Synthesis of highly isotactic poly 1-hexene using Fe-doped Mg(OEt)₂/TiCl₄/ED Ziegler–Natta catalytic system

Figures & data

Figure 1. The XRD patterns of Mg(OEt)₂ and Mg(OEt)₂/FeCl₃ 10%.

Table 1. Composition, abbreviation, and Ti content of the prepared catalysts.

Catalytic precursor	Catalyst code	Ti %
TiCl4/Mg(OEt)2	Cat A	7.8
TiCl4/Mg(OEt)2/FeCl3/SiCl4	Cat B	4.41
TiCl4/Mg(OEt)2/FeCl3/SiCl4/EB	Cat C	4.12
TiCl4/Mg(OEt)2/FeCl3/SiCl4/DNBP	Cat D	3.95
TiCl4/Mg(OEt)2/FeCl3/SiCl4/DNBP/CMMS	Cat E	3.95

Figure 2. The XRD patterns of Cat C and Cat D.

Figure 3. Expanded side chain methylene (C3) resonance patterns of PHs synthesized using Cat B, Cat C, and Cat D.

Figure 4. Expanded side chain methylene (C3) resonance patterns of poly(1-hexene) polymerized using Cat D in 25 °C.

Figure 5. MWD curve of PHs synthesized by different catalytic systems.

Figure 6. DSC curves of PHs obtained from (a) Cat C, Cat D, and Cat E in Tg region and (b) Cat C in Tm region.

Figure 7. DTMA curves of PHs obtained from Cat D and Cat E.

Figure 8. The TGA analysis of PH synthesized with Cat D.

Figure 9. Employed models for the simulation of propene insertion into Ti-iBu active center. (a) MgCl-UD as undoped catalyst, (b) MgCl-D1 and (c) MgCl-D2 as doped catalyst models.

Figure 10. Complex viscosity versus frequency for PHs obtained from Cat C, D and E at 140 °C.

Figure 11. Storage and loss modulus versus frequency for poly(1-hexene) obtained with Cat-C, D and E at 140 °C.

Table 2. Elemental analysis of the prepared catalysts.

Sample	Cl	Mg	Fe	C	Si
Cat A	61.4	10.3	–	3	–
Cat B	66.2	8.6	1.6	2.8	1.2
Cat C	47.43	8.1	0.9	24.7	1.9
Cat D	51.23	7.8	1.2	27.6	1.6

Table 3. Activity of the synthesized catalysts toward 1-hexene polymerization.^a

Catalysts	Activity (g polymer/g Ti h)
Cat A	950
Cat B	6500
Cat C	10,050
Cat D	9900
Cat E	5200

^a Polymerization conditions: Cocatalyst: TEA, Al/Ti = 30, T = 50 °C, t = 2 h.

Scheme 1. PH structural unit.

Table 4. The tacticity pentad content in C3 methylene region.

Sample	Isotactic^a %	Heterotactic^b %	Syndiotactic^b %	Tacticity %
Cat A	66	29	5	72
Cat B	65	30	4	75
Cat C	74	15	11	83
Cat D	77	13	10	85
Cat E	87	10	3	90

^a Isotactic(mm).

^b Heterotactic(rm).

^c Syndiotactic(rr).

Table 5. Molecular weight and MWD of PHs by different catalysts.^a

Catalysts	Mw	Mn	PDI
Cat A	318,065	40,936	7.7
Cat B	271,505	27,394	9.9
Cat C	193,215	21,756	8.8
Cat D	483,425	48,802	9.9
Cat E	311,705	33,516	9.3

^a Polymerization conditions: Cocatalyst: TEA, Al/Ti = 30, T = 50 °C, t = 2 h.

Table 6. The melting and glass transition temperatures by DSC trace of PHs obtained from different catalysts.

Catalysts	Thermal transitions (°C)
	Tg^a	Tm^a	Tg^b
Cat A	−42.3	–	–
Cat B	−41.7	–	–
Cat C	−47.6	83.0	−29.3
Cat D	−41.2	–	−26.1
Cat E	−41.9	–	−26.3

^a From DSC.

^b From DMTA.

Table 7. ΔE_re-si for the primary insertion of propene into the Ti-iBu bond of the models depicted in Figure 9 in the presence and absence of DNBP and EB EDs.

Catalyst label	ΔEre-si (kcal/mol)
MgCl-UD	0.23
MgCl-D1	0.19
MgCl-D2	0.20
MgCl-D1-DNBP	2.69
MgCl-D2-DNBP	2.64
MgCl-D1-EB	2.50
MgCl-D2-EB	2.48

Table 8. The cross-fitting parameters and crossover point characteristics.

Sample	Cross model			Cross over point
	η0 (Pa s)		1 − n	ωC (s^−1)	GC (Pa)
Cat C	485.92	3.09	0.396	188	7000
Cat D	18950.5	9.15	0.67	0.576	1140
Cat E	1250.86	5.52	0.49	33.2	5190