Chain flexibility and glass transition temperatures of poly(n-alkyl (meth)acrylate)s: Implications of tacticity and chain dynamics

Tianyu Li; Hui Li; Huiqun Wang; Wei Lu; Masashi Osa; Yangyang Wang; Jimmy Mays; Kunlun Hong

doi:10.1016/j.polymer.2020.123207

Chain flexibility and glass transition temperatures of poly(n-alkyl (meth)acrylate)s: Implications of tacticity and chain dynamics

Tianyu Li, Hui Li, Huiqun Wang, Wei Lu, Masashi Osa, Yangyang Wang, Jimmy Mays, Kunlun Hong

Macromolecular Nanomaterials

Research output: Contribution to journal › Article › peer-review

28 Scopus citations

Abstract

The relationship between chain microstructure and glass transition temperature (T_g) is complicated for poly(alkyl methacrylate)s and poly(alkyl acrylate)s. Despite intensive studies, relationships between the structures of these polymers and their properties, including solution characteristics and T_g, are still controversial. Solution properties, chain conformations, including Flory's characteristic ratio (C_∞), persistence length (l_p), and chain diameters, and T_g are reported for series of poly(n-alkyl acrylate)s and poly(n-alkyl methacrylate)s having alkyl side chain lengths (n) ranging from 1 to 10 carbons in length, with uniform and well-characterized tacticities. Chain flexibilities of both series of polymers decrease as n increases, reflecting increased hindrances to rotation about backbone bonds as side chains become longer. Conversely, the T_gs for both series of polymers decrease substantially as n increases, reflecting the greater side chain mobilities of long alkyl substituents. For shorter alkyl chain lengths, T_gs for the poly(n-alkyl acrylate)s are much lower than for the corresponding poly(n-alkyl methacrylate)s, a difference which has been attributed in the past to the presumed reduced chain flexibility of polymethacrylates due to the presence of the α-methyl substituent. However, contrary to such expectations, C_∞ and l_p values for these two series of polymers are nearly identical at a given n value, except for the longest n-alkyl substituents. Instead, the differences in T_g may be attributed to the differences in tacticity of the two series – almost ideally atactic for the poly(n-alkyl acrylate)s but high in syndiotacticity for the poly(n-alkyl methacrylate)s. The T_gs for the two series of polymers approach that of polyethylene at longer alkyl chain lengths. In addition, the effects of tacticity and chain dynamics on C_∞, l_p, and T_g of poly(methyl methacrylate) is discussed.

Original language	English
Article number	123207
Journal	Polymer
Volume	213
DOIs	https://doi.org/10.1016/j.polymer.2020.123207
State	Published - Jan 20 2021

Funding

This manuscript has been authored in part by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ). This manuscript has been authored in part by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan).

Funders	Funder number
DOE Public Access Plan
US Department of Energy
U.S. Department of Energy

Keywords

Chain flexibility
Characteristic ratio
Glass transition temperature
Persistence length
Poly(n-alkyl acrylate)
Solution properties
Tacticity
poly(n-alkyl methacrylate)

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title = "Chain flexibility and glass transition temperatures of poly(n-alkyl (meth)acrylate)s: Implications of tacticity and chain dynamics",

abstract = "The relationship between chain microstructure and glass transition temperature (Tg) is complicated for poly(alkyl methacrylate)s and poly(alkyl acrylate)s. Despite intensive studies, relationships between the structures of these polymers and their properties, including solution characteristics and Tg, are still controversial. Solution properties, chain conformations, including Flory's characteristic ratio (C∞), persistence length (lp), and chain diameters, and Tg are reported for series of poly(n-alkyl acrylate)s and poly(n-alkyl methacrylate)s having alkyl side chain lengths (n) ranging from 1 to 10 carbons in length, with uniform and well-characterized tacticities. Chain flexibilities of both series of polymers decrease as n increases, reflecting increased hindrances to rotation about backbone bonds as side chains become longer. Conversely, the Tgs for both series of polymers decrease substantially as n increases, reflecting the greater side chain mobilities of long alkyl substituents. For shorter alkyl chain lengths, Tgs for the poly(n-alkyl acrylate)s are much lower than for the corresponding poly(n-alkyl methacrylate)s, a difference which has been attributed in the past to the presumed reduced chain flexibility of polymethacrylates due to the presence of the α-methyl substituent. However, contrary to such expectations, C∞ and lp values for these two series of polymers are nearly identical at a given n value, except for the longest n-alkyl substituents. Instead, the differences in Tg may be attributed to the differences in tacticity of the two series – almost ideally atactic for the poly(n-alkyl acrylate)s but high in syndiotacticity for the poly(n-alkyl methacrylate)s. The Tgs for the two series of polymers approach that of polyethylene at longer alkyl chain lengths. In addition, the effects of tacticity and chain dynamics on C∞, lp, and Tg of poly(methyl methacrylate) is discussed.",

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T2 - Implications of tacticity and chain dynamics

AU - Li, Tianyu

AU - Li, Hui

AU - Wang, Huiqun

AU - Lu, Wei

AU - Osa, Masashi

AU - Wang, Yangyang

AU - Mays, Jimmy

AU - Hong, Kunlun

PY - 2021/1/20

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N2 - The relationship between chain microstructure and glass transition temperature (Tg) is complicated for poly(alkyl methacrylate)s and poly(alkyl acrylate)s. Despite intensive studies, relationships between the structures of these polymers and their properties, including solution characteristics and Tg, are still controversial. Solution properties, chain conformations, including Flory's characteristic ratio (C∞), persistence length (lp), and chain diameters, and Tg are reported for series of poly(n-alkyl acrylate)s and poly(n-alkyl methacrylate)s having alkyl side chain lengths (n) ranging from 1 to 10 carbons in length, with uniform and well-characterized tacticities. Chain flexibilities of both series of polymers decrease as n increases, reflecting increased hindrances to rotation about backbone bonds as side chains become longer. Conversely, the Tgs for both series of polymers decrease substantially as n increases, reflecting the greater side chain mobilities of long alkyl substituents. For shorter alkyl chain lengths, Tgs for the poly(n-alkyl acrylate)s are much lower than for the corresponding poly(n-alkyl methacrylate)s, a difference which has been attributed in the past to the presumed reduced chain flexibility of polymethacrylates due to the presence of the α-methyl substituent. However, contrary to such expectations, C∞ and lp values for these two series of polymers are nearly identical at a given n value, except for the longest n-alkyl substituents. Instead, the differences in Tg may be attributed to the differences in tacticity of the two series – almost ideally atactic for the poly(n-alkyl acrylate)s but high in syndiotacticity for the poly(n-alkyl methacrylate)s. The Tgs for the two series of polymers approach that of polyethylene at longer alkyl chain lengths. In addition, the effects of tacticity and chain dynamics on C∞, lp, and Tg of poly(methyl methacrylate) is discussed.

AB - The relationship between chain microstructure and glass transition temperature (Tg) is complicated for poly(alkyl methacrylate)s and poly(alkyl acrylate)s. Despite intensive studies, relationships between the structures of these polymers and their properties, including solution characteristics and Tg, are still controversial. Solution properties, chain conformations, including Flory's characteristic ratio (C∞), persistence length (lp), and chain diameters, and Tg are reported for series of poly(n-alkyl acrylate)s and poly(n-alkyl methacrylate)s having alkyl side chain lengths (n) ranging from 1 to 10 carbons in length, with uniform and well-characterized tacticities. Chain flexibilities of both series of polymers decrease as n increases, reflecting increased hindrances to rotation about backbone bonds as side chains become longer. Conversely, the Tgs for both series of polymers decrease substantially as n increases, reflecting the greater side chain mobilities of long alkyl substituents. For shorter alkyl chain lengths, Tgs for the poly(n-alkyl acrylate)s are much lower than for the corresponding poly(n-alkyl methacrylate)s, a difference which has been attributed in the past to the presumed reduced chain flexibility of polymethacrylates due to the presence of the α-methyl substituent. However, contrary to such expectations, C∞ and lp values for these two series of polymers are nearly identical at a given n value, except for the longest n-alkyl substituents. Instead, the differences in Tg may be attributed to the differences in tacticity of the two series – almost ideally atactic for the poly(n-alkyl acrylate)s but high in syndiotacticity for the poly(n-alkyl methacrylate)s. The Tgs for the two series of polymers approach that of polyethylene at longer alkyl chain lengths. In addition, the effects of tacticity and chain dynamics on C∞, lp, and Tg of poly(methyl methacrylate) is discussed.

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KW - Glass transition temperature

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KW - Solution properties

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DO - 10.1016/j.polymer.2020.123207

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Chain flexibility and glass transition temperatures of poly(n-alkyl (meth)acrylate)s: Implications of tacticity and chain dynamics

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