G.C. Eastmond

1,2-Bis(carboxyphenoxy)arylenes and aramids and polyarylates therefrom: synthesis and properties

The synthesis of a new series of aromatic bis(ether acid)s and bis(ether acid chloride)s by fluorodisplacement with catechol or its derivatives has been developed and exemplified. These monomers allow the synthesis of new aramids (poly(ether amide)s), polyarylates (poly(ether ester)s) and copolyarylates in which ortho-phenylene units are enchained through ether linkages. These polymers are significantly more flexible and, therefore, more soluble than conventional aromatic polyamides and polyesters. They have useful levels of thermal stability, associated with relatively high glass-transition temperatures ( > 200°C), are processable from solution or the melt, and are potentially crystallizable. Liquid crystalline poly(ether ester)s were prepared. Polyamides prepared from bis(ether acid)s in which all three aromatic rings, separated by ether linkages, are all ortho-substituted gave low-molecular weight polymers.

Isomeric poly(ether imide)s: synthesis, thermal properties and permeabilities

Abstract This paper describes the synthesis of a novel series of poly(ether imide)s formed as isomeric pairs of polymers by interchanging the diol and diamine derived units. The polymers contained units having flexible and stiff hinges and groups to hinder segmental rotation. Most polymers were soluble in a variety of solvents, which allowed them to be characterized and cast into membranes. Permeabilities to carbon dioxide and methane and glass transition temperatures were determined. Consideration of structure-property relations showed the properties of the polymers to be sensitive to the position of the structural units within the polymer. The polymers showed a linear relationship between permeabilities to the two gases. There was a strong trend between high permeability and high glass transition temperature, suggesting that rigid polymers incapable of inefficient packing lead to highly permeable membranes and that such factors were enhanced by the presence of bulky substituents.

Network formation III—Influence of organometallic initiator on network structure

The nature of the primary radicals arising from the interaction of halides and organometallic derivatives has been investigated with the aid of tracer and gelation techniques. Halides studied include carbon tetrachloride and esters of trichloracetic acid; with Mo(CO)6, Mn2(CO)10 and Pt(PPh3)4 these yield radicals derived from the halide by removal of chlorine atoms to give ‘attached’ primary radicals. The nickel derivatives Ni{P(OPh)3}4, Ni(CO)4, Ni(CO)2(PPh3)2 produce some radicals which do not contain an organic residue and are therefore ‘unattached’; these may be chlorine atoms or an adduct with monomer. Since unattached radicals promote branch formation, the use of the nickel derivatives increases the range of available network structures. Values for the ratio of combination to disproportionation in the termination reaction of methyl methacrylate polymerization are a byproduct of these investigations and are given for three temperatures.

Macroscopic phase separation in multicomponent polymer homopolymer blends: general considerations based on studies of AB—crosslinked polymers

Abstract This paper explores the significance of, and presents additional evidence in support of, our earlier conclusion that molecules of multicomponent polymers (i.e. copolymers consisting of long sequences of different components), such as AB-crosslinked polymers, are normally incompatible with homopolymers of the individual components. The arguments are generalized to include block copolymer systems. After a brief review of relevant previous studies, schematic phase diagrams appropriate to multicomponent polymer/homopolymer blends and common solvent are constructed. The consequences of solvent-casting mixtures of multicomponent species with one homopolymer from homogeneous dilute solution are considered for cases where equilibrium is always achieved, and more practical situations where equilibrium is not attained in bulk polymer. Electron micrographs of ultra-thin sections of solvent-cast blends of AB-crosslinked polymers with homopolymer are presented to substantiate and illustrate points made in the preceding discussion. Conclusions are drawn regarding possible morphologies which can exist in multicomponent polymer/homopolymer blends and it is proposed that unusual morphologies in block copolymer blends reported by various workers are the direct consequences of combinations of macroscopic phase separation and subsequent microphase separation within phases of different composition. We suggest that the incompatibility of chemically identical blocks and homopolymers arises from an unfavourable entropy of mixing as a result of the blocks in the vicinity of microphase interfaces adopting different sets of conformations than randomly-coiled chains in bulk polymer.

Network properties: (1) Multiple glass transitions

Abstract Networks composed of polyvinyl trichloracetate ( Pvtca ) cross-linked by polymethyl methacrylate or polystyrene were prepared from mixtures of Pvtca and the appropriate monomer by thermal initiation with molybdenum carbonyl at 80°C or photoinitiation with manganese carbonyl at 25°C. From details of the syntheses the following properties of the networks were calculable: (1) the mean numbers of cross-linked units per weight average Pvtca chain, (2) the mean degree of polymerization of the cross-links and (3) the ratio (number of branches)/(number of cross-links). Dilatometric observations showed that normally the networks have two glass temperatures and are two-phase systems. The slopes of the volume-temperature curves between the transition points were higher than expected, markedly so with copolymers containing methyl methacrylate and to a much smaller extent with those containing styrene. It is concluded that in the former systems the Pvtca -rich phase contains considerable proportions of polymethyl methacrylate while in the latter there is only a small degree of incorporation of styrene into the Pvtca -rich phase. In agreement with these conclusions is the observation that for the polymethyl methacrylate systems the lower glass temperature is appreciably higher than the glass temperature of Pvtca . With the systems containing styrene this difference is not found. The influence of structural characteristics of the networks, particularly the branch/cross-link ratio and the length of the cross-links, on the compositions of the two phases is discussed.

The synthesis of a catechol-based bis(ether anhydride) and poly(ether imide)s derived therefrom

This work reports the development of nitrodisplacement reactions between catechol and nitrophthalodinitriles, thus providing a bis(ether anhydride) and high-molecular-weight, thermally stable poly(ether imide)s with ortho-linked units. These polymers are far more soluble and more readily processable than corresponding polymers with para- and meta-linked diol units.

Some morphological aspects of AB crosslinked polymers

Abstract The structures of multicomponent species present in AB crosslinked polymers (ABCPs) formed by the random introduction of crosslinks of polymer B into an assembly of chains of polymer A are described for different extents of crosslinking. Microphase separation has been observed in solvent cast samples of ABCPs prepared by crosslinking poly(vinyl trichloroacetate) and a styrene copolymer (A-components) with polychloroprene (B-component). The morphologies of the polymers at low and high degrees of crosslinking are presented. Polychloroprene domain sizes have been determined for various crosslink lengths and crosslink densities. Domain sizes and their variation with molecular weight of the B-chains are discussed in terms of the structures of the multicomponent species present in the ABCPs and with theoretically predicted domain sizes in linear block copolymers. Distributions of domain sizes have been determined and compared with the molecular weight distributions of the B-chains.

Poly(ether imide)s with hindering substituents in the anhydride moiety: synthesis, properties and gas permeabilities

Abstract The synthesis of a series of bis(ether anhydride)s with hindering substituents, especially t-butyl and methyl, has been developed using nucleophilic displacement reactions between nitrophthalodinitriles and substituted hydroquinones, bisphenols and a naphthalene diol. The bis(ether anhydride)s have been successfully incorporated into poly(ether imide)s with hindering residues by polymerization with diamines, with and without alkyl substituents. The thermal and mechanical properties of a number of the polymers and their permeabilities to several gases have been determined. The properties of the polymers are discussed, along with those of related polymers. It is shown that the properties are strongly controlled by their structural features. In particular, the flexibilities of polymer backbones and substituents are found to influence glass transition temperatures and, in conjunction with the influence of chain rigidity on packing, to influence gas permeabilities and permselectivities.

Interfacial activity of polycarbonate/PMMA graft copolymers in polycarbonate/PMMA blends: effect of copolymer concentration

Abstract This paper discusses the effectiveness of polycarbonate/poly(methyl methacrylate) graft copolymers as emulsifiers in solvent-cast dispersions of poly(methyl methacrylate)/polycarbonate blends. The molecular weight of the copolymer block corresponding to the minor (polycarbonate) phase was distinctly higher than that of the corresponding homopolymer. The results indicate that small amounts (

Network properties: 2. A broadline n.m.r. study of molecular motions in some multicomponent crosslinked polymers

Abstract A series of multicomponent polymers of known structure and consisting of poly(vinyl trichloroacetate) crosslinked with poly(methyl methacrylate) (PMMA) have been examined by broadline n.m.r. Both enhanced and retarded rotation of the α-methyl groups on the PMMA chains, compared with those in PMMA homopolymer, have been observed. A previous assessment of the morphologies of the same polymers, based on the results of dilatometric studies, has been extended. The modifications to the rotations of the α-methyl groups have been correlated with the morphologies of the multicomponent polymers and it is proposed that both effects arise as a result of changes in the distribution of conformations adopted by the PMMA chains in the multicomponent polymers compared with that in the pure homopolymer.