Star-shaped poly(N-vinylcaprolactam) and...
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Centro de Graduados e Investigación en Química, Instituto Tecnológico
de Tijuana.
A. P. 1166. Tijuana, B. C. 22000, México. E-mail: [email protected]
Norma Aidé Cortez-Lemus, 2019
Star-shaped poly(N-vinylcaprolactam) and copolymers
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❖High density of internal and peripheral functional groups
compared to linear polymers of similar molecular weight
❖Synthesis of star polymers with a precise number of arms
❖The star polymers exhibit lower solution viscosity in dilute
solutions
❖Smaller hydrodynamic volume
❖Amphiphilic star block copolymers can encapsulate
efficiently drugs
Importance of the study of star-shaped
polymers
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Kowollik, B. C.; Davis, P. T.; Stenzel, H. M. Aust. J. Chem. 2006,
59, 719-727.
Comparison of star synthesis using the core-first
technique using the Z-group (left) and R-group (right)
approaches.
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G. D. García-Olaiz, K. A. Montoya-Villegas, A. Licea-Claverie, N. A. Cortez-Lemus. Synthesis andcharacterization of four- and six-arm star-shaped poly(ε-caprolactone)-b-poly(N-vinylcaprolactam): Micellar and core degradation studies. Reactive & Functional Polymers2015, 88, 16-23.
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PNVCLPEGPEHA
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(PVAc-b-(PNVCL-co-PNVP))6
(PNVCL-co-PNVP)6
(PNVCL)6
((PNVCL-co-PNVP)-b-PVAc)6
(PNVCL-b-PVAc)6
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Poly(N-vinylcaprolactam) (PNVCL)
Poly(N-isopropylacrylamide) (PNIPAM)
Thermally responsivepolymers
LCST ~32 °CLCST ~30-50 °C
C=O ---- H-N
Internal hydrogen-bond:
Flory–Huggins type I
Flory–Huggins type II
Biocompatible
Thermosensitive polymers
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Influence of End Groups on aqueous
properties of thermosensitive polymers
The LCST decreased or increased in thermosensitive polymers having
hydrophobic or hydrophilic end groups.
Solubility
Strong influence of end-groups on activity and cytotoxicity in
antimicrobials polymers.
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G. D. García-Olaiz, K. A. Montoya-Villegas, A. Licea-Claverie, N. A. Cortez-Lemus. Synthesis andcharacterization of four- and six-arm star-shaped poly(ε-caprolactone)-b-poly(N-vinylcaprolactam): Micellar and core degradation studies. Reactive & Functional Polymers2015, 88, 16-23.
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G. D. García-Olaiz, K. A. Montoya-Villegas, A. Licea-Claverie, N. A. Cortez-Lemus. Synthesis andcharacterization of four- and six-arm star-shaped poly(ε-caprolactone)-b-poly(N-vinylcaprolactam): Micellar and core degradation studies. Reactive & Functional Polymers2015, 88, 16-23.
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G. D. García-Olaiz, K. A. Montoya-Villegas, A. Licea-Claverie, N. A. Cortez-Lemus. Synthesis andcharacterization of four- and six-arm star-shaped poly(ε-caprolactone)-b-poly(N-vinylcaprolactam): Micellar and core degradation studies. Reactive & Functional Polymers2015, 88, 16-23.
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Fig. 1. 1H NMR spectra (200 MHz) of six-arm star-shaped block copolymers with different molarcompositions. a) Mn,GPC=75,300 g/mol and b) Mn,GPC=26,900 g/mol.
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G. D. García-Olaiz, K. A. Montoya-Villegas, A. Licea-Claverie, N. A. Cortez-Lemus. Synthesis andcharacterization of four- and six-arm star-shaped poly(ε-caprolactone)-b-poly(N-vinylcaprolactam): Micellar and core degradation studies. Reactive & Functional Polymers2015, 88, 16-23.
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Fig. 6. Hydrodynamic diameter of micellar aggregates determined by DLS at 25 °C (c = 1 mg/mL).
Fig. 7. LCST determined by DLS showingaggregation (samples S(PCL20-b-PNVCL69)4,S(PCL19-b-PNVCL75)6 and S(PCL19-b-PNVCL27)6 ora decrease in the hydrodynamic diameterS(PCL19-b-PNVCL13)6 in the micelle above theLCST.
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Fig. 4. Representative images for micellescorresponding to sample S(PCL10-b-PNVCL46)4. a) SEM images of micelles (c =0.013 mg/mL), b) AFM image of a deposit ona mica substrate of an aqueous dispersion ofmicelles (c = 0.02 mg/mL). The solventdisplacement method was used in thepreparation of the micelles.
Fig. 5. AFM images of deposits of aqueousdispersions of micelles obtained from six-armstar(PCL-b-PNVCL) block copolymers on a micasubstrate. a) Sample S(PCL19-b-PNVCL75)6 andb) Sample S(PCL19-b-PNVCL13)6. The solventdisplacement method was used in thepreparation of the micelles.
a) b)
a) b)
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Synthesis and characterization of “living” star-shaped
poly(N-vinylcaprolactam) with four arms and carboxylic
acid end-groups
Norma A. Cortez Lemus, Angel Licea-Claverie. J. Polym. Sci., Part A: Polym. Chem., 2016, 54,2156-2165. DOI: 10.1002/pola.28086.
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Synthesis of tetra-functional RAFT agent functionalized with carboxylic acid end groups.
RAFT AGENT 1
RAFT AGENT 1
Norma A. Cortez Lemus, Angel Licea-Claverie. J. Polym. Sci., Part A: Polym. Chem., 2016, 54,2156-2165. DOI: 10.1002/pola.28086.
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FIGURE 3 FT-IR spectra of a) CTA-1, b) star-shaped PNVCL-COOHpolymers and c) star-shaped S(PNVCL-b-PEHA) copolymers
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1.502.002.503.003.504.00
d
d
a
a
b
b
c e
ce
f g
f f
g
ppm
ppm
10.0010.5011.0011.50
h
h
1H NMR spectra (400 MHz) of tetra-functional CTA-1 with carboxylic acid end groups
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FIGURE 4 1H NMR (400 MHz) of star-shaped PNVCL-COOH polymers (sample S(PNVCL47)4)
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Table 1 Results for RAFT polymerization of NVCL in p-dioxane at 65 ˚C for 36 h in the
presence of CTA-1.a
Entry Sample [NVCL]o: [CTA]o
Conv.b
(%) Mn theor
c Mn GPC
(g/mol)d
Ðe Mn UV-vis
f
1 S(PNVCL18)4 108:1 53 9,200 10,000 1.12 8,800
2 S(PNVCL47)4 246:1 45 16,621 26,000 1.05 21,200
3 S(PNVCL68)4 540:1 49 38,000 38,000 1.15 43,100
4 S(PNVCL94)4 700:1 41 41,100 52,000 1.02 53,500
5 S(PNVCL122)4 900:1 52 64,100 66,300 1.03 84,000
a[NVCL]= 4.8 mol/L.
bDetermined gravimetrically.
cCalculated using eqn Mn theo= MCTA + conversion (MNVCL[NVCL]o/[CTA]o)
d,eBy GPC in THF with RI detector using polystyrene linear standards for calibration and using dn/dc
0.109 (mL/g) for PNVCL.28
fCalculated by end group analysis of UV band (trithiocarbonate absorbance at λ 307 nm, employing ε of the CTA-1).
Norma A. Cortez Lemus, Angel Licea-Claverie. J. Polym. Sci., Part A: Polym. Chem., 2016, 54,2156-2165. DOI: 10.1002/pola.28086.
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DLS measurements. Effects of molecular weight on the LCST of star PNVCL-COOH polymers determined by DLS (c = 1 mg/mL).
Norma A. Cortez Lemus, Angel Licea-Claverie. J. Polym. Sci., Part A: Polym. Chem., 2016, 54,2156-2165. DOI: 10.1002/pola.28086.
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DLS measurements. Effects of molecular weight on the LCST ofstar PNVCL-COOH polymers (c = 1 mg/mL)
Norma A. Cortez Lemus, Angel Licea-Claverie. J. Polym. Sci., Part A: Polym. Chem., 2016, 54,2156-2165. DOI: 10.1002/pola.28086.
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FIGURE 10 Effect of concentration on the LCST of star PNVCL-COOHpolymers (sample S(PNVCL47)4, Table 1, Mn GPC=26,000 g/mol).
Norma A. Cortez Lemus, Angel Licea-Claverie. J. Polym. Sci., Part A: Polym. Chem., 2016, 54,2156-2165. DOI: 10.1002/pola.28086.
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ppm0.01.02.03.04.05.0
a
bc,i
d,e,h,j
f
g
a
d
cb
e ee
fg
g
h i
j
k
kkk
k
1H-NMR (400 MHz) spectrum of star-shaped PNVCL-b-PEHA-COOH copolymer in CDCl3
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FIGURE 8 DLS measurements (c = 1 mg/mL). Hydrodynamic diameter of S(PNVCL)polymer (Mn GPC=66,300 g/mol) and hydrodynamic diameter of micellar aggregatesfrom S(PNVCL-b-PEHA) copolymer (Mn GPC=69,200 g/mol);
Norma A. Cortez Lemus, Angel Licea-Claverie. J. Polym. Sci., Part A: Polym. Chem., 2016, 54,2156-2165. DOI: 10.1002/pola.28086.
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PNVCLPEGPEHA
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CTA trithiocarbonate type
N. A. Cortez Lemus and A. Licea-Claverie, Aust. J. Chem. 2017, 70, 1291-1301.
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N. A. Cortez Lemus and A. Licea-Claverie, Aust. J. Chem. 2017, 70, 1291-1301.
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N. A. Cortez Lemus and A. Licea-Claverie, Aust. J. Chem. 2017, 70, 1291-1301.
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N. A. Cortez Lemus and A. Licea-Claverie, Aust. J. Chem. 2017, 70, 1291-1301.
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N. A. Cortez Lemus and A. Licea-Claverie, Aust. J. Chem. 2017, 70, 1291-1301.
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(PNVCL-b-PEHA-b-PEG)6
PNVCLPEGPEHA
Triblock copolymer Micellar aggregate
N. A. Cortez Lemus and A. Licea-Claverie, Aust. J. Chem. 2017, 70, 1291-1301.
Aggregates in aqueous solution from star (PNVCL-
b-PEHA-b-PEG)6 triblock copolymer
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N. A. Cortez Lemus and A. Licea-Claverie, Aust. J. Chem. 2017, 70, 1291-1301.
Figure 12 Drug release from thermoresponsive star polymeric aggregates containing MTX, a) 33 °C and b) 37 °C.
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(PVAc-b-(PNVCL-co-PNVP))6
(PNVCL-co-PNVP)6
(PNVCL)6
((PNVCL-co-PNVP)-b-PVAc)6
(PNVCL-b-PVAc)6
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Preparation of a Mini-Library of Thermo-Responsive Star(NVCL/NVP-VAc) Polymers with Tailored Properties Using aHexafunctional Xanthate RAFT Agent
Norma A. Cortez Lemus and A. Licea-Claverie, Polymers , 2018, 10 (1), 20
(PVAc-b-(PNVCL-co-PNVP))6
(PNVCL-co-PNVP)6(PNVCL)6((PNVCL-co-PNVP)-b-PVAc)6
(PNVCL-b-PVAc)6
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Norma A. Cortez Lemus and A. Licea-Claverie, Polymers, 2018, 10 (1), 20
Scheme 1. Synthesis of hexafunctional star polymers and block copolymers based onPNVCL using a multifunctional xanthate as a RAFT agent.
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Figure 2. Dynamic light scattering (DLS) measurements (c = 1 mg/mL in water): (a) effects ofmolecular weight on the lower critical solution temperature (LCST) of star (PNVCL)6 polymers;and (b) evolution of the Dh of the (PNVCL)6 polymers as a function of the temperature.
Norma A. Cortez Lemus and A. Licea-Claverie, Polymers, 2018, 10 (1), 20
Star (PNVCL)6 polymers in aqueous solution: LCST and Dh
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Figure 3. DLS measurements. Evolution of the Dh of the star (PNVCL)6 polymers as a function of the molecular weight (c = 1 mg/mL).
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Figure 5. 1H-NMR (400 MHz) spectrum of a star (PNVCL-b-PVAc)6 copolymer in CDCl3(Table 2, sample (PNVCL99-b-PVAc21)6, Mn GPC = 94,300 g/mol, Ð = 1.04, 20% of PVAc).
Norma A. Cortez Lemus and A. Licea-Claverie, Polymers, 2018, 10 (1), 20
Star (PNVCL-b-PVAc)6
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Figure 6. DLS measurements (c = 1 mg/mL in water) for star (PNVCL-b-PVAc)6 block copolymers:(a) Dh of (PNVCL99)6 and the corresponding (PNVCL99-b-PVAc)6 block copolymers, measured at 20°C; and (b) evolution of the Dh of the (PNVCL99)6 and (PNVCL99-b-PVAc)6 as a function of thetemperature.
Star (PNVCL-b-PVAc)6
Norma A. Cortez Lemus and A. Licea-Claverie, Polymers, 2018, 10 (1), 20
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Figure 7. Self-assembly in aqueous solution of star (PNVCL-b-PVAc)6 block copolymers: (a) multiple star micelles; and (b) single flower-like micelle.
Norma A. Cortez Lemus and A. Licea-Claverie, Polymers . 2018, 10 (1), 20
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Scheme 3. Synthesis of the star [PVAc-b-(PNVCL-co-PNVP)]6
block copolymers.
Norma A. Cortez Lemus and A. Licea-Claverie, Polymers . 2018, 10 (1), 20
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Figure 8. 1H NMR spectrum (400 MHz) in CDCl3 of star-shaped (PVAc-b-(PNVCL-co-PNVP))6
block copolymers. Sample (PVAc30-b-(PNVCL28-co-PNVP17))6, Mn GPC = 42,290 g/mol, Ð = 1.1 (Table 4, Entry 2).
Norma A. Cortez Lemus and A. Licea-Claverie, Polymers . 2018, 10 (1), 20
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Figure 9. “Height” image and “3D reconstruction“ from AFM of almost spherical aggregates obtained from six-arm star block copolymers on a mica substrate (c = 0.02 mg/mL): (a,b) Sample (PVAc22-b-PNVCL11)6, Entry 1, Table 4; (c,d) Sample [PVAc30-b-(PNVCL28-co-PNVP17)]6, Entry 2, Table 4; and (e,f) Sample [PVAc17-b-(PNVCL10-co-PNVP7)]6, Entry 3, Table 4.
AFM of almost spherical aggregates from star [PVAc-b-(PNVCL-co-PNVP)]6 block copolymers.
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1730 MTX
Sample (PVAc22-b-PNVCL11)6 loaded with MTX
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17108C
RMS: 1.16DP = 140 nm
Sample [PVAc30-b-(PNVCL28-co-PNVP17)]6 loaded with MTX
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Star [PVAc-b-(PNVCL-co-PNVP)]6 block copolymers.
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1766