Glass‐transition temperatures of nanostructured amorphous bulk polymers and their blends

Joijode, Abhay; Antony, Gerry J.; Tonelli, Alan E.

doi:10.1002/polb.23306

Cited by 9 publications

(30 citation statements)

References 26 publications

(49 reference statements)

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“…In general, the glass transition temperatures, T g s, of amorphous guest polymers coalesced from their stoichiometric CD-and U-ICs and (n-s)-CD-ICs and those un-included chain portions in the (n-s)-CD-ICs exhibit significantly elevated T g s. This is demonstrated [34] for atactic PVAc and PMMA in Figure 8. In addition, as observed and noted above for semi-crystalline guest polymers coalesced from their CD-and U-ICs, the T g s of amorphous guest polymers coalesced from their CD-and U-ICs also remain elevated above those of their as-received samples even upon being annealed considerably above T g for long periods of time.…”

Section: Amorphous Polymers Coalesced From Their Stoichiometric and (mentioning

confidence: 66%

“…In addition, as observed and noted above for semi-crystalline guest polymers coalesced from their CD-and U-ICs, the T g s of amorphous guest polymers coalesced from their CD-and U-ICs also remain elevated above those of their as-received samples even upon being annealed considerably above T g for long periods of time. The T g s of coalesced (c)-poly(vinyl acetates) (PVAcs) annealed at 70 °C for 0, 8, 14, and 28 days were 41.5, 41.7, 41.5, and 41.2° C, respectively [34].…”

Section: Amorphous Polymers Coalesced From Their Stoichiometric and (mentioning

confidence: 99%

“…(N-S)-CD-ICs were formed with amorphous PVAc and PMMA and examined by DSC [34]. Table 2 presents the T g s measured for (n-s)-PVAc-γ-CD-ICs with different stoichiometries, which lead to distinct lengths of uncovered un-included PVAc chain portions, as well as those of asr-and c-PVAcs.…”

Section: (N-s)-ics With Amorphous Guest Polymersmentioning

confidence: 99%

“…Behaviors of amorphous polymers threaded through and coalesced from their (n-s)-CD-ICs and stoichiometric CD-and U-ICs (see Figure 7) have also been blended/mixed and examined [32][33][34]. In general, the glass transition temperatures, T g s, of amorphous guest polymers coalesced from their stoichiometric CD-and U-ICs and (n-s)-CD-ICs and those un-included chain portions in the (n-s)-CD-ICs exhibit significantly elevated T g s. This is demonstrated [34] for atactic PVAc and PMMA in Figure 8.…”

Section: Amorphous Polymers Coalesced From Their Stoichiometric and (mentioning

confidence: 99%

“…Comparison of blending poly(methyl methacrylate) (PMMA) and poly(vinyl acetate) (PVAc) via coalescence from stoichiometric U-IC and formation of (n-s)-γ-CD-ICs [34].…”

Section: Figurementioning

confidence: 99%

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Non-Stoichiometric Polymer-Cyclodextrin Inclusion Compounds: Constraints Placed on Un-Included Chain Portions Tethered at Both Ends and Their Relation to Polymer Brushes

Tonelli

2014

Polymers

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When non-covalently bonded crystalline inclusion compounds (ICs) are formed by threading the host cyclic starches, cyclodextrins (CDs), onto guest polymer chains, and excess polymer is employed, non-stoichiometric (n-s)-polymer-CD-ICs, with partially uncovered and "dangling" chains result. The crystalline host CD lattice is stable to ~300 °C, and the uncovered, yet constrained, portions of the guest chains emanating from the CD-IC crystal surfaces behave very distinctly from their neat bulk samples. In CD-IC crystals formed with α-and γ-CD hosts, each containing, respectively, six and eight 1,4-α-linked glucose units, the channels constraining the threaded portions of the guest polymer chains are ~0.5 and 1.0 nm in diameter and are separated by ~1.4 and 1.7 nm. This results in dense brushes with ~0.6 and 0.4 chains/nm 2 (or 0.8 if two guest chains are included in each γ-CD channel) of the un-included portions of guest polymers emanating from the host CD-IC crystal surfaces. In addition, at least some of the guest chains leaving from a crystalline CD-IC surface re-enter another CD-IC crystal creating a network structure that leads to shape-memory behavior for (n-s)-polymer-CD-ICs. To some extent, (n-s)-polymer-CD-ICs can be considered as dense polymer brushes with chains that are tethered on both ends. Not surprisingly, the behavior of the un-included portions of the guest polymer chains in (n-s)-polymer-CD-ICs are quite different from those of their neat bulk samples, with higher glass-transition and melt crystallization temperatures and crystallinities. Here we additionally compare their behaviors to samples coalesced from their stoichiometric ICs, and more importantly to dense polymer brushes formed by polymer chains chemically bonded to surfaces at only one end. Judging on the basis of their glass-transition, crystallization and melting temperatures, and crystallinities, we generally find the un-included portions of OPEN ACCESSPolymers 2014, 6 2167 chains in (n-s)-polymer-CD-ICs to be more constrained than those in neat bulk as-received and coalesced samples and in high density brushes. The last observation is likely because many of the un-included chain portions in (n-s)-polymer-CD-ICs are tethered/constrained at both ends, while the chains in their dense brushes are tethered at only one end.

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Section: Amorphous Polymers Coalesced From Their Stoichiometric and (mentioning

confidence: 66%

Section: Amorphous Polymers Coalesced From Their Stoichiometric and (mentioning

confidence: 99%

Section: (N-s)-ics With Amorphous Guest Polymersmentioning

confidence: 99%

Section: Amorphous Polymers Coalesced From Their Stoichiometric and (mentioning

confidence: 99%

“…Comparison of blending poly(methyl methacrylate) (PMMA) and poly(vinyl acetate) (PVAc) via coalescence from stoichiometric U-IC and formation of (n-s)-γ-CD-ICs [34].…”

Section: Figurementioning

confidence: 99%

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Non-Stoichiometric Polymer-Cyclodextrin Inclusion Compounds: Constraints Placed on Un-Included Chain Portions Tethered at Both Ends and Their Relation to Polymer Brushes

Tonelli

2014

Polymers

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Inclusion Compounds Containing Polymers

Zhong

Gao

Guo

et al. 2016

Kirk-Othmer Encyclopedia of Chemical Technology

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Inclusion compounds formed between host and guest molecules via noncovalent interaction exhibit novel properties and functions compared to the constituting species. The focus in this encyclopedia article is on the inclusion compounds containing polymers, as either hosts or guests. Among the hosts, the small molecular hosts can be divided into two categories: the small molecular hosts with intramolecular cavity, such as cyclodextrins (CDs) and cucurbiturils (CBs); the others with intermolecular cavity, such as urea, thiourea, choleic acids, deoxycholic acids, perhydrotriphenylene, tris(o‐phenylenedioxy)cyclotriphosphazene, some small molecular drugs, etc. Depending on the size of the cavity and the intermolecular interactions, chains of polyolefins, polyethers, polyesters, conjugated polymers, and ionic polymers can be accommodated in the cavities to form inclusion compounds. Besides the small molecular host, there are also many inclusion compounds with polymer chains as hosts, among them amylose, poly( l ‐lactic acid), stereoregular polystyrene, linear d,l ‐peptides, oligophenylacetylenes, and poly(ethylene oxide) are reviewed. Finally, applications of inclusion compounds containing polymers in the fields of separation, stereocontrolled polymerization, sensors, drug and gene delivery, nucleating agents, gels, self healing materials, molecular rotor, and molecular wires, are introduced.

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The Role of Polymer Crystallizability on the Formation of Polymer-Urea-Inclusion Compounds

Shen¹,

Li²,

Caydamli³

et al. 2018

Crystal Growth & Design

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Polymer-urea inclusion compounds (P-U-ICs) were formed using a series of linear aliphatic polyesters with varying crystallizabilities: from highly crystalline to wholly amorphous. The traditional hexagonal P-U-ICs were obtained irrespective of the crystallinities of the neat guest polyesters. Two distinct co-crystallization mechanisms were evident based on the observation of the change in thermal stabilities of the ICs using DSC and the crystal morphologies by SEM; one involves polymer chain folding back and forth in a lamella-like crystal structure and the other grows much like short chain molecule U-ICs absent of chain reentering different channels. For polymers with sufficient chain length, their inherent flexibility is the key factor determining the co-crystallization mechanism while their crystallizability affects the kinetics, the consequences of which are more pronounced during recrystallization from melt. The amorphicity induced by random ester group placement is an interchain property, which does not play a role in affecting IC thermal stability. Rather, increasing the average ester group content can be understood as introducing more defects in the IC crystal and therefore reduces its thermal stability. The understanding gleaned in this study provides a new avenue for designing P-U-ICs to be used in both theoretical modeling and engineering of high-performance materials.

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Glass‐transition temperatures of nanostructured amorphous bulk polymers and their blends

Cited by 9 publications

References 26 publications

Non-Stoichiometric Polymer-Cyclodextrin Inclusion Compounds: Constraints Placed on Un-Included Chain Portions Tethered at Both Ends and Their Relation to Polymer Brushes

Non-Stoichiometric Polymer-Cyclodextrin Inclusion Compounds: Constraints Placed on Un-Included Chain Portions Tethered at Both Ends and Their Relation to Polymer Brushes

Inclusion Compounds Containing Polymers

The Role of Polymer Crystallizability on the Formation of Polymer-Urea-Inclusion Compounds

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