Dual Light-emitting Properties of Hydroxyl-terminated Poly(lactic acid) Based on Benzophenone Derivatives†

doi:10.7503/cjcu20160326

Abstract

Abstract:

Two kinds of benzophenone derivatives:(4-[(2-hydroxyethyl)(methyl)amino] phenyl) benzophenone(NBP), (4-chlorophenyl)(4-[(2-hydroxyethyl)(methyl)amino] benzophenone(NBP-Cl), and a series of hydroxyl-terminated polylactic acid(PLA) with different molecular weight were prepared based on D,L-lactide polymerization. The structures and properties of NBP, NBP-Cl and PLA were characterized. Optical test results showed that the NBP and NBP-Cl only had fluorescence emission property at room temperature, however, PLA demonstrated fluorescence and phosphorescence dual light-emitting properties; the heavy atom effect enhanced the room temperature phosphorescence of PLA, but which decreased the phosphorescence lifetime; with the decrease of the molecular weight of PLA, the phosphorescence lifetime increased and then reduced. PLA thermal gravimetric analysis(TGA) data showed that this material had excellent thermal performance, which greatly broaden the applications of the dual light-emitting materials.

Key words: Benzophenone derivative, Hydroxyl-terminated polylactic acid, Fluorescence, Room temperature phosphorescence, Dual light-emitting property

CLC Number:

O632.4

TrendMD:

RONG Jiameng,ZHOU Cao,XU Dong,SUN Wei,HUANG Xiaowen,ZHANG Xingyuan. Dual Light-emitting Properties of Hydroxyl-terminated Poly(lactic acid) Based on Benzophenone Derivatives^†[J]. Chem. J. Chinese Universities, 2016, 37(8): 1542.

Figures/Tables 17

Scheme 1 Synthetic route of NBP

Scheme 2 Synthetic route of NBP-Cl

Table 1 Synthesis of NBP-PLA with different contents of NBP and NBP-Cl-PLA with different contents of NBP-Cl

Sample	m_NBP(NBP-Cl)/g	m_D_,_L_-Lactide/g	$m Sn (Oct) 2$ /g	Sample	m_NBP(NBP-Cl)/g	m_D_,_L_-Lactide/g	$m Sn (Oct) 2$ /g
NBP-PLA1	0.15	14.85	0.30	NBP-Cl-PLA1	0.15	14.85	0.30
NBP-PLA2	0.30	14.50	0.35	NBP-Cl-PLA2	0.30	14.50	0.35
NBP-PLA5	0.45	8.55	0.18	NBP-Cl-PLA5	0.45	8.55	0.18
NBP-PLA10	1.20	10.50	0.23	NBP-Cl-PLA10	1.20	10.50	0.23

Table 1 Synthesis of NBP-PLA with different contents of NBP and NBP-Cl-PLA with different contents of NBP-Cl

Sample	m_NBP(NBP-Cl)/g	m_D_,_L_-Lactide/g	$m Sn (Oct) 2$ /g	Sample	m_NBP(NBP-Cl)/g	m_D_,_L_-Lactide/g	$m Sn (Oct) 2$ /g
NBP-PLA1	0.15	14.85	0.30	NBP-Cl-PLA1	0.15	14.85	0.30
NBP-PLA2	0.30	14.50	0.35	NBP-Cl-PLA2	0.30	14.50	0.35
NBP-PLA5	0.45	8.55	0.18	NBP-Cl-PLA5	0.45	8.55	0.18
NBP-PLA10	1.20	10.50	0.23	NBP-Cl-PLA10	1.20	10.50	0.23

Scheme 3 Preparation process of NBP-PLA and NBP-Cl-PLA

Fig.1 1H NMR(A, C) and 13C NMR spectra(B, D) of NBP(A, B) and NBP-Cl(C, D)

Fig.2 FTIR spectra of NBP(A) and NBP-Cl(B)

Fig.3 1H NMR spectra of NBP-PLA1(A), NBP-PLA2(B), NBP-PLA5(C) and NBP-PLA10(D)

Fig.4 1H NMR spectra of NBP-Cl-PLA1(A), NBP-Cl-PLA2(B), NBP-Cl-PLA5(C) and NBP-Cl-PLA10(D)

Table 2 Polymerization, relative molecular mass and PDI of NBP-PLA 1—10 and NBP-Cl-PLA 1—10

Sample	Degree of polymerization		Molecular weight(actual value of NMR)		$M n *$	$M w *$	PDI
Sample	Theoretical	Actual			$M n *$	Theoretical	Actual
NBP-PLA1	350.6	330.6	25500	24000	34200	58000	1.69
NBP-PLA2	171.2	155	12500	11400	18100	23000	1.27
NBP-PLA5	67.3	76.7	5100	5700	9400	12000	1.27
NBP-PLA10	30.9	37.2	2400	2900	5200	6600	1.26
NBP-Cl-PLA1	397.4	356.7	28900	25900	75000	91000	1.21
NBP-Cl-PLA2	194.0	195.0	14200	14300	29000	50000	1.72
NBP-Cl-PLA5	76.3	88.0	5700	6600	12000	19000	1.58
NBP-Cl-PLA10	35.1	36.0	2800	2800	8600	11100	1.39

Table 2 Polymerization, relative molecular mass and PDI of NBP-PLA 1—10 and NBP-Cl-PLA 1—10

Sample	Degree of polymerization		Molecular weight(actual value of NMR)		$M n *$	$M w *$	PDI
Sample	Theoretical	Actual			$M n *$	Theoretical	Actual
NBP-PLA1	350.6	330.6	25500	24000	34200	58000	1.69
NBP-PLA2	171.2	155	12500	11400	18100	23000	1.27
NBP-PLA5	67.3	76.7	5100	5700	9400	12000	1.27
NBP-PLA10	30.9	37.2	2400	2900	5200	6600	1.26
NBP-Cl-PLA1	397.4	356.7	28900	25900	75000	91000	1.21
NBP-Cl-PLA2	194.0	195.0	14200	14300	29000	50000	1.72
NBP-Cl-PLA5	76.3	88.0	5700	6600	12000	19000	1.58
NBP-Cl-PLA10	35.1	36.0	2800	2800	8600	11100	1.39

Fig.5 FTIR spectra of NBP-PLA(A) and NBP-Cl-PLA(B) (A) a. NBP-PLA1; b. NBP-PLA2; c. NBP-PLA5; d. NBP-PLA10. (B) a. NBP-Cl-PLA1; b. NBP-Cl-PLA2; c. NBP-Cl-PLA5; d. NBP-Cl-PLA10.

Fig.6 DSC curves of NBP-PLA1(a), NBP-PLA2(b), NBP-PLA5(c) and NBP-PLA10(d)(A) and NBP-Cl-PLA1(a), NBP-Cl-PLA2(b), NBP-Cl-PLA5(c) and NBP-Cl-PLA10(d)(B) powders under nitrogen condition

Fig.7 XRD curves of NBP-PLA1(a), NBP-PLA2(b), NBP-PLA5(c) and NBP-PLA10(d)(A) and NBP-Cl-PLA1(a), NBP-Cl-PLA2(b), NBP-Cl-PLA5(c) and NBP-Cl-PLA10(d)(B) powders

Table 3 Crystallinity of NBP-PLA and NBP-Cl-PLA powders*

Sample	X_c (%)	Sample	X_c(%)
NBP-PLA1	33.28	NBP-Cl-PLA1	51.28
NBP-PLA2	48.80	NBP-Cl-PLA2	54.83
NBP-PLA5	37.23	NBP-Cl-PLA5	35.78
NBP-PLA10	28.62	NBP-Cl-PLA10	23.68

Fig.8 Excitation spectra and fluorescence spectra for NBP(A) and NBP-Cl(B)

Fig.9 Photoluminescence excitation and fluorescence emission and photoluminescence emission mixed fluorescence and strong phosphoresce of NBP-PLA1(a), NBP-PLA2(b), NBP-PLA5(c) and NBP-PLA10(d)(A) and NBP-Cl-PLA1(a), NBP-Cl-PLA2(b), NBP-Cl-PLA5(c) and NBP-Cl-PLA10(d)(B) films in vacuum

Fig.10 Phosphorescence lifetime spectra of NBP-PLA1(a), NBP-PLA2(b), NBP-PLA5(c) and NBP-PLA10(d) films(A) an NBP-Cl-PLA1(a), NBP-Cl-PLA2(b), NBP-Cl-PLA5(c) and NBP-Cl-PLA10(d) films(B) Insets: Decay vs. content of NBP.

Fig.11 TGA curves of NBP-PLA1(a), NBP-PLA2(b), NBP-PLA5(c) and NBP-PLA10(d)(A) and NBP-Cl-PLA1(a), NBP-Cl-PLA2(b), NBP-Cl-PLA5(c) and NBP-Cl-PLA10(d)(B) powders

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