摘要:

Free‐radical polymerizations of triallyl cyanurate (TAC) and its isomer triallyl isocyanurate (TAIC) were conducted in bulk at 60°C. In the polymerization of TAIC, gelation occurred at 12.4% conversion, quite early compared to 21.3% for TAC. The primary chain length of TAIC polymer, as estimated from GPC‐LALLS measurements, was quite high. Although TAIC undergoes more cyclic polymerization than TAC, its greater primary chain length causes it to gel at a lower conversion. On the other hand, the difference in the rate of polymerization between TAC and TAIC was quite small compared to that of the primary chain length. These results are discussed mechanistically in connection with the degradative chain transfer characteristics of the polymerization of allyl compounds.

ISSN:0022-233X    

DOI:10.1080/00222338908052048

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Thiol polymer, which is known as a reactive and functional polymer, is synthesized and evaluated quantitatively by the modified Ellman method. The synthesis was accomplished by 1) hydrolysis of an isothiouronium salt that is the adduct of 4‐chloromethylstyrene (CMS) homopolymer or CMS‐styrene (St) copolymer with thiourea; 2) hydrolysis of a precursor copolymer made from 4‐vinylbenzylN‐ethyldithio‐carbamate (VBEC) and St orN‐vinyl‐2‐pyrrolidone (NVP); 3) solvolysis of an iminium salt polymer obtained from the reaction of CMS‐NVP copolymer withN,N‐dimethylthioformamide (TDMF). When a higher thiol content is desired, more severe hydrolysis conditions are required which however, also increase the loss of thiol. Hence, it is clear that the best synthesis of thiol polymers is Method 3. A quantitative yield of functional thiol polymer is obtained by this method, and the product is soluble in DMSO, DMF, and CHCI3.

ISSN:0022-233X    

DOI:10.1080/00222338908052049

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The aim of this research was to develop a quantitative treatment of the consequences of relatively slow initiation onMnandN(the number of molecules formed,Wp/Mn, whereWp=weight of polymer formed) in living carbocationic polymerizations, particularly for the case of the incremental monomer addition (IMA) technique. This has been achieved by analysis of the effect of initiator efficiency (Ieff(%) = 100N/[I0], where [I0] = initiator input) onMnversusWp, andNversusWpplots. Three types of systems have been discerned: 1)Ieffequal to 100%; 2)Ieffconstant but less than 100%; and 3)Ieffless than 100% but increasing with increasing number of monomer incrementsjby the IMA technique. Thus conditions can be found under which slowly initiating systems yield close to “ideal” product, i.e., one withMn= [M0]/[I0] and narrow molecular weight distribution (Mw/Mn≈ 1.1). The corresponding equations and plots can be used to diagnose the mechanism. Subsequently, this quantitative analysis was used to describe a novel living system,trans‐2,5‐diacetoxy‐2,5‐dimethyl‐3‐hexene (DiOAcDMH6)/BCI3/isobutylene/CH3CI. This system produces lineart‐chlorine‐telechelic polyisobutylenes under homogeneous conditions. Surprisingly, cationation seems to be rate determining. This conclusion is illustrated by chemical equations.

ISSN:0022-233X    

DOI:10.1080/00222338908052050

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Polythiocarbonates were synthesized from five different diphenols and thiophosgene under phase‐transfer catalysis conditions, with quaternary ammonium and phosphonium salts as catalysts and dichloromethane as solvent. The polythiocarbonates were characterized by IR,1H NMR, and elemental analysis. Viscosity‐average molecular weights were estimated from inherent viscosity measurements. The influence of the catalysts and the structure of the diphenols both exert an important effect on the molecular weight. The hydrolysis of the polythiocarbonates was studied by observing the variation ofninh.The polymer undergoes a hydrolytic process in the organic phase, and this is influenced by the catalysts.

ISSN:0022-233X    

DOI:10.1080/00222338908052051

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Thermal and chemical dehydrochlorination of head‐to‐tail 1,4‐trans‐poly(‐1‐chlorobutadiene) prepared by inclusion polymerization in deoxycholic acid canals resulted in formation of atrans‐polyacetylene‐type polymer. The dehydrochiorinated polymer was characterized by UV/VIS, IR, Raman, and ESR spectroscopy. The number of conjugated double bonds in the polymer was about 10–20. Doping with iodine was also studied.

ISSN:0022-233X    

DOI:10.1080/00222338908052052

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A new photoinitiating system (eosin‐periodate) was employed for the polymerization of acrylonitrile in which dye acts as both sensitizer and reducing agent. The rate of polymerization was found to be proportional to monomer concentration, dye concentration, and light intensity, but independent of periodate concentration. A mechanism involving initiation by OH radicals and termination by periodate is proposed to explain the results.

ISSN:0022-233X    

DOI:10.1080/00222338908052053

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The photopolymerization ofN,N′‐methylenebisacrylamide has been studied withN‐bromosuccinimide as photoinitiator in the presence and absence of isopropyl alcohol (ISP). The rate of polymerization in the presence of ISP was found to be very high, and this is explained on the basis of the relative reactivities of the initiating radicals. A probable mechanism consistent with the observed results is proposed and discussed.

ISSN:0022-233X    

DOI:10.1080/00222338908052054

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue.

ISSN:0022-233X    

DOI:10.1080/00222338908052047

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor