Synchronized Tandem Catalysis of Living Radical Polymerization and Transesterification: Methacrylate Gradient Copolymers with Extremely Broad Glass Transition Temperature

Abstract

Gradient copolymers with differential sequences linearly changing from methyl methacrylate (MMA) to dodecyl methacrylate (DMA) were efficiently synthesized by a concurrent tandem catalysis in the ruthenium-catalyzed living radical (co)polymerization coupled with the in situ transesterification of MMA with 1-dodecanol assisted by titanium isopropoxide [Ti(Oi-Pr)4]. The key is to perfectly synchronize the two reactions throughout the tandem catalysis by using molecular sieves (MSs), which facilitates the MMA transesterification into DMA by removing the resulting methanol. The MMA/DMA gradient copolymers had an extremely broad glass transition temperature range (i.e., hardly detectable by differential scanning calorimetry (DSC)), in sharp contrast to the random and the block counterparts of similar compositions.

Synthesis and characterization of sugar-based methacrylates and their random copolymers by ATRP

“…The thermal properties of the obtained random copolymers were evaluated using the glass transition temperatures (T g ) determined by DSC (Table 1) all copolymers exhibited relatively similar Tg g values between 101.2 and 102.9°C (entry [1][2][3][4]. This differences could be related to either the molecular weight differences or nature of random copolymer with nonuniform composition, which was previously reported by other groups [52][53][54].…”

Sequence-Regulated Polymers via Living Radical Polymerization: From Design to Properties and Functions

“…Typically, the combination of molecular sieves 4A and a small amount of titanium isopropoxide (5 mM) with 1-dodecanol fully synchronized in situ transesterification of MMA into DMA and the copolymerization to give a gradient copolymer with the sequence distribution almost linearly changing from MMA to DMA. Owing to the gradient sequence, the MMA/DMA gradient copolymer exhibited extremely broad range of glass transition temperature (~170°C), different from MMA/DMA random or block copolymers (13).…”

“…Molecular sieves further enhanced the efficiency and yield of in situ transesterification of MMA with alcohols by the removal of generating methanol (13). Typically, the combination of molecular sieves 4A and a small amount of titanium isopropoxide (5 mM) with 1-dodecanol fully synchronized in situ transesterification of MMA into DMA and the copolymerization to give a gradient copolymer with the sequence distribution almost linearly changing from MMA to DMA.…”

Sequence-controlled polymers via reversible-deactivation radical polymerization

“…The synchronized rate control is essential, and various functional groups can be incorporated by selecting different alcohols. [27][28][29][30] UNIQUE COPOLYMERS VIA CONCURRENT TRANSFORMATION OF ACTIVE SPECIES Different active species can be generated from identical dormant species according to the stimulus. For example, a carbon-halogen bond that is activated into a carbocationic species via Lewis acid catalysis for living cationic polymerization 31,32 is also available as the dormant species in conjunction with one-electron redox catalysis for metal-catalyzed living radical polymerization 4,5 or ATRP.…”