James V. Crivello

The synthesis and characterization of side-chain liquid crystal polymers based on polystyrene and poly-α-methystyrene

Abstract The polymer analogous synthesis of new liquid-crystalline side-chain polymers having polystyrene and poly-α-methylstyrene backbones bearing pendant azo-benzene mesogenic groups is described. The effects of various spacer lengths on the mesophase types were examined. Several liquid-crystalline copolymers were also prepared and their mesophase types determined.

Structure-property behaviour of free radical synthesized polydimethylsiloxane-polystyrene multiblock polymers: 1. Effect of the siloxane block length

Abstract The morphological structure and the physical properties of free radical synthesized PDMS-PS multiblock polymers have been studied. The polymers were prepared by free radical copolymerization of PDMS macroinitiators with styrene monomer. The length of the PDMS blocks was basically predetermined by the molecular weight of the PDMS macroinitiators which were cationically prepared. However, the PS blocks were formed during the free radical copolymerization. Therefore, the molecular weight and the molecular weight distribution of the PS blocks varied with the PDMS block length at constant styrene conversion level. Hence, the morphology of these polymers as well as the degree of phase separation was altered by the block length of both components. Specific mechanical properties of these polymers were directly related to their morphological structure.

The synthesis and characterization of cationic photoinitiators bearing two and three photoactive triarylsulfonium groups in the same molecule

SummaryA novel series of photoinitiators for cationic polymerization have been prepared which bear two and three photoactive triarylsulfonium groups in the same molecule. These compounds have been fully characterized by means of their UV and C-NMR spectra and liquid chromatography as well as by their elemental analyses. The multifunctional triarylsulfonium salts have been compared among themselves and against monofunctional triarylsulfonium salts in the photoinitiated cationic polymerization of dl-limonene dioxide.

A New Route to Triarylsulfonium Salts via the Double Arylation of Thiophenols

Abstract Although the literature contains a number of synthetic procedures for the preparation of triarylsulfonium salts, 1−10 there existed no single general method capable of giving a wide variety of substituted symmetrical and unsymmetrical triarylsulfonium salts in high yields. Recently, we reported that the copper catalyzed diaryliodonium salt arylation of diarylsulfides (equation 1) proceeds smoothly at moderate temperatures to give good to excellent yields of triarylsulfonium salts.11

Cyclic silyl pinacole ethers

SummaryCyclic silyl pinacole ethers are a new class of difunctional free radical initiators which have been prepared and characterized. On the basis of their first order kinetic rates of dissociation and half-lives, these compounds are high temperature initiators useful generally above 120°C. The unusual difunctional character of these initiators suggests some rather interesting applications for their use.

Mid-UV Photoresists Combining Chemical Amplification And Dissolution Inhibition

This paper describes the development of mid-UV photoresist materials based on the combined principles of chemical amplification and dissolution inhibition. These resists are composed of a novolac resin, a dissolution inhibitor containing an acid labile blocking group, and a photosensitive onium salt. A positive image is obtained by exposure to mid-UV irradiation, which generates a strong Bronsted acid from the onium salt, heating the resist so that the acid can catalyze deblocking of the acid labile groups on the dissolution inhibitor, and finally development with aqueous base. Interestingly, this system works well despite the fact that novolacs have previously been shown to become insolubilized by heating them in the presence of onium salt photoproducts.

The synthesis and characterization of polymer-bound diaryliodonium salts and their use in photo and thermally initiated cationic polymerization

SummaryA new method for the synthesis of polymer-bound diaryliodonium salts has been developed which facilitates the preparation of these polymeric initiators. The polymer-bound diaryliodonium salts were used in both photo and thermally initiated cationic polymerizations.

The Oxidation of Aliphatic Hydrocarbons in the Presence of Higher Oxidation States of Silver

Abstract The compound silver “peroxide”∗ has been known for some time and its preparation is described in the literature.1 The structure of this compound has been in dispute; however it appears to have been resolved using neutron diffraction techniques. Scatturin, Bellon and Salkind2 have shown that silver “peroxide” is a rather complex material in which silver is present in two different oxidation states, namely Ag(I) and Ag(III). In the crystal, Ag(III) atoms are coordinated to oxygen in a square planar array and the Ag(I) atoms are linearly coordinated. There are no peroxide oxygens. Hence the formula for silver “peroxide” is more properly written Ag(I)Ag(III)02.

A Novel and Convenient Preparation of Tropylium Ion Salts

Abstract Tropylium ion salts are a class of charged, non-benzenoid aromatic compounds possessing 6π electrons and obeying Huckels rule. The chemistry of these compounds has received considerable attention during the past few years and continues to involve many workers. The synthesis of these compounds by a number of routes has been described in the literature.1–3 Some of these methods are suitable for small scale laboratory synthesis, while others are unwieldy and inconvenient even for these purposes. To date, the best route for the synthesis of tropylium ion salts has been the oxidation of cycloheptatriene by phosphorous pentachloride.4,5

Bismaleimide-bisvinylether copolymers: A new class of thermosetting resins

SummaryThe free radical network copolymerization of bismaleimides with bisvinylethers containing aromatic groups gives rise to a new class of thermally stable imide-containing thermosets. The chief assets of these thermosetting materials are their ability to cure rapidly at low temperatures without the evolution of volatile byproducts.