Phenolic copolymers, structures

Peroxidase-catalyzed grafting of polyphenols on lignin was performed by HRP-catalyzed polymerization of />cresol with lignin in the aqueous 1,4-dioxane or reverse micellar system.57 Phenol moiety in lignin was reacted with />cresol to produce a lignin—phenol copolymer with a branched and/or cross-linked structure. The product was highly insoluble in common organic solvents. 

After reviewing the structure and chemistry of the main constituents of polyphenols and the possible mechanism of their polymerization, it was believed that some useful phenolic copolymer resins with better quality as adhesives could be synthesized by carefully controlling and manipulating the process of raw materials and synthesis of resins. 

Polymer II (a sample with [n] 0.35 dl/g) was used as a phenol for copolymerization with 2,6-dimethylphenol. The physical properties of the product (intrinsic viscosities as high as 0.68 dl/g no fractionation of VIII during methylene chloride complex-ation l no long range nmr effects) suggested a block copolymer structure for the product. Since it is likely that polymer II did not redistribute under the mild conditions of polymerization (Table I shows little equilibration with monomer even at 80 ), polymer II was functioning as a monofunctional consonant which did not readily co-equilibrate with the oth r oligomers. Polymer II can be viewed as a chain stopper for reaction (4) and the product can be represented by structure XIII. Colorless, hazy... 

Since the last edition several new materials have been aimounced. Many of these are based on metallocene catalyst technology. Besides the more obvious materials such as metallocene-catalysed polyethylene and polypropylene these also include syndiotactic polystyrenes, ethylene-styrene copolymers and cycloolefin polymers. Developments also continue with condensation polymers with several new polyester-type materials of interest for bottle-blowing and/or degradable plastics. New phenolic-type resins have also been announced. As with previous editions I have tried to explain the properties of these new materials in terms of their structure and morphology involving the principles laid down in the earlier chapters. 

Covalent polymeric networks which are completely disordered. Continuity of structure is provided by an irregular three-dimensional network of covalent links, some of which are crosslinks. The network is uninterrupted and has an infinite molecular weight. Examples are vulcanized rubbers, condensation polymers, vinyl-divinyl copolymers, alkyd and phenolic resins. 

Structure of phenolic resin-poly(dimethyl siloxane) copolymers. 

No free PDMSX should be found in these systems however, unreacted starting novolac will be present. Hence, each copolymer system consisted of a blend of novolac resin and novolac-PDMSX copolymer. Hie structure of these copolymer systems is complex. Since all phenolic groups possess equal reactivity towards silylamine groups, the difunctional PDMSX may react anywhere between two novolac chains (an A-B-A triblock species) or twice with the same novolac molecule. The second reaction type would yield a macrocyclic compound whose size would depend upon the proximity of the two phenolic groups to one another. 

The above description of the process is tentative because it is based on limited data. If it is correct, the predominate structures in the PHBA-modified products have amorphous PA/AA/NPG center sections end-capped with single units or short blocks of oligomeric PHBA. Random distribution of the PHBA cannot be ruled out, but the hetero-geneiety of the products suggests that a substantial fraction of PHBA is incorporated into short blocks. The FT-IR and GPC data are consistent with the proposal that short, phenolic-tipped oligomers are the predominant structure present. The possibility that the materials are physical mixtures of oligo-PHBA and amorphous diols can be virtually ruled out on the basis of the extreme insolubility of oligo-PHBA (IJ) and of the model PHBA-benzoic acid adduct synthesized in this study. These materials separate readily from solutions and dispersions of PHBA copolymers. 

The catalytic activity of the metal complex on the oxidative reaction in solution is much influenced not only by the species and the structure of the complexes but also by the chemical environment around them. For instance, in the oxidative polymerization of phenols catalyzed by a Cu complex, the reaction rate varied about 102 times with changes in the composition of the solvent, and the highest rate was observed for polymerization in a benzene solvent162. Thus, we used the copolymer of styrene and 4-vinylpyridine(PSP) as the polymer ligand and studied the effect on the catalysis of the non-polar field formed by the polymer ligand163. ... 

Kaneda et al. synthesized [61] a series of high molecular weight extended chain copolyimides (XV) by the reaction of PMDA and 3,3, 4,4 -biphenyltetra-carboxylic dianhydride (PPDA) with 3,3 -dimethyl-4,4 -diaminobiphenyl. Solvents used for the one-step synthesis to the fully cyclized imide structure were phenol, p-chlorophenol, m-cresol, p-cresol and 2,4-dicholorophenol. The polycondensations were performed at 180°C for 2h with a monomer concentration of 6% by weight and p-hydroxybenzoic acid used as a catalytic accelerator. A maximum of 50 mol % of PMDA could be used before the copolymer precipitated from solution. Reconstituted copolymers as isotropic dopes (8-10% by weight) in p-chlorophenol were dry-jet wet spun between 80 and 100 °C [62]. 

This reaction has been actively studied since it was first reported by Hay in 1959 (I), but most of the extensive literature, which includes several recent reviews (2-8), deals primarily with the complex polymerization mechanism. Few copolymers have been prepared by oxidative coupling of phenols, and only one copolymer system has been examined in any detail. Copolymers of 2,6-dimethylphenol (DMP) and 2,6-diphenylphenol (DPP) have been prepared and the effect of variations in polymerization procedure on the structure and properties of the copolymers examined (4, 9) this work has now been extended to copolymers of each of these monomers with a third phenol, 2-methyl-6-phenylphenol (MPP). This paper presents a study of the DMP-MPP and MPP-DPP copolymers and a comparison with the DMP-DPP system previously reported. 

Oxidation of mixtures of 2,6-disubstituted phenols leads to linear poly(arylene oxides). Random copolymers are obtained by oxidizing mixtures of phenols. Block copolymers can be obtained only when redistribution of the first polymer by the second monomer is slower than polymerization of the second monomer. Oxidation of a mixture of 2,6-di-methylphenol (DM ) and 2fi-diphenylphenol (DPP) yields a random copolymer. Oxidation of DPP in the presence of preformed blocks of polymer from DMP produces either a random copolymer or a mixture of DMP homopolymer and extensively randomized copolymer. Oxidation of DMP in the presence of polymer from DPP yields the block copolymer. Polymer structure is determined by a combination of differential scanning calorimetry, selective precipitation from methylene chloride, and NMR spectroscopy. 

---