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Ethylene (E) copolymers with isoprene (IP) possessing higher glass-transition temperatures (Tgvalues, −7.1 to 29.2 °C) than those prepared by the reported catalysts (Tgbelow −18 °C) have been prepared in the copolymerization by using half-titanocene catalysts containing phenoxide ligand, Cp′TiCl2(O-2,6-iPr2-4-R-C6H2) [Cp′ = C5Me5(Cp*), R = H (1), SiEt3(2)]. Their microstructural analysis by NMR spectra revealed that the copolymers contained cyclopentane (major) and cyclohexane units, formed by cyclization after IP and subsequent ethylene insertions, in addition to 1,4- and 3,4-IP inserted units observed as major units in those prepared by reported catalysts. The 1,2,4-Me3C5H2analogue (R = H) showed better IP incorporation, but the resulting E/IP copolymers possessed rather low Tgvalues compared to those prepared by 1,2due to less cyclopentane unit in the microstructure. The Tgvalue in the E/IP copolymer increased upon the increase of the IP content, and the degree was dependent upon the catalyst employed. Due to their unique microstructure, the resulting E/IP copolymers prepared by 1,2–MAO catalyst systems exhibit promising tensile and elastic properties. The tensile strength initially decreased with an increase in the IP content along with an increase of the elongation at break (up to 600%, IP 3.3–15.6 mol %) and then increased gradually with further increase in the IP contents (IP 18.1–21.5 mol %); the elongation at break then decreased with preserving the tensile strength along with the observation of the yield stress.

The mechanism of the ring‐opening polymerization (ROP) of lactide catalyzed by two partner hydrogen‐bonding organocatalysts was explored. New amidoindoles 4 a,c, thioamidoindoles 4 b,d, amidobenzimidazoles 5 a,c, and thioamidobenzimidazoles 5 b,cwere synthesized and used as activators of the monomer. In the solid state and in solution, compounds 4and 5showed a propensity for self‐association, which was evaluated. (Thio)Amides 4and 5do catalyze the ROP of lactide in the presence of a cocatalyst, tertiary amine 3 aor 3 b, which activates the growing polymer chain through hydrogen‐bonding. Reactions were conducted in 2–24 h at 20 °C; conversion yields ranged between 22 and 100 %. A detailed study of the intermolecular interactions undertaken between the participating species showed that, as expected, simultaneous weak hydrogen bonds do exist to activate the reagents. Moreover, interactions have been revealed between the partner catalysts 4/5+3. ROP catalyzed by these partner activators is thus governed by multiple dynamic equilibria. The latter should be judiciously adjusted to fine‐tune the catalytic properties of (thio)amides and organocatalysts, more generally.

Summary: Epoxy resins are widely used in electronics and electric industries because of their superior properties. In recent years, excellent bonding properties for metals (e.g., copper, gold, aluminium, silver, etc.), to which it is hard to adhere, have become desirable for epoxy resins in the electric and electronics industrial fields. However, epoxy resins have only poor bonding strength to the metals. In order to increase the heterojunction strength between epoxy resins and copper, the introduction of sulfur, providing strong interactions with metals, was investigated. TDP polyester and MPS polythioesters containing sulfur moieties were employed as the sulfur-containing modifiers for the epoxy resin. Epoxy resins containing a modifier (5–20 phr) and a curing agent were cured between copper plates at 120 °C for 2 h and at 170 °C for 2 h. The effect of the added modifiers was evaluated by the lap‐shear testing method. It could be demonstrated that MPS polythioesters have a beneficial effect on the enhancement of the epoxy resin/copper heterojunction. The most effective example was the addition of 20 phr of the MPS_7 polythioester, which increased the lap shear strength from 5.7 to 17 MPa.Improvement of lap shear strengths of adhesive copper joints by sulfur-containing modifiers.

Summary: New positive-type photoresist systems based on enzymatically synthesized polyphenols have been developed. The photoresist thin film consisting of the polyphenol and a diazonaphthoquinone derivative was prepared on copperfoil-coated epoxy resins and exposed to UV light with different doses. The polyphenols from the bisphenol monomers exhibited high photosensitivity, comparable with a conventional cresol novolac. The sensitivity could be controlled by changing the structure of the polyphenols. Furthermore, the present photoresist showed excellent etching resistance. Characteristic exposure curves of poly(1)/DNQ and poly(5)/DNQ (both 70:30 wt.-%) with different phenylene unit contents.

Summary:New positive‐type photoresist systems based on enzymatically synthesized polyphenols have been developed. The photoresist thin film consisting of the polyphenol and a diazonaphthoquinone derivative was prepared on copperfoil‐coated epoxy resins and exposed to UV light with different doses. The polyphenols from the bisphenol monomers exhibited high photosensitivity, comparable with a conventional cresol novolac. The sensitivity could be controlled by changing the structure of the polyphenols. Furthermore, the present photoresist showed excellent etching resistance.

The synthesis of ethylene/myrcene copolymers was performed using half-titanocene catalysts in the presence of a methylaluminoxane (MAO) cocatalyst. Cyclopentadienyl-phenoxide catalysts, Cp*TiCl2(O-2,6-iPr2-4-RC6H2) [R = H (1), SiEt3(2)], showed rather efficient myrcene (My) incorporation to afford high-molecular-weight (semicrystalline or amorphous, depending on the My content) copolymers, which possess unimodal molecular weight distributions as well as uniform compositions. Microstructural analysis of poly(ethylene-co-My)s by NMR spectroscopy revealed that the resultant copolymers possessed cyclopentane units with a My pendant arm (−CH2CH═CMe2), formed by 2,1- or 1,4-My insertion and subsequent cyclization after ethylene insertion. The resultant copolymer showed promising elastic properties; the elongation at break increased upon increasing the My content, accompanied by a decrease in the tensile strength and toughness.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.