Heterogeneous graft copolymerization

Other methods derived from surface modification, including heterogeneous graft copolymerization or in situ radical polymerization and deposition of polyelectrolyte... 

Thermoplasticization of Cellulose by Heterogeneous Graft Copolymerization. As the first trial to obtain a thermoplastic cel-... 

Table I. Heterogeneous Graft Copolymerization of MMA onto Cellulose Using Ammonium Persulfate as a Catalyst...

Thermoplasticization of Wood by Heterogeneous Graft Copolymerization (Redox Initiation). A redox grafting method using ferrous sulfate-hydrogene peroxide as the initiator was conducted to copolymerize MMA to wood meal. The results of grafting are shown in Table III. 

Heterogeneous Graft Copolymerization Polymers with Functional End Groups... 

Heterogeneous Graft Copolymerization. Poly(vinyl chloride) films and powders (183) and chlorinated polypropylene (184) fibers were grafted with styrene, isobutylene, and styrene, respectively. Grafting from techniques were used. By using the same technique a silica surface first treated with chlorosilyl functional groups was grafted with polyIsobutylene and butyl rubber (185. 186) ... 

Ulbricht and Schwarz (1997) applied for the first time the pore-filling heterogeneous graft copolymerization concept to asymmetric membranes. Asymmetric PAN membranes (average pore sizes of 7 or 12 nm) were used as matrix of polymeric PV separation phases, which were prepared in situ by heterogeneous photo-initiated graft copolymerization. By this means, defect-free and stable layers were synthesized from moderately hydrophilic methacrylates such as poly(ethylene glycol methacrylates). 

These graft copolymerizations became heterogeneous almost immediately, but in the case of MAN this did not lead to difficulties in measuring the rate of polymerization via dilatometry 36). 

Various free radicals are generated in cellulose and cellulose derivatives by ultraviolet light, which may be capable of initiating graft copolymerization reactions with vinyl monomers. The graftability of these photoinduced free radicals in homogeneous and heterogeneous media was studied. 

We have conducted a graft copolymerization of MM A onto FVA making use of potassium persulfate (KPS) in three different ways with water-swollen PVA film containing KPS and with PVA solutions containing KPS in H20 and DMSO. The polymerization of MMA proceeds heterogeneously in the two former cases and homogeneously in the latter case. 

Kinetics of Chemically Initiated Graft Copolymerization and its Features Arising from the Heterogeneous Nature of the Process... 

The foregoing aspects of graft copolymerization with cellulose as a heterogeneous process are crucial to the use of this method in technology, e.g. for the synthesis of graft-modified hydrated cellulose fibres7,685. 

Keywords Heterogenization, Immobilization, Support, Grafting, Copolymerization, Adsorption, Entrapment, Site isolation... 

Gabara and Porejko proposed that the heterogeneous radical catalyzed graft copolymerization of MAH onto LDPE film suspended in acetic anhydride at 80-110 C proceeded through the coupling of PE macroradicals with poly(maleic anhydride) (poly-MAH) radicals. 

Gaylord et al. " reported that the in situ polymerization of MAH in the presence of molten PE, using conditions which initiated the heterogeneous or bulk polymerization of MAH, i.e. catalysts used at high concentrations and at temperatures where the half-life is short, e.g. t-butyl perbenzoate at 150 C, resulted in the grafting of poly-MAH on the PE. Graft copolymerization of MAH onto HDPE has been carried out in an extruder at 190-250 u in the presence of BPO and at 260 C in the presence of t-butyl hydroperoxide. ... 

Using this approach, hydrophilic (neutral or ionic) comonomers, such as end-captured short polyethylene oxide (PEO) chains (macromonomer), l-vinyl-2-pyrrolidone (VP), acrylic acid (AA) and N,N-dimethylacrylamide (DMA), can be grafted and inserted on the thermally sensitive chain backbone by free radical copolymerization in aqueous solutions at different reaction temperatures higher or lower than its lower critical solution temperature (LCST). When the reaction temperature is higher than the LOST, the chain backbone becomes hydrophobic and collapses into a globular form during the polymerization, which acts as a template so that most of the hydrophilic comonomers are attached on its surface to form a core-shell structure. The dissolution of such a core-shell nanostructure leads to a protein-like heterogeneous distribution of hydrophilic comonomers on the chain backbone. 

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