydrofuran. The influence of reaction time, reaction temperature, initial concentrations of silver perchlorate and partially α‐brominated polystyrene, etc., on the graft polymerization was studied. It partially α‐brominated polystyrene with a bromination degree of 5–15% was used, a leather‐like graft copolymer was obtained with a high grafting effici

ISSN:0025-116X    

DOI:10.1002/macp.1987.021880506

出版商:Hüthig&Wepf Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractPolymethacrylates and polyacrylates containing 4‐[5‐(4‐methoxyphenyl)‐1,3‐dioxan‐2‐yl]‐phenol moieties as mesogenic units and an aliphatic spacer containing eleven methylene units were synthesized. Their phase behavior was studied by differential scanning calorimetry and optical polarizing microscopy, and compared with the phase behavior of the corresponding polymethacrylates and polyacrylates containing 4′‐methoxy‐4‐biphenylol as mesogens. All polymers present smectic mesomorphism. The substituted 2,5‐diphenyl‐1,3‐dioxane mesogen resembles a terphenyl mesogen in which the internal phenyl ring is hydrogenated. Even so, when compared with polymers containing biphenyl moieties, the glass transition temperatures of the polymers containing 1,3‐dioxane moieties are lower, although their isotropizatio

ISSN:0025-116X    

DOI:10.1002/macp.1987.021880507

出版商:Hüthig&Wepf Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractThe first examples of aromatic‐aliphatic polyformals were synthesized from 4,4′‐isopropylidenediphenol (2) and 1,4‐bis(chloromethoxy)butane (1) by a two‐phase (aqueous NaOH/toluene), phase transfer catalyzed (PTC) polyetherification. The influence of the reaction conditions upon the polymerization was studied by varying the phase transfer catalyst concentration, NaOH concentration and nucleophile to electrophile ratio. Changes in these parameters and their effects upon the microstructure of these polymers were also examined by1H NMR (200 MHz) spectroscopy. The reactivity of1has permitted, according to our knowledge, the first examples of interfacial polyetherification. Further, this reactivity has also permitted the homopolymerization of1through its hydrolysis byproducts under PTC c

ISSN:0025-116X    

DOI:10.1002/macp.1987.021880508

出版商:Hüthig&Wepf Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractThe alkaline hydrolysis of some methyl methacrylate‐ethyl acrylate copolymers in alkaline dimethyl sulfoxide leads to products containing carboxyl groups and having molecular weights which are significantly lower than those of the original copolymers. Size exclusion chromatographic (SEC) investigations provide detailed information on the degree of degradation and the influence of hydrolysis rate on degradation. Comparing the reactivities of structural units it is assumed that the degradation reaction occurs at the ethyl acrylate unit

ISSN:0025-116X    

DOI:10.1002/macp.1987.021880509

出版商:Hüthig&Wepf Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractTelomers were prepared from acrylic or methacrylic acid and CCl3Br, C12H25SH, C18H37SH or C8F17C2H4SH by initiation with 2,2'‐azoisobutyronitrile. The transfer constant of CCl3Br and the thiols, which are about 0,03 and 0,5, respectively, were determined. These telomers were used as supports of photopolymerizable functions, which were introduced by grafting of 2,3‐epoxypropyl methacrylate, catalysed with dodecyldimethylamine. The reactions were followed by1H NMR, elemental analyses, tonometrie, and especially by GPC and titration of the acid functions. The grafting telomers, holding many acrylic functions which react upon UV and electron irradiation, give photoreticulated varnish coatings with very interesting propert

ISSN:0025-116X    

DOI:10.1002/macp.1987.021880510

出版商:Hüthig&Wepf Verlag    

年代:1987

数据来源: WILEY