Synthesis of high molecular weight isobutylene-α-methylstyrene copolymers containing alkenyl groups with a half sandwich scandium initiator system under mild conditions

Ke, Yang; Niu, Hui; Yu, Hui; Dong, Jing; Wang, Jing; Yu, Jianlin; Shen, Kaihua; Li, Yang

doi:10.1039/c8py01749b

Cited by 5 publications

(4 citation statements)

References 31 publications

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“…Glass transition temperature and compositions of (a) MMA–VDC copolymers (data from ref ) and MMA–IB copolymers (data from ref ) and (b) αMS–IB copolymers (data from ref ).…”

Section: More Complex Casesmentioning

confidence: 87%

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Glass Transition Temperatures of Copolymers: Molecular Origins of Deviation from the Linear Relation

Huang

Zhang

et al. 2022

Macromolecules

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The glass transition temperature (T g) is an important material parameter in determining polymer properties. The main molecular structure factors affecting T g are chain stiffness and cohesive energy, causing polymers to exhibit the complex micro-structure dependence of T g. The composition dependence of the T gs of binary random copolymers mainly shows as three cases: the linear relation, the negative deviation (or concave curve), or the positive deviation (convex curve). The study of the T g’s composition dependence can guide the design of copolymer materials with desirable properties. On the other hand, it can provide insights into understanding the precise nature of the glass transition. In this study, the root cause of the T g deviation from the linear relation in random copolymers was revealed, and new molecular origins were proposed. First, the theoretical basis of why there exists a linear T g relation for copolymers was clarified, and the influence of the specific polar interactions between components was discussed briefly. More importantly, it has been identified that the negative T g deviation is related to copolymers composed of the mono-substituted (M-type) monomer and asymmetrical di-substituted (AD-type) monomer, and the positive T g deviation is related to copolymers composed of the M-type monomer and symmetrical di-substituted (SD-type) monomer. The molecular origin of the T g deviations from the linear relation is the destruction of the special conformational structures (e.g., the locally rigid conformational structure in the AD-type homopolymer or the dynamic flexible structure in the SD-type homopolymer) caused by copolymerization. The behaviors for more complex binary copolymers (AD–AD, SD–SD, and AD–SD types) were also discussed. Finally, the variation in T g of a statistical copolymer as a function of composition was summarized.

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“…Glass transition temperature and compositions of (a) MMA–VDC copolymers (data from ref ) and MMA–IB copolymers (data from ref ) and (b) αMS–IB copolymers (data from ref ).…”

Section: More Complex Casesmentioning

confidence: 87%

“…Data of MMA–VDC and MMA–IB copolymers in Figure a seem to support these predictions. However, this conclusion requires more data to test because Yang et al . recently reported an opposite example that αMS–IB copolymers showed a negative deviation in the high IB content region (>78%, Figure b).…”

Section: More Complex Casesmentioning

confidence: 99%

Glass Transition Temperatures of Copolymers: Molecular Origins of Deviation from the Linear Relation

Huang

Zhang

et al. 2022

Macromolecules

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“…RIS is a generalized conformational approach dependent on the types of comonomers, as each bond pair is explicitly examined and all energy levels are statistically summed along any specific chain connectivities, e.g., any regio-, stereo-, or comonomer-sequence distributions can be explicitly considered. Thus it has great potential in future studies to explain the more peculiar comonomer sequence dependent Tgp deviations observed for AD-SD type comonomers [23]. In addition, similar to stereosequence dependence of local conformational geometry and subsequently the dynamics of the glass transition process [24], comonomer sequence dependence of glass transition dynamics of copolymers with tunable chain architectures can be studied in combined experimental and simulation studies which ultimately contribute to the understanding of the molecular bases of polymer glass transition phenomena.…”

Section: Current Status and Future Perspectivesmentioning

confidence: 99%

Conformational Source of Comonomer Sequence-Dependent Copolymer Glass-Transition Temperatures

Tonelli,

Shen

2023

Preprint

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This brief review addresses the source of the dependence of copolymer glass transition temperatures (Tgps) on their comonomer sequences. Here we show that a comparison of the conformational entropies obtained from the Rotational Isomeric State (RIS) conformational models of the poly-A and poly-B homopolymers and their resultant poly-A/B co-polymers, i.e., ΔSconf = (XASA + XBSB) - SA/B (X = comonomer fraction), can be used to predict/understand the Tgps of copolymers. For copolymers with ΔSconf ~ 0, we expect their Tgps to follow Fox behavior and to depend only on copolymer composition, because of the similar conformational flexibilities of the A and B homo- and A/B-copolymers. When the conformational entropy ΔSconf is negative the A/B copolymer is assumed more flexible than the weighted sum of polymer-A and polymer-B conformational entropies, resulting in Tgps that are lower than expected from the Fox equation. Conversely, a positive ΔSconf suggests the copolymer’s lower flexibility, resulting in higher Tgps than expected from the Fox relation. We use the successful comparison of the observed dependence of numerous copolymer Tgps to demonstrate the validity of using their calculated RIS conformational entropies to predict their comonomer sequence dependencies.

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“…[31,32] According to the IB polymerization of polyisobutylene (PIB) in our research, the synthesis of well-defined copolymer of IB and St can be controllable within the scandium initiator system. [23,33,34] As a result, we attempted to synthesize the copolymers with sPS blocks and PIB blocks, in order to create novel materials combining the favorable properties of both sPS and PIB.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of syndiotactic polystyrene—Polyisobutylene graft copolymers by cationic half‐sandwich scandium complex

Wang

Zhou

et al. 2022

Polymer Engineering & Sci

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Syndiotactic polystyrene is a high strength engineering plastic, and polyisobutylene is an excellent elastomers. In order to combine the advantages of syndiotactic polystyrene and polyisobutylene, isobutylene was achieved to graft onto the crystalline syndiotactic polystyrene, forming graft copolymers, under half sandwich scandium complex [(C 5 Me 4 SiMe 3 )Sc(CH 2 SiMe 3 ) 2 THF]/[Ph 3 C] [B(C 6 F 5 ) 4 ] after the application of syndiotactic copolymers of styrene and 4-isopropenylstyrene with pendant double bonds. Grafted copolymers based on crystalline polystyrene and rubbery polyisobutylene block have both high T m (270 C) and low T g (À67 C), meanwhile, these materials have relative good mechanical properties.

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Synthesis of high molecular weight isobutylene-α-methylstyrene copolymers containing alkenyl groups with a half sandwich scandium initiator system under mild conditions

Abstract: Copolymerizations of isobutylene and two alkenyl functionalized α-MeSt derivatives respectively, catalyzed by [(C5Me4SiMe3)Sc(CH2SiMe3)2THF], at −35 °C produced high Mn random copolymers with pendant alkenyl groups.

Cited by 5 publications

References 31 publications

Glass Transition Temperatures of Copolymers: Molecular Origins of Deviation from the Linear Relation

Glass Transition Temperatures of Copolymers: Molecular Origins of Deviation from the Linear Relation

Conformational Source of Comonomer Sequence-Dependent Copolymer Glass-Transition Temperatures

Synthesis of syndiotactic polystyrene—Polyisobutylene graft copolymers by cationic half‐sandwich scandium complex

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