Particles with radial variation
A polymeric bead having radius R wherein the polymer comprises 0.3% to 20% by weight, based on the weight of the polymer, of polymerized units of one or more multifunctional vinyl monomer and 80% to 99.7% by weight, based on the weight of the polymer, of polymerized units of one or more monofunctional vinyl monomer, (a) wherein the polymerized units of multifunctional vinyl monomer have radial distribution factor MR of 0.9 to 1.1, and (b) wherein some of the vinyl groups in the polymerized units of multivinyl monomer are unreacted, and the unreacted vinyl groups have a radial distribution factor VR of 2.5 or higher.
1. A polymeric bead having radius R wherein the polymer comprises 0.3% to 20% by weight, based on the weight of the polymer, of polymerized units of one or more multifunctional vinyl monomer and 80% to 99.7% by weight, based on the weight of the polymer, of polymerized units of one or more monofunctional vinyl monomer,
(a) wherein the polymerized units of multifunctional vinyl monomer have radial distribution factor MR of 0.9 to 1.1, wherein MR=CMSHELL/CMCORE, wherein CMSHELL is the average concentration of polymerized units of multifunctional vinyl monomer located at a distance from the center of the bead of 0.8*R to R, and wherein CMCORE is the average concentration of polymerized units of multifunctional vinyl monomer located at a distance from the center of the bead of 0 to 0.5*R, and
(b) wherein some of the vinyl groups in the polymerized units of multivinyl monomer are unreacted, and the unreacted vinyl groups have a radial distribution factor VR of 2.5 or higher, wherein VR is determined by a Raman spectroscopic measurement performed on the bead, wherein
VR=V 1SHELL/ V 1CORE,
wherein V1SHELL is the average of ratio V1 for measurements made at a distance from the center of the bead of 0.8*R to R, wherein V1CORE is the average of ratio V1 for measurements made at a distance from the center of the bead of 0 to 0.5*R, wherein V1=PCC/PAR, wherein PCC is the height of the Raman spectroscopic peak due to stretching of carbon-carbon double bonds, and PAR is the height of the Raman spectroscopic reference peak due to stretching of the aromatic ring at 1000 cm −1 .
2. The polymeric bead of claim 1 , wherein the polymeric bead comprises a gel-type resin.
3. The polymeric bead of claim 1 , wherein the monofunctional vinyl monomers comprise one or more styrenic monomer.
4. The polymeric bead of claim 1 , wherein the multifunctional vinyl monomers comprise one or more styrenic monomer.
5. The polymeric bead of claim 1 , wherein the polymer comprises 8% to 15% by weight, based on the weight of the polymer, of polymerized units of one or more multifunctional vinyl monomer and 85% to 92% by weight, based on the weight of the polymer, of polymerized units of one or more monofunctional vinyl monomer.
6. The polymeric bead of claim 1 , having an average particle diameter of 50 μm or larger.
7. The polymeric bead of claim 1 , having an average particle diameter of 100 μm or larger.
8. The polymeric bead of claim 1 , having an average particle diameter of 200 μm or larger.
9. The polymeric bead of claim 1 , having an average particle diameter of 400 μm or larger.
10. The polymeric bead of claim 1 , having an average particle diameter ranging from 50 μm to 1,500 μm.
11. The polymeric bead of claim 1 , having an average particle diameter ranging from 100 μm to 1,000 μm.
12. The polymeric bead of claim 1 , having an average particle diameter ranging from 200 μm to 1,000 μm.
13. The polymeric bead of claim 1 , having an average particle diameter ranging from 400 μm to 1,000 μm.
14. The polymeric bead of claim 1 , wherein the monofunctional vinyl monomers comprise styrene.
15. The polymeric bead of claim 1 , wherein the multifunctional vinyl monomers comprise divinylbenzene.
16. The polymeric bead of claim 1 , wherein the monofunctional vinyl monomers comprise styrene and the multifunctional vinyl monomers comprise divinylbenzene.