Copolymers from tert‐Butyl Methacrylate with Trimethylsilyl Methacrylate or Methacrylic Acid: Models for Resist Polymers

Abstract

Free radical copolymerisation of tert‐butyl methacrylate (1) with trimethylsilyl methacrylate (2) and methacrylic acid (3) has been investigated. Reactivity ratios for methacrylic acid and tert‐butyl methacrylate indicate an azeotropic copolymerisation (r1 = 0.476 ± 0.103; r3 = 0.300 ± 0.032), whereas the two esters show preferential incorporation of 2 (r1 = 0.170 ± 0.050; r2 = 1.170 ± 0.124). Thermal cis‐elimination of isobutylene from the tert‐butyl ester and subsequent formation of six‐membered cyclic anhydride moieties has been studied. For poly(methacrylic acid‐co‐tert‐butyl methacrylate) thermogravimetry could be used to determine copolymer composition. Solvolytic desilylation of the trimethylsilyl ester groups has been investigated as an alternative route to poly(methacrylic acid‐co‐tert‐butyl methacrylate). The tert‐butyl ester is not affected under the conditions of desilylation. Sequence distribution of both copolymers has been calculated using the method introduced by Bruns and Motoc.

Polyhedral Oligomeric Silsesquioxane (POSS) Based Resists: Material Design Challenges and Lithographic Evaluation at 157 nm

“…Since the polymerizations were carried to near completion (>90% yields), the ratios of the starting monomers in the copolymers are similar to the feed ratios and compositional homogeneity is expected. [30][31][32] Note that the electrondeficient monomers IA, TFMA, and TBTFMA do not undergo homopolymerization under conventional (AIBN-initiated) radical conditions. 33,34 They were copolymerized with electronacceptor monomers such as TBMA, forming random copolymers.…”

Stereospecific Free Radical and RAFT Polymerization of Bulky Silyl Methacrylates for Tacticity and Molecular Weight Controlled Poly(methacrylic acid)

“…Although Kitayama and Hatada reported stereospecific anionic polymerization of trimethylsilyl methacrylate at low temperature, there have been no studies focusing on the stereospecific radical polymerization of a series of various silyl methacrylates with different bulkiness. In addition, trimethylsilyl and its related silyl methacrylates have been synthesized − and homo- or copolymerized radically or anionically, which were particularly directed to photoresist applications as precursors of PMAA moieties. , …”

Synthesis and characterization of D‐(−)‐Salicine‐based star copolymers containing pendant carboxyl groups with fluorophore dyes

“…Literature reports the synthesis of linear copolymers, where the reactivity ratios were determined for t BMA copolymerized by ATRP with 2‐(dimethylamino ethyl) methacrylate indicating slightly higher reactivity of t BMA ( r t BMA = 1.10, r M 2 = 0.66), whereas FRP of the same comonomers makes that their reactivities are opposite ( r t BMA = 0.65 and r M2 = 1.40) . FRP of t BMA with other methacrylates, that is solketal methacrylate [(2,2′‐dimethyl‐1,3‐dioxolan‐4‐yl)methyl methacrylate] ( r t BMA = 1.40 and r M2 = 0.79), 2‐bromoethyl methacrylate ( r t BMA = 0.82 and r M2 = 1.15), trimethylsilyl methacrylate ( r t BMA = 0.17 and r M2 = 1.17), and methacrylic acid ( r t BMA = 0.48 and r M2 = 0.30) has been also investigated.…”