摘要:

AbstractLow molecular weight hydroxy terminated polyethylene (HTPE) containing on average an ethyl group every 16–18 carbon atoms, and a hydroxy functionality of 2.6, has been used to prepare polyurethane copolymers and block copolymers which have good solvent resistance. The polymers show somewhat complicated thermal behavior, including Tg's at around −40°C due to the HTPE and diffuse endotherms between 40 and 60°C. The simple copolymers, containing only the polyol and a diisocyanate, show infrared evidence for two phases in the case where CHDI (trans‐1,4‐diisocyanatocyclohexane) was used, and poorer phase separation where other diisocyanates were used. Dynamic mechanical spectra show very broad tan delta transitions for the copolymers in the range of ‐9 to −23°C. All the polymers exhibit another transition in the G” curve above room temperature. SAXS reveals a microphase separated structure at 30°C for the simple copolymers which increases in spacing, then disappears in the 60–70°C range. With cooling, the microphase separated structure reappears readily for the CHDI‐based copolymer, while its reappearance shows a hysteresis resulting from rate effects fo

ISSN:1022-1360    

DOI:10.1002/masy.19950910103

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractTriblock and three arm, poly(ether amide) star block copolymers have been synthesized and characterized. Di‐ and tri‐functional amine terminated polyethers were reacted with caprolactam at elevated temperatures to produce the block copolymers. The polyether amines were incorporated at levels ranging from 5%‐40%. Differential scanning calorimetry(DSC) evaluation reveals no reduction in the crystalline melting point of the polycaprolactam end blocks up to 40% polyether incorporation. Dynamic mechanical spectroscopy and FTIR were used to confirm the incorporation of the polyether. A comparison is made between triblock and star block copolymers, and between poly(propylene glycol) and poly(ethylene glycol) polyether midblocks. These block copolymers have improved impact performance as well as a flexural modulus that first increases and then decreases as the amount of polyether is increased in the block copo

ISSN:1022-1360    

DOI:10.1002/masy.19950910104

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractMacrocyclic poly(styrene‐b‐butadiene) (SB) block copolymers were prepared by coupling a living poly(styrene‐b‐butadiene‐b‐styrene) (SBS) block copolymer using a living coupling agent, 1,3‐bis(1‐phenylethylenyl)benzene (DDPE), or a difunctional electrophile, dimethyldichlorosilane. The living poly(styrene‐b‐butadiene‐b‐styrene) block copolymer was generated from an addition product of sec‐butyllithium and DDPE. A living heteroarmed star block copolymer has been prepared by coupling two moles of monolithium polystyrene with one mole of DDPE followed by reinitiation and polymerization of the butadiene monomer. The dilithium 4‐armed star block copolymer was then coupled using dimethyldichlorosilane to form a cyclic polybutadiene with two at

ISSN:1022-1360    

DOI:10.1002/masy.19950910105

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractIonic living polymerization methods are well suited for the synthesis of macromolecules of known structure, molecular weight and composition, and exhibiting low fluctuations in composition and in molecular weight. They were the first to allow the synthesis of well characterized block and graft copolymers. The present paper discusses a number of recent developments concerning these syntheses based on anionic or cationic living polymerization.

ISSN:1022-1360    

DOI:10.1002/masy.19950910106

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractAllylic sulfides such as α‐(tert‐butylthiomethyl)styrene and α‐(2‐hydroxyethylthiomethyl)styrene worked as effective chain transfer agents in the radical polymerization of methacrylic acid, to afford a one‐step synthesis of water‐soluble macromonomers with the 2‐phenylallyl end groups. The macromonomers were found to be effective, particularly in the partially neutralized form, in emulsion copolymerization with styrene in water, to give stable emulsions with nearly monodisperse, submicron‐sized particles. The microspheres thus obtained are considered to have carboxyl groups densely bound on the surface as a result of an organized

ISSN:1022-1360    

DOI:10.1002/masy.19950910107

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractWe have covalently attached fullerenes to amine containing flexible hydrocarbon polymers such as amino‐ethylene propylene terpolymer (EPDM‐amine) to obtain novel fullerene functionalized polymers. These materials are soluble in solvents such as heptane or tetrahydrofuran (THF), in which the fullerene is essentially insoluble. The reaction of the fullerene and polymer was followed by infra‐red spectroscopy and viscosity measurements. Thermogravimetric analysis (TGA) scans of EPDM‐amine and Fullerene reacted EPDM‐amine show that the fullerene grafted polymer is thermoxidatively more stable than the original polymer. Furthermore, the fullerene grafted polymer could be reacted further with primary‐tertiary diamines to obtain novel polymers in which the fullerene acts as a bridging group for attaching polar functional groups to nonpolar hydrocarb

ISSN:1022-1360    

DOI:10.1002/masy.19950910108

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractPolymers substituted with thio groups are useful for the photochemical synthesis of graft copolymers. Such copolymers have been prepared by the initial conversion of backbone polymers containing chlorinated substituents into polymers containing diethyldithiocarbamate (TC), isopropyl xanthate (IX) or mercaptobenzothiazole (BT) functionality. The photochemical reaction of monomers with these products produced graft copolymers. A variety of halogenated polymers were investigated as starting materials for these syntheses, including poly(vinyl chloride), chlorinated polyvinyl chloride), chlorinated polyethylene, chlorobutyl rubber and neoprene. Characteristics of the grafting reactions, including “pseudo‐living” behavior and tandem grafting aspects, were investigated. Glass transitions of the grafted polymers were found to vary uniformly with composition for most of the grafted pro

ISSN:1022-1360    

DOI:10.1002/masy.19950910109

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractWe report the use of a triisobutylaluminium/tert‐butyllithium initiator in the preparation of living methacrylate homopoloymers and a wide range of methacrylic block copolymers. The system, which we have referred to as Screened Anionic Polymerisation (SAP), is very tolerant of impurities and is effective in hydrocarbon solution with reaction rates such that high molecular weight polymers can be produced at temperatures readily accessible for large scale industrial use. A mechanism for the reaction is proposed based on preliminary spectroscopic evidenc

ISSN:1022-1360    

DOI:10.1002/masy.19950910110

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractPolystyrene and polybutadiene were block copolymerized with high density polyethylene using a transformation reaction from an anionic to a Ziegler‐Natta type polymerization. Various reaction parameters were investigated and optimized. Efficiencies of conversion of the anionic block to diblock were as high as 33% (100% normalized) consistent with the known 3/1 Li‐R/Ti relationship in the active catalyst species. The activity of the polymeric Li‐R/Ti catalyst with regards to ethylene polymerization was as high as 40 000 grams of polymer/mole Ti. Characterization of the resultant polymers is consistent with diblock copolymer structures but transmission electron microscopy shows distinct differences between the morphological behavior of these materials and the now well established morphological behavior of amorphous‐amorphous diblock copolymers. These differences are readily explained by consideration of the interactions between the competing thermodynamic processes of microphase separation and crystall

ISSN:1022-1360    

DOI:10.1002/masy.19950910111

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractSynthesis, characterization and properties of microphase separated mixed (ionic and electronic) conducting or MIEC block copolymers are reported. Poly{[ω‐methoxyocta(oxyethylene) methacrylate]‐block‐(4‐vinylpyridine)}, abbreviated as P[MG8–4VP], and poly{(3‐methylthiophene)‐block‐[(ω‐methoxyocta(oxyethylene) methacrylate]}, abbreviated as P[3MT‐MG8], have been synthesized. Differential scanning calorimetry (DSC) studies indicate that the polymers form a microphase separated structure. P[3MT‐MG8] can be doped with I2and LiClO4to generate electronic and ionic conducting microdomains, respectively. For the P[3MT‐MG8] series, bulk electronic conductivity as high as 1×10−3S cm−1and bulk ionic conductivity as high as 6.6×10−7S cm−1is observed at 30°C. This work represents a new concept in the area of electroactive polymers and should impact the

ISSN:1022-1360    

DOI:10.1002/masy.19950910112

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY