Synthesis and characterization of novel copolymers with acid‐labile ketal moieties derived from camphor

Abstract

Novel diastereomeric acrylic ketal monomers derived from (ϩ)-camphor and (Ϯ)-camphor were synthesized. To investigate the applications of the camphor derivatives on positive-tone photoresists, the acrylic ketal monomers were copolymerized with methyl methacrylate, methacrylic acid, and n-butyl methacrylate. The optical activities of the chiral monomers and polymers were all evaluated. After UV irradiation and postexposure baking, the optical activity of the polymers decreased because of the decomposition of the acid-labile pendant chiral groups. The existence of alicyclic camphyl groups increased the etching resistance of the photoresists. The thermogravimetric properties of the copolymers, the exposure curves, the lithographic evaluation of the positive-tone photoresists, and the effects of alicyclic groups on the plasma etching resistance of the copolymers were all investigated. A resolution of a lineand-space pattern of 0.3 m was achieved. Acid-catalyzed dehydration crosslinking was also found in this system. Sufficient UV irradiation and heat treatment could cause the acid-catalyzed dehydration crosslinking of pendant carboxyl groups and thereby increase the efficiency of the thermal resistance of the polymers.

Fast Hydrolysis Polyesters with a Rigid Cyclic Diol from Camphor

“…This is because the PE x CaG y T copolyesters contained both ester and ketal groups in the main polymer chain, and the hydrolysis of ketal bonds is faster than that of ester bonds in acidic conditions. 23 The substance eluted from PE 50 CaG 50 T by hydrolysis and eluted with the acidic aqueous solution was detected by NMR, but no substance was detected. If the ester bond was degraded, signals of ethylene glycol dissolved in water would have appeared.…”

“…The higher the proportion of the CaG diols in the copolyester, the faster the molecular weight was reduced. This is because the PE x CaG y T copolyesters contained both ester and ketal groups in the main polymer chain, and the hydrolysis of ketal bonds is faster than that of ester bonds in acidic conditions . The substance eluted from PE 50 CaG 50 T by hydrolysis and eluted with the acidic aqueous solution was detected by NMR, but no substance was detected.…”

“…1,7,7-Trimethyl-spiro­[bicyclo­[2.2.1]­heptane-2,2′-[1,3]­dioxolane]-4′-methanol (CGB) was synthesized according to ref .…”

High Thermal Stability of Bio-Based Polycarbonates Containing Cyclic Ketal Moieties

“…In synthesis process, simple one-step synthesis of CaG is expected to induce a straightforward work-up and separation leading to high purity as monomer of engineering bioplastics. It was anticipated that the rigid property derived from camphorquinone (CQ) was combined with high reactivity of primary alcohol derived from glycerol, generating two cyclic ketal moieties linked by norbornane . Additionally, cyclic ketal functional groups are more stable than the ester group against hydrolysis in acidic, neutral, and basic media, but this acid-cleavable linkages leave ketone and alcohol as degradation products; in our case those are the bio-based starting materials of a monomer. , The plant-based CaG is expected to the next generation of cereal-based and other biomass compounds beyond ISS.…”

Synthesis of ArF photoresist polymer composed of three methacrylate monomers via reversible addition-fragmentation chain transfer (RAFT) polymerization

“…[1][2][3][4][5][6][7][8] These ArF PR polymers are composed of several monomeric units having lithographic functionalities and are usually prepared through free radical polymerization (FRP). However, controlling molecular weight and chemical structure of polymers through FRP are limited because of the very fast cycle of chain growth mechanism.…”