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Graft copolymerization of methyl methacrylate onto poly(ethylene-co-propylene)

100%

Tomašek L. , Janović Z.

tom Vol. 50, nr 23

438-441

The graft copolymerization of methyl methacrylate (MMA) onto amorphous ethylene-propylene copolymer (EPC) with benzoyl peroxide (BPO) as the initiator in toluene solution was studied. The influence of reaction parameters, such as MMA, EPC, BPO concentrations and temperature, on the extent of grafting were described and discussed. Solvent extraction, infrared spectra (IR), 1 H NMR, and turbidimetric tiration verified the existence of a grafted copolymer. The grafted copolymers were also characterized by their rheology behavior in xylene solutions.

Flocculation properties of Dextran-graft-Polyacrylamide of various internal structure

72%

Kutsevol N. , Bezuglyi M. , Vysotska V.

tom Vol. 16, nr 1-2

127-133

Two series of Dextran-graft-Polyacrylamide copolymers (D-g-PAA) with polysaccharide backbone having different molecular weights (Mw= 20 000 and Mw= 70 000) and willi 5, 10, 15 or 20 PAA-grafts per one Dextran macromolecule were tested as flocculation aids in the model kaolin suspensions. These copolymers have shown high flocculation efficiency significantly dependent upon their internal structure. The flocculation ability or D-g-P AA samples with the same number or P AA-grafts inversely relates to the spacing or the grafts (ie the length or back-bone between the grafts).

Badano właściwości flokulacyjne kopolimerów dekstran-graft-poliakryloamidowych (DG-PAA) ze szkieletem dekstranowym o dwóch różnych masach molekularnych (Mw = 20 000 i Mw = 70 000) oraz z 5, 10, 15 lub 20 molekułami PAA dołączonymi (zaszczepionymi) do tego makromolekularnego szkieletu. Do pomiarów wykorzystywano zawiesinę kaolinu w wodzie. Kopolimery te miały dużą skuteczność flokulacyjną zależną od ich struktury molekularnej. Zdolność flokulacyjna próbek D-g-PAA, z taką samą liczbą zaszczepionych molekuł P AA, jest odwrotnie proporcjonalna do odległości między molekułami zaszczepionymi do szkieletu molekuły dekstranu.

Synteza amfifilowych kopolimerów szczepionych metodą kontrolowanej (ko)polimeryzacji rodnikowej hydrofilowego makromonomeru poli(tlenku etylenu)

72%

Neugebauer D.

tom [Z] 62, 1-2

49-66

A combination of hydrophilic and hydrophobic characters in one macromolecule of a polymer provides amphiphilic behavior [1, 2]. Such unique properties, which have found significant interest, are exhibited by graft copolymers containing poly(ethylene oxide) (PEO) as side chains attached to the backbone (Scheme 1) [20]. They have greatly expanded a class of materials important for science and biomedicine. This review article describes the PEO graft copolymers prepared by a variety of synthetic procedures used for the atom transfer radical (co)polymerization (ATRP) (Scheme 2) [15-17], i.e. directly by the grafting through, which is also named as the macromonomer method or by the grafting from technique, which requires the use of a multifunctional macroinitiator. Densely homografted copolymers also called molecular brushes [21-25] were obtained by homopolymerization of PEO macromonomer (Scheme 3). The density of PEO grafts was decreased in the copolymerization of PEO macromonomer with a low molecular weight comonomer resulting in loosely grafted copolymers contai-ning uniform PEO side chains (Scheme 4) [46-48]. Consequently, the copolymerization of two macromonomers yielded heterografted brushes (Scheme 5) [21, 23, 26, 45, 53-57]. In this case, the composition of copolymers was designed by the selection of proper comonomers with comparable (rM1 = rM2/rM1 ~ rM2) or different (rM1 > rM2, rM1 < rM2) reactivity ratios, which can form alternating/ random copolymers or spontaneous gradient of PEO chains along backbone, respectively. Using monofunctional macroinitiators with comb or linear composition for polymerization of PEO macromonomer resulted in comb-comb [31] or semi-comb diblock copolymers [21, 23, 27-30]. The reverse structures were also obtained, when the PEO graft copolymers were applied as the monofunctional macroinitiators [31, 32]. The use of polymeric multifunctional macroinitiators (graft or linear) in the polymerization of monomer or macromonomer led to the heterografted copolymers (Scheme 4) [32, 50, 51] or more complexed double grafted copolymers (Scheme 3) [25]. The applications of the PEO graft copolymers in numerous fields are also presented to show their versatile potential [25, 26, 46, 53, 55, 56, 68-76].