Dilute and semi-dilute solution properties of several classes of branched macromolecules are outlined and discussed. The dilute solution properties are needed for a control of the chemical synthesis. The molecular parameters also determine the overlap concentration which is an essential quantity for description of the semi-dilute state. This state is represented by a multi-particle, highly entangled ensemble that exhibits certain similarities to the corresponding bulk systems. Because of the rich versatility in branching the present contribution made a selection and deals specifically with the two extremes of regularly branched polymers, on the one hand, and the randomly branched macromolecules on the other. Some properties of hyperbranched chains are included, whereas the many examples of slight deviations from regularity are mentioned only in passing. The treatment of the two extremes demonstrates the complexity to be expected in the general case of less organized but non-randomly branched systems. However, it also discloses certain common features.

Solution Properties of Branched Macromolecules

An electrophotographic photosensitive member that can not easily cause charging lines even where it is an electrophotographic photosensitive member employing as a conductive layer a layer containing metal oxide particles is disclosed. Also disclosed are a process cartridge and an electrophotographic apparatus which have such an electrophotographic photosensitive member. The electrophotographic photosensitive member has a conductive layer which contains titanium oxide particles coated with tin oxide doped with phosphorus or tungsten.

Electrophotographic photosensitive member, process cartridge and electrophotographic apparatus

Unique copolymers comprising propylene, ethylene and/or one or more unsaturated comonomers are characterized as having: at least one, preferably more than one, of the following properties: (i) 13C NMR peaks corresponding to a regio-error at about 14.6 and about 15.7 ppm, the peaks of about equal intensity, (ii) a B-value greater than about 1.4 when the comonomer content of the copolymer is at least about 3 wt%, (iii) a skewness index, S?ix?, greater than about -1.20, (iv) a DSC curve with a Tme that remains essentially the same and a Tmax that decreases as the amount of comonomer in the copolymer is increased, and (v) an X-ray diffraction pattern that reports more gamma-form crystals than a comparable copolymer prepared with a Ziegler-Natta catalyst. These polypropylene polymers are made using a nonmetallocene, metal-centered, heteroaryl ligand catalyst. These polymers can be blended with other polymers, and are useful in the manufacture of films, sheets, foams, fibers and molded articles.

Isotactic propylene copolymers, their preparation and use

A process for the preparation of a toner comprising: preparing an organic phase comprised of a first nonpolar olefinic monomer, a second nonpolar diolefinic monomer, a pigment, a free radical initiator, and optionally a charge control agent; adding the organic phase to an aqueous phase comprised of at least one surfactant; shearing the organic phase into the aqueous phase to form a microdroplet suspension of the organic phase dispersed in the aqueous phase; heating and polymerizing the microdroplets in the suspension to form nonpolar olefinic resin particles; halogenating the nonpolar olefinic resin particle mixture to form a nonpolar toner having a halopolymer resin outer surface or encapsulating shell; and optionally isolating the surface halogenated nonpolar toner.

Toner compositions and processes thereof

The present invention encompasses a solid dose delivery vehicle for ballistic administration of a bioactive material to subcutaneous and intradermal tissue, the delivery vehicle being sized and shaped for penetrating the epidermis. The delivery vehicle further comprises a stabilizing polyol glass loaded with the bioactive material and capable of releasing the bioactive material in situ. The present invention further includes methods of making and using the solid dose delivery vehicle of the invention.

Solid dose delivery vehicle and methods of making same

A low fusing temperature toner powder with excellent keep and grindability characteristics is provided which employs a polyblend of a crystalline polyester and an amorphous polyester that has been cross-linked with an epoxy novolac resin in the presence of a crosslinking catalyst.

Low fusing temperature toner powder of cross-linked crystalline and amorphous polyester blends

A low fusing temperature toner powder with good keep and broad fusing latitude characteristics is provided. The toner powder is comprised of polymer particles of a partially carboxylated crystalline polyester and partially carboxylated amorphous polyester that has been crosslinked together at elevated temperature with the aid of an epoxy novolac resin and a crosslinking catalyst.

Low fusing temperature tone powder of crosslinked crystalline and amorphous polyesters

We report viscosity, recoverable compliance, and molar mass distribution for a series of randomly branched polyester samples with long linear chain sections between branch points. Molecular structure characterization determines tau=2.47+/-0.05 for the exponent controlling the molar mass distribution, so this system belongs to the vulcanization (mean-field) universality class. Consequently, branched polymers of similar size strongly overlap and form interchain entanglements. The viscosity diverges at the gel point with an exponent s=6.1+/-0.3, that is significantly larger than the value of 1.33 predicted by the branched polymer Rouse model (bead-spring model without entanglements). The recoverable compliance diverges at the percolation threshold with an exponent t=3.2+/-0.2. This effect is consistent with the idea that each branched polymer of size equal to the correlation length stores k(B)T of elastic energy. Near the gel point, the complex shear modulus is a power law in frequency with an exponent u=0.33+/-0.05. The measured rheological exponents confirm that the dynamic scaling law u=t/(s+t) holds for the vulcanization class. Since s is larger and u is smaller than the Rouse values observed in systems that belong to the critical percolation universality class, we conclude that entanglements profoundly increase the longest relaxation time. Examination of the literature data reveals clear trends for the exponents s and u as functions of the chain length between branch points. These dependencies, qualitatively explained by hierarchical relaxation models, imply that the dynamic scaling observed in systems that belong to the vulcanization class is nonuniversal.

Viscoelasticity of randomly branched polymers in the vulcanization class.

Viscoelasticity of randomly branched polymers in the critical percolation class

The growth of branched polymer structures up to the gel point has been examined in a polyester system at two different branch agent concentrations. Several independent measurements of the size and molecular weight of these polymers were made using elastic light scattering, quasi-elastic light scattering, intrinsic viscosity (SI, and size-exclusion chromatography with low-angle light scattering detection. In all cases, scaling relationships between these various properties were displayed for the whole range of molecular weights examined. The weight-average molecular weight scaled as @, - p)T, where p is the extent of reaction and pc is the extent of reaction at the gel point. The exponent y was found to be 1.8 f 0.3. Scaling exponents from the radius-M, and (+M, relationships were evaluated for unfractionated samples. Using these exponents, another critical exponent of gelation, T, and the exponent relating size to molecular weight for a branched polymer in a good solvent, $, could be evaluated. These were compared with values for the same exponents obtained through size-exclusion chromatography of the polymers. The critical exponent 7 was obtained from this fractionation experiment through the shape of the observed distribution function and from the scaling relation between the molecular weight M-, corresponding to the fraction making the largest contribution to light scattering in this separation, and M, for each sample. Good agreement was observed between these two separate measures of T and the one from the unfractionated samples, as well as from both fractionated and unfractionated samples. The measured values were T = 2.29 f 0.03 and $ = 0.48 f 0.02. The distribution functions for polymers were described by a single universal distribution function. The critical exponents for gelation were compared to percolation and Flory-Stockmayer predictions and were found to favor the percolation results, but the agreement with percolation for the exponent 7 was marginal.

John C. Wilson

Papers

Low fusing temperature toner powder of cross-linked crystalline and amorphous polyester blends

Low fusing temperature tone powder of crosslinked crystalline and amorphous polyesters

Viscoelasticity of randomly branched polymers in the vulcanization class.

Viscoelasticity of randomly branched polymers in the critical percolation class

Scaling properties of branched polyesters